View Full Version : VT Communications London 25695 KHz DW/Premier (formerlyUBC/DW)
Hi,
Following James Briggs' message in DRM-L Yahoo group I checked around this frequency. There is a DRM transmission with apparently a wide spectrum extending from approx. 25690.5 KHz to 25709.5 KHz.
Two channels - UBC Classic Gold and Deutsche Welle both 19Kps AAC mono.
I found best decoding was obtained at 25700 KHz (not 25695 KHz as per James' message). Hence I'm not sure exactly what the true transmission frequency is !
Reception is right on the extreme at my location but improved tonight with some periods of continuous decoding. Good audio on both channels.
regards
Bob
Hi,
Attached is unattended overnight log.
regards
Bob
I found best decoding was obtained at 25700 KHz (not 25695 KHz as per James' message). Hence I'm not sure exactly what the true transmission frequency is !
Hi Bob,
obviously the transmission frequency is 25700 kHz with a 20kHz wide spectrum, but could you post a screenshot of Dreams SE window showing the input spectrum, I guess with a 20kHz signal the DC freq. is not in the center of the DRM spectrum (see attached example), so with some DRM receivers you need to tune 5 kHz below as James mentioned.
Simone
Hi Simone,
Of course - it's obvious now you explained it ! I should have checked the SE screen. Screenshot attached (SNR somewhat lower than your example!)
regards
Bob
I took our DRM car for a drive through central London last night, excellent results and the UBC Classic Gold and DW are both great programmes to listen to, it is a shame you have to chose just one! I was delighted with reception amongst all the tall buildings in London.
BTW I had an e mail from Roberts today saying I can order radios (Roberts MP40) 299 Euros. Christian Vision already received 10! so it seems at last there is some availability of Rx, I don't know if the restriction is just to consortium members at the moment. Sorry its a bit off topic!
James
Bob,
The frequency for 20 kHz DRM transmissions is not straightforward. As you point out the centre frequency of the transmssion is 25.700 MHz. And a converted radio using Dream software needs to be tuned to this centre frequency for best results. But a consumer Rx like the Roberts I mention above will need to be tuned to 25.695 MHz because that's the location of the Fast Access Channel (FAC). I did note that when I tuned my AOR 7030 via dream to 25695 kHz the other day it did set the Rx to 25700, so maybe Dream is inteligent enough to realise that there is a 4.5 or 5 kHz offset with the double channel modes. I did not have time to repeat that experiment though so I am not sure about it.
James
Hi James, Bob,
as I already mentioned, the DC frequency is not 12kHz as usual with 10kHz wide signals, the 5kHz offset is no problem with Dream (it locks at 7kHz), the fact that results with modified receivers are better when tuning to 25700kHz is probably because then the DRM signal is in the centre of your filter, but with FhG software you would not even get sync due to the 5kHz offset (of the location of the FAC reference pilots). Thatīs the same problem as with the 5 kHz datatransmission on 5972 (5970) kHz, see my comment here: http://www.drmrx.org/forum/showthread.php?t=1385
Simone
Hi all.
Her is report via sporadic " E " only 13min but I have sound under 15sek. .
very nice to see this UBC Classic Gold.
:)
Please see copy of e mail received from DL9MDV in Bavaria, Southern Germany (not a member of the forum so I am posting this)
Dear Mr. Briggs,
I send to you some screenshots from last Sundays DRM reception on frequency 25700 Khz.
The conditions was sporadic E with heavy fading. The signal was sometimes up to 27 db SNR. Receiving the signal without dropouts was possible within 10 Minutes.
It was a big surprise for me to receive a 20 khz DRM-Signal for the first time !!
I wonder why the impulse response in A Modus was so good !?
Might it be possible to answer me following questions:
Where is the location of the transmitter ?
What antenna and output power is used?
Is this test running until end of 2006 or longer?
My location at home:
City of Rosenheim, located between Munich and Salzburg ( Austria )
Equiqment:
Antenna: 2 x 10 m indoor dipol under the roof
TRX: Yaesu Amateur Radio FT 840
IF: FM-UNIT 10,7 MHz > homemade 12 Khz IF with NE 612 and ceramic crystal
455 tuned
Software: Dream 1.50 ( also 1.62)
CPU 1.8 GHz Celeron
Soundcard on board AC 97
The reception with Dream was a dream ;-) Switching between both services was very fast, like analog radio.
Audio from DW was fantastic, better as DWs own transmittions ;-) . UBC sounds good but little bit compressed.
See also the picture of WRN at same time: Sunday 4. June 2006 , about 1500 UTC, 26000 KHz.
Iīm not a member in the drm-dx forum, thatīs the reason why I send you a mail like this ( only for this time ! ).
I agree ( 80 % ) to most of the reception reports from member dk8cb ( near munich ).
I hope this information was helpfull.
Greatings from Munich and best regards
DL9MDV
Hi James,
in the past whenever I tried I never could see a signal on this transmission, in contrast to the WRN test on 26MHz also from London which I can receive quite often.
So this morning for the first time I got a signal, SNR was about 3-5 dB most of the time, at least I got the service labels etc. and audio for some seconds (minutes -3 to -8.5 in the history window in the attachment).
So I think even on days with "good" conditions for sporadic E this transmission would not cause problems in our area.
Btw this was the first time I received a 20kHz wide signal on a real transmission, great :)
Simone
Again a weak signal with a few minutes when decoding was possible today.
