Friday, December 08, 2006
From the King s Village Test Bench
First of all, it seems we are under the worse geomagnetic situation for more than a year due to the solar storm ... so no "High Latitude" DX now ...
Some DX lately in the beginning of December include an opening towards Colombia on Dec 5 and some SW-stations (Papua, Indonesia 5 Dec afternoon and Brazil 6 Dec. morning)...
A BRIEF TEST OF A LAPTOP "ACER WLMI 8210"
I was happy to have this model for a brief test using my sdr-receivers for a few days.
The model is somewhat pricy 2000 $ model w a HD of 120 GB, 1 G memory,
DVD writer of double layer DVDs (optional Blue Ray of 50 G!)... and all the bells and whistles.
The good news:
It was no problem to hook up both SDR-14 and WinR sdr-rx´s at the same time, but that is possible also with the older models. The battery of this brand new machine was still ok and it has a "power management" system to do some adjustments of cpu etc do extend the battery time. With normal settings it was possible to run 3-4 hours of sdr-listening without any problems. So it was nice to check that there was no interference from the power supply to my other receiver (ICOM9000) which was on the same antenna via an antenna splitter & 10dB amplifier. Even the very lowest siganl levels were heard (down to -120...-130 dBm). As the QTH is rather quiet above 1 MHz (on low MF band there seems to be an ADSL qrn from the telephone lines near by!) it was possible at least with low noise BOG-antennas. The lcd screen is a wide one with high resolution (1680x1200) so you have a lot of space to put all the windows on it. Of course you need to have good eyes to look at the tiny windows! The model has also a sound system with equalizers etc not standardly seen on Windows systems.
The bad news:
All changed when I plugged the power supply to AC! Suddenly you have a noise overall on the medium wave band with increased noise level of 15-20 dB! So using the AC connected all the weak signals were gone! That was the end of the test and it was easy to say this is not the machine for low level signals on MW using SDR-receivers & powered from the AC - using the own battery is ok, of course. I had a reference PC, a table-top older Fujitsu-Siemens model (P4, 1.6Gb/1G + 250 GB internal HD). It does emit some noise at least from the LCD-screen (which you can switch off using the SDR-14´s IF-recording), but not so much - at least with a little bit stronger signals than the usual background noise of -120...-100 dbm depending on antennas, frequencies & weather conditions.
What about DRM-decoding:
Maybe this is not the best place to speak about the "cancer of the airwaves", but of course I made a short test trying to use WinRadio 313e´s own DRM-decoder. The signal was ok (of BBC 1296 for example) with some typical drop-outs however. But the worse situation happened again like with other laptops I have tested: after about an half an hour, the system freezed and I had to reboot the computer. As this seems not to be related to the CPU-power (this model is even more powerfull than the old table-top one - which decodes DRM without any problems for hours) the problem should be somehow related to the laptop-computers. Maybe due to the sound chip? Research of this problem should be continued ...