I have a rough list of topics for future articles, a scratchpad of two-word ideas that I sometimes struggle to interpret. Some items have been on that list for years now. Sometimes, ideas languish because I'm not really interested in them enough to devote the time. Others have the opposite problem: chapters of communications history with which I'm so fascinated that I can't decide where to start and end. They seem almost too big to take on. One of these stories starts in another vast frontier: northeastern Canada. It was a time, rather unlike our own, of relative unity between Canada and the United States. Both countries had spent the later part of World War II planning around the possibility of an Axis attack on North America, and a ragtag set of radar stations had been built to detect inbound bombers. The US had built a series of stations along the border, and the Canadians had built a few north of Ontario and Quebec to extend coverage north of those population centers. Then the war ended and, as with so many WWII projects, construction stopped. Just a few years later, the USSR demonstrated a nuclear weapon and the Cold War was on. As with so many WWII projects, freshly anxious planners declared the post-war over and blew the dust off of North American air defense plans. In 1950, US and Canadian defense leaders developed a new plan to consolidate and improve the scattershot radar early warning plan. This agreement would become the Pinetree Line, the first of three trans-Canadian radar fences jointly constructed and operated by the two nations. For the duration of the Cold War, and even to the present day, these radar installations formed the backbone of North American early warning and the locus of extensive military cooperation. The joint defense agreement between the US and Canada, solidified by the Manhattan Project's dependence on Canadian nuclear industry, grew into the 1968 establishment of the North American Air Defense Command (NORAD) as a binational joint military organization. This joint effort had to rise to many challenges. Radar had earned its place as a revolutionary military technology during the Second World War, but despite the many radar systems that had been fielded, engineer's theoretical understanding of radar and RF propagation were pretty weak. I have written here before about over-the-horizon radar, the pursuit of which significantly improved our scientific understanding of radio propagation in the atmosphere... often by experiment, rather than model. A similar progression in RF physics would also benefit radar early warning in another way: communications. One of the bigger problems with the Pinetree Line plan was the remote location of the stations. You might find that surprising; the later Mid-Canada and DEW lines were much further north and more remote. The Pinetree Line already involved stations in the far reaches of the maritime provinces, though, and to provide suitable warning to Quebec and the Great Lakes region stations were built well north of the population centers. Construction and operations would rely on aviation, but an important part of an early warning system is the ability to deliver the warning. Besides, ground-controlled interception had become the main doctrine in air defense, and it required not just an alert but real-time updates from radar stations for the most effective response. Each site on the Pinetree Line would require a reliable real-time communications capability, and as the sites were built in the 1950s, some were a very long distance from telephone lines. Canada had only gained a transcontinental telephone line in 1932, seventeen years behind the United States (which by then had three different transcontinental routes and a fourth in progress), a delay owing mostly to the formidable obstacle of the Canadian Rockies. The leaders in Canadian long-distance communications were Bell Canada and the two railways (Canadian Pacific and Canadian National), and in many cases contracts had been let to these companies to extend telephone service to radar stations. The service was very expensive, though, and the construction of telephone cables in the maritimes was effectively ruled out due to the huge distances involved and uncertainty around the technical feasibility of underwater cables to Newfoundland due to the difficult conditions and extreme tides in the Gulf of St. Lawrence. The RCAF had faced a similar problem when constructing its piecemeal radar stations in Ontario and Quebec in the 1940s, and had addressed them by applying the nascent technology of point-to-point microwave relays. This system, called ADCOM, was built and owned by RCAF to stretch 1,400 miles between a series of radar stations and other military installations. It worked, but the construction project had run far over budget (and major upgrades performed soon after blew the budget even further), and the Canadian telecom industry had vocally opposed it on the principle that purpose-built military communications systems took government investment away from public telephone infrastructure that could also serve non-military needs. These pros and cons of ADCOM must have weighed on Pinetree Line planners when they chose to build a system directly based on ADCOM, but to contract its construction and operation to Bell Canada [1]. This was, it turned out, the sort of compromise that made no one happy: the Canadian military's communications research establishment was reluctant to cede its technology to Bell Canada, while Bell Canada objected to deploying the military's system rather than one of the commercial technologies then in use across the Bell System. The distinct lack of enthusiasm on the part of both parties involved was a bad omen for the future of this Pinetree Line communications system, but as it would happen, the whole plan was overcome by events. One of the great struggles of large communications projects in that era, and even today, is the rapid rate of technological progress. One of ADCOM's faults was that the immense progress Bell Labs and Western Electric made in microwave equipment during the late '40s meant that it was obsolete as soon as it went into service. This mistake would not be repeated, as ADCOM's maritimes successor was obsoleted before it even broke ground. A promising new radio technology offered a much lower cost solution to these long, remote spans. At the onset of the Second World War, the accepted theory of radio propagation held that HF signals could pass the horizon via ground wave propagation, curving to follow the surface of the Earth, while VHF and UHF signals could not. This meant that the higher-frequency bands, where wideband signals were feasible, were limited to line-of-sight or at least near-line-of-sight links... not more than 50 miles with ideal terrain, often less. We can forgive the misconception, because this still holds true today, as a rule of thumb. The catch is in the exceptions, the nuances, that during the war were already becoming a headache to RF engineers. First, military radar operators observed mysterious contacts well beyond the theoretical line-of-sight range of their VHF radar sets. These might have been dismissed as faults in the equipment (or the operator), but reports stacked up as more long-range radar systems were fielded. After the war, relaxed restrictions and a booming economy allowed radio to proliferate. UHF television stations, separated by hundreds of miles, unexpectedly interfered with each other. AT&T, well into deployment of a transcontinental microwave network, had to adjust its frequency planning after it was found that microwave stations sometimes received interfering signals from other stations in the chain... stations well over the horizon. This was the accidental discovery of tropospheric scattering. The Earth's atmosphere is divided into five layers. We live in the troposhere, the lowest and thinnest of the layers, above which lies the stratosphere. Roughly speaking, the difference between these layers is that the troposphere becomes colder with height (due to increasing distance from the warm surface), while the stratosphere becomes warmer with height (due to decreasing shielding from the sun) [2]. In between is a local minimum of temperature, called the tropopause. The density gradients around the tropopause create a mirror effect, like the reflections you see when looking at an air-water boundary. The extensive turbulence and, well, weather present in the troposhere also refract signals on their way up and down, making the true course of radio signals reflecting off of the tropopause difficult to predict or analyze. Because of this turbulence, the effect has come to be known as scattering: radio signals sent upwards, towards the troposphere, will be scattered back downwards across a wide area. This effect is noticeable only at high frequencies, so it remained unknown until the widespread use of UHF and microwave, and was still only partially understood in the early 1950s. The locii of radar technology at the time were Bell Laboratories and the MIT Lincoln Laboratory, and they both studied this effect for possible applications. Presaging one of the repeated problems of early warning radar systems, by the time Pinetree Line construction began in 1951 the Lincoln Laboratory was already writing proposals for systems that would obsolete it. In fact, construction would begin on both of the Pinetree Line's northern replacements before the Pinetree Line itself was completed. Between rapid technological development and military planners in a sort of panic mode, the early 1950s were a very chaotic time. Underscoring the ever-changing nature of early warning was the timeline of Pinetree Line communications: as the Pinetree Line microwave network was in planning, the Lincoln Laboratory was experimenting with troposcatter communications. By the time the first stations in Newfoundland completed construction, Bell Laboratories had developed an experimental troposcatter communications system. This new means of long-range communications would not be ready in time for the first Pinetree Line stations, so parts of the original ADCOM-based microwave network would have to be built. Still, troposcatter promised to complete the rest of the network at significantly reduced cost. The US Air Force, wary of ADCOM's high costs and more detached from Canadian military politics, aggressively lobbied for the adoption of troposcatter communications for the longest and most challenging Pinetree Line links. Bell Laboratories, long a close collaborator with the Air Force, was well aware of troposcatter's potential for early warning radar. Bell Canada and Bell Laboratories agreed to evaluate the system under field conditions, and in 1952 experimental sites were installed in Newfoundland. These tests found reliable performance over 150 miles, far longer than achievable by microwave and---rather conveniently---about the distance between Pinetree Line radar stations. These results suggested that the Pinetree Line could go without an expensive communications network in the traditional sense, instead using troposcatter to link the radar stations directly to each other. Consider a comparison laid out by the Air Force: one of the most complex communications requirements for the Pinetree Line was a string of stations running not east-west like the "main" line, but north-south from St. John's, Newfoundland to Frobisher Bay, Nunavut. These stations were critical for detection of Soviet bombers approaching over the pole from the northwest, otherwise a difficult gap in radar coverage until the introduction of radar sites in Greenland. But the stations covered a span of over 1,000 miles, most of it in formidably rugged and remote arctic coastal terrain. The proposed microwave system would require 50 relay stations, almost all of which would be completely new construction. Each relay's construction would have to be preceded by the construction