[GreenKeys] Early Fax Machine/ NBC Radio News on the Hour

[Sheldon Daitch]

The AP wirephoto circuit was still amplitude tone modulated at least up until the 1980s.

I think the same for the UPI wirephoto network.

I don't remember the frequencies used and I am almost sure the two networks had different tone standards.

The AP (and I would guess the UPI) system started each photo with a tone set up, I think the maximum level, but I don't know if that was for black or white.  Then the system sent a staircase of tones from the lowest level to the highest level, that would set up the machine for the black and white extremes, then the photo scan information was sent.  Of couirse, this long initial tone also brought the photo receiver out of idle status.

The system relied on the level stability of the AT&T network which apparently was satisfactory for the most part.  Level shift would show up as changes in the black level in the photo.

The reason I don't think the two wirephoto networks used the same tone frequencies is that when I was with the AP out of Raleigh, I went to a newspaper which was having wirephoto machine problems.  I did the usual checks of the machine, the newer AP laserphoto machines (made by Harris) and did a maintenance cleanup of the heater/developer shoe and put the unit back in service.  I waited for several photo cycles but the unit never printed out a photo.

At first, I wasn't paying a lot of attention to the wirephoto audio chatter, the talkup for the photos and then I realized the voices didn't seem to be the right folks and the locations mentioned weren't the usual AP bureaus.  Turned out that AT&T in Raleigh had patched the wirephoto circuit to the newspaper to the UPI network instead of the AP network.  Changing the patch to the correct circuit, and yep, the machine came to life.

73

Sheldon


________________________________
From: GreenKeys <greenkeys-bounces at mailman.qth.net> on behalf of Bruce Gentry <ka2ivy at verizon.net>
Sent: Friday, December 30, 2016 7:58 AM
To: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Early Fax Machine/ NBC Radio News on the Hour

Into the early 1960s the tone of a fax machine with a tympani roll in
the background was used as the intro to the hourly news report on NBC
radio. As best I can recall, the tone was amplitude modulated. However,
I have seen  another wirephoto machine that used FM audio tone.
Probably from the 50s or 60s, it was all tube and used a tuning fork
oscillator to drive the drum motor.

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