Please feel to share this link with anyone and everyone...
Modern Radio SDR-101 V1.pdf
https://www.dropbox.com/l/qMaun4aqLPfoh5zQyVz4du
I hope you will find it interesting and informative.
KY6LA - Howard, Elmer
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- confident
Posted 5 years ago
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This will help explain how we got here.
Dan --- KC4GO
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Cliff (N4CCB)
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My only nit, would be a suggestion to add to your history lesson Armstrong's regenerative detector as a bridge between the crystal receiver and the superset. The regen ruled for decades as a combination of 1) an increased sensitivity crystal detector when not oscillating, and 2) a self-oscillating direct conversion receiver when it is oscillating.
Thanks for a great slide show.
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KY6LA - Howard, Elmer
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No dates promised for updates. Hi hi.
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Thanks for that. Your presentations are always useful and always find pride of place on my computer.
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Dennis, k0eoo
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KY6LA - Howard, Elmer
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https://www.youtube.com/watch?v=1DWnqk_taac
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My real, all time fave is the Lancaster Bomber. In my career I have had the honour to treat several members of flight crew and ground staff.
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Nice presentation sir!
I actually flipped through every slide.
How long did it take you to present it?
I do a lot of presentations for my job and they can go a looong time with that many slides!
Regardless, very interesting.
Thanks
KY6LA - Howard, Elmer
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Very nice presentation!
But, I think the first SDR actually happened back c.a. 1989 or so. Marconi Radio + E Systems, working on massive parallel pipelined array processors, controlled by a DEC/VAX computer. I don't recall how we did the I&Q. As far as I can remember, it was done numerically in a big Hilbert transform. We had a 10 MHz pass band, taken from the downlinks of overhead assets.
73 de Dave, N7AIG
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Based on my own experience, and from the many posts on this blog, it appears that the weak link in the whole system is Windows OS. Given enough time, FRS can work out most of the bugs inside the radios with their DSP + FGPA's. But Windows will continue to evolve in directions that are likely anathema to the needs of SDR.
But Windows, and most other OS, run now on VM capable CPU chips. We ought to develop a dedicated SDR OS that runs alongside the user OS, where you can have better control over the I/O and interrupt processing. No reason, given VM, that this can't coexist with all of Windows, OS X, and Linux.
73 de Dave, N7AIG
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By way of examples, have a look at the Berkeley Sprite OS, and the X-Kernel (nothing to do with MIT's X-Windows). These were early experiments, c.a., mid-90's to get higher performance from networked, diskless workstations - back in the day when memory was becoming cheap and hard disk space was still expensive. The bottlenecks were in the packet handling of the ISO Ethernet stack, much like many of the current bottlenecks for high-rate audio and I&Q streams.
73 de Dave, N7AIG
KY6LA - Howard, Elmer
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Here is a link to the PDF Files
https://dl.dropboxusercontent.com/u/10740053/Modern%20Radio%20SDR-101%20V2.pdf
Here is a link to the full Power Point which now takes about 75 minutes to present. The PowerPoint is Editable... Please Feel Free to use it as long as you give appropriate credit to the author.
https://dl.dropboxusercontent.com/u/10740053/Modern%20Radio%20SDR-101%20V2.pptx
Somewhere in the future I plan to add a section on Direct Up Conversion Transmitters found in SDR radios... but that is another day....
N4HY, Elmer
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KY6LA - Howard, Elmer
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Alex - DH2ID, Elmer
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Antenna used by above station. Arecibo 1,000 ft. dish, 61db forward gain at 70cm.

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