of a harbor or airfield for access, and then establishment of a power plant, to say nothing of the ongoing logistics of transporting fuel and personnel for maintenance. The proposed troposcatter system, on the other hand, required only ten relays. All ten would be colocated with radar stations, and could share infrastructure and logistical considerations. Despite the clear advantages of troposcatter and its selection by the USAF, the Canadian establishment remained skeptical. One cannot entirely blame them, considering that troposcatter communications had only just been demonstrated in the last year. Still, the USAF was footing most of the bill for the overall system (and paying entirely for the communications aspect, depending on how you break down the accounting) and had considerable sway. In 1954, well into construction of the radar stations (several had already been commissioned), the Bell Canada contract for communications was amended to add troposcatter relay in addition to the original microwave scheme. Despite the weaselly contracting, the writing was on the wall and progress on microwave relay stations almost stopped. By the latter part of 1954, the microwave network was abandoned entirely. Bell Canada moved at incredible speed to complete the world's first troposcatter long-distance route, code named Pole Vault. One the major downsides of troposcatter communications is its inefficiency. Only a very small portion of the RF energy reaching the tropopause is reflected, and of that, only a small portion is reflected in the right direction. Path loss from transmitter to receiver for long links is over -200 dB, compared to say -130 dB for a microwave link. That difference looks smaller than it is; dB is a logarithmic comparison and the decrease from -130 dB to -200 dB is a factor of ten million. The solution is to go big. Pole Vault's antennas, manufactured as a rush order by D. S. Kennedy Co. of Massachusetts. 36 were required, generally four per site for transmit and receive in each direction. Each antenna was a 60' aluminum parabolic dish held up on edge by truss legs. Because of the extreme weather at the coastal radar sites, the antennas were specified to operate in a 120 knot wind---or a 100 knot wind with an inch of ice buildup. These were operating requirements, so the antenna had not only to survive these winds, but to keep flexing and movements small enough to not adversely impact performance. The design of the antennas was not trivial; even after analysis by both Kennedy Co. and Bell Canada, after installation some of the rear struts supporting the antennas buckled. All high-wind locations received redesigned struts. To drive the antennas, Radio Engineering Laboratories of Long Island furnished radio sets with 10 kW of transmit power. Both of these were established companies, especially for military systems, but were still small compared to Bell System juggernauts like Western Electric. They had built the equipment for the experimental sites, though, and the timeline for construction of Pole Vault was so short that planners did not feel there was time to contract larger manufacturers. This turn of events made Kennedy Co. and REL the leading experts in troposcatter equipment, which became their key business in the following decade. The target of the contract, signed in January of 1954, was to have Pole Vault operational by the end of that same year. Winter conditions, and indeed spring and fall conditions, are not conducive to construction on the arctic coast. All of the equipment for Pole Vault had to be manufactured in the first half of the year, and as weather improved and ice cleared in the mid-summer, everything was shipped north and installation work began. Both militaries had turned down involvement in the complex and time-consuming logistics of the project, so Bell Canada chartered ships and aircraft and managed an incredibly complex schedule. To deliver equipment to sites as early as possible, icebreaker CCGS D'Iberville was chartered. C-119 and DC3 aircraft served alongside numerous small boats and airplanes. All told, it took about seven months to manufacture and deliver equipment to the Pole Vault sites, and six months to complete construction. Construction workers, representing four or five different contractors at each site and reaching about 120 workers to a site during peak activity, had to live in construction camps that could still be located miles from the station. Grounded ships, fires, frostbite, and of course poor morale lead to complications and delays. At one site, Saglek, project engineers recorded a full 24-hour day with winds continuously above 75 miles per hour, and then weeks later, a gust of 135 mph was observed. Repairs had to be made to the antennas and buildings before they were even completed. In a remarkable feat of engineering and construction, the Pole Vault system was completed and commissioned more or less on schedule: amended into the contract in January of 1954, commissioning tests of the six initial stations were successfully completed February of 1955. Four additional stations were built to complete the chain, and Pole Vault was declared fully operational December of 1956 at a cost of $24.6 million (about $290 million today). Pole Vault operated at various frequencies between 650 and 800 MHz, the wide range allowing for minimal frequency reuse---interference was fairly severe, since each station's signal scattered and could be received by stations further down the line in ideal (or as the case may be, less than ideal) conditions. Frequency division multiplexing equipment, produced by Northern Electric (Nortel) based on microwave carrier systems, offered up to 36 analog voice circuits. The carrier systems were modular, and some links initially supported only 12 circuits, while later operational requirements lead to an upgrade to 70 circuits. Over the following decades, the North Atlantic remained a critical challenge for North American air defense. It also became the primary communications barrier between the US and Canada and European NATO allies. Because Pole Vault provided connections across such a difficult span, several later military communications systems relied on Pole Vault as a backhaul connection. An inventory of the Saglek site, typical of the system, gives an idea of the scope of each of the nine primary stations. This is taken from "Special Contract," a history by former Bell Canada engineer A. G. Lester: (1) Four parabolic antennas, 60 feet in diameter, each mounted on seven mass concrete footings. (2) An equipment building 62 by 32 feet to house electronic equipment, plus a small (10 by 10 feet) diversity building. (3) A diesel building 54 by 36 feet, to house three 125 KVA (kilovolt amperes) diesel driven generators. (4) Two 2500 gallon fuel storage tanks. (5) Raceways to carry waveguide and cables. (6) Enclosed corridors interconnecting buildings, total length in this case 520 feet. Since the Pole Vault stations were colocated with radar facilities, barracks and other support facilities for the crews were already provided for. Of course, you can imagine that the overall construction effort at each site was much larger, including the radar systems as well as cantonment for personnel. Pole Vault would become a key communications system in the maritime provinces, remaining in service until 1975. Its reliable performance in such a challenging environment was a powerful proof of concept for troposcatter, a communications technique first imagined only a handful of years earlier. Even as Pole Vault reached its full operating capability in late 1956, other troposcatter systems were under construction. Much the same, and not unrelated, other radar early warning systems were under construction as well. The Pinetree Line, for all of its historical interest and its many firsts, ended as a footnote in the history of North American air defense. More sophisticated radar fences were already under design by the time Pinetree Line construction started, leaving some Pinetree stations to operate for just four years. It is a testament to Pole Vault that it outlived much of the radar system it was designed to support, becoming an integral part of not one, or even two, but at least three later radar early warning programs. Moreover, Pole Vault became a template for troposcatter systems elsewhere in Canada, in Europe, and in the United States. But we'll have to talk about those later. [1] Alexander Graham Bell was Scottish-Canadian-American, and lived for some time in rural Ontario and later Montreal. As a result, Bell Canada is barely younger than its counterpart in the United States and the early history of the two is more one of parallel development than the establishment of a foreign subsidiary. Bell's personal habit of traveling back and forth between Montreal and Boston makes the early interplay of the two companies a bit confusing. In 1955, the TAT-1 telephone cable would conquer the Atlantic ocean to link the US to Scotland via Canada, incidentally making a charming gesture to Bell's personal journey. [2] If you have studied weather a bit, you might recognize these as positive and negative lapse rates. The positive lapse rate in the troposphere is a major driver in the various phenomenon we call "weather," and the tropopause forms a natural boundary that keeps most weather within the troposphere.

I have been slowly working on a book. Don't get too excited, it is on a very niche topic and I will probably eventually barely finish it and then post it here. But in the mean time, I will recount some stories which are related, but don't quite fit in. Today, we'll learn a bit about the self-illumination industry. At the turn of the 20th century, it was discovered that the newfangled element radium could be combined with a phosphor to create a paint that glowed. This was pretty much as cool as it sounds, and commercial radioluminescent paints like Undark went through periods of mass popularity. The most significant application, though, was in the military: radioluminescent paints were applied first to aircraft instruments and later to watches and gunsights. The low light output of radioluminescent paints had a tactical advantage (being very difficult to see from a distance), while the self-powering nature of radioisotopes made them very reliable. The First World War was thus the "killer app" for radioluminescence. Military demand for self-illuminating devices fed a "radium rush" that built mines, processing plants, and manufacturing operations across the country. It also fed, in a sense much too literal, the tragedy of the "Radium Girls." Several self-luminous dial manufacturers knowingly subjected their women painters to shockingly irresponsible conditions, leading inevitably to radium poisoning that disfigured, debilitated, and ultimately killed. Today, this is a fairly well-known story, a cautionary tale about the nuclear excess and labor exploitation of the 1920s. That the situation persisted into the 1940s is often omitted, perhaps too inconvenient to the narrative that a series of lawsuits, and what was essentially the invention of occupational medicine, headed off the problem in the late 1920s. What did happen after the Radium Girls? What was the fate of the luminous radium industry? A significant lull in military demand after WWI was hard on the radium business, to say nothing of a series of costly settlements to radium painters despite aggressive efforts to avoid liability. At the same time, significant radium reserves were discovered overseas, triggering a price collapse that closed most of the mines. The two largest manufacturers of radium dials, Radium Dial Company (part of Standard Chemical who owned most radium mines) and US Radium Corporation (USRC), both went through lean times. Fortunately, for them, the advent of the Second World War reignited demand for radioluminescence. The story of Radium Dial and USRC doesn't