AT&T Archives: Single Sideband, a 1977 film about microwave transmission

See more from the AT&T Archives at techchannel.att.com/archives
This short film, made by Bell Laboratories in 1977, gives a basic overview of what single-sideband transmission consists of, and why it was implemented in the phone system that year. Single sideband transmission allowed the Bell System to carry a greater number of data, voice, and broadcast signals along the microwave network.
Single Sideband transmission was first recognized during the first overseas radio transmission tests conducted by the Bell System in concert with the U.S. Navy, in 1915. These tests took place at the U.S. Naval Radio Station in Arlington, Virginia, and were overseen by Harold D. Arnold of Bell Telephone (Bell Laboratories was formed later, in 1925). The tests built on scientific work by Raymond A. Heising and John Renshaw Carson at Bell Telephone and Western Electric.
The first cross-country microwave network call was placed in 1951. By 1977, the Bell System's microwave network carried 70% of the long-distance transmissions in the United States.
In 1974-77, new single sideband systems were tested in Georgia and Massachusetts: the plan was to bring this increased transmission capacity to the long distance network by 1980.
The microwave network continued to shoulder the bulk of the company's transmission capacity for another decade or so, but required a line-of-sight connection. As fiber optic transmission research and digital switching technologies made great strides in the 1980s, it became more feasible to fit a greater amount of information through fiber optic lines rather than relying on the microwave system.
The 1977 Massachusetts single sideband tests were of the AR6A system. A 1983 issue of the Bell System Technical Journal explains this technology and how it came about.
Footage Courtesy of AT&T Archives and History Center, Warren, NJ

[@russellm7530]

My dad worked on the Union Pacific microwave systems for much of his life. God bless you Dad. I wish I'd seen you more before you passed away.

[@jr2904]

You'll meet again, may God be with you and yours

[@Shakawhenthewallsfell102]

narrator is Peter Thomas. Best voice ever.

[@iamatis20]

Thank you for letting me know this as I have heard him my whole life and NEVER who he was.... This dude did OSHA and all type of dubs. Dam I learned from KZbin again!

[@jdmac44]

I was just about to ask, thanks!

[@macdaddybill]

I miss him what a kind gentleman. I had emailed him years ago about his narration on the forensic files and he responded! I was quite tickled by that as he was one of my heroes in voice work. A True pro!

[@XBradTC]

Decorated veteran of World War II.

[@UnOrigionalOne]

He narrated Forensic Files. I half expected a line in here about DNA evidence.

[@ajjacksonthelonglinestower8073]

Those towers are amazing, AT&T's tallest microwave tower is in Catawba, Ohio. The cement tower was too small to communicate between springfield and Columbus so a 456 foot tall steel tower was added on in 1966. It is a well known site for being a really tall tower.

[@kilodeltaeight]

I remember driving by the Springfield tower along I-70 when we'd go visit my grandparents out that way - though by the time I saw it, it was long disused for Microwave.

[@travisglantonthetowerenthusias]

The Johnston, South Carolina long lines tower is a iconic tower too.

[@30Xa]

Saw the Catawba tower this weekend on vacation

[@w8lvradio]

Raymond E. Markle (1929-2017) worked for Bell Labs as a department head for thirty nine years. He was also a Korean War Veteran. He was born in Hanover Pennsylvania and a graduate of Penn State.

[@ojsilva1975]

Wow, he loved what he was doing for 39 Years. R.I.P. to Mr. Markle.

[@mikemac2888]

I remember this guys voice from filmstrips in grade school.

[@Animalwon]

I remember him best from his years working on FORENSIC FILES.

[@wecontrolthevideo]

They used SSB for phone calls via satellite as well. Back in the early 1980's my parents lived in a rural area and the only way cable channels were available were by C Band TVRO dishes. There were some satellite transponders that carried nothing nut telephone traffic, I assume between the US and the Caribbean islands. I would hook the baseband IF output of the receiver to the antenna input on a shortwave receiver and tune down to longwave and start tuning up and down and hearng all kinds of phone traffic in SSB. It was only a few years later that fiber started to quickly replace satellites for phone calls.

[@reallyrarestuff]

The IF was always SSB even on the FM radio systems.

