Before Broadcasting Satellite

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  • #18512
    e_dawg
    Participant

    Before broadcast satellite, how did tv and radio stations pick up live network feed back in the day. How did KATU, KOIN, KGW, pick up network feeds from New York, and how did radio back the days (KGW 620, KOIN 970, KEX 1190, etc) pick up radio network news back then?

    #18515
    Dxer1969
    Participant

    Teletypes, I believe. KNX had several.

    #18516
    QPatrickEdwards
    Participant

    They used special long distance telephone company circuits.

    #18517
    jr_tech
    Participant

    Much information here about AT&T “Long Lines”, which linked coast to coast tv radio and telephone before satellites:
    http://long-lines.net/places-routes/

    #18521
    Andy Brown
    Participant

    Immediately preceding satellite delivery, the major radio and television networks leased bandwidth on primarily point to point microwave relays to get across the country and up and down the two coast lines. Some AT&T long line circuits (coaxial) were used to reach some markets where microwave was not possible and to carry higher bandwidth feeds to broadcasters (sort of like the ‘last mile’). These microwave networks were put in place starting after the 2nd World War by AT&T using technology developed in the military. I believe most of this service was at 6 GHz. which was later also used by C band uplinks. When the networks moved to satellite (1980’s), AT&T long lines and microwave networks continued to carry their own network (phone call) traffic as well as continued to serve other bandwidth demanding clients. What put the microwave and long lines into the obsolete category was the growth and affordability of fiber optics. Many of their towers are still standing (four legged with broad faces on all sides) but the 6 GHz horns are often removed for more modern equipment. The old 6 GHz horns were huge, as big as a full size automobile. Radio networks were using long line coaxial feeds for years before there even were TV networks or video signals anywhere but in the lab. AT&T Long Lines, in fact, was founded in 1880.

    http://www.wired.com/2015/03/spencer-harding-the-long-lines/

    #18524
    QPatrickEdwards
    Participant

    Fantastic detailed explanation, Andy!

    #18529
    jr_tech
    Participant

    While many of the sites have been retrofitted or scrapped, don’t the old C band sugar scoops still reside on the tower at 9th and Burnside? If so, Are they still being used for local links, like perhaps the link to Stacker butte?

    #18532
    Andy Brown
    Participant

    Thanks, QPE.

    jr tech, the horns are still downtown (https://goo.gl/maps/g4CbxrCRPiE2). On Saturday, I was shopping downtown and found myself heading north on SW 12th and noticed that they are still there, however it is unclear if all of the horns still have a clear path. I know the switch that used to be up on Livingston Mtn. in Clark County is no longer in use, that is to say the AT&T square tower is there with a weather radar dome on it (https://goo.gl/maps/p9Wjt2Jcz7n).

    #18535
    Andy Brown
    Participant

    This 1976 map shows the microwave and long lines in Oregon. With Livingston Mtn. out of the circuit, it’s unclear if any of the eastward hops it fed would still be illuminated.

    http://long-lines.net/places-routes/maps/OR76.html

    #18541
    jr_tech
    Participant

    A sad collection of sugar scoop horn antennas

    #18570
    Broadway
    Participant

    In the 80’s I heard about up and coming networks using subcarriers on “super” TV cable channels that were on in different markets to distribute their audio.

    #18571
    Alfredo_T
    Participant

    ^^^
    The MTS analog TV standard had an audio subcarrier at 102.271 kHz called the “PRO” channel. This was a one-way audio channel meant to be used in a similar way to how FM stations used SCA.

    [One interesting fact that I did not realize until very recently is that in MTS TV, all of the subcarriers were broadcast by frequency modulating the video subcarrier, not the audio subcarrier. The 4.5 MHz intercarrier sound detector used in virtually all TVs would contain the combination of the mono audio and the subcarriers because it is demodulating the difference between the two carrier frequencies.]

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