end in the 1920s---of course it doesn't, luminous paints having had a major 1970s second wind. Both companies survived, in various forms, into the current century. In this article, I will focus on the post-WWII story of radioactive self-illumination and the legacy that we live with today. During its 1920s financial difficulties, the USRC closed the Orange, New Jersey plant famously associated with Radium Girls and opened a new facility in Brooklyn. In 1948, perhaps looking to manage expenses during yet another post-war slump, USRC relocated again to Bloomsburg, Pennsylvania. The Bloomsburg facility, originally a toy factory, operated through a series of generational shifts in self-illuminating technology. The use of radium, with some occasional polonium, for radioluminescence declined in the 1950s and ended entirely in the 1970s. The alpha radiation emitted by those elements is very effective in exciting phosphors but so energetic that it damages them. A longer overall lifespan, and somewhat better safety properties, could be obtained by the use of a beta emitter like strontium or tritium. While strontium was widely used in military applications, civilian products shifted towards tritium, which offered an attractive balance of price and half life. USRC handled almost a dozen radioisotopes in Bloomsburg, much of them due to diversified operations during the 1950s that included calibration sources, ionizers, and luminous products built to various specific military requirements. The construction of a metal plating plant enabled further diversification, including foil sources used in research, but eventually became an opportunity for vertical integration. By 1968, USRC had consolidated to only tritium products, with an emphasis on clocks and watches. Radioluminescent clocks were a huge hit, in part because of their practicality, but fashion was definitely a factor. Millions of radioluminescent clocks were sold during the '60s and '70s, many of them by Westclox. Westclox started out as a typical clock company (the United Clock Company in 1885), but joined the atomic age through a long-lived partnership with the Radium Dial Company. The two companies were so close that they became physically so: Radium Dial's occupational health tragedy played out in Ottawa, Illinois, a town Radium Dial had chosen as its headquarters due to its proximity to Westclox in nearby Peru [1]. Westclox sold clocks with radioluminescent dials from the 1920s to probably the 1970s, but one of the interesting things about this corner of atomic history is just how poorly documented it is. Westclox may have switched from radium to tritium at some point, and definitely abandoned radioisotopes entirely at some point. Clock and watch collectors, a rather avid bunch, struggle to tell when. Many consumer radioisotopes are like this: it's surprisingly hard to know if they even are radioactive. Now, the Radium Dial Company itself folded entirely to a series of radium poisoning lawsuits in the 1930s. Simply being found guilty of one of the most malevolent labor abuses of the era would not stop free enterprise, though, and Radium Dial's president founded a legally distinct company called Luminous Processes just down the street. Luminous Processes is particularly notable for having continued the production of radium-based clock faces until 1978, making them the last manufacturer of commercial radioluminescent radium products. This also presents compelling circumstantial evidence that Westclox continued to use radium paint until sometime around 1978, which lines up with the general impressions of luminous dial collectors. While the late '70s were the end of Radium Dial, USRC was just beginning its corporate transformation. From 1980 to 1982, a confusing series of spinoffs and mergers lead to USR Industries, parent company of Metreal, parent company of Safety Light Corporation, which manufactured products to be marketed and distributed by Isolite. All of these companies were ultimately part of USR Industries, the former USRC, but the org chart sure did get more complex. The Nuclear Regulatory Commission expressed some irritation in their observation, decades later, that they weren't told about any of this restructuring until they noticed it on their own. Safety Light, as expressed by the name, focused on a new application for tritium radioluminescence: safety signage, mostly self-powered illuminated exit signs and evacuation signage for aircraft. Safety Light continued to manufacture tritium exit signs until 2007, when they shut down following some tough interactions with the NRC and the EPA. They had been, in the fashion typical of early nuclear industry, disposing of their waste by putting it in a hole in the ground. They had persisted in doing this much longer than was socially acceptable, and ultimately seem to have been bankrupted by their environmental obligations... obligations which then had to be assumed by the Superfund program. The specific form of illumination used in these exit signs, and by far the most common type of radioluminescence today, is the Gaseous Tritium Light Source or GTLS. GTLS are small glass tubes or vials, usually made with borosilicate glass, containing tritium gas and an internal coating of phosphor. GTLS are simple, robust, and due to the very small amount of tritium required, fairly inexpensive. They can be made large enough to illuminate a letter in an exit sign, or small enough to be embedded into a watch hand. Major applications include watch faces, gun sights, and the keychains of "EDC" enthusiasts. Plenty of GTLS manufacturers have come and gone over the years. In the UK, defense contractor Saunders-Roe got into the GTLS business during WWII. Their GTLS product line moved to Brandhurst Inc., which had a major American subsidiary. It is an interesting observation that the US always seems to have been the biggest market for GTLS, but their manufacture has increasingly shifted overseas. Brandhurst is no longer even British, having gone the way of so much of the nuclear world by becoming Canadian. A merger with Canadian company SRB created SRB Technologies in Pembroke, Ontario, which continues to manufacture GTLS today. Other Canadian GTLS manufacturers have not fared as well. Shield Source Inc., of Peterborough, Ontario, began filling GTLS vials in 1987. I can't find a whole lot of information on Shield Source's early days, but they seem to have mostly made tubes for exit signs, and perhaps some other self-powered signage. In 2012, the Canadian Nuclear Safety Commission (CNSC) detected a discrepancy in Shield Source's tritium emissions monitoring. I am not sure of the exact details, because CNSC seems to make less information public in general than the US NRC [2]. Here's what appears to have happened: tritium is a gas, which makes it tricky to safely handle. Fortunately, the activity of tritium is relatively low and its half life is relatively short. This means that it's acceptable to manage everyday leakage (for example when connecting and disconnecting things) in a tritium workspace by ventilating it to a stack, releasing it to the atmosphere for dilution and decay. The license of a tritium facility will specify a limit for how much radioactivity can be released this way, and monitoring systems (usually several layers of monitoring systems) have to be used to ensure that the permit limit is not exceeded. In the case of Shield Source, some kind of configuration error with the tritium ventilation monitoring system combined with a failure to adequately test and audit it. The CNSC discovered that during 2010 and 2011, the facility had undercounted their tritium emissions, and in fact exceeded the limits of their license. Air samplers located around the facility, some of which were also validated by an independent laboratory, did not detect tritium in excess of the environmental limits. This suggests that the excess releases probably did not have an adverse impact on human health or the environment. Still, exceeding license terms and then failing to report and correct the problem for two years is a very serious failure by a licensee. In 2012, when the problem was discovered, CNSC ordered Shield Source's license modified to prohibit actual tritium handling. This can seem like an odd maneuver but something similar can happen in the US. Just having radioisotope-contaminated equipment, storing test sources, and managing radioactive waste requires a license. By modifying Shield Source's license to prohibit tritium vial filling, the CNSC effectively shut the plant down while allowing Shield Source to continue their radiological protection and waste management functions. This is the same reason that long-defunct radiological facilities often still hold licenses from NRC in the US: they retain the licenses to allow them to store and process waste and contaminated materials during decommissioning. In the case of Shield Source, while the violation was serious, CNSC does not seem to have anticipated a permanent shutdown. The terms agreed in 2012 were that Shield Source could regain a license to manufacture GTLS if it produced for CNSC a satisfactory report on the root cause of the failure and actions taken to prevent a recurrence. Shield Source did produce such a report, and CNSC seems to have mostly accepted it with some comments requesting further work (the actual report does not appear to be public). Still, in early 2013, Shield Source informed CNSC that it did not intend to resume manufacturing. The license was converted to a one-year license to facilitate decommissioning. Tritium filling and ventilation equipment, which had been contaminated by long-term exposure to tritium, was "packaged" and disposed. This typically consists of breaking things down into parts small enough to fit into 55-gallon drums, "overpacking" those drums into 65-gallon drums for extra protection, and then coordinating with transportation authorities to ship the materials in a suitable way to a facility licensed to dispose of them. This is mostly done by burying them in the ground in an area where the geology makes groundwater interaction exceedingly unlikely, like a certain landfill on the Texas-New Mexico border near Eunice. Keep in mind that tritium's short half life means this is not a long-term geological repository situation; the waste needs to be safely contained for only, say, fifty years to get down to levels not much different from background. I don't know where the Shield Source waste went, CNSC only says it went to a licensed facility. Once the contaminated equipment was removed, drywall and ceiling and floor finishes were removed in the tritium handling area and everything left was thoroughly cleaned. A survey confirmed that remaining tritium contamination was below CNSC-determined limits (for example, in-air concentrations that would lead to a dose of less than 0.01 mSv/year for 9-5 occupational exposure). At that point, the Shield Source building was released to the landlord they had leased it from, presumably to be occupied by some other company. Fortunately tritium cleanup isn't all that complex. You might wonder why Shield Source abruptly closed down. I assume there was some back-and-forth with CNSC before they decided to throw in the towel, but it is kind of odd that they folded entirely during the response to an incident that CNSC seems to have fully expected them to survive. I suspect that a full year of lost revenue was just too much for Shield Source: by 2012, when all of this was playing out, the radioluminescence market had seriously declined. There are a lot of reasons. For one, the regulatory approach to tritium has become more and more strict over time. Radium is entirely prohibited in consumer goods, and the limit on tritium activity is very low. Even self-illuminating exit signs now require NRC oversight in the US, discussed shortly. Besides, public sentiment has increasingly turned against the Friendly Atom