Monday, January 08, 2007

King s Village DX Tests: Can a 150 Grams Box be a Communications Receiver”

Before the results of the test project testing several sdr-receivers will be published I will unveil something interesting while making a short test of a new DRB-30 premium model. Everyone interested in digital AM (DRM) reception may be aware that the latest model of this German little “box” is pretty good capturing DRM-signals. Together with the freeware Dream-software it seems to achieve good price/quality ratio among this “hard” job receiving and demodulation those signals which are like jammers for the rest of us. More about the box can be found at The manufacturer kindly supplied the test group already last summer with the box for some time (the basic model) and now I had the opportunity to test the latest model which is in Finland for reviews and tests by a DRM-research group.

I made a simply “real world” test comparing this tiny box to a 3 times pricier WinRadio and a CIAO-sdr receiver which is at about same price level as the DRB-30 (around 350 euros). I hooked up all these boxes to my laptop (HP Pentium 1.6, 512K memory) which has enough USB-ports to eat all these gears. You can drive the DRB either via the parallel cable or nowadays also via a USB-Parallel cable and adapter. I had a second soundcard as well (the iMic at the picture, the white round box), but it is not needed for analog signals. At the picture the equipments is just receiving good quality digital signal from Radio New Zealand 9890 which is often at about 99% ok at around 9.30 utc.

During quite good propagation conditions I took a distant station, Wantok Radio Light 7120 (slightly below I suppose) to be a test station and compared the reception by my own ears. No measurements whatsoever were made. The environment was urban with heavy RF-interference and the antenna was a ALA100 (3x7meters loop). The results of the intelligibility of that faint signal were:

1st prize: DRB30 with Dirabox (console software) & SDRadio modulating software
2nd prize: Divided between CIAO H101 and WinRadio 313e.

The reception was of course very bad, but something could be heard particularly from the equipments with the DRB-box while with other receivers I could only tell that the station was there. This station is not widely heard at urban situations normally while in a countryside QTH it is a common guest at 12.30-13.00ut time slot in Finland.

This test was made on shortwaves and the interference situation of adjacent channels was not that bad. If there is a lot of interference which you can kill by notch, the WinR and CIAO are better with the notch ability on the software.
I have to make a comparison between the box and my communications receivers ICOM9000 and AOR7030 later on, but as far as sensitivity and intelligibility is concerned these tiny boxes are usually as good as older, typical communication receivers like ICOMs & AORs.

So it was quite nice to discover that with a good program to modulate received signals (I did make a try with a WinRad software as well), the small box is really capable to receive signals as good as more expensive models. This box now with the USB-parallel adapter cable seems to be nice companion to the laptop taking to trips. However, the CIAO does have two alternatives: the program together with nice synchro-AM and it takes the power via the USB, so no need for additional power supply.

I hope to publish more about the tests of the last months including something also about the SDR-14 panadapter-receiver system. The first articles in Finnish can be found at the “Radiomaailma” –magazines of the last year.

73 TK

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