[hpsdr] computer memory added question

[Tony Langdon]

At 10:26 PM 7/16/2007, michael taylor wrote:


>This is a good example why we weren't playing with SDR twenty years
>ago, it was not just the cost/availability of high performance A/D
>converters, but also the availability of low cost yet sufficient
>computing resources necessary to decode signals in "soft" real-time.

Well, I can tell you what it was like using 20 year old 
technology.  During my uni years, I studied some DSP at an 
introductory level, but we did get to do a bit of practical stuff 
like implement filters and basic things like tone decoders.

We were using 12 bit A/D and D/A (some proprietary data acquisition 
boards) and 10 or 12 MHz 80286 based machines (what would have been 
state of the art in 1987 :) ).  Software wise, we were using C, which 
was compiled using Borland Turbo C under DOS.  Only one of the 
machines had an 80287 math co-processor.

Well, with these machines, the best sampling frequency we could 
manage, while doing useful DSP work (such as basic filtering) was 
around 200 - 400 Hz.  The machine with the co-processor managed 
around 10 times that sample rate.

Fast forward to 2007, and it's nice to see most of us have PC 
technology capable of doing complex (pun intended) processing at 96 
or even 192 kHz sampling rates in real time, and at the same time, 
manage a complex GUI (our DOS based stuff had no interface, we had to 
monitor its performance using CROs and spectrum analysers.

Back then, one could only dream.  Now it's a reality (and I'd better 
get the proverbial into gear and build my Atlas!). :)

73 de VK3JED
http://vkradio.com


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