is consumer contexts, and you can imagine that people are especially sensitive to the use of tritium in classic institutional contexts for self-powered exit signs: schools and healthcare facilities. At the same time, alternatives have emerged. Non-radioactive luminescent materials, the kinds of things we tend to call "glow in the dark," have greatly improved since WWII. Strontium aluminate is a typical choice today---the inclusion of strontium might suggest otherwise, but strontium aluminate uses the stable natural isotope of strontium, Sr-88, and is not radioactive. Strontium aluminate has mostly displaced radioluminescence in safety applications, and for example the FAA has long allowed it for safety signage and path illumination on aircraft. Keep in mind that these luminescent materials are not self-powered. They must be "charged" by exposure to light. Minor adaptations are required, for example a requirement that the cabin lights in airliners be turned on for a certain period of time before takeoff, but in practice these limitations are considered preferable to the complexity and risks involved in the use of radioisotopes. You are probably already thinking that improving electronics have also made radioluminescence less relevant. Compact, cool-running, energy-efficient LEDs and a wide variety of packages and form factors mean that a lot of traditional applications of radioluminescence are now simply electric. Here's just a small example: in the early days of LCD digital watches, it was not unusual for higher-end models to use a radioluminescent source as a backlight. Today that's just nonsensical, a digital watch needs a power source anyway and in even the cheapest Casios a single LED offers a reasonable alternative. Radioluminescent digital watches were very short lived. Now that we've learned about a few historic radioluminescent manufacturers, you might have a couple of questions. Where were the radioisotopes actually sourced? And why does Ontario come up twice? These are related. From the 1910s to the 1950s, radioluminescent products were mostly using radium sourced from Standard Chemical, who extracted it from mines in the Southwest. The domestic radium mining industry collapsed by 1955 due to a combination of factors: declining demand after WWII, cheaper radium imported from Brazil, and a broadly changing attitude towards radium that lead the NRC to note in the '90s that we might never again find the need to extract radium: radium has a very long half life that makes it considerably more difficult to manage than strontium or tritium. Today, you could say that the price of radium has gone negative, in that you are far more likely to pay an environmental management company to take it away (at rather high prices) than to buy more. But what about tritium? Tritium is not really naturally occurring; there technically is some natural tritium but it's at extremely low concentrations and very hard to get at. But, as it happens, irradiating water produces a bit of tritium, and nuclear reactors incidentally irradiate a lot of water. With suitable modifications, the tritium produced as a byproduct of civilian reactors can be concentrated and sold. Ontario Hydro has long had facilities to perform this extraction, and recently built a new plant at the Darlington Nuclear Station that processes heavy water shipped from CANDU reactors throughout Ontario. The primary purpose of this plant is to reduce environmental exposure from the release of "tritiated" heavy water; it produces more tritium than can reasonably be sold, so much of it is stored for decay. The result is that tritium is fairly abundant and cheap in Ontario. Besides SRB Technologies which packages tritium from Ontario Hydro into GTLS, another major manufacturer of GTLS is the Swiss company mb-microtec. mb-microtec is the parent of watch brand Traser and GTLS brand Trigalight, and seem to be one of the largest sources of consumer GTLS overall. Many of the tritium keychains you can buy, for example, use tritium vials manufactured by mb-microtec. NRC documents suggest that mb-microtec contracts a lot of their finished product manufacturing to a company in Hong Kong and that some of the finished products you see using their GTLS (like watches and fobs) are in fact white-labeled from that plant, but unfortunately don't make the original source of the tritium clear. mb-microtec has the distinction of operating the only recycling plant for tritium gas, and press releases surrounding the new recycling operation say they purchase the rest of their tritium supply. I assume from the civilian nuclear power industry in Switzerland, which has several major reactors operating. A number of other manufacturers produce GTLS primarily for military applications, with some safety signage side business. And then there is, of course, the nuclear weapons program, which consumes the largest volume of tritium in the US. The US's tritium production facility for much of the Cold War actually shut down in 1988, one of the factors in most GTLS manufacturers being overseas. In the interim period, the sole domestic tritium supply was recycling of tritium in dismantled weapons and other surplus equipment. Since tritium has such a short half-life, this situation cannot persist indefinitely, and tritium production was resumed in 2004 at the Tennessee Valley Authority's Watts Bar nuclear generating station. Tritium extracted from that plant is currently used solely by the Department of Energy, primarily for the weapons program. Finally, let's discuss the modern state of radioluminescence. GTLS, based on tritium, are the only type of radioluminescence available to consumers. All importation and distribution of GTLS requires an NRC license, although companies that only distribute products that have been manufactured and tested by another licensee fall under a license exemption category that still requires NRC reporting but greatly simplifies the process. Consumers that purchase these items have no obligations to the NRC. Major categories of devices under these rules include smoke detectors, detection instruments and small calibration sources, and self-luminous products using tritium, krypton, or promethium. You might wonder, "how big of a device can a I buy under these rules?" The answer to that question is a bit complicated, so let me explain my understanding of the rules using a specific example. Let's say you buy a GTLS keychain from massdrop or wherever people get EDC baubles these days [3]. The business you ordered it from almost certainly did not make it, and is acting as an NRC exempt distributor of a product. In NRC terms, your purchase of the product is not the "initial sale or distribution," that already happened when the company you got it from ordered it from their supplier. Their supplier, or possibly someone further up in the chain, does need to hold a license: an NRC specific license is required to manufacture, process, produce, or initially transfer or sell tritium products. This is the reason that overseas companies like SRB and mb-microtec hold NRC licenses; this is the only way for consumers to legally receive their products. It is important to note the word "specific" in "NRC specific license." These licenses are very specific; the NRC approves each individual product including the design of the containment and and labeling. When a license is issued, the individual products are added to a registry maintained by the NRC. When evaluating license applications, the NRC considers a set of safety objectives rather than specific criteria. For example, and if you want to read along we're in 10 CFR 32.23: In normal use and disposal of a single exempt unit, it is unlikely that the external radiation dose in any one year, or the dose commitment resulting from the intake of radioactive material in any one year, to a suitable sample of the group of individuals expected to be most highly exposed to radiation or radioactive material from the product will exceed the dose to the appropriate organ as specified in Column I of the table in § 32.24 of this part. So the rules are a bit soft, in that a licensee can argue back and forth with the NRC over means of calculating dose risk and so on. It is, ultimately, the NRC's discretion as to whether or not a device complies. It's surprisingly hard to track down original licensing paperwork for these products because of how frequently they are rebranded, and resellers never seem to provide detailed specifications. I suspect this is intentional, as I've found some cases of NRC applications that request trade secret confidentiality on details. Still, from the license paperwork I've found with hard numbers, it seems like manufacturers keep the total activity of GTLS products (e.g. a single GTLS sold alone, or the total of the GTLS in a watch) under 25 millicurie. There do exist larger devices, of which exit signs are the largest category. Self-powered exit signs are also manufactured under NRC specific licenses, but their activity and resulting risk is too high to qualify for exemption at the distribution and use stage. Instead, all users of self-powered safety signs do so under a general license issued by the NRC (a general license meaning that it is implicitly issued to all such users). The general license is found in 10 CFR 31. Owners of tritium exit signs are required to designate a person to track and maintain the signs, inform the NRC of that person's contact information and any changes in that person, to inform the NRC of any lost, stolen, or damaged signs. General licensees are not allowed to sell or otherwise transfer tritium signs, unless they are remaining in the same location (e.g. when a building is sold), in which case they must notify the NRC and disclose NRC requirements to the transferee. When tritium exit signs reach the end of their lifespan, they must be disposed of by transfer to an NRC license holder who can recycle them. The general licensee has to notify the NRC of that transfer. Overall, the intent of the general license regulations is to ensure that they are properly disposed of: reporting transfers and events to the NRC, along with serial numbers, allows the NRC to audit for signs that have "disappeared." Missing tritium exit signs are a common source of NRC event reports. It should also be said that, partly for these reasons, tritium exit signs are pretty expensive. Roughly $300 for a new one, and $150 to dispose of an old one. Other radioluminescent devices you will find are mostly antiques. Radium dials are reasonably common, anything with a luminescent dial made before, say, 1960 is probably radium, and specifically Westclox products to 1978 likely use radium. The half-life of radium-226 is 1,600 years, so these radium dials have the distinction of often still working, although the paints have usually held up more poorly than the isotopes they contain. These items should be handled with caution, since the failure of the paint creates the possibility of inhaling or ingesting radium. They also emit radon as a decay product, which becomes hazardous in confined spaces, so radium dials should be stored in a well-ventilated environment. Strontium-90 has a half-life of 29 years, and tritium 12 years, so vintage radioluminescent products using either have usually decayed to the extent that they no longer shine brightly or even at all. The phosphors used for these products will usually still fluoresce brightly under UV light and might even photoluminesce for a time after light exposure, but they will no longer stay lit in a dark environment. Fortunately, the decay that makes them not work also makes them much safer to handle. Tritium decays to helium-3 which is quite safe, strontium-90 to yttrium-90 which quickly decays to zirconium-90. Zirconium-90 is stable and only about as toxic as any other heavy metal. You can see why these radioisotopes are now much preferred over radium. And that's the modern story