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Author Topic: Early SDR radios?  (Read 647 times)

AC7CW

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Re: Early SDR radios?
« Reply #15 on: March 16, 2021, 10:56:56 AM »

I read an article in an engineering magazine, late '80's, wherein a ham walked us through the design of a Tayloe architecture rx using a PGA to do the repetitive motion of FFT to produce what was essentially a self contained SDR receiving way above the HF freq's. I recall that I was stunned by that, had no idea Tayloe existed at all and doing the FFT in a PGA seemed like pure genius. The author, a ham, just walked through the design like it was just another ho-hum day after hours in the lab...

The Tayloe IQ architecture patent wasn't filed until 1998.  Was that magazine article in the late 80's or late 90's?

Tayloe published in the 1930's
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AC7CW

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Re: Early SDR radios?
« Reply #16 on: March 16, 2021, 11:19:02 AM »

I'm working from memory here but I had to check. Search on "Tayloe Detector" in wikipedia gives me Taylor Swift.... Digging more I find that Van Grass published in the '50's http://www.arrl.org/files/file/Technology/tis/info/pdf/030304qex020.pdf... at any rate the radio I talk of in the article had I/Q and a DSP processor programmed into a PGA of some kind. It was pure brilliant at the time and I wanted one but too lazy to learn PGA programming. I went to the XYLEX school but never really got started on it. FFT processing is just a couple of steps repeated a thousand times. It's a natural for a PGA
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K6BRN

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Re: Early SDR radios?
« Reply #17 on: March 16, 2021, 11:48:45 AM »

Hi Max:

Digital Signal Processing (DSP), also sometimes called "SDR" (though it rarely is), has been around for a long time.

In the space industry, large scale digital signal processing became widespread in the 1980's with processed bandwidth increasing rapidly in the 1990's and by the 2000's dominated broadband flexible communications payloads for satellites.  By 2010, a typical broadband DSP payload fielded 10 GHz of processed bandwidth while the latest payloads handled double that using real/IF sampling.

Hughes Space and Communications, later purchased by Boeing in 2000, commanded the field due to a combination of very efficient and outrageously flexible DSP architectures and adaptation of cutting edge terrestrial ASIC technologies to the space radiation environment - a VERY successful venture.

DSP processing included not only channelization and demodulation/modulation and switching, but precision beamforming for hundreds of beams that could lock on to and track individual clients or adapt satellite coverage as needed.  Adaptive RX/TX equalization was pretty standard on these payloads as well.  About thirty years ago.

Today, Boeing still produces many DSP spacecraft payloads, frequently marketed under 3rd party names. 

https://www.researchgate.net/scientific-contributions/Brian-A-Clebowicz-70255857

https://boeing.mediaroom.com/2001-09-18-Boeing-Delivers-Final-Designs-of-Powerful-Next-Generation-Integrated-Circuits-for-Spaceway-Satellite-Payloads

https://patents.google.com/patent/US7542716/de  (Broadband channelizer payload seminal patent)

Brian - K6BRN
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N6YWU

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Re: Early SDR radios?
« Reply #18 on: March 16, 2021, 12:40:41 PM »

The earliest reference in Wikipedia for actual real-time software radio hardware was an 1984 E-Systems (Raytheon) implementation for the DoD, likely using something like multiple FPS AP-120B array processor boxes, which were roughly 1 to 10 Mflops and $100k (in 1980 dollars) per box.  Even earlier, radio frequency processing may or may not have been possible at national labs on Cray 1's or CDC 7600's (several million $USD per).

e.g. not affordable by any typical ham
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KS2G

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Re: Early SDR radios?
« Reply #19 on: March 16, 2021, 01:33:46 PM »

Tentec Pegasus 1999.

Kachina 505DSP
Introduced at Dayton Hamvention in 1997
http://kachina.wrarc.net/pdf/505bro.pdf


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K6BRN

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Re: Early SDR radios?
« Reply #20 on: March 16, 2021, 02:10:59 PM »

Hi Ron (N6YWU):

The Hughes TDM Comm Processor (commercial) was introduced at about the same time.

But before that, TRW in Space Park had built and fielded complex DSP payloads, as early as 1980.  Hughes surpassed their efforts only in the late 1980's and until about 1995 it was a close race.  Then Hughes surged ahead, buoyed by many commercial sales, adaptation of IBM ASIC technology and more advanced/radical DSP algorithms, while TRW attempts to commercialize their DSP space technology just did not work out.

Wikipedia is nice, but actually being in the middle of this race provides a little more insight.

Brian - K6BRN
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W6RZ

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Re: Early SDR radios?
« Reply #21 on: March 16, 2021, 04:15:11 PM »

Tayloe published in the 1930's

Dan Tayloe (N7VE) was born in 1957.
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K7LZR

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Re: Early SDR radios?
« Reply #22 on: May 29, 2021, 10:10:18 AM »

Tentec Pegasus 1999.


This is often a source of confusion. The TenTec Pegasus is NOT a Software Defined Radio (SDR). The Pegasus and other radios of the time like it - Tentec RX-320, 340, Icom PCR series, Kachina 505, etc. are simply conventional superhetrodyne hardware receivers with Digital Signal Processing (DSP) added into their IF or AF architecture.

These radios are designed to be controlled BY a computer using appropriate software, but that is as far as it goes. The computer is not involved in any way with signal demodulation nor processing. Very similar to CAT control of an analog radio.

So definitely not true SDR as we are used to with, say, the SDRPlay receivers etc. but technically software definable due to their firmware.
« Last Edit: May 29, 2021, 10:18:40 AM by K7LZR »
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N6YWU

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Re: Early SDR radios?
« Reply #23 on: May 29, 2021, 11:25:56 AM »

If you add DSP to the audio after the demodulator, then that seems to be a radio with an audio processor, not an SDR, as nothing is done in software in the radio/RF signal path.

But if a radio adds digital sampling and DSP to even at a very low IF (VLF or ELF) and before the listenable audio demodulation, it's hard to tell that architecturally or signal-path-wise from newer or current (much higher IF) superhet SDRs, except by the lower digital processing and ADC sample rate requirements, as limited by the earlier technology.

So it's a matter of how you slice the definition between audio processing (audio CW filters and TNCs, etc.) and SDRs.
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