[Premium-Rx] Worlds First DSP-Receiver

[Tim Shoppa]

"Rev. Harry Winter" <Rev-hwinter at msmisp.com> wrote:
> My name is Harry Winter and I am a retired "Member-of-Staff" 
> with Bell Labs. (Now Lucent Technology)  I am at the present 
> working on "upgrading" my CEI-type 232-2 receiver. --- (marketed 
> first in 1969, shortly before CEI became part of Watkins-Johnson)
>
> This receiver was called a "TUNABLE FILTER" by the designers and 
> has a very low third IF of 15 or 25 KHz. No signal demodulation 
> circuits or narrow band-pass filters are provided. Final filtering and 
> demodulation was obviously to be done by a very powerful mini computer or 
> even a Control-data or IBM Mainframe; --- in 1969 there was no PC,
> that came only in the late 70's and they were running only at a 
> few megahertz. Maybe even the Mainframes were not fast enough at that 
> time and a tape record of the 15 or 25 KHz had to be used instead.

When I was doing this sort of stuff in the 70's, no computer (at
least accessible by large corporations...) was available to do the DSP
in real time. What we used, were large PCB's stuffed full of 7400
(or sometimes ECL) series ALU's that daisy-chained to implement the
DSP algorithms. Often, but not always, the constants that drove
the ALU-based filtering was based out of a mini-computer. (Sometimes
we just drove it with thumbwheel switches).

Multichannel instrumentation recorders abounded. Most of this
was heavily shared with analog telemetry logging - in fact your
15 to 25kHz IF sounds a lot like the telemetry bandwidths we
worked within for FM. Is it obvious that your receiver was not
intended for telemetry through to the instrumentation recorders?

Up through the 80's "bigger better faster" was done by stuffing
very dense PCB's (actually mostly Multiwire, not printed, circuitry)
with ECL logic, stacking the logic boards next to cooling fans, and
running it all with power supplies that sourced several hundred
amps of DC to run it all. This would've been overkill for 15 to 25kHz :-).

Tim.