AT&T’s Abandoned Microwave Tower Network (2017)
99percentinvisible.org
99percentinvisible.org
Some of them short (<~50 miles) links with horn antennas like you see in this article. Longer links with parabolic dishes and tropospheric scatter. All "portable" equipment on camouflaged trucks and trailers that could be unloaded and assembled anywhere.
All of that started being replaced in the mid-90's with a combination of dedicated military satellite equipment and more use of commodity stuff like small commercial microwave network bridges, cellular phones, satellite phones, and so on. They closed out the "microwave tech" jobs and folded them in with "satcom" or other specialties.
Some of the equipment:
https://en.wikipedia.org/wiki/AN/TRC-97
https://www.marines.mil/Photos/igphoto/2001740716/ (apparently still used by the Marine Corps)
I'm not saying you're incorrect that the military had similar tech to what AT&T had, but I'll split the hair that they actually worked together hand-in-hand.
They actually populated AT&T Long Lines towers with AUTOVON equipment which was the old military phone system in the US. Also used the same switching network to support Air Force One with the Echo Fox Presidential Aircraft network. Some of the locations were hardened for nuclear attack.
You seem to be talking about military use of FIXED (not portable/tactical) microwave, which is a different space.
Which is what the original post/article was about - the fixed terrestrial microwave network that AT&T ran... which was a major joint effort with the US military.
Sorry I got caught up on "similar" being confusing when the military was 100% involved with what the original post was discussing (specifically the AT&T Long Lines network) - I regret my comments.
(I see you’ve added a new culpa, no worries! We all learn new stuff)
Wanna go down a rabbit hole? Remember that spectrum sale in the 2010s? What if I told you the FBI had their own microwave network that they divested of around that time?
Interesting stuff!
Specifically - what am I wrong about? As-per HN guidelines specify exactly what I have said that is factually incorrect? Please quote it directly if you can, and in good faith provide sources so I can better inform myself.
I simply disagree that I'm wrong about anything that I've stated here - I have specifically visited a Long Lines AUTOVON switching site; 100% the US military was partnered with AT&T for this. I actually possess first-hand knowledge on this - I've met with site owners.
> I see you’ve added a new culpa, no worries! We all learn new stuff
OK? Honestly I was just trying to be polite and it was less of an apology and more taking the passive road out when we were obviously talking about two separate things. I don't disagree with anything that tyingq was saying - I was just trying to make a nuanced point regarding the partnership between AT&T and the US Military which is directly related to the article that was originally posted. Somewhere wires got crossed and I just decided to bow out as politely as I could.
Sometimes socializing on this site really weirds me out. Please, in good faith: what have I factually said that is incorrect here?
Former Submarine communications specialist here.
I literally opened my original response to tyingq with "I'm not saying you're incorrect" as I did not want to invalidate anything they had written. I was not trying to argue a single point. I just found the grammar/set theory of "A similar thing happened in the US military" odd when that specific thing (the Long Lines microwave network) happened in the US military in a big way.
On your newly introduced point: "military had contracts with AT&T, but those were a tiny subset of microwave efforts". I do not describe the backbone of AUTOVON as a "tiny subset" of anything... The AT&T Long Lines was an engineering marvel. The achievement to reliably transmit coast to coast audio, video, and data through hundreds of redundant radio/switching sites was huge - that simply did not exist before. AT&T Long Lines is very significant to the history of microwave communications in the military specifically through AUTOVON.
I'm absolutely not arguing against the existence of military microwave tech independent of AT&T - I feel like this is obvious, but I also feel I have to state it outright after reading your comment.
Of course, AT&T was one of the founders of RCA, but by the time microwave and troposcatter were coming into use AT&T had sold their shares. Nonetheless there was plenty of technical interchange between AT&T and RCA during that period, and some of the RCA equipment for the military was based on Bell Laboratories and WECo work.
The military often made practical decisions of whether it was better to field themselves or contract - and so military connectivity was sometimes contracted to AT&T even in surprising situations like overseas. But field-deployable portable systems have always been impractical to contract out and so the military tends to keep its own assets.
Other parts of the government took this other directions. The State Department nearly exclusively contracted to AT&T including for foreign installations. The FAA did so surprisingly infrequently, maintaining its own expansive microwave network until just recently.