[@wecontrolthevideo]

I did the same thing with my parents C-band dish. The baseband output on the receiver made it easy to do. Tune to a transponder where the "noise" in the picture darkened, usually a sign of some kind of acivity, and tune my shortwave receiver from longwave up and would find all kinds of phone traffic.

[@MrBrandonVegas]

Hear any interesting conversations?

[@eman99a]

@@MrBrandonVegas YES! One night a guy was describing in gory detail how he murdered a rival drug dealer.. Brains splattered all over the dashboard. "That Dave is a Mad Dog. He better settle down." Connection from LA to AK via ANIK

[@greaterbridgeportamateurra8429]

How would rain and other weather affect these satelite phone links I wonder? Excatly what frequencies were used?

[@JGott0001]

There's a bunch of these old towers around where I live in KY. I learned they were once used for this purpose, but it's neat to see an old film about them.

[@ojsilva1975]

Not to mention they were used a lot during the Cold War Era.

[@SallySallySallySally]

That's Peter Thomas doing the narration -- one of the busiest voice talents ever. His 90th birthday is coming up in June and, as far as I know, he's still working. He voiced the Burger King ads a couple of years ago.

[@RyanSchweitzer77]

Thanks for the info! I always wondered who that voice talent was, having heard Mr. Thomas' voice countless times in various commercials, educational films, and other media throughout the years! He's definitely done a lot--I have an instructional audio cassette from the 1970s on how to operate an automotive air conditioner recharging system, that was narrated by him!!!

[@RCAvhstape]

+SallySallySallySally Thanks, I was about to ask whose voice that was, I'm pretty sure I've heard him in commercials, too.

[@netdog713]

you can also hear him in the song 19 by Paul Hardcastle

[@ChristopherUSSmith]

Died April 30, 2016. RIP Peter Thomas.

[@johnkern7075]

Oh! No! He had such a good voice. He did the narrations for the tv show Forensic Files.

[@dusterdude238]

1:35 at first glance I thought the Guys name was R.E. MARKABLE LOL

[@JJceo]

Me too!

[@TheAnubis57]

You made me think of a little boy in a Little Rascal short who annoying the kids by saying "remarkable" all the time. :)

[@SilvaD702]

Thank you AT&T Tech Channel. Please keep posting more videos!

[@SallySallySallySally]

Oh, by the way, it's a real delight to see these coming back after an almost year-long hiatus!

[@James_Knott]

1980? In a few years, fibre would start replacing long haul microwave. Now, you rarely see it. Also, part of the C band that was used for it has been reallocated to 5G cell phones.

[@414s4]

It’s amazing how fiber changed the world.

[@luisreyes1963]

AT&T makes the most interesting films about science & technology.

[@misterwhipple2870]

0:43 That stereo receiver is a Marantz. I'd love to have it today!

[@wecontrolthevideo]

Just a few year later, fiberoptics started replacing all the Long LInes sites.

[@TexasRailfan2008]

Bruce on the Loose more than a few years, more like 50

[@MrJruta]

@@TexasRailfan2008 I live near an Att Building that has two of these antennas on the side of their building (high up). Are they no longer functional I wonder?

[@TexasRailfan2008]

MrJruta most likely not in use anymore.

[@ArtStoneUS]

The problem with microwave signals is that satellites can listen in to them

[@TexasRailfan2008]

@@ArtStoneUS yeah, especially since they didn’t bother to encode them at all

[@kvlteacher5911]

Loved the video! But had to chuckle at the oscilloscope traces (time domain) used to “represent” frequency domain sidebands.

[@L33tSkE3t]

I wouldn’t have been born for nearly two decades when this was made but watching how this old tech was operated is fascinating

[@johnsiders7819]

And now those towers are sitting around all over the country abandoned . The good news is we bought a couple to use for our wireless internet service at a rock bottom price .american tower is unloading them cheap ! Most have a sturdy concrete building at the base and have a acre or more of land around them .

[@jordanhazen7761]

Had the horns and other microwave equipment already been removed when you bought them? The closest to me was turned into a Verizon cell site, which T-mobile later co-located onto. Antenna mounting was a bit odd since they go for 120-degree sectors, and these (all?) have a square profile.

