Peer-Axel's DX blog

Signal level of Opel test mode close to dBµV

The Opel car radio CD MP30 (not only this one) offers a test mode which you can enter by long-pressing "SETTINGS", wait for the beep, press SETTINGS again and then FM. The display will switch to something like "89.6 66 A001" (frequency / signal strength / RDS and SNR evaluation). I've compared signal strength value to dBµV measurements of a dipole antenna in a simular position with a quick check. Up to 40 dB the values are almost equal. Signal 50 is about 55 dB, signal 60 is 65 dB, signal 63 is 70 dB, signal 66 is 75 dB and all above. Maybe it's the preamp that flattens the displayed values here.

Experiencing the "Luxemburg" effect

11-Mar-2017
Since the end of France Inter on the Allouis 162 KHz transmitter, the effect has been discussed again. On LW some stations seem to carry the modulation of other LW frequencies. On the empty carrier 162, now a mixture of Europe 1 (183 KHz) and RMC (234) can be heard here. Mathematically there is no connection. And here in Handewitt, 234 is not a strong signal (34 dBµV). This would speak for the assumption that the modulation is originated on the transmitter size, where 183 and 234 definitely come in strong. On the other hand observing 279 KHz with weak modulated TR1 Watan radio from Turkmenistan, you can hear the Polskie Radio Jedynka from 225 KHz in the background (quite a distance from Turkmenistan). Switching to a remote Perseus receiver in Doha (UAE), Watan Radio can be heard without Poland. So the original signal is clean. This all makes the thesis about a modulated ionosphere plausible. Turkmenistan and Poland are east from here (97 and 105 °). The Turkmenistan path leads over Poland. 162/183/234 are all from the Southwest (213/198/201 °). A little confusing that RMC 234 is behind Allouis - this cannot be the path. Is the signal in Nothern France still strong enough to cause the effect? Seems to...

Airspy Mini with TV Sharp

TV# is an extension that enables SDR# to display TV pictures. DX advise: use bandwidth decimation. With 300 KHz BW you can already decode something visible even if the signal is relatively weak (carrier 30-40 dB above floor). This is some East European TV signal on R1 / offset 8M via Sporadic E propagation received in Handewitt, Germany (18.6.2016).

UK and Ireland medium wave pirates

Yes, there is some activity, not only the well known 549 Spirit R / 846 R North / 981 Star Country. Apart from that I could receive some loop music station on 612.007 and tweo guys with Scottish accent talking on 1530.06 via the Scottish Perseus receiver. Definitely not Celtic Music R from Glasgow. 9.2.2014

avoid LED bulbs and tubes

many of the the ones I've tried produce heavy noise on MW/SW which make DX almost impossible. If there are any recommendable products in this respect please let me know.

AM modulation levels

It's amazing how different they are. Audio peaks of well modulated stations usually reach up to about -8 dB relative to the carrier. In combination with a satisfying spectral compression this leads to a satisfying efficiency and a good SNR. Maybe half of the power goes into the modulation. This is a reason why many low power stations from the UK make a fat signal all over Europe. An example for the other extreme is Belarus Radio on 279 KHz. They seem to make only -18 dB without compression. For the 500 KW tranbsmitter this means: Only about 10 KW carry the information. Maybe it would be worth considering to list the modulation power in DX lists. By the way this stuck me when I was searching for a parallel frequency for current OIRT-FM receptions. The web stream of BR1 is off, the SW schedule seems to be cut down to a few hours. 16.05.2013

Midnight sun around the the polar circle opens bands for Sporadic E and SW reception

Recently I wondered a little that the 68 MHz opening to the Arkhangelsk area remained stable till 2100 UTC (midnight there). But then I realized it's not getting dark there. This could be a factor. I was also amazed that I could receive many stations on the higher 19 and 16m SW bands using the Karelia Perseus DX receiver around midnight. This was not short skip, it was world wide reception to Siberia, the Carrebean and the USA. 16.05.2013

Scandinavian CB in Moscow

While there was constant Sporadic E activity with some OIRT FM stations coming in here from Russia, it was nice to check the back link via the Moscow Perseus receiver. Found some CB activity from Denmark and Sweden. 05.2013

North Korea strong in Japan

On the Japan Perseus remote receivers you can see how active the North Koreans are. Of course you can get some of their SW services here. But there, they're all over the SW band. I tuned over 25m on a Japanese morning. And Chinas domestic services all over the place of course. 08.01.2011 01:30

Wide AM in Japan

It also occurred to me again that 2 x 10 KHz wide AM modulation is the common standard in Japan. Sounds much better than our strict 4,5 KHz limits here in Germany. 08.01.2011 01:30

pirates extend their range

Just tuned the so called 48m band. Some pirates there, mostly Dutch I guess, as to expect on a Sunday. Some years ago they were concentrated between 6200-6300 khz. But not anymore it seems. Some were on 6385, 6450. And 6930 /6940 have become common frequencies, too. 08.01.2011 10:28

Australia without interference

Things have changed since the 80ies. Back then it was rather difficult to get Radio Australia or New Zealand because the SW bands were full. Now it has become so easy. Just listening on 11945. Clear frequency. Nice audio. 08.01.2012 10:43

new AM bandwidth record

While China regularly modulates with 2 x 10KHz audio I just came across Radio Rossii on 12075 KHz doing 2 x 14 KHz. Needs to be notched at 5 KHz. But a good experience. But even there is SAM mode, fading still disturbs the audio. This is the main field where DRM could gain score. On the other hand, AM signals never completely disappear in difficult situations while DRM would abruptly stop. In the spectrum you can clearly see the fading lines and the fact that audio is cut above 4,5 KHz by some extent. back to Radiovibrations.com