That EAC rider was certainly rare, but we were told tropo was still in play in South Korea, and as late as 2015, another company in my reserve ESB had a few tropo systems they were still maintaining and training on.
But yes, by and large, most microwave-based signal MOS were rolled into either point-to-point "multichannel transmissions" (25Q) by which a good part of your qualifications include deployment of satellite transportable trailers (STT), SMART/T systems (shared with the Marines),and the Phoenix system; and the dedicated SATCOM MOS (25S).
My favorite AT&T artifact, though, has gotta be the Project Offices: https://en.wikipedia.org/wiki/Project_Offices
The gist of it seems to be that these are secure, physically guarded, literal underground bunkers built into the tops of mountains along the East Coast, housing troposcatter antennas and satellite dishes. Super cool. As far as I can tell, nobody ever truly figured out exactly what they're for, and most are still operational today. I tried driving up to one once, out of curiosity, and there are some pretty intimidating "stay out of here" signs and cameras, even at the very base of the mountain.
Chances are they were simply just meant for the military AUTOVON network, mentioned near the top of this thread. But I suppose that doesn't explain why they're still operational nowadays.
https://coldwar-c4i.net/ATT_Project/index.html (Funny enough, this website is maintained by the same Albert LaFrance who runs long-lines.net, mentioned in the article)
https://coldwar-c4i.net/ATT_Project/VA01/ATTsiteB.html
This one is actually decommissioned and has pictures of the inside: https://coldwar-c4i.net/ATT_Project/Buckingham/index.html
Super interesting stuff, IMO
https://www.flickr.com/photos/legeros/albums/721576916034825...
http://www.thetownofliberty.com/2018/01/the-mystery-of-big-h...
It's interesting to me how all the signs in that Flickr album say "People" instead of "Personnel" (Delivery People, Authorized People Only). Was this an AT&T thing?
Fun fact if you're curious about this stuff: Site R is pretty well-known, but slightly more obscure is the "Site C"[1] radio outpost atop Quirauk Mountain a few miles away. It's kind of funny since High Rock is a crowded day-trip destination, being right on the Appalachian Trail and all, but then just a few yards away at the edge of the parking lot, there's some stern-looking security dudes guarding the Site C access road. Also, Site R supposedly links into the "Presidential Emergency Facilities"[2] network, a bunch of weird grain-silo-looking structures historically used for communications and relocation https://coldwar-c4i.net/PEF/
The DMV area is dotted with all sorts of fun "spooky" stuff. I've always wanted to make some kind of website or map summarizing it all. coldwar-c4i.net is awesome and contains crazy amounts of information, but is admittedly pretty cluttered.
[1] https://aboutsiter.blogspot.com/2015/06/site-c.html
[2] https://coldwar-c4i.net/PEF/presidential_emergency_facilitie...
Personally, I feel the same way about cell sites today. There's a surprisingly enthusiastic community online for keeping tabs on them and tracking site design changes/upgrades. Cellmapper.net is the homebase these days and their subreddit has tons of posts asking the community to identify sites based on pictures of the equipment.
> requested that the names and exact locations of active AT&T network facilities not be published.
Three minutes on Google Maps is all the effort it takes...
When I was a kid, you could hear the white noise stack successively louder on a long-distance call, as it went through each additional link. And sometimes you could hear the hum of it all, just below the threshold of intelligibility. In hindsight it's amazing how well it all worked.
But sometimes it didn't work so well: https://vocaroo.com/1oCxkWyNDusp
Maybe a filter was slightly out of tune on that day. Recorded mid-1970s New York. The electronic beeps are in-band call establishment tones. (Yes, the same ones phone phreaks exploited. The recording was in fact made by one of those phreaks who has gone back and narrated some of his old recordings http://www.evan-doorbell.com/ )
Will you accept the charges from United States?”
I always wondered what those beeping tones were in the recording at the end of that song (“Young Lust”). I guess I’m not old enough :)
See also: Facebook's recent outage.
Other than, you know, the entire Internet (BGP) and pretty much every corporate WAN (OSPF, EIGRP, RIP) and LAN (spanning tree, ARP).
Having an out-of-band control plane is very much the exception. Now OOB emergency access, on the other hand...
edit okay, SS7 is out-of-band, but parent was talking about IP networks.