[@johnsiders7819]

@@jordanhazen7761 a contractor had removed the horns and drums from the towers but left one at a site they are really big on the ground and made of fiberglass they also had stolen the generator set and pulled up the ground grid on one site both have all most full propane 500 gallon tanks inside the fence

[@jordanhazen7761]

@@johnsiders7819 I unfortunately never had the chance to see one up close, but wonder how their size compared to the famous ground-mounted Holmdel antenna near Bell Labs, built for early satellite work but famously used to discover the cosmic microwave background radiation: www.atlasobscura.com/places/holmdel-horn-antenna .. the door on that equipment shed at its feedpoint could be a useful frame of reference. I'm surprised anyone bothered to dig up part of a grounding grid.

[@incubus_the_man]

I used to see those transmitters from the highway as a kid and I always wanted to know what they were.

[@robminmonaca]

These were also used for television before satellites came out in the 70s and 80s as well.

[@ishotthetrixbunny9773]

Thank you for choosing AT&T😉

[@markarca6360]

Single sideband, similar technology used in marine and citizens' band radio communications.

[@wyliesdiesels4169]

cool. i just did some work on an old long lines site on fremont peak outside of mariposa. the horns and tower platform are long gone but there are some microwave relay circuits for yosemite valley up there

[@undefinedname1398]

I saw a traveling wave tube. I broke a couple of them while installing. I miss microwave.

[@themagus5906]

You savage Earthlings...still cooking your bacon bits the same way that you communicate...

[@DrBovdin]

@@themagus5906 of course, we treat anything going either in or out of our mouths with RF… it is tradition.

[@cyclenut]

I live in N.W. GA. The local power company has a microwave tower that still stands. It was used for local office to communicate to main office. I am sure it is no longer used. One day they'll take it down.

[@erzahler1930]

The microwave tower where I live is still standing next to the switch house, but it no longer has the microwave waveguides installed. Now the switch house uses dishes for uplink/downlink of distant calls, which are switched by AT&T's 5ESS computerized switch (I think that is the current system). The tower is now used by a couple of commercial radio systems, which have vertical antennas on the waveguide platform. I've been told that all of the original mechanical 1ESS switches, and later 3ESS solid-state switches, have all been removed and scrapped.

[@cameronbenton1045]

In Conway South Carolina there is a SSB tower that’s still standing. Idk if it’s still used or not but I always remember it by it’s distinctive red paint and how different it looks from other communication tower. **edit I looked it up and it’s currently used by the SCDOT**

[@ojsilva1975]

There’s one in Wadesboro, NC on 74; AT&T, still up & running. Well protected too!

[@rearspeaker6364]

probably for the 911 system.........

[@desertbob6835]

AR6A...the WORST long haul microwave system ever devised by Bell Labs. It had a VERY short lifespan, and most of it was converted to digital. The older TD, TH, TN and others using FM was far better, but lower capacity. Phase jitter to the baseband was the chief problem to data cusomters for as long as this lousy system was in service. This was supposed to replace the aging TH-1 systems from the 1950s. How do I know? I turned up the first AR6A system on the West Coast in 1980...total disaster.

[@reallyrarestuff]

Yep - an older radio system with 3 MasterGroups did a fine job and was quite stable.

[@jimpiper5297]

@@smitty9398 I wrote the KarKar KR6S installation and service manual (still have a copy on my bookshelf). My technical source was Jerry Siegel who was the KarKar service engineer at the time. Smitty, you must be complaining of the effort to set-up the predistorter which was a real bitch. At the time, Fujitsu has SSB telecom radios that automatically set up their predistorter. MCI opted for the manually adjusted ones that KarKar had because they were a lot cheaper than Fuji's, possibly (my guess) because they knew the radios would have a short life in service.. Presuming you worked for MCI, you probably recall that MCI had them in service for a relatively short time. MCI's game plan was to increase route capacity (effectively doubling it over the Collins FM radios) with the goal to increase customer base while it built out its fiber network. I understand that once the fiber routes were built out, MCI scrapped out and sold the KR6S' by the pound. It's interesting that, at the same time SPRINT was touting their fiber network (remember the pin-drop commercials?), that it didn't owned, All their fiber was LEASED! A side-story about MCI and its fiber: MCI scored bit with an easement and right-of-way down the California aquaduct. Somebody screwed up because the first fiber dropped into the trench wasn't armored -- gophers got it. Oops! Post script to the tale: some ham radio operators acquired several of the scrapped out radios, converted them to FM (fairly easy to do by replacing the up-converter (?). These hams now have a 6GHz repeater network surrounding the SF Bay. (OBTW, the first KarKar SSBs were some of MCI's Collins radios converted from FM to SSB.) Wow. The memories of that 1980s project come back.

