IS 101 Collins Radio System
(Rearward Communications)
Courtesy Bob Davis
This is a high power VHF over the horizon ionosphere
scatter system. It is synchronous for timing reasons.
It was single sideband, supressed carrier, time division
multiplex, dual diversity reception system.
It featured multi teletype channels and one voice channel.
When you used the voice channel the whole station knew
it because the diesels hummed a song. One strange feature
of the system was that it read out info faster than it was
reading it in so it pause to let the system catch up.
It passed a thirty day 24 hour/day reliability test before
acceptance by the Air Force and it passed with flying
colors. Upon completion I was re-assigned but I
understand the system started having multi-path
problems so modifications had to be made.
To find out about that you would have to contact
the Federal Electric people who received the
operational contract.
Additional Comments
By Bob Davis
I was just looking over your site and I noticed one thing I did not mention about
the rearward site at Anchorage Alaska.
The antenna used for the IS101 system did not conform to the specs for the rest
of the line. We used the old rhombic antenna that they had been using and it
seemed to work fine and perhaps thats why we had the multipath problems
that I had told you about because you would not get the directional pattern
that would occur if you had a dish like the rest of the sites.
Bob Davis.