View Full Version : See much -hear nothing
Hi to all DRM experts,
I'm still new to DRM reception and still optimising my equipment. The latest achievement is an active rod antenna, mounted on the balcony, which is if course only a compromise, when you live in a very noisy surrounding, e.g. there is a 100 kW Tx on 972 kHz only 2,3 km away....
Besides that Reception results have already improved, but:
When you look at these two logs, you will notice a repeated loss in SNR as well as a complete breakdown in audio roughly every 7 minutes. After these droputs it takes some time until the signal is decoded correctly again. Howewer a "clean" spectrum" is shown on the screen. It seems not to be not caused by local QRM, because my Mayah DRM 2010 Receiver operated in parallel is going on to play during these periods. Also periodic dropouts occur on 7/24 an all frequencies !
Who is to blame? The Rx or my Computer?
My equipment is as follows:
TenTec RX-350D with DRM line-out
Rohde & Schwarz HE 011 Active Rod Antenna
Apple Power Book G4 with
DRM software, running under Windows XP in a Virtual PC 7.0 environment.
Has anybody got an idea, where to continue with debugging?
51 & 73, Andreas
Uuups, once again a droput, but here is my first log:
..and here the second one. Bayerischer Rundfunkt is so "nice" to provide a carrier, so I can exclude it's a problem with the Synch-Detector (lol)
Hello Andreas,
do you use a CPU with a cool n quiet function?
I had regular audio interruptions after I changed to my new PC with an AMD CPU with this cool n quiet function. Every time the CPU clock speed changed in automatic mode DRM reception was interrupted. I solved the problem first by disabeling this function in "Systemsteuerung", later I found a software from AMD with which you can choose different CPU-clock-speeds. Now for 90 % of time the clock is fixed to low with very low fan noise and no problems with DRM.
73s,
Bernd, DF9RB
Originally posted by df9rb
do you use a CPU with a cool n quiet function?
Hi Bernd,
Andreas is not using a regular PC. He uses an Apple Mac under its own operating system. Windows XP is running in a PC emulation mode. Perhaps that causes a few problems for a software that must run in realtime.
Who knows.
Roland
Hi!
That's right. Perhaps my exotic configuiration may be the reason.
I checked the power management of my processor, but it is already set to maximum perfomance which I suppose means no change in processor speed any time.
You must imagine that first of all I have the Apple MacOS 10.4 running. Inside I have a software named Virtual PC, which emulates roughly a Pentium PII with 600 MHz (oh dear!). The operating sytem in this environment then is Windows XP SP 2 Home Edition.
Finally I get the DRM Software 2.0.34 started.
Now the system is running at about 90 to 100% of it's ressources. When running DRM software I cannot even start any other program.
Also it was impossible, to get started with the DREAM software.
So if I do not find any other remedy, I have to wait until the beginning of september when I will get handed out a Toshiba Notebook from my employer.
By the way: Thanks to Roland for his hints how to silence local sources of QRM. Unfortunately there seems to be a shortage of ferrite rings at my favourite dealer conrad here in Hamburg.............
51 & 73, Andreas
Yippiiiee!!!!
It seems I am near the solution!
Indeed it was the Computer to blame!
I do not know, whether it is the system running on the border of its ressources, or the sound system.
However todays log was madefor comparision on a ordinary notebook with Intel Celeron 1,33 GHz processor (I guess) . Besides some local interference (switching lights, TV on etc.) for me it looks quite perfect.
Sorry for mistyping (or not giving correct ) data in the log. Of course it was NOT RTL nor do I have moved to the equator, it was just the most reliable Deutsche Welle Sines Transmitter on 15435 MHz.
However for your hints.
For a necomer it is most useful to search this forum -there are so many things to learn..
Good DX an 73
Andreas
radiomann
15-08-2005, 21:48
Originally posted by Andreas
Yippiiiee!!!!
It seems I am near the solution!
Indeed it was the Computer to blame!
I do not know, whether it is the system running on the border of its ressources, or the sound system.
However todays log was madefor comparision on a ordinary notebook with Intel Celeron 1,33 GHz processor (I guess) . Besides some local interference (switching lights, TV on etc.) for me it looks quite perfect.
Sorry for mistyping (or not giving correct ) data in the log. Of course it was NOT RTL nor do I have moved to the equator, it was just the most reliable Deutsche Welle Sines Transmitter on 15435 MHz.
However for your hints.
For a necomer it is most useful to search this forum -there are so many things to learn..
Good DX an 73
Andreas
Well it states 5990 in your log Andreas which is RTL?
FritzWue
16-08-2005, 06:42
Anyway, SNR peaking 31dB is a good result for the little TenTec box.
Originally posted by radiomann
Well it states 5990 in your log Andreas which is RTL?
Hello radiomann!
After I resolved some hardware problems now I have to get accomplished with software, i.e. how to correct your logs, when you haven't inserted the correct data first.
So I'm quite sure it was DW and not RTL . Btw RTL is received here at around 18 - 20 dB SNR only with some dropots - no real fun to listen.
Good DX (also on 208 m)
Andreas
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