[@SkylerF]

bell labs is the best

[@felicciasc]

those are some tight as filters

[@AdamEbelgccengineering]

It's possible to use Single Side Band for Lower Side Band for (Left Audio) and Upper Side Band (Right Audio) for stereo audio.

[@isaacu]

About 375Mbps by today's standards?? Not too shabby..

[@jonmchang]

isaacu It was actually a 135 Mb/s system.

[@lazerusmfh]

Jonathan Chang still pretty incredible given the timeframe! And the passive repeaters systems we’re simply amazing feats of engineering.

[@visionofwellboyofficial]

Some can reach up to 2Gbit/s, using QAM modulation and high bandwidth

[@visionofwellboyofficial]

and MIMO or Spatial Diversity

[@yfs9035]

GAWD DAYUM

[@yfs9035]

Amazing

[@rob1248996]

Almost EVERYTHING was invented by Bell Labs. Usually decades before normal people had a chance to use it.

[@Detroit8V92tta]

I remember these microwave transmitters on the tower at Canterbury road Surrey Hills.

[@TheRock-zo7zl]

BELL Labs is very visionary

[@TexasRailfan2008]

The Rock indeed

[@rob1248996]

Was

[@chooch1995]

Narrated by the late, great Peter Thomas { 1024-2016}............Classic!

[@MrTantalust]

Yup, I recognized Pete immediately ...the narrator of the great Forensic Files series.

[@hellmuth26]

holy cow, he was 992 years old?

[@rearspeaker6364]

@@hellmuth26 gonna say that too, wasn't born on this planet!

[@paulborneo7535]

A system doomed to launch just as fiber optics would arrive.

[@currentphonograph7487]

I hope to work for AT&T

[@keitha.9788]

AT&T isn't the company it use to be...... It's best days are in the distant past.........

[@compu85]

Can you re-upload, or somehow turn off the youtube video stabilizer? It turns your great film into jello vision. Was the original very jittery?

[@alsehl3609]

A huge investment by Bell just in time for fiber optics to make it obsolete! Happened very fast!

[@DrLumpy]

Us boomers didn't wait around before re-inventing new technology.

[@johnnyblaze9217]

@@DrLumpy 😂 well bell labs was a monopoly....but a good one tbh

[@fishhaulergreatlakes8208]

I've used Skyway. Even alaska had RCA, microwave tx with a 4sec delay. 907 to 313 5 second delay. Golden . MARS, BELL, AT&T, WESTERN, SOUTHERN, comms.✌️

[@jeffkardosjr.3825]

And then you argue over who is off frequency.

[@Solocat1]

Why the guy still running a tube rig is of course. :-)

[@timothykearns2232]

ha!

[@CritterFritter]

My wife and I were driving along and passed a huge microwave tower. She asked me what’s the tower was? After explaining it was a microwave tower, she shrugged and said she knew it had something to do with one of our kitchen appliances. Sure glad we were in our car - alone.

[@borntoclimb7116]

Interesting

[@RayoAtra]

Ma Bell in full swing.

[@djijspeakerguy4628]

Now, these things are being taken down, or abandoned and not usable due to being broken.

[@jordanhazen7761]

Though fiber's now superior in almost every way, microwave in making a small comeback in niche uses like data links for stock trading willing to pay well for shaving microseconds off end-to-end-latency. Speed of light in fiber is only ~60% that of the speed of light/radio through free space. Upcoming low-orbit satellite constellations like SpaceX Starlink will enjoy a similar advantage, for paths long enough to make up for the extra uplink/downlink distance.

[@netdog713]

The average age of the telecom tech at AT&T was 19 nuh nuh nuh nuh nineteen

[@ojsilva1975]

Seriously? Wow!

[@netdog713]

@@ojsilva1975 lol it was a joke- this narrator is also in the music video for Paul Hardcastle's song "19".

