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R: possibly OT - ATS-3

----- Original Message -----
From: Paul Yeager <w4ski@arrl.net>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, September 05, 2002 8:00 PM
Subject: [amsat-bb] possibly OT - ATS-3

> Does anyone have current information regarding the ATS-3 satellite?  Is it
> still alive, and if so, who is coordinating it's use?
> Best I've been able to find is a web page around 2 years old that states
> operating schedule.  Email to the author of that page (Paul Eden) bounce
> I realize this may be a bit off-topic, as ATS-3 is not a ham satellite.  I
> was hoping somewhere out in amsat-bb-land, someone might have an answer.
> Thanks in advance,
> Paul W4SKI

Hi Paul W4SKI,

Back in 1970 i was receiving excellent WEFAX photos on 135,600 MHz from
ATS-3 (Applications Technology Satellite ) when it was shifted time to time
from over the Caribbeans up to 40 degrees West longitude over the equator
and than it was available from Naples with only 6° elevation.

Only i was using a 10+10 element crossed yagi with a 135-137 MHz home made
converter antenna mounted but signals where strong enough.

The APT standard used on VHF 135,600 MHz for WEFAX was the same as for
ESSA-8 and TIROS meteorological satellites.

The 135,600 carrier on satellite was frequency modulated by a 2400 Hz
subcarrier and this subcarrier was amplitude (AM) modulated by the video

At that time no PC or software was available for the APT radio ham and
it was necessary to extract the 2400 Hz subcarrier from the RX FM
discriminator and than phase-lock with it a local 2400 Hz oscillator on the
ground station.

The 2400 Hz  satellite-sincronized signal on the ground was than divided
by 40 to get a 60 Hz signal that after tube amplification at a level of
around 10 watt was used to drive a syncronous motor with a gear box to let
rotate at 4 rpm the drum of a home made faximile and this represented the
horizontal scan rate of the picture.

At that time,1970 to divide by 10 it was necessary to use 4  JK FLIP FLOP
and a NOR but i was fortunate enough to get integrated RTL MC790P and
MC789P flip flop from Motorola because many other friends where using
6SN7 and 12AT7 tubes to divide !

The video signal ranging from 150 to 1600 Hz was amplitude detected by two
diodes from the 2400 Hz signal and than tube amplified at a level of around
15 watt to modulate a AR-3 argon bulb inserted in to an optical focusing
lens system got from a microscope wich was mounted on board of a carriage
slowly traveling in front of the faximile drum and this represented the
vertical scan rate of the picture.

The focused and modulated light from the argon bulb was sent to make a
sharp spot on a positive photographic paper folded over the drum that at the
end was developed to get the picture.

Everyting was made in the dark shack with the only aid of a green lamp and
a lot of bottles full of chemical  developing ingredients but at the end,as
soon the picture was born  it was very exciting indeed.

I still have many picture and many tape recorded with signals as well the
faximile in good condition to work for a museum by nobody like to get it and
i dont like to scrap it,except my wife.

The ATS-3 satellite was managed by the National Environmental Satellite
Center  and if you are interested in more technical details try to get from
Goddard Space Flight Center Greenbelt,Maryland, if they still have in their
archive,a copy of the following document:

NASA/ESSA Application Technology Satellite (ATS)-3 Weather Facsimile
(WEFAX) Experiment Participants' Guide" june 1968

I believe that ATS-3 died but i am not completely sure but in any case the
opportunity was welcome to remember a nice time.

73" de i8CVS Domenico

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