SDR kit - Software Defined Radio

fat-tony

One for watty I think:)
I've been researching the purchase of an SDR kit (receiver only), but I'm having difficulty in getting up-to-date info. There are lots of references to $20 - $30 starter kits, but when you dig you find that the website info is 4 -5 years old. Tony Parks KB9YIG seems to be the source of most of the Softrock kits, but availability seems to be an issue. On the other hand, it would appear that commercial built examples can retail at €1,000 or more:eek: I'm looking for a reliable source of a multi-band receiver that I could build myself. Any pointers?

watty

See http://groups.yahoo.com/group/softrock40/?yguid=271843613

Membership might be required. Last message about kits 15 June 2010. Last KB9YIG site update maybe May 2009.

Yahoo Groups Softrock 40 seems the most up to date place.



Some of these are SDR (but not all)
http://wsplc.com/acatalog/Computer_controlled.html

Google GNU Radio

Softrock is the cheapest and are quite good. I have built two versions, inc one with transmitter. The earlier versions you change crystal or daughter board. Latest version does most of HF band using a USB driven DDS as direct conversion clock.

These section has softrock kits

http://wsplc.com/acatalog/SOFTROCK-LITE.html

http://wsplc.com/acatalog/SOFTROCK-RXTX.html

http://wsplc.com/acatalog/Kits_-_Softrock.html

Flex Radio
http://wsplc.com/acatalog/Flex-Radio_HF_Transceivers.html


I have use the Free SDR SW
Rocky
PowerSDR
M0KGK
Spectrum Lab
Winrad from "weaksignals"

I have used XP, best other alternative is Ubuntu. Vista is not good. Win7 isn't compatible with much SDR & Ham SW.

Using VAG (Virtual Audio Cable, not free but cheap) I have connected SDR SW to MIXW, Digpan, Spectrum Lab, WSJT, DReam, DigiSSTV, MMSSTV, JVcomm etc.

You need two sound cards for some software or if transmitting. The "high end" SDR use USB, ethernet or Firewire and instead of a band equal to twice the sound card bandwidth (usually a bit under 1/2 the sample rate) can do in some cases up to 30MHz at once and record multiple stations.

Most cards only do 22KHz bandwidth no matter even if set to 192kHz sampling due to analog input filters. Some "HD Audio" cards do about 40KHz .. 45KHz bandwidth on 96KHz sampling.

The only sound card I found useless was the PCMCIA soundblaster. Most builtin Mobo chips on Desktop & Laptop seem to work with some adjustment. The Soundblaster PCI cards and USB external boxes seem to work. For SDR you need matched Left & Right inputs for I & Q. Mono only won't work.

fat-tony

Many thanks for the detailed reply watty. It certainly gives me a lot to go on. Although, in the arena of fully-built commercial SDRs it's somewhat ironic that a device which contains a fraction of the components of a fully-specced HF receiver should cost so much more.

I actually found a built PCB on the Elektor website for £86 - this is a USB controlled SDR with frequency range 150kHz to 30mHz.

Have you found that the kit versions compare favourably with the performance of conventional HF receivers or are they really just an interesting sideline?

watty

Both the Softrock I built very good but only could be "tuned" +/- 20kHz either side of crystal frequency ( I have two crystals) due to bandwidth of sound card. Inside about +/- 20Hz to 100 Hz of crystal frequency can't be tuned due to low frequency limit of sound cards.

The performance on 80m or 40m exceeds many HF receivers, especially older ones like FRG7700 or any vintage Eddystone or Racal. My current one is Softrock RXTX v6.2 which does 80m or 40m (jumper). It has a choice of two crystals (jumper) and I put a socket for one of them. It uses a crystal frequency x4 the 40m band center frequency.

The USB "wideband" ones need addtional band low pass filters (about 6 to cover 2MHz to 30MHz ) for TX and RF tuning (varicap or mechanical) for RX or TX for best performance I think. The DDS based VCO (USB controlled) will be noisier than a crystal but quieter than most PLL synthesisers.

I have "header pins" that fit IC style turned pin sockets on underneath on all the SR RXTX 6.2 connections and the socket strips on a single 100 x160mm eurocard veroboard/stripboard.

On left there is 5 x 3.5mm stereo jack sockets and 2 x bicolour LED

1. Ear
2. TX Line in from PC I & Q
3. TX/RX LED (Green RX, Green+Red = Orange on TX)
4. RX Line/Mic out to PC I & Q
5. Mic
6. dot/dash green/Red LED
7. Paddle/Key

On right

1. Power Coax jack for +12V
2. BNC for RX/TX
3. On/OFF slide switch
4. DB9 female to PC serial port (Handshake lines in are key or dot/dash paddle, handshake out is PTT-TX)

I'll probably give it to some newcomer (if they passed the test today ) as I have a FT817, FT101ZD MKIII and Racal Syncal30.

I bought a Spartan FPGA starter kit with idea of a standalone SDR (no PC). I'd use a PIC & 128x64 mono GLCD for display, or ARM with 320x240 touch screen for UI. I'm stuck on choosing suitable ADC and DAC as the included ADC and DAC are only a little better than Sound Card.

watty

See also
http://groups.yahoo.com/group/ham-designers/
http://groups.yahoo.com/group/lazydogsdr/

619C

I know its about kits but to see what you can achieve have a look at this



http://websdr.ewi.utwente.nl:8901/

Parent site is
http://www.websdr.org/

fat-tony

I found that site last week during my initial research. It's absolutely fascinating to have that level of control over the receiver and signal bandwidth on-line and useful to compare a receiver based in the Netherlands against my own (Fairhaven RDS 500).

619C

I would like to setup one of those but it seems difficult to get the kit at the moment.
I have listened to the 'telescope' 70cm dish one quite a lot and it is fascinating.
At the moment they are just replaying recorded stuff but when its live and there is a contest or lots of activity it is great to hear eme stuff especially when I dont have any eme kit.

Also the number of users per site is great.

watty

see
http://www.tapr.org/

http://openhpsdr.org/wiki/index.php?title=MAGISTER

http://www.hamsdr.com/

I bought my FPGA board for DSP Radio here
http://www.trenz-electronic.de/products/fpga-boards/digilent.html

They have a good selection of Spartan 3 boards.

See also
http://www.techtir.ie/info/electronics-suppliers

and
http://www.techtir.ie/node/1001701