of radioluminescence. Sometime soon, probably tomorrow, I will be sending out my supporter's newsletter, EYES ONLY, with some more detail on environmental remediation at historic processing facilities for radioluminescent products. You can learn a bit more about how US Radium was putting their waste in a hole in the ground, and also into a river, and sort of wherever else. You know Radium Dial Company was up to similar abuses. [1] The assertion that Ottawa is conveniently close to Peru is one of those oddities of naming places after bigger, more famous places. [2] CNSC's whole final report on Shield Source is only 25 pages. A similar decommissioning process in the US would produce thousands of pages of public record typically culminating in EPA Five Year Reviews which would be, themselves, perhaps a hundred pages depending on the amount of post-closure monitoring. I'm not familiar with the actual law but it seems like most of the difference is that CNSC does not normally publish technical documentation or original data (although one document does suggest that original data is available on request). It's an interesting difference... the 25-page report, really only 20 pages after front matter, is a lot more approachable for the public than a 400 page set of close-out reports. Much of the standard documentation in the US comes from NEPA requirements, and NEPA is infamous in some circles for requiring exhaustive reports that don't necessarily do anything useful. But from my perspective it is weird for the formal, published documentation on closure of a radiological site to not include hydrology discussion, demographics, maps, and fifty pages of data tables as appendices. Ideally a bunch of one-sentence acceptance emails stapled to the end for good measure. When it comes to describing the actual problem, CNSC only gives you a couple of paragraphs of background. [3] Really channeling Guy Debord with my contempt for keychains here. during the writing of this article, I bought myself a tritium EDC bauble, so we're all in the mud together.

Recently, I covered some of the history of Ethernet's tenuous relationship with installed telephone cabling. That article focused on the earlier and more business-oriented products, but many of you probably know that there have been a number of efforts to install IP networking over installed telephone wiring in a residential and SOHO environment. There is a broader category of "computer networking over things you already have in your house," and some products remain pretty popular today, although seemingly less so in the US than in Europe. The grandparent of these products is probably PhoneNet, a fairly popular product introduced by Farallon in the mid-'80s. At the time, local area networking for microcomputers was far from settled. Just about every vendor had their own proprietary solution, although many of them had shared heritage and resulting similarities. Apple Computer was struggling with the situation just like everyone; in 1983 they introduced an XNS-based network stack for the Lisa called AppleNet and then almost immediately gave up on it [1]. Steve Jobs made the call to adopt IBM's token ring instead, which would have seemed like a pretty safe bet at the time because of IBM's general prominence in the computing industry. Besides, Apple was enjoying a period of warming relations with IBM, part of the 1980s-1990s pattern of Apple and Microsoft alternately courting IBM as their gateway into business computing. The vision of token ring as the Apple network standard died the way a lot of token ring visions did, to the late delivery and high cost of IBM's design. While Apple was waiting around for token ring to materialize, they sort of stumbled into their own LAN suite, AppleTalk [2]. AppleTalk was basically an expansion of the unusually sophisticated peripheral interconnect used by the Macintosh to longer cable runs. Apple put a lot of software work into it, creating a pretty impressive zero-configuration experience that did a lot to popularize the idea of LANs outside of organizations large enough to have dedicated network administrators. The hardware was a little more, well, weird. In true Apple fashion, AppleTalk launched with a requirement for weird proprietary cables. To be fair, one of the reasons for the system's enduring popularity was its low cost compared to Ethernet or token ring. They weren't price gouging on the cables the way they might seem to today. Still, they were a decided inconvenience, especially when trying to connect machines across more than one room. One of the great things about AppleTalk, in this context, is that it was very slow. As a result, even though the physical layer was basically RS-422, the electrical requirements for the cabling were pretty relaxed. Apple had already taken advantage of this for cost reduction, using a shared signal ground on the long cables rather than the dedicated differential pairs typical for RS-422. A hobbyist realized that you could push this further, and designed a passive dongle that used telephone wiring as a replacement for Apple's more expensive dongle and cables. He filed a patent and sold it to Farallon, who introduced the product as PhoneNet. PhoneNet was a big hit. It was cheaper than Apple's solution for the same performance, and even better, because AppleTalk was already a bus topology it could be used directly over the existing parallel-wired telephone cabling in a typical house or small office. For a lot of people with heritage in the Apple tradition of computing, it'll be the first LAN they ever used. Larger offices even used it because of the popularity of Macs in certain industries and the simplicity of patching their existing telephone cables for AppleTalk use; in my teenage years I worked in an office suite in downtown Portland that hadn't seen a remodel for a while and still had telephone jacks labeled "PhoneNet" at the desks. PhoneNet had one important limitation compared to the network-over-telephone products that would follow: it could not coexist with telephony. Well, it could, in a sense, and was advertised as such. But PhoneNet signaled within the voice band, so it required dedicated telephone pairs. In a lot of installations, it could use the second telephone line that was often wired but not actually used. Still, it was a bust for a lot of residential installs where only one phone line was fully wired and already in use for phone calls. As we saw in the case of Ethernet, local area networking standards evolved very quickly in the '80s and '90s. IP over Ethernet became by far the dominant standard, so the attention of the industry shifted towards new physical media for Ethernet frames. While 10BASE-T Ethernet operated over category 3 telephone wiring, that was of little benefit in the residential market. Commercial buildings typically had "home run" telephone wiring, in which each office's telephone pair ran directly to a wiring closet. In residential wiring of the era, this method was almost unheard of, and most houses had their telephone jacks wired in parallel along a small number of linear segments (often just one). This created a cabling situation much like coaxial Ethernet, in which each telephone jack was a "drop" along a linear bus. The problem is that coaxial Ethernet relied on several different installation measures to make this linear bus design practical, and home telephone wiring had none of these advantages. Inconsistently spaced drops, side legs, and a lack of termination meant that reflections were a formidable problem. PhoneNet addressed reflections mainly by operating at a very low speed (allowing reflections to "clear out" between symbols), but such low bitrate did not befit the 1990s. A promising solution to the reflection problem came from a system called Tut Systems. Tut's history is unfortunately obscure, but they seem to have been involved in what we would now call "last-mile access technologies" since the 1980s. Tut would later be acquired by Motorola, but not before developing a number of telephone-wiring based IP networks under names like HomeWire and LongWire. A particular focus of Tut was multi-family housing, which will become important later. I'm not even sure when Tut introduced their residential networking product, but it seems like they filed a relevant patent in 1995, so let's say around then. Tut's solution relied on pulse position modulation (PPM), a technique in which data is encoded by the length of the spacing between pulses. The principal advantage of PPM is that it allows a fairly large number of bits to be transmitted per pulse (by using, say, 16 potential pulse positions to encode 4 bits). This allowed reflections to dissipate between pulses, even at relatively high bitrates. Following a bit of inter-corporate negotiation, the Tut solution became an industry standard under the HomePNA consortium: HomePNA 1.0. HomePNA 1.0 could transmit 1Mbps over residential telephone wiring with up to 25 devices. A few years later, HomePNA 1.0 was supplanted by HomePNA 2.0, which replaced PPM with QAM (a more common technique for high data rates over low bandwidth channels today) and in doing so improved to 10Mbps for potentially thousands of devices. I sort of questioned writing an article about all of these weird home networking media, because the end-user experience for most of them is pretty much the same. That makes it kind of boring to look at them one by one, as you'll see later. Fortunately, HomePNA has a property that makes it interesting: despite a lot of the marketing talking more about single-family homes, Tut seems to have envisioned HomePNA mainly as a last-mile solution for multi-family housing. That makes HomePNA a bit different than later offerings, landing in a bit of a gray area between the LAN and the access network. The idea is this: home run wiring is unusual in residential buildings, but in apartment and condo buildings, it is typical for the telephone lines of each unit to terminate in a wiring closet. This yields a sort of hybrid star topology where you have one line to each unit, and multiple jacks in each unit. HomePNA took advantage of this wiring model by offering a product category that is at once bland and rather unusual for this type of media: a hub. HomePNA hubs are readily available, even today in used form, with 16 or 24 HomePNA interfaces. The idea of a hub can be a little confusing for a shared-bus media like HomePNA, but each interface on these hubs is a completely independent HomePNA network. In an apartment building, you could connect one interface to the telephone line of each apartment, and thus offer high-speed (for the time) internet to each of your tenants using existing infrastructure. A 100Mbps Ethernet port on the hub then connected to whatever upstream access you had available. The use of the term "hub" is a little confusing, and I do believe that at least in the case of HomePNA 2.0, they were actually switching devices. This leads to some weird labeling like "hub/switch," perhaps a result of the underlying oddity of a multi-port device on a shared-media network that nonetheless performs no routing. There's another important trait of HomePNA 2.0 that we should discuss, at least an important one to the historical development of home networking. HomePNA 1.0 was designed not to cause problematic interference with telephone calls but still effectively signaled within the voice band. HomePNA 2.0's QAM modulation addressed this problem completely: it signaled between 4MHz and 10MHz, which put it comfortably above not only the voice band but the roughly up-to-1MHz band used by early ADSL. HomePNA could coexist with pretty much anything else that would have been used on a telephone line at the time. Over time, control of HomePNA shifted away from Tut Systems and towards a competitor called Epigram, who had developed the QAM modulation for HomePNA 2.0. Later part of Broadcom, Epigram also developed a 