[@ojsilva1975]

@@netdog713 oh I was about to say, lmfao… no way AT&T would allow a 19 Year Old work in those. Unless they’re a super computer genius outta HS.

[@netdog713]

@@ojsilva1975 when I was a tech at Lucent Technologies I was 34-35

[@cartman4885]

The Bell System

[@stupossibleify]

Is each of the 3000 channels transmitted as time-division multiplex, it do they all have their own frequency? If the latter, does that mean the system has 3000 individually tuned devices per sideband?

[@timothykearns2232]

If it's SSB, I believe it would be FDM as opposed to TDM......But, I'm not really sure. I retired when digital was coming of age on 6 Ghz......

[@stargazer7644]

Each narrowband channel operates on a slightly different frequency. So this would be considered FDM. These were analog systems, not digital. This is the same way the amateur radio bands work.

[@josephdunkle1152]

Next on Forensic Files

[@johnbroski1993]

This guy is the FORENSIC FILES VOICE TOO

[@jalexgans932]

I wonder how much bandwith eash sideband was, the said each sideband could carry 3,000 phone calls, and in Amatuer(Ham) Radio its 3 KHz?

[@AugustusTitus]

An audio response bandwidth of 300 Hz to 4 KHz is the basic standard for communications quality voice, but on the early transatlantic cables, this was cut further to 300 Hz - 2.7 KHz, and TASI used to put speech into silence. K, O, and N-carrier are all documented on Wikipedia. Many of those systems were FM or AM (DSB+Carrier).

[@wecontrolthevideo]

Amateur radio frequently uses 300 Hz - 2.4 kHz for SSB, for a total of 2.1 kHz bandwidth. It's amazing though how much the audio quality improves, on SDR receivers where it can easily be changed to 0 kHz - 3.0 kHz

[@stargazer7644]

They were carried in a 29.65MHz channel. Individual conversations were carried in about 2.5 kHz

[@KC-nd7nt]

Still waiting on a clear call . I'm in my 40's and miss clear conversation

[@jordanhazen7761]

G.722 as used in some VoIP systems, and the related AMR-WB (VoLTE "HD voice" cellular codec) are not so bad these days, assuming support at both ends and a solid network link. With poor signal VoLTE does seem to drop out more readily, though.

[@user2C47]

"You're breaking up!" - Something that is generally only shouted across packet switched telephone networks.

[@stargazer7644]

Are you serious? I can easily remember the days when you knew a call was long distance before the first word was spoken due to the hiss on the line. The longer the call, the louder the noise. Todays digital landline calls are silent, and much higher quality. Mobile phones are trying to move us back to the stone age though.

[@Dr.JustIsWrong]

Is this from Mad Max; Beyond the Thunderdome?

[@kd1s]

And the interesting part is even TD type microwave couldn't hold a candle to what was to come just a few years later - fiber optics.

[@RyanSchweitzer77]

Indeed--and even the first fiber-optic circuits upon their introduction around the early '80s pale in comparison to today's fiber lines utilizing DWDM (Dense Wavelength Division Multiplexing), basically using different wavelengths (colors) of light to multiply the capacity of a fiberoptic line...

[@kd1s]

***** Yes indeed. I know about fiber's capabilities. And we've squeezed the hell out of RF systems as of late too.

[@wecontrolthevideo]

I read once that the fiber we already have in use could handle communication needs for the next 100 years.

[@timothykearns2232]

Ham Ops think they know everything! LOL de NN6A

[@jordanhazen7761]

True in every metric except for latency. Speed of light in fiber is only ~60% of free-space...

[@phoneticau]

Today 600M/bit transmission speed using 28 Mhz of spectrum

[@kd1s]

And then fiber came around and goodbye microwave.

[@nkm901]

kd1s Microwave towers are still used in for lots of things.

[@timothyrosman6371]

Not true - go read Flashboys by Michael Lewis. High Frequency traders built microwave networks because it was nanoseconds faster than fiber.

[@v12alpine]

A bunch of these horn towers still exist in rural maryland and delaware.

[@stargazer7644]

Microwaves are still used, but it is all digital now.

[@jpolar394]

This narrator reminds me of George Page so much but I know it's Peter Thomas.