Huh. I never heard that in the 70s and 80s. Cool.
https://en.wikipedia.org/wiki/Carrier_system
I learned just a little about these after making the decision that my drives through Nevada would never again be boring. Once I started asking questions about what I was seeing, the "ice cream cones" or horn antennas really did stand out in a fascinating way. And $25K to buy one does seem like it could be a terrific deal in the right situation.
Another thing I asked about: When I stopped to get gas or groceries, I realized there were tall visibility flags on the back of so many Nevadan trucks, even what looked like personal vehicles. I had overlooked them for years. An interesting dive into an industry and its culture started there.
BTW, speaking of old towers that went up for sale and are possibly interesting to ham radio operators: Here's one near me (NorCal Bay Area) that was purchased by a local bay leaf grower and then opened for ham radio use--in exchange for a refurbishment effort.
ref: https://www.startribune.com/after-50-plus-years-the-centuryl...
In way, if you try hard enough, most powerlines could act like inside out waveguides for high data rate RF backhaul.
https://az276019.vo.msecnd.net/valmontstaging/vsna-resources...
For the most part these are almost obsolete, the typical data link that many of them carried was one DS3, or at most, three DS3... The path loss is extreme. Usual setup was to go from a small town central office (CO), 3-5 km up to a nearby mountain, then bounce it off there, and 25-30 km to another nearby mountain. With big old power hungry PTP microwave gear that occupied a full 42U rack, took 1200W of power, and carried a whole lot of DS0.
Nowadays a modern PTP microwave radio that can carry 1400Mbps full duplex in the 6 or 11 GHz bands is as little as 35W of power, so many hilltop tower sites either have built electrical grid connections, off grid solar, or whatever.
Building some of those passive repeater billboards in places with no road access was very costly. Big helicopter bills and very labor intensive.
You can still see a number of them on hillsides in eastern Oregon.
I'm not sure exactly why AT&T eschewed them besides the speculation that AT&T built much of their microwave network relatively early and so the attenuation may not have been acceptable given the already short range on their links. AT&T's first generation of microwave sites had to put the RF amplifier in a hut on top of the tower because the waveguide loss was unacceptable, for example.
A very common place to find passive repeaters in the desert west is at dams, where they were almost invariably installed to provide the telephone connections to the power house.
A later interesting example of passive reflectors is the "periscope antenna," mostly used by Western Union when they operated a microwave network for a time. The actual microwave antennas were mounted on the roof of the shack pointed up, and at the top of the tower passive reflectors at a 45 degree angle "bent" it to horizontal. It put the more maintenance intensive parts on the ground at the cost of some power loss.
https://en.wikipedia.org/wiki/Aquacade_(satellite)
Fun fact 2: back in the day you could make a "station-to-station" long distance calls - these are the "stations" they were talking about.
Even from the other side of the globe I can tell that it seems strangely short-lived. Built for a decade, then used for a decade?
Wikipedia notes tersely:
> The launch of communication satellites in the 1970s provided a cheaper alternative.
Microwave relays were obsoleted by fiber optics.
https://www.telcomhistory.org/resources/online-exhibits/scie...
e.g. I found this government report report from 1983 stating that "microwave is the chief means of transmitting long-distance telephone calls..." in the U.S., this is well after the advent of satellites: https://www.google.com/books/edition/A_Five_year_plan/NbGS1A...
In the early 1930s, both time and frequency multiplexing were introduced on coaxial cable, carrying up to 600 channels per conductor, it rendered the above twisted pair multiplexed lines obsolete within about a decade.
c. 1950 microwave relay is introduced (the AT&T long lines in question here) and undergoes explosive growth, with the cross-continental system linking most major cities built by 1960, and reaching essentially every part of the country by 1970. Such links could carry hundreds of megabit/s worth of data (or multiple 6 MHz TV analogue channels). Much cheaper than coaxial, it largely halted new coax installations. It would remain dominant into the 1980s, so more like 20 years.
Fibre optic communication was introduced in the mid-1970s. Immune to atmospheric problems, less path loss, potentially capable of carrying far more data than microwave. It made most of the microwave systems obsolete by the 1990s.
They effectively had a commercial life of 35-40 years, and went thru 2-3 generations of technology, some of them were even upgraded to digital.
https://telephoneworld.org/long-distance-companies/the-histo...