100Mbps HomePNA 3.0 in 2005. The wind was mostly gone from HomePNA's sails by that point, though, more due to the rise of WiFi than anything else. There was a HomePNA 3.1, which added support for operation over cable TV wiring, but shortly after, in 2009, the HomePNA consortium endorsed the HomeGrid Forum as a successor. A few years later, HomePNA merged into HomeGrid Forum and faded away entirely. The HomeGrid Forum is the organization behind G.hn, which is to some extent a successor of HomePNA, although it incorporates other precedents as well. G.hn is actually fairly widely used for the near-zero name recognition it enjoys, and I can't help but suspect that that's a result of the rather unergonomic names that ITU standards tend to take on. "G.hn" kind-of-sort-of stands for Gigabit Home Networking, which is at least more memorable than the formal designation G.9960, but still isn't at all distinctive. G.hn is a pretty interesting standard. It's quite sophisticated, using a complex and modern modulation scheme (OFDM) along with forward error correction. It is capable of up to 2Gbps in its recent versions, and is kind of hard to succinctly discuss because it supports four distinct physical media: telephone, coaxial (TV) cable, powerline, and fiber. G.hn's flexibility is probably another reason for its low brand recognition, because it looks very different in different applications. Distinct profiles of G.hn involve different band plans and signaling details for each physical media, and it's designed to coexist with other protocols like ADSL when needed. Unlike HomePNA, multi-family housing is not a major consideration in the design of G.hn and combining multiple networks with a "hub/switch" is unusual. There's a reason: G.hn wasn't designed by access network companies like Tut; it was mostly designed in the television set-top box (STB) industry. When G.hn hit the market in 2009, cable and satellite TV was rapidly modernizing. The TiVo had established DVRs as nearly the norm, and then pushed consumers further towards the convenience of multi-room DVR systems. Providing multi-room satellite TV is actually surprisingly complex, because STV STBs (say that five times fast) actually reconfigure the LNA in the antenna as part of tuning. STB manufacturers, dominated by EchoStar (at one time part of Hughes and closely linked to the Dish Network), had solved this problem by making multiple STBs in a home communicate with each other. Typically, there is a "main" STB that actually interacts with the antenna and decodes TV channels. Other STBs in the same house use the coaxial cabling to communicate with the main STB, requesting video signals for specific channels. Multi-room DVR was basically an extension of this same concept. One STB is the actual DVR, and other STBs remote-control it, scheduling recordings and then having the main STB play them back, transmitting the video feed over the in-home coaxial cabling. You can see that this is becoming a lot like HomePNA, repurposing CATV-style or STV-style coaxial cabling as a general-purpose network in which peer devices can communicate with each other. As STB services have become more sophisticated, "over the top" media services and "triple play" combo packages have become an important and lucrative part of the home communications market. Structurally, these services can feel a little clumsy, with an STB at the television and a cable modem with telephone adapters somewhere else. STBs increasingly rely on internet-based services, so you then connect the STB to your WiFi so it can communicate via the same cabling but a different modem. It's awkward. G.hn was developed to unify these communications devices, and that's mostly how it's used. Providers like AT&T U-verse build G.hn into their cable television devices so that they can all share a DOCSIS internet connection. There are two basic ways of employing G.hn: first, you can use it to unify devices. The DOCSIS modem for internet service is integrated into the STB, and then G.hn media adapters can provide Ethernet connections wherever there is an existing cable drop. Second, G.hn can also be applied to multi-family housing, by installing a central modem system in the wiring closet and connecting each unit via G.hn. Providers that have adopted G.hn often use both configurations depending on the customer, so you see a lot of STBs these days with G.hn interfaces and extremely flexible configurations that allow them to either act as the upstream internet connection for the G.hn network, or to use a G.hn network that provides internet access from somewhere else. The same STB can thus be installed in either a single-family home or a multi-family unit. We should take a brief aside here to mention MoCA, the Multimedia over Coax Alliance. MoCA is a somewhat older protocol with a lot of similarities to G.hn. It's used in similar ways, and to some extent the difference between the two just comes down to corporate alliances: AT&T is into G.hn, but Cox, both US satellite TV providers, and Verizon have adopted MoCA, making it overall the more common of the two. I just think it's less interesting. Verizon FiOS prominently uses MoCA to provide IP-based television service to STBs, via an optical network terminal that provides MoCA to the existing CATV wiring. We've looked at home networking over telephone wiring, and home networking over coaxial cable. What about the electrical wiring? G.hn has a powerline profile, although it doesn't seem to be that widely used. Home powerline networking is much more often associated with HomePlug. Well, as it happens, HomePlug is sort of dead, the industry organization behind it having wrapped up operations in 2016. That might not be such a big practical problem, though, as HomePlug is closely aligned with related IEEE standards for data over powerline and it's widely used in embedded applications. As a consumer product, HomePlug will be found in the form of HomePlug AV2. AV2 offers Gigabit-plus data rates over good quality home electrical wiring, and compared to G.hn and MoCA it enjoys the benefit that standalone, consumer adapters are very easy to buy. HomePlug selects the most complex modulation the wiring can support (typically QAM with a large constellation size) and uses multiple OFDM carriers in the HF band, which it transmits onto the neutral conductor of an outlet. The neutral wiring in the average house is also joined at one location in the service panel, so it provides a convenient shared bus. On the downside, the installation quality of home electrical wiring is variable and the neutral conductor can be noisy, so some people experience very poor performance from HomePlug. Others find it to be great. It really depends on the situation. That brings us to the modern age: G.hn, MoCA, and HomePlug are all more or less competing standards for data networking using existing household wiring. As a consumer, you're most likely to use G.hn or MoCA if you have an ISP that provides equipment using one of the two. Standalone consumer installations, for people who just want to get Ethernet from one place to another without running cable, usually use HomePlug. It doesn't really have to be that way, G.hn powerline adapters have come down in price to where they compete pretty directly with HomePlug. Coaxial-cable and telephone-cable based solutions actually don't seem to be that popular with consumers any more, so powerline is the dominant choice. I can take a guess at the reason: electrical wiring can be of questionable quality, but in a lot of houses I see the coaxial and telephone wiring is much worse. Some people have outright removed the telephone wiring from houses, and the coaxial plant has often been through enough rounds of cable and satellite TV installers that it's a bit of a project to sort out which parts are connected. A large number of cheap passive distribution taps, common in cable TV where the signal level from the provider is very high, can be problematic for coaxial G.hn or MoCA. It's usually not hard to fix those problems, but unless an installer from the ISP sorts it out it usually doesn't happen. For the consumer, powerline is what's most likely to work. And, well, I'm not sure that any consumers care any more. WiFi has gotten so fast that it often beats the data rates achievable by these solutions, and it's often more reliable to boot. HomePlug in particular has a frustrating habit of working perfectly except for when something happens, conditions degrade, the adapters switch modulations, and the connection drops entirely for a few seconds. That's particularly maddening behavior for gamers, who are probably the most likely to care about the potential advantages of these wired solutions over WiFi. I expect G.hn, MoCA, and HomePlug to stick around. All three have been written into various embedded standards and adopted by ISPs as part of their access network in multi-family or at least as an installation convenience in single-family contexts. But I don't think anyone really cares about them any more, and they'll start to feel as antiquated as HomePNA. And here's a quick postscript to show how these protocols might adapt to the modern era: remember how I said G.hn can operate over fiber? Cheap fiber, too, the kind of plastic cables used by S/PDIF. The HomePlug Forum is investigating the potential of G.hn over in-home passive optical networks, on the theory that these passive optical networks can be cheaper (due to small conductor size and EMI tolerance) and more flexible (due to the passive bus topology) than copper Ethernet. I wouldn't bet money on it, given the constant improvement of WiFi, but it's possible that G.hn will come back around for "fiber in the home" internet service. [1] XNS was a LAN suite designed by Xerox in the 1970s. Unusually for the time, it was an openly published standard, so a considerable number of the proprietary LANs of the 1980s were at least partially based on XNS. [2] The software sophistication of AppleTalk is all the more impressive when you consider that it was basically a rush job. Apple was set to launch LaserWriter, and as I mentioned recently on Mastodon, it was outrageously expensive. LaserWriter was built around the same print engine as the first LaserJet and still cost twice as much, due in good part to its flexible but very demanding PostScript engine. Apple realized it would never sell unless multiple Macintoshes could share it---it cost nearly as much as three Mac 128ks!---so they absolutely needed to have a LAN solution ready. LaserWriter would not wait for IBM to get their token ring shit together. This is a very common story of 1980s computer networks; it's hard to appreciate now how much printer sharing was one of the main motivations for networking computers at all. There's this old historical theory that hasn't held up very well but is appealing in its simplicity, that civilization arises primarily in response to the scarcity of water and thus the need to construct irrigation works. You could say that microcomputer networking arises primarily in response to the scarcity of printers.