[@carterrouth7801]

I know where two of these sites are still standing. Someone broke into one quite a few years ago and stole a bunch of the copper off the base of the tower.

[@nofxslc]

Downtown Portland, Oregon?

[@DrLumpy]

@@nofxslc Every tower, everywhere.

[@michaeldomansky8497]

And then came the digital revolution and Fiber Optics!

[@daviddavidson1372]

Those towers use to distroy c band satellite tvro systems. Glad there gone.but one love to have the tower to load up with antennas.

[@vinceplacanica7813]

And then came fibre optic cable…

[@calbob750]

And all these towers had to be line of sight.

[@stargazer7644]

Nah, there were troposcatter systems too, often used between islands. Those weren’t line of sight.

[@teltri]

I don´t understand it. Radiowaves are electromagnetic waves. Why do they contain 3 parts?

[@wecontrolthevideo]

An amplitude modulated signal on a "radiowave" has three parts, two sidebands (lower and upper) that carry the modulation and the carrier wave (that "carries" the modulation with it) Since the sidebands are identical, you can eliminate one of them, with no loss of information. The carrier can also be eliminated and a new one inserted in its place in the receiver.

[@Paul-gz5dp]

@@wecontrolthevideo Very well said!

[@jordanhazen7761]

@@wecontrolthevideo Eliminating the carrier and one sideband is not without cost, of course, requiring much better frequency stability at the receiver, and higher SNR given no more redundancy in transmission. This is probably why analog TV standards use vestigial sideband rather than full SSB-- keep an attenuated but present carrier to aid in tuning, and use the bandwidth-limited lower sideband to improve SNR for important things like vertical & horizontal sync pulses... so reception had to get *really* bad to cause rolling or tearing. ATSC with 8-VSB might have taken advantage of this for hierarchical modulation, to make e.g. annoying audio dropouts less common, but as far as I know did not.

[@stargazer7644]

The 3 parts have to do with how the radio wave is modulated with information.

[@Steven-re7xt]

Radio school ft Gordon. Georgia. I got a good education on different modes. Actually got to use some modes in practice. so many to explore, the older F.D.M. TO PULSE WITH MODULATION. ECT. AND ALL WAYS GETTING BETTER FASTER . I thought 3,200 CPS was fast hi hi

[@VaporheadATC]

I remember seeing these antennas all along the highways. Now you never find them.

[@themagus5906]

"The Galaxy Being" in the first episode of "The Outer Limits" was sucked to Earth because he was made of solidified microwave radiation...be careful what you engineers f**k with!

[@adkforever6997]

@@themagus5906 Yes, but the Galaxy Being was a peaceful wave, a reluctantly and inadvertently teleported one at that. He wasn't a monster, and all of the silly humans (other than the radio station engineer who first made contact with him) were bent on destroying him. He proved his benevolence when he cauterized the engineer's wife's bullet-wound when the trigger-happy Army commander shot her instead of his intended target, the Being. THAT was some show almost 60 years old!!

[@adkforever6997]

@@themagus5906 The engineer in the Galaxy Being was played by Cliff Robertson, who during the 1980's was the TV spokesman for....wait for it.......A T & T Long Distance!!!

[@dalenewby1366]

How could AT&T go from such a remarkable, innovate company to the worst company on earth? Their greedy hands have now ruined yet another company - direct tv.

[@timothyrosman6371]

they got broken up and Bell Labs fell into disarray.

[@jordanhazen7761]

Present-day AT&T is really the old SBC (Southwestern Bell Corp) which was probably the worst RBOC in the country. They bought out what was left of the old AT&T (Long Lines, etc.), then changed *their* name to AT&T, for better brand recognition and to escape SBC's bad reputation. Divisions like Bell Labs and Western Electric were spun off or sold off (first as part of Lucent, then Alcatel) and are now only a shadow of their former selves.

[@visionofwellboyofficial]

Anti-trust

[@jameslawrence6260]

🌳🐾

[@kd1s]

You know what is really funny about this. AT&T used lots of Microwave but Bill McGowan one upped them with his own microwave systems. Its what destroyed the Bell System.

[@ericsvalland4417]

No, fiber optics killed the AT&T "Long Lines" microwave system.

