SDR? What does that mean? I know I asked myself the same question when first looking into how to get on the air on with the HF bands. After a visit to a local Hamfast and talking to some very helpful Hams, I was turned onto the SoftRock SDR. My mind was filled with SoftRocks and SDR’s and more questions… I still wasn’t very clear on how it actually worked. I knew three things: You needed a computer, SDR stood for Software Defined Radio and I really wanted one.
Whenever I “Googled” SoftRock the top links were pointing to Tony Parks, KB9YIG site: http://www.kb9yig.com/ and WB5RVZ, http://www.wb5rvz.com/sdr/. Ok, I thought I will check out these kits and see if I can afford one. What was shocking to see was how inexpensive the kits are. Only one problem, every kit said to “Come Back Soon”. Just on a whim I decided to email the admin, which of course turned out to be Tony himself. I wanted to see when some kits would come available. He just happened to have some SoftRock Lite II Combined Receiver Kits available. I just couldn’t wait to get my first SDR!
It arrived shortly after the order and I began feverishly putting the receiver together. Between Tony’s kit and WB5RVZ’s build notes it was a quick build even with the surface mount components. I downloaded the SDR-Radio software that I stumbled on during my SDR research and fired it up. All I could say was WOW, it was amazing to see all the signals spread across the waterfall and I could just change the mode and click on one and it started demodulating the signal. Even more surprising was that I built it right the first time! CW, SSB, PSK31 RTTY all of it was right there for the taking. I was hooked!
Visions of an all mode, all band HF receiver danced around in my head, so back to Tony’s site. He had a SoftRock RX Ensemble II available so I snatched that up as soon as I could. You will notice that these kits are in VERY high demand and you may have to be patient. Again, the SoftRock SDR was amazing! I could hop around bands and instantly see how the conditions were on each band. The SDR-Radio software has many, many digital modes for decoding including CW and the most popular PSK31. It is something that needs to been seen to be appreciated.
Like all hobbies one of anything is just not enough. Tony was beginning to be my one stop shop for SDR’s. I stopped looking anywhere else because of price. This time I was seeking a SoftRock RXTX for transmitting. No such luck, no kits available. Like many Hams, on to eBay!
I found a SoftRock RXTX 6.1 for sale as a “tech special”, meaning it doesn’t work but you are welcome to buy it and try to fix it or use it for parts. I ended up winning the bid for about what the kit cost originally. After receiving the kit I bought a RS enclosure, switches, audio jacks, etc. Much drilling and dremelling and a few nights later it was all packaged in a little aluminum enclosure. Of course I knew it wasn’t going to work but it was much easier to work with initially connected up correctly. To my dismay and no surprise it was dead, nothing, not a peep. It powered up and the PTT circuit worked but no audio (or I/Q signals rather). I worked on it for as long as my patience could afford before I shelved it and moved onto something else.
I thought it would be a complete loss but I decided to tackle it one more time. This time I took a more methodical approach and went component by component to cross-check them with the schematic and bill of materials. I checked all the solder joints and toroids. I found several mistakes that the previous builder made including some components that were missing from the PCB. Thankfully the eBay seller included the original parts bag so it was a matter finding the right one and soldering it in. I also had to remove some band specific components that were soldered in by mistake. I hooked it up to the computer and watched the waterfall. Finally success at last! Since the enclosure was basically done from my initial attempt it was essentially a completed rig.
I asked a fellow local Ham, Marv, KK4DKT if he would test listen for me to make sure I was getting out and with a little tweaking he was hearing me 100%. Fantastic! After that confirmation from Marv, I went onto calling CQ using PSK31. N4UED was the first to pick me up. He was over 600 miles away. That was truly exciting to see what 1 watt could do. Since that first QSO on the SoftRock I have made over 20 contacts with the furthest being the Republic of Panama at over 1500 miles. All with 1 WATT (or less)! Very impressive indeed, if you were thinking of getting into SDR, do it, you won’t regret it!
Ok, after that long winded exhortation of my SDR experience and why you should have one, onto the technical stuff.
Software:
SDR-Radio Console (Great receive software!)
Rocky (for RX and TX of CW and PSK31)
HDSDR (for RX and TX of AM, FM, CW, SSB)
Update Feb 08, 2012: Added SDR-Radio I/Q wav files for your testing (also works with HDSDR but without time and freq markers):
Recorded for 5 minutes at 96Khz bandwidth
Hardware:
Important: You MUST have a sound card capable of left and right channel split on the stereo input. In other words true stereo line in.
Note: The SoftRock isn’t the only game in town for SDR , there are many other options available but they come with a bigger $$$ tag. Just google it.
Technical documentations:
Abbreviations:
- CW -Continuous Wave
- HF- High Frequency 3Mhz-30Mhz
- PSK31 – Phase Shift Keying 31.25 Hz wide
- PTT -Push to Talk
- QSO – Communicate with
- SDR -Software Defined Radio
- WOW – In awe, Amazing!
Pictures
Online