I've seen them at least twice on /r/whatisthisthing, a good couple dozen times on the road, and these days, even in press photos: GMC trucks with custom square boxes on the back, painted dark blue, with US Government "E" plates. These courier escorts, "unmarked" but about as subtle as a Crown Vic with a bull bar, are perhaps the most conspicuous part of an obscure office of a secretive agency. One that seems chronically underfunded but carries out a remarkable task: shipping nuclear weapons. The first nuclear weapon ever constructed, the Trinity Device, was transported over the road from Los Alamos to the north end of the White Sands Missile Range, near San Antonio, New Mexico. It was shipped disassembled, with the non-nuclear components strapped down in a box truck and the nuclear pit nestled in the back seat of a sedan. Army soldiers, of the Manhattan Engineering District, accompanied it for security. This was a singular operation, and the logistics were necessarily improvised. The end of the Second World War brought a brief reprieve in the nuclear weapons program, but only a brief one. By the 1950s, an arms race was underway. The civilian components of the Manhattan Project, reorganized as the Atomic Energy Commission, put manufacturing of nuclear arms into full swing. Most nuclear weapons of the late '40s, gravity bombs built for the Strategic Air Command, were assembled at former Manhattan Project laboratories. They were then "put away" at one of the three original nuclear weapons stockpiles: Manzano Base, Albuquerque; Killeen Base, Fort Hood; and and Clarksville Base, Fort Campbell [1]. By the mid-1950s, the Pantex Plant near Amarillo had been activated as a full-scale nuclear weapons manufacturing center. Weapons were stockpiled not only at the AEC's tunnel sites but at the "Q Areas" of about 20 Strategic Air Command bases throughout the country and overseas. Shipping and handling nuclear weapons was no longer a one-off operation, it was a national enterprise. To understand the considerations around nuclear transportation, it's important to know who controls nuclear weapons. In the early days of the nuclear program, all weapons were exclusively under civilian control. Even when stored on military installations (as nearly all were), the keys and combinations to the vaults were held by employees of the AEC, not military personnel. Civilian control was a key component of the Atomic Energy Act, an artifact of a political climate that disfavored the idea of fully empowering the military with such destructive weapons. Over the decades since, larger and larger parts of the nuclear arsenal have been transferred into military control. The majority of "ready to use" nuclear weapons today are "allocated" to the military, and the military is responsible for storing and transporting them. Even today, though, civilian control is very much in force for weapons in any state other than ready for use. Newly manufactured weapons (in eras in which there were such a thing), weapons on their way to and from refurbishment or modification, and weapons removed from the military allocation for eventual disassembly are all under the control of the Department of Energy's National Nuclear Security Administration [2]. So too are components of weapons, test assemblies, and the full spectrum of Special Nuclear Material (a category defined by the Atomic Energy Act). Just as in the 1940s, civilian employees of the DoE are responsible for securing and transporting a large inventory of weapons and sensitive assets. As the Atomic Energy Commission matured, and nuclear weapons became less of an experiment and more of a product, transportation arrangements matured as well. It's hard to find much historical detail on AEC shipping the 1960s, but we can pick up a few details from modern DoE publications showing how the process has improved. Weapons were transported in box trucks as part of a small convoy, accompanied by "technical couriers, special agents, and armed military police." Technical courier was an AEC job title, one that persisted for decades to describe the AEC staff who kept custody of weapons under transport. Despite the use of military security (references can be found to both Army MPs and Marines accompanying shipments), technical couriers were also armed. A late 1950s photo published by DoE depicts a civilian courier on the side of a road wielding a long suit jacket and an M3 submachine gun. During that period, shipments to overseas test sites were often made by military aircraft and Navy vessels. AEC couriers still kept custody of the device, and much of the route (for example, from Los Alamos to the Navy supply center at Oakland) was by AEC highway convoy. There have always been two key considerations in nuclear transportation: first, that an enemy force (first the Communists and later the Terrorists) might attempt to interdict such a shipment, and second, that nuclear weapons and materials are hazardous and any accident could create a disaster. More "broken arrow" incidents involve air transportation than anything else, and it seems that despite the potentially greater vulnerability to ambush, the ground has always been preferred for safety. A 1981 manual for military escort operations, applicable not only to nuclear but also chemical weapons, lays out some of the complexity of the task. "Suits Uncomfortable," "Radiation Lasts and Lasts," quick notes in the margin advise. The manual describes the broad responsibilities of escort teams, ranging from compliance with DOT hazmat regulations to making emergency repairs to contain leakage. It warns of the complexity of such operations near civilians: there may be thousands of civilians nearby, and they might panic. Escort personnel must be trained to be prepared for problems with the public. If they are not, their problems may be multiplied---perhaps to a point where satisfactory solutions become almost impossible. During the 1960s, heightened Cold War tensions and increasing concern of terrorism (likely owing to the increasingly prominent anti-war and anti-nuclear movements, sometimes as good as terrorists in the eyes of the military they opposed) lead to a complete rethinking of nuclear shipping. Details are scant, but the AEC seems to have increased the number of armed civilian guards and fully ended the use of any non-government couriers for special nuclear material. I can't say for sure, but this seems to be when the use of military escorts was largely abandoned in favor of a larger, better prepared AEC force. Increasing protests against nuclear weapons, which sometimes blocked the route of AEC convoys, may have made posse comitatus and political optics a problem with the use of the military on US roads. In 1975, the Atomic Energy Commission gave way to the Energy Research and Development Administration, predecessor to the modern Department of Energy. The ERDA reorganized huge parts of the nuclear weapons complex to align with a more conventional executive branch agency, and in doing so created the Office of Transportation Safeguards (OTS). OTS had two principal operations: the nuclear train, and nuclear trucks. Trains have been used to transport military ordnance for about as long as they have existed, and in the mid-20th century most major military installations had direct railroad access to their ammunition bunkers. When manufacturing operations began at the Pantex Plant, a train known as the "White Train" for its original color became the primary method of delivery of new weapons. The train was made up of distinctive armored cars surrounded by empty buffer cars (for collision safety) and modified box cars housing the armed escorts. Although the "white train" was repainted to make it less obvious, railfans demonstrate that it is hard to keep an unusual train secret, and anti-nuclear activists were often aware of its movements. While the train was considered a very safe and secure option for nuclear transportation (considering the very heavy armored cars and relative safety of established rail routes), it had its downsides. In 1985, a group of demonstrators assembled at Bangor Submarine Base. Among their goals was to bring attention to the Trident II SLBM by blocking the arrival of warheads on the White Train. 19 demonstrators were arrested and charged with conspiracy for their interference with the shipment. The jury found all 19 not guilty. The DoE is a little cagey, in their own histories, about why they stopped using the train. We can't say for sure that this demonstration was the reason, but it must have been a factor. At Bangor, despite the easy rail access, all subsequent shipments were made by truck. Trucks were far more flexible and less obvious, able to operate on unpredictable schedules and vary their routes to evade protests. In the two following years, use of the White Train trailed off and then ended entirely. From 1987, all land transportation of nuclear weapons would be by semi-trailer. This incident seems to have been formative for the OTS, which in classic defense fashion would be renamed the Office of Secure Transportation, or OST. A briefing on the OST, likely made for military and law enforcement partners, describes their tactical doctrine: "Remain Unpredictable." Sub-bullets of this concept include "Chess Match" and "Ruthless Adherence to Deductive Thought Process," the meaning of which we could ponder for hours, but if not a military briefing this is at least a paramilitary powerpoint. Such curious phrases accompanied by baffling concept diagrams (as we find them here) are part of a fine American tradition. Beginning somewhere around 1985, the backbone of the OST's security program became obscurity. An early '00s document from an anti-nuclear weapons group notes that there were only two known photographs of OST vehicles. At varying times in their recent history, OST's policy seems to have been to either not notify notify law enforcement of their presence at all, or to advise state police only that there was a "special operation" that they were not to interfere with. Box trucks marked "Atomic Energy Commission," or trains bearing the reporting symbol "AEC," are long gone. OST convoys are now unmarked and, at least by intention, stealthy. It must be because of this history that the OST is so little-known today. It's not exactly a secret, and there have been occasional waves of newspaper coverage for its entire existence. While the OST remains low-profile relative to, say, the national laboratories, over the last decade the DoE has rather opened up. There are multiple photos, and even a short video, published by the DoE depicting OST vehicles and personnel. The OST has had a hard time attracting and retaining staff, which is perhaps the biggest motivator of this new publicity: almost all of the information the DoE puts out to the public about OST is for recruiting. It is, of course, a long-running comedy that the federal government's efforts at low-profile vehicles so universally amount to large domestic trucks in dark colors with push bumpers, spotlights, and GSA license plates. OST convoys are not hard to recognize, and are conspicuous enough that with some patience you can find numerous examples of people with no idea what they are finding them odd enough to take photos. The OST, even as an acknowledged office of the NNSA with open job listings, still feels a bit like a conspiracy. During the early 1970s, the AEC charged engineers at Sandia with the design of a new, specialized vehicle for highway transportation of nuclear weapons. The result, with a name only the government could love, was the Safe Secure Transporter (SST, which is also often expanded as Safe Secure Trailer). Assembly and maintenance of the SSTs was contracted to Allied Signal, now part of Honeywell. During the 1990s, the SST was replaced by the Safeguards Transporter (SGT), also designed by Sandia. By M&A, the Allied Signal contract had passed to Honeywell Federal Manufacturing & Technology (FM&T), also the operating contractor of the Kansas City Plant where many non-nuclear components of nuclear weapons are made. Honeywell FM&T continues to service the SGTs today, and is building their Sandia-designed third-generation replacement, the Mobile Guardian [3]. Although DoE is no longer stingy about photographs of the SGT, details of its design remain closely held. The SGT consists of a silver semi-trailer, which looks mostly similar to any other van trailer but is a bit shorter than the typical 53' (probably because of its weight). Perhaps the most distinctive feature of the trailers is an underslung equipment enclosure which appears to contain an air conditioner; an unusual way to mount the equipment that I have never seen on another semi-trailer. Various DoE-released documents have given some interior