Simone
Today again a weak signal and a few bits of decoding.
Simone
tradio99
08-07-2006, 19:44
Deutsche Welle on 25700 kHz today in A/20 mode - no audio and QRM on the lower part of the signal
Here is a 10 hours (unattended) log from today, signal appeared for about 100 minutes in the afternoon, but not much decoding. As most days, signal on the other London 26 MHz transmission was much stronger when I listened to it on another radio. Also the WRN 26 MHz transmission can be received a lot more often in my area.
Simone
Signal appeared for about 45min in the early afternoon.
Simone
Sometimes a weak signal this morning.
Simone
Signal could be received for about an hour today, UBC was back to 19 kbps.
Simone
Around 10:10 signal could be received for 5 min, no reception for the rest of the day.
Using 16 QAM again, good decoding of both services with SNR of 13dB.
Simone
Some decoding with a weak signal this morning.
Simone
A weak signal today for 10 minutes, nearly no decoding possible.
Simone
I took our measurement car up to London yesterday, we used a Fraunhofer DT700 receiver this time to log results.http://www.iis.fraunhofer.de/fhg/iis/bf/db/produkte/drmmr.jsp
Great results driving round the London streets, there was very reliable service. The multiplex configuration is now Service 0 for DW & service 1 is for Premier radio. Both services have an allocated bitrate of 19kbps each.
The Fraunhofer DT700 we used has the optional 12V power supply fitted so its really easy to use it in the car, the only other required connections are antenna and USB GPS antenna so the cars position can be tracked in the log file. The DT700 logs results onto its internal HDD or an external USB device (HDD or flash memory stick)
Hi James,
I could get a signal from your London transmission today for the first time this year when I tuned in a few times between 10:30 and 11:15 , MER was up to 14-16 dB and I got some audio decoding from both services :)
I also did an unattended log in the afternoon, but no reception possible then.
Simone
Today the signal could be received again at 1500- 1545, good decoding (audio and text messages from both services) with MER of about 15 dB, short IR as usual on this transmission.
Simone
Again some decoding this evening.
Simone
Hi James,
again in June here is the best time to receive crystal palace.
Hi Andy,
seems the signal was a bit stronger in Bavaria :(
Simone
Stronger signal today, pretty good decoding for half an hour, just using the whip antenna on the car, MER up to 30 dB.
Simone
Some quite good periods today.
Simone
Hi all.
Small test on 25700 in my RX this day. Ihave audio CDA 7% ok !!!!!!
LOg 11min. today. Strong signal in fading.
I had to decide whether to log TDF or this QRG, so I took the stronger signal....
Hi all.
Very big Sporadic " E " today give strong signal on 25Mhz. Her log 11min from Premier radio/ DW.
I was fiddling around with the Kchibo KK-DRM01 this afternoon hooked it up to an ACER Travelmate Laptop and caught a bit of 25695 kHz around 1630 UTC. This is the first time I have received anything with this receiver on such a high frequency.
I have put a small amplifier in the 12 kHz output line as the output level from this receiver is next to nothing. The amplifier is battery operated. I had to put a ferrite ring on the shielded wire leading into the laptop to get rid of some rubbish from the PC.
My temporary location: N 59° 24.5' / E 18° 00.8'
Small part of Es today log 48min. CDA 59% ok.
Some 25695 kHz via sporadic E on the 19th July was constantly messed up by an intermittent digital "something" on or nearby this frequency. Therefore the SNR nose-dived to zero every 3 to 10 seconds.
Temporary location: Near Stockholm, Sweden, N59° 24.5' / E18° 00.8'
"Receiver": Kchibo KK-DRM01
Antenna: Built-in Telescopic
12 kHz connection: 12 meter shielded wire, 2 m wound on a ferrite ring
12 kHz amplifier: Battery operated, about 10 dB gain
PC: ACER Travel Mate 2480, battery operated when using Dream
Hi all.
Big " E " today. Log Premier/DW 74min. CDA 87%ok.
Hi,
My first catch of Mode A/20 kHz BW. Not much audio and a fairly short log, just 10 minutes.
Only DW produced audio, nothing from Premier?
Hi Sixten and Fritz,
no signal here from Luxembourg on 11m today, but a bit from London. :)
SDC/ MSC Mode 4 QAM/16QAM, 19.10 kpbs.
Hi Andy .
Her is short log from this freq. only 15min, problem for very fast fading.
Nice to hear crystal palace again. Deep fading at the moment.
Therefore only a short log.
Nice to receive a signal from CP again :)
Simone
Signal appeared again today.
Simone
25695 popped up for longer periods on my Roadstar with the active antenna. There was very little signal on the telescopic aerial. The log shows no label; the screen had an ID: 445700, the language was "English" and the programme "Religion". No decoded sound. Again a rather short log between antenna configuration try-outs.
A weak signal from CP could ber received from 1320- 1620 today, best time was around 1600 with MER about 15 dB, which was good enough for decoding of both services.
Simone
Hi,
Sporadic E resulted in a "trace" of the 20 kHz wide signal from London. No audio, though..
Managed to get some audio a few days ago.
Simone
Hi,
I managed to get some audio too today. Both from Premier Radio and DW.
Time: 17:03 - 17:28 UTC.
A weak signal from CP this morning.
Simone
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