For those not familiar MCI was a real innovator and an important part of internet history. Vincent Cerf, an internet giant, worked for MCI[1]. Sadly MCI was relegated to the dustbin of history as a result of the WorldCom scandal[2]. They are sadly just a part of Verizon Business today.
Interview started, talking about something glanced over the background and muttered verbally "Microwave" as it hit me that it was a microwave waveguide of some sort.
Didn't get the job...
Looks like this inside.
https://www.jagelectromagnetics.com/images/jag_cataloug_imag...
Nowadays there is some 2.0GHz band ENG stuff up there for live news gathering stand ups.
It was actively maintained, with various antenna arrays being attached or removed frequently. The building below was packed full of gear and service vans were coming and going all the time.
I was sorely tempted to try and climb it over the various years I lived in Seattle, but decided it wasn't worth either the arrest or death by electrocution or ground impact!
1. https://www.google.com/maps/place/315+W+Galer+St,+Seattle,+W...
fairly typical USWest/Qwest central office otherwise.
There are many new microwave links being deployed now using modulation techniques for digital data.
There is also a big site out in the fraser valley on a hilltop that was part of the long lines network with shots going east towards Hope (trans canada microwave) and down into Whatco County.
Were the microwave links to Nanaimo and the Sunshine Coast replaced by fiber?
Still is some microwave operational on sunshine coast but not as a primary thing.
Big parts of trans Canada microwave have now been dismantled. There was a mountain top site slightly NE of Hope that could only be reached by its own cable car. And lots of other mountain top sites east of it going all the way to Lethbridge.
>Vintage Skynet: AT&T’s Abandoned “Long Lines” Microwave Tower Network
The original title of the article, actually make sense in the subject of "Long Lines". But the submitted title make it sounds like AT&T totally abandoned Microwave Network. I dont know about AT&T but Microwave Network is still actively being used today and refined even in the latest 5G 3GPP Spec Rel 16, 17 and 18.
Other than that it is a nice piece and history of the system.
Dismantling and scrapping such a tower would be enormously expensive and bring no value to AT&T shareholders.
If they're in total disrepair, I'm sure a case can be made for safety in an urban area. The two towers closest to me are in rural areas with several other radio service tenants where maintenance is a covered cost.
It's also worth mentioning that big equipment like this isn't designed to be removed from towers, and not only would be expensive to remove, but extremely dangerous. It's a lot safer and cheaper to just leave it there, and mount additional equipment (cellular equipment, etc) elsewhere on the tower.
https://long-lines.net/places-routes/Lake_Zurich_IL/index.ht...
People do everything from run cellular on them, run datacenters in the nuclear hardened bunker sites, etc. Even though they're old as heck and look like something out of a sci-fi many structures are still solid and some of the sites have things like diversified utilities.
Then finally, there's the EPA... these towers can be a nightmare for EPA - specifically the ones with backup generator fuel tanks that were buried. I'm guessing AT&T didn't want to deal with the complex logistics of digging those up, horn removal, etc. and just sold many of the properties off.
https://www.google.com/maps/place/37°55'27.3%22N+102°36'36.5...
There is still active microwave, but its usually in the ownership of the RBOC/IOC not a long distance carrier, and is used to link the end office to the rest of the PSTN. Microwave is also used extensively to link cell sites to other cell sites, so you need to install less fiber.
Microwave backhaul fascinates me... I think the most interesting example of it that blows my mind is the private backhauls that are going up between major financial hubs in the US like Chicago <-> New York. Since latency is a huge deal for a lot of these HFT traders some intense stuff gets engineered:
https://arstechnica.com/information-technology/2016/11/priva...
Specific quote I'm referencing:
> The researchers then used the FCC and other records to deduce that, at the time of their 2013 study, there were 15 (!) networks licensed to operate microwave links between the two cities.
Freakin' wild!
I've often dreamed about building a private national microwave network to sell capacity on. They're not expensive to build or operate with modern hardware, which doesnt need much power or servicing.
Wanna see something truly wild?
https://archive.org/details/bstj56-10-1829
Buried waveguide! a path not taken, as fast as microwave, with more controlled path characteristics. Had fiber not worked out to be practical, this would have been the replacement for the L-5 Coax network, as fiber proved to be.