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UHF channels 70 to 83

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Re: UHF channels 70 to 83

Post by Turkeytop » Sat Dec 31, 2016 8:54 pm

Plate Cap wrote:
Fingerboard Corners wrote: Then they made it illegal to listen to cell phones, whereas portable phones were legal to listen to and you had a good idea on who it might be close by on those.
My first mobile telephone, in 1978 or so, was UHF (454-459 MHz) system, first operating on Michigan Bell's IMTS system, then later on RAM Broadcasting's system.

Listening to the other users was easy; there were only 12 channels on each system. Some very, very interesting conversations went on....I knew someone who often drove with me, and when I was out of the car on errands, he would amuse himself by listening. He even got to know the personality of a few other users, from listening so much. There were some movers and shakers, and they had no clue on earth their calls were essentially public.

If you are doing the math in your head, you're right....24 simultaneous conversations on UHF, and another 13 on VHF....the 28th person in southeast Michigan trying to make mobile call couldn't.

Cellular didn't come into viable use in the area until about 1981 or so; I get a kick out of the 'kids' at the Verizon store that think mobile telephony started with cellular bag phones. It was a difficult transition from IMTS to cellular, as the cellular build out was rather slow.

The forerunner to what is now Verizon here, "Detroit Cellular Telephone Company" was especially slow to build out, choosing tall sites (and therefore not a lot of channel reuse) and ended up suing and winning the right to place their customers on Ameritech's system, pretending all the while the service was coming from them.

Ah, history.
That answers something I've wondered about for a long time. I remember the days long before cell phones and some people did have phones in their cars. It was mostly important people in Limos..

Was the range on those devices limited to line of sight from a single tower?

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Re: UHF channels 70 to 83

Post by Plate Cap » Sun Jan 01, 2017 7:45 am

Turkeytop wrote:
Was the range on those devices limited to line of sight from a single tower?
Generally speaking, yes.

Larger geography systems (locally for me, Detroit and Lansing) used voting receivers. There was one base transmit site, but a few receiver sites scattered around the service area. They would all listen for the transmissions from the mobile on the channel in use, send the audio down a leased line to a central voting comparator, and the best audio would be automatically selected and used. Since the first 'side' to fail in most base-mobile systems is the mobile to base side, this would increase the service area somewhat.

The box that many broadcasters won’t look outside of was made in 1969 and hasn’t changed significantly since.

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Re: UHF channels 70 to 83

Post by WOHO » Mon Jan 02, 2017 9:27 am

Thanks Rugrat- I was going to mention WBGU channel 70 - I recall them doing a remote at the Wood County Fair in the early 70's and was wondering if my rotary UHF tuner went beyond CH30 (and as you mentioned, then moved twice going to 57 and then 27 with a flashcut).

I don't recall what the BGSU board decided about them taking a TV buyout from the crazed FCC TV auction, but if they even moved their unique programming to a subchannel of WGTE30, the WGBU transmitter is way SW of the area, and CH30 might not make it that far out in digital fashion.

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