[@kd1s]

@@ericsvalland4417 actually what killed long lines wasn't just fiber. Automation played a big part and so reduced the cost of long distance calls. That's what killed the Bell System

[@timothykearns2232]

I'm surprised that SSB came of it's own in 1980.........Analog channels were replaced by digital systems, used mostly on "cable carrier" systems. TDM vs FDM favored TDM years after this video was made.

[@orgami100]

Exactly I was thinking the same thing.. Trained at the US Army Signal school on the TR1000 a 96 Channel TDM multiplexer in 1969..

[@timothykearns2232]

@@orgami100 TDM in 1969? Wow. I had no idea TDM was around back then. I worked for LADWP Telecommunications for over 31-years, and it was all TDM on cable, and FDM on microwave when I retired in 2011.....only one FDM cable I remember---Lenkurt Panhandle carrier that was finally replaced in 1987. 12-channels, when they all worked, with OOB signaling....It was ancient!

[@orgami100]

@@timothykearns2232 First of all let me congratulations on your long term employment, hopefully your enjoying your pension... unfortunately I jumped around looking for that perfect elusive job.. As I recall from instructors, the multiplexer was part of a larger tropospheric scatter system stationed in ( Phillipines, Vietnam, Thailand, ) we probably spent over a month going through the schematics everyday and I never seen it again.. I'm retired in Thailand not far from U-Tapao air base where the B-52 where based during the Vietnam War, it was the southern leg of the tropo terminal..

[@obeyconformtoday829]

Then cell phones came out. Then smart phones came out. Then humanity was forever dumbed down with entertainment. The end

[@scratchdog2216]

Sounds So Bad, Slopbucket, Scientific Set Back, vs Angels Music, Advanced Modulation, Always Memorable. Yup, I'm biased.

[@jordanhazen7761]

Well, if you don't mind the doubled bandwidth and extra TX power... but for analog microwave systems I think FM carriers were the main alternative.

[@adkforever6997]

I see someone from the AM (A_ncient M_odulation) Ghetto has made an appearance. While AM is nice for broadcast/hobbyist radio, it is a serious joke for the non-broadcast radio user, especially on HF. Why do you think the telephone company employed SSB way back in the early 30's for transoceanic telephone service via radio? SSB saves AC mains power, saves spectrum space, is virtually immune to selective fading distortion which for the phone company was a BITCH for angry customers, gives many dB's of signal strength of ERP over AM, and is better at being heard by the far-end's receiver's noise floor. YAY-EM is fun. SSB is all work, no play. :)

[@jameslawrence6260]

Wont let me subscribe

[@theabbottagencylive5210]

Are they ALL abandon. Like the once’s in Wisconsin. By abandon does no one own them.

[@frzstat]

Another commenter said AT&T sold them. Some are used for cell phone, some for public safety communication etc.

[@thomasweeks3936]

There is an interesting microwave tower in key largo florida. It seems to be retrofitted for newer technology

[@theabbottagencylive5210]

@@thomasweeks3936 there’s one like that close to Washington IL. It’s been retrofitted. Another interesting things is that the Benson IL tower was destroyed by the infamous Washington IL EF-4 tornado.

[@westwasbest]

Bell labs and Western Electric were way ahead of their time, amazing Innovations, amazing people, and proof that the real technology and intelligence is still in the United States of America!

[@user2C47]

*was. We no longer have Intelligence and all of our technology is made somewhere in Asia.

[@johnnyblaze9217]

@@user2C47 is* china stole our shit

[@am74343]

Peter Thomas: The creepiest voice ever, besides Vincent Price!

[@Nighthawke70]

I bet they are regretting demolishing all those towers when fiber started to roll out in earnest. Those towers could have been used as cell towers.

[@ericsvalland4417]

AT&T didn't demolish the towers, they sold them to companies like American Tower. The "new" owners leased out tower space. Only sites that were not bringing in any revenue got demolished over time.

[@johansvensson830]

FORENSIC FILES NARRATOR!!!!!!!!!!!!!!!

[@christopher9727]

John 3:16-21 16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. 17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved. 18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God. 19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil. 20 For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved. 21 But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God. Mark 1.15 15 And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel. Come to the Father through Jesus Christ today he is the way to heaven and to the father repent today salvation is today repent tomorrow might be to late