IOTA Contest, 29 July 2006
HB9CZF - SOAB LP 12h-CW non-assisted
Rig: SDR-1000 with 100W; PowerSDR v1.6.2 and PreSonus Firebox Soundcard; Ant: 3el SteppIR and 42m LW
The previous three years I took part in the QRP section which I could even win with a CW only entry. For 2006 I planned a new experiment. The probably most exiting development in amateur radio today is around "Software Defined Radio" - SDR. Instead of using an e.g. normal K2 the SDR mixes the antenna signal to an e.g. 11kHz IF-signal where A/D conversion occurs. From then on anything else is done in software on a standard PC.
 |
This picture shows my setup during the IOTA contest.
The Dell D610 notebook to the right is the userinterface of the SDR-1000 manufactured by Flex-Radio. The Hardware itself is hiding
behind the screen. The model I'm running includes the 100W PA. The antenna jack is routed
through the Drake powermeter and then to either a 42m LW (40/80M) or the 3el SteppIR for
10/15/20m. The TL-922 PA in the background wasn't used. The PC to the left (Dell D600) was running Win-Test v3.0.7 and CW interface was performed by the EZMaster sitting on top of the power meter. Luckilly the CW-keyer-cable was compatible with the one I soldered for the K2. |
Since I'm living in HB9 the only tactic that pays off during IOTA Contest is to S&P the whole time. In previous years I was using my K2 and S&P works like this. Select one band and work up the frequencies an try to get into the log whatever you hear. At the same time Win-Test will add all QSO to the bandmap. As soon as you reached the upper bandlimit jump back and try to find more stations in the holes you can spot on the bandmap. After you worked the whole band you switch to the next one and start all over. As a QRP-station you are not able to work all stations first time and therefore I moved on after lets say 5 tries and came back later.
Working with a Software Defined Radio is a bit different, I would say a bit easier. First of all you can see on the PowerSDR (V1.6.2) console the spectrum +/- 10kHz of your centre frequency. And this screen is simply amazing. Even the weakest signal will show up as a small needle (the FFT resolution is 11Hz). All you need to do is to take the mouse and spin the wheel. As soon as the signal is in the passband press the "0 beat" button on PowerSDR and the signal is where it should be (works only in CW). I discovered during the contest that a smaller filter can be benefitial again. Since I see what is going on the screen I can filter as narrow as possible. Even the 25Hz filter and QRQ is no issue with an SDR. The 250Hz filter was my choice. You can also see on the panadapter that the background noise on 40m was 20dB higher compared to the higher bands.
Now S&P was an easy task. Jump from signal to signal and press F4 on the Win-Test computer. Since 15m was open until 8pm it was simply a question of a few dozen seconds to check on the few remaining signals.
On the technical side the SDR-1000 worked flawlessly on RX but showed approximately every 10th QSO a glitch while TX-ing. Usually the sound in the headset turned silent during one letter/number and recovered but a repeat had to conclude the QSO. I didn't try to figure out what is was but I guess some buffer over/under-run in PowerSDR. I just received an e-mail from one of the Flex-Radio-SW-developer. This glitch has already been fixed in a newer version :-) What a superb support we receive in the word of SDR!
SDR is definetely the way amateur radio will go. We are still in an early phase but when I look at the opportunities we have it's an amazing world to be in. A few ideas:
- You know the bandmap with all the callsigns in Win-Test. On the PowerSDR window you see the spectrum. One day some SW engineer (unfortunately I'm more on the HW side and now on the technical Pre-Sales front) will map the bandmap with the spectrum.
- The panadapter shows the actual spectrum and the waterfall displays a longer history. If you add both views at the same time we can easily dig out the weakest signal on e.g. topband (160m) or V/U/SHF.
- The Firebox soundcard as I'm using right now samples at 48kHz. Therefore, I can store 48kHz of spectrum received at the antenna connector onto my (big) harddisk. Some day later I can fire up this time machine and tune the band. I performed such a joy during the ARRL CW contest back in February and it's nice to see who has the strongest signal while the band closes ...
- Do you know what a 4-square for 40/80/160m (in case you have the luxury of space) is? These are four verticals fed by a phasing network. You get more gain and can change the azimut you are RX/TX to. Well, since several SDR can be clocked of the same GPS reference software can take over the phasing task.
All these ideas will come true with help of the HPSDR project. The Atlas board was put together on August 1st and now I'm eagerly waiting for Janus and Ozy boards which will replace the PreSonus Firebox soundcard.
To close off my claimed score. Playing for 6h 53' with technology was more important that chassing QSO's although I worked 14 new IOTA entities where I have no QSL card so far :-)
Claimed Score
BAND QSO DUP IOTA POINTS AVG
-----------------------------------
80 0 0 0 0 0.00
40 97 0 38 999 10.30
20 87 2 34 825 9.48
15 14 0 9 150 10.71
10 0 0 0 0 0.00
-----------------------------------
TOTAL 198 2 81 1974 9.97
===================================
TOTAL SCORE : 159 894