details, although they're a bit confusing on close reading, probably because the trailers have been replaced and refurbished multiple times and things have changed. They are heavily armored, the doors apparently 12" thick. They are equipped with a surprising number of spray nozzles, providing fire suppression, some sort of active denial system (perhaps tear gas), and an expanding foam that can be released to secure the contents in an accident. There is some sort of advanced lock system that prevents the trailer being opened except at the destination, perhaps using age-old bank vault techniques like time delay or maybe drawing from Sandia's work on permissive action links and cryptographic authentication. The trailers are pulled by a Peterbilt tractor that looks normal until you pay attention. They are painted various colors, perhaps a lesson learned from the conspicuity of the White Train. They're visibly up-armored, with the windshield replaced by two flat ballistic glass panels, much like you'd see on a cash transport. The sleeper has been modified to fit additional equipment and expand seating capacity to four crew members. Maybe more obvious, they're probably the only semitrailers and tractors that you'll see with GSA "E" prefix license plates (for Department of Energy). SGTs are accompanied on the road by a number of escort vehicles, although I couldn't say exactly how many. From published photographs, we can see that these fall into two types: the dark blue, almost black GMC box trucks with not-so-subtle emergency lights and vans with fiberglass bodies that you might mistake for a Winnebago were they not conspicuously undecorated. I've also seen at least one photo of a larger Topkick box truck associated with the OST, as well as dark-painted conventional cargo vans with rooftop AC. If you will forgive the shilling for my Online Brand, I posted a collection of photos on Mastodon. These were all released by NNSA and were presumably taken by OST or Honeywell staff, you can see that many of them are probably from the same photoshoot. Depending on what part of the country you are in, you may very well be able to pick these vehicles out on the freeway. Hint: they don't go faster than 60, and only operate during the day in good weather. These escort vehicles probably mostly carry additional guards, but one can assume that they also have communications equipment and emergency supplies. Besides security, one of the roles of the OST personnel is prompt emergency response, taking the first steps to contain any kind of radiological release before larger response forces can arrive. Documents indicate that OST has partnerships with both DoE facilities (such as national labs) and the Air Force to provide a rapid response capability and offer secure stopping points for OST convoys. There is, perhaps, a reason for the OST's low profile besides security and anti-nuclear controversy: classic government controversy. The OST is sort of infamously not in great shape. Some of the vehicles were originally fabricated in Albuquerque in a motley assortment of leased buildings put together temporarily for the task, others were fabricated at the Kansas City Plant. It's hard to tell which is which, but when refurbishment of the trailers was initiated in the 2000s, it was decided to centralize all vehicle work near the OST's headquarters (also a leased office building) in Albuquerque. At the time, the OST's warehouses and workshops were in poor and declining condition, and deemed too small for the task. OST's communications center (discussed in more detail later) was in former WWII Sandia Base barracks along with NNSA's other Albuquerque offices, and they were in markedly bad shape. To ready Honeywell FM&T for a large refurbishment project and equip OST with more reliable, futureproof facilities, it was proposed to build the Albuquerque Transportation Technology Center (ATTC) near the Sunport. In 2009, the ATTC was canceled. To this day, Honeywell FM&T works out of various industrial park suites it has leased, mostly the same ones as the 1980s. Facilities plans released by the DoE in response to a lawsuit by an activist organization end in FY2014 but tell a sad story of escalating deferred maintenance, buildings in unknown condition because of the lack of resources to inspect them, and an aging vehicle fleet that was becoming less reliable and more expensive to maintain. The OST has 42 trucks and about 700 guards, now styled as Federal Agents. They are mostly recruited from military special forces, receive extensive training, and hold limited law enforcement powers and a statutory authorization to use deadly force in the defense of their convoys. Under a little-known and (fortunately) little-used provision of the Atomic Energy Act, they can declare National Security Areas, sort of a limited form of martial law. Despite these expansive powers, a 2015 audit report from the DoE found that OST federal agents were unsustainably overworked (with some averaging nearly 20 hours of overtime per week), were involved in an unacceptable number of drug and alcohol-related incidents for members of the Human Reliability Program, and that a series of oversights and poor management had lead to OST leadership taking five months to find out that an OST Federal Agent had threatened to kill two of his coworkers. Recruiting and retention of OST staff is poor, and this all comes in the context of an increasing number of nuclear shipments due to the ongoing weapons modernization program. The OST keeps a low profile perhaps, in part, because it is troubled. Few audit reports, GSA evaluations, or even planning documents have been released to the public since 2015. While this leaves the possibility that the situation has markedly improved, refusal to talk about it doesn't tend to indicate good news. OST is a large organization for its low profile. It operates out of three command centers: Western Command, at Kirtland AFB, Central Command, in Texas at Pantex, and Eastern Command, at Savannah River. The OST headquarters is leased space in an office building near the Sunport, and the communications and control center is in the new NNSA building on Eubank. Agent training takes place primarily on a tenant basis at a National Guard base in Arkansas. OST additionally operates four or five (it was five but I believe one has been decommissioned) communications facilities. I have not been successful in locating those exactly besides that they are in New Mexico, Idaho, Missouri, South Carolina, and Maryland. Descriptions of these facilities are consistent with HF radio sites. That brings us to the topic of communications, which you know I could go on about at length. I have been interested in OST for a long time, and a while back I wrote about the TacNet Tracker, an interesting experiment in early mobile computing and mesh networking that Sandia developed as a tactical communications system for OST. OST used to use a proprietary, Sandia-developed digital HF radio system for communications between convoys and the control center. That was replaced by ALE, for commonality with military systems, sometime in the 1990s. More recent documents show that OST continues to use HF radio via the five relay stations, but also uses satellite messaging (which is described as Qualcomm, suggesting the off-the-shelf commercial system that is broadly popular in the trucking industry). Things have no doubt continued to advance since that dated briefing, as more recent documents mention real-time video links and extensive digital communications. The OST has assets beyond trucks, although the trucks are the backbone of the system. Three 737s, registered in the NNSA name, make up their most important air assets. Released documents don't rule out the possibility of these aircraft being used to transport nuclear weapons, but suggest that they're primarily for logistical support and personnel transport. Other smaller aircraft are in the OST inventory as well, all operating from a hanger at the Albuquerque Sunport. They fly fairly often, perhaps providing air support to OST convoys, but the NNSA indicates that they also use the OST aircraft for other related NNSA functions like transportation of the Radiological Assistance Program teams. It should be said that despite the OST's long-running funding and administrative problems, it has maintained an excellent safety record. Many sources state that there was only been one road accident involving an OST convoy, in which the truck slid off the road during an ice storm in Nebraska. I have actually seen OST documents refer to another incident in Oregon in the early '80s, in which an escort vehicle was forced off the road by a drunk driver and went into the ditch. I think it goes mostly unmentioned since only an escort vehicle was involved and there was no press attention at the time. Otherwise, despite troubling indications of its future sustainability, OST seems to have kept an excellent track record. Finally, if you have fifteen minutes to kill, this video is probably the most extensive source of information on OST operations to have been made public. Even though I'm pretty sure a couple of the historical details it gives are wrong, but what's new. Special credit if you notice the lady that's still wearing her site-specific Q badge in the video. Badges off! Badges! Also, if you're former military and can hold down a Q, a CDL, EMT-B, and firearms qualifications, they're hiring. I hear the overtime is good. But maybe the threats of violence not so much. [1] The early Cold War was a very dynamic time in nuclear history, and plans changed quickly as the AEC and Armed Forces Special Weapons Project developed their first real nuclear strategy. Many of these historic details are thus complicated and I am somewhat simplifying. There were other stockpile sites planned that underwent some construction, and it is not totally clear if they were used before strategies changed once again. Similarly, manufacturing operations moved around quite a bit during this era and are hard to summarize. [2] The NNSA, not to be confused with the agency with only one N, is a semi-autonomous division of the Department of Energy with programmatic responsibility for nuclear weapons and nuclear security. Its Administrator, currently former Sandia director Jill Hruby, is an Under Secretary of Energy and answers to the Secretary of Energy (and then to the President). I am personally very fond of Jill Hruby because of memorable comments she made after Trump's first election. They were not exactly complimentary to the new administration and I have a hard time thinking her outspokenness was not a factor in her removal as director of the laboratory. I assume her tenure as NNSA Administrator is about to come to an end. [3] Here's a brief anecdote about how researching these topics can drive you a little mad. Unclassified documents about OST and their vehicles make frequent reference to the "Craddock buildings," where they are maintained and overhauled in Albuquerque. For years, this lead me to assume that Craddock was the name of a defense contractor that originally held the contract and Honeywell had acquired. There is, to boot, an office building near OST headquarters in Albuquerque that has a distinctive logo and the name "Craddock" in relief, although it's been painted over to match the rest of the building. Only yesterday did I look into this specifically and discover that Craddock is a Colorado-based commercial real estate firm that developed the industrial park near the airport, where MITS manufactured the Altair 8800 and Allied Signal manufactured the SSTs (if I am not mistaken Honeywell FM&T now uses the old MITS suite!). OST just calls them the Craddock buildings because Craddock is the landlord. Craddock went bankrupt in the '80s, sold off part of its Albuquerque holdings, and mostly withdrew to Colorado, probably why they're not a well-known name here today.