Homebrew SDR?

H

holobox

New Member
I'm starting this new topic as a place for enterprising amateurs to share their SDR design experiences. I'm taking the plunge and designing my own SDR transceiver. I'm sure that 1) it will never measure up to that of a Flex and 2) I'll probably spend more $$$ in the end than it would cost me to own a Flex. But, I'm of the opinion that the experience will be invaluable. I'm an electrical engineer and I love to build - but SDR will stretch me quite a bit. I hope that others will join in the discussion here, or tell me where the discussions have already started - I'm afraid I haven't found the holy grail for SDR homebrew.

To get startrd, I'll share some details of my design which is starting with a simple general coverage receiver. I'm using Analog Devices AD8333 which is a dual-channel I/Q demodulator (i'm only using one of them!) in a very tiny QFP. The local oscillator is a Silicon Devices Si570 I2C programmable VCXO. I/Q sampling is on my laptop using (presently) the PowerSDR 1.9.0sr40 software.

Soldering down the AD8333 was an exciting adventure. Four of these devices could rest comfortably on the top of my little fingernail. But I was able to do the trick using a surfboard adapter that was "close" to what I needed accomplishing the reflow operation in a fry-pan. (remarkably easy!)

Early results are very encouraging, When the bands are cooperating, I'm hearing many signals from -100dBm to -20dBm (as measured by PowerSDR). I'm having to use a separate program to control the Si570 having not figured out how to get PowerSDR to talk to the USB interface. (I'm using the Si570 kit from SDR-Kits.net)



Anyone else out there?

Charlie
WA4APL
 
Hiya Charlie

I've moved your topic here (in the SDR forum) because I thought that you might get more 'takers' here. Also, because this is the SDR section you are more likely to get 'SDR-heads' reading your posting.

Wow, what a project! It's been a long time since I've done any R&D work, my days are filled with bringing dead radios back to life.

I used to work all day long with QFP devices, but I never used a frying pan hi hi.

You'll have to take a picture or two and add them to the post (look for the attachment button when you are typing in a post).

I've seen a few sites that mention the softrock radios, but these are generally just folks trying to get their kits to function.

Flex are supposed to be introducing a new 'toy' to their range (Flex 1500), but there is no supply as yet, at least not in the UK.

It will be interesting to see how your project develops. Don't panic if you don't get a immediate rush of replies, I've noticed that we seem to get more visitors to particular topics once Google has indexed them.

Welcome to the forum by the way.

Best 73, Mark.

p.s. you could always make this the SDR home-brew holy grail!
 
Thanks Mark for getting me in the right area! I'm blogging this project on Tumblr at the link below for anyone who's interested.

holobox: Software Defined Radio


So far, mysterious spectral ghost images seem my biggest problem. Sensitivity seems good enough for now, although I'm getting a fair amount
of hash from somewhere so, the sensitivity may be somewhat better.

73, Charlie WA4APL
 
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