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Old 16-04-2007, 19:16   #16
FDJ
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Quote:
Originally Posted by jbriggs
Frank - thanks for the Mp3 file, it does not sound too bad at all, what bitrate was being used (for DRM not Mp3)?
23k.

Quote:
Originally Posted by jbriggs
Concerning the logging, I recently saw a presentation at BBC R&D, they mentioned there will be 2 or 3 long term logging receivers in the Plymouth area that are already set up. I think some of these Rx will be in the 15 - 20 km range, and so will pick up & log skywave interference. In fact they even demonstrated an application to send the received audio via the internet (both AM and DRM) combined with Google Earth - it was a very impressive demonstration.

James


Signal is not so good here. Too much man-made noise

Frank

Last edited by FDJ : 20-04-2007 at 11:16.
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Old 17-04-2007, 10:12   #17
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Hi Frank, can I ask out of interest what antenna do you use with the WinRadio?

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Old 27-04-2007, 21:58   #18
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Could we have a new sample from Radio Devon as they are now using stereo mode sounfing very good apparently acc to one listener who was given a roberts radio for the trial
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Old 30-04-2007, 21:54   #19
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Could we have a new sample from Radio Devon as they are now using stereo mode sounfing very good apparently

I am planning a trip down to Plymouth tomorrow, I am going to take a Fraunhofer DT700 receiver, & will make a few recordings. Hopefuly I will post some MP3's and thoughts on coverage tomorrow.

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Old 02-05-2007, 20:50   #20
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I am planning a trip down to Plymouth tomorrow, I am going to take a Fraunhofer DT700 receiver, & will make a few recordings. Hopefuly I will post some MP3's and thoughts on coverage tomorrow.

James

How did you get on James ?
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Old 03-05-2007, 23:35   #21
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Hi, Sorry for the delay, we had a good day checking reception of the Plymouth transmitter. I would say reliable coverage extends for 20 miles (30km) around the transmitter and it is possible to get audio up to 35 miles away but only when conditions are right. We managed to get the service ID at Honiton (95km) SNR about 5dB with a large unidentified co-channel interferer. These were daytime measurements would be interesting to see what happens at night I suspect the service area shrinks a bit.
There was a discussion about the trial on air while we were recording, I hope to get that audio extracted and posted next week as an mp3 file. I also already asked Simone to host a 28 second wav file to give an idea of sound quality. Be warned the file size is large as its uncompressed! Simone can you post a link to that file below?
Thanks James

RadioDevon_SandyDenny.wav (4.8 MB), the service was running 23kbps in Parametric stereo with a 15.375kHz audio bandwidth
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Old 04-05-2007, 01:27   #22
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Hmm great. DRM is very well suited for MW, hope we have some more tests in the future from other MW relays. If you had recorded on a MR radio then the DRM file could have been played on any other MR radio of course, oh well !
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Old 09-05-2007, 16:07   #23
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Some more analysis of trip to Plymouth

Here are some maps created from the data we recorded. The required SNR for audio was about 13 dB or better.
Thanks to Simone for creating and hosting the maps!
James
you really need a broadband connection to view these links

route from Exeter towards Plymouth transmitter

results from within the service area of the transmitter

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Old 20-05-2007, 23:47   #24
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Any chance of testing at the maximum bitrate (PL 3 @ approx 30.8 kbps)

It would be good to compare the increased audio quality with any potential loss of coverage.
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Old 23-05-2007, 09:50   #25
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Hi BofH,

I don't think NGW/BBC (the trial sponsors) will be inclined to change any of the parameters now for the rest of the year long trial, as it will just lead to confusion amongst the 100 or so panel of listeners.
I think the Mode/bitrate they chose was a good choice. The higher bitrate would make the signal more prone to dropouts, and while 30 kb/s sounds fantastic with the DRM AAC audio codec, dropouts are more annoying than the slight improvement in sound quality going from 23 to 30 kb/s.

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Old 24-05-2007, 11:25   #26
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I don't think NGW/BBC (the trial sponsors) will be inclined to change any of the parameters now for the rest of the year long trial, as it will just lead to confusion amongst the 100 or so panel of listeners.

Is it just one transmitter, IIRC I read somewhere that they were hoping to set up a single frequency network. Looking at the last Ofcom future of radio document they seemed interested in using DRM in this way.
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Old 29-05-2007, 13:49   #27
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It is just one transmitter at the moment although I think there will be a 2nd one added later this year at another location but using the same frequency.

James
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Old 06-06-2007, 19:11   #28
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Bandwidth of BBC Radio Devon?

Could anybody tell me what the bandwidth is on the BBC Radio Devon trial signal please? And is the bit rate 23 kbps or is it 23.6 kbps? Thanks.

edit: new thread merged with the already existing thread, Simone
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Old 06-06-2007, 20:47   #29
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Bandwidth should be 9 kHz, if you mean only the audio bitrate, it is 23 kbps, parametric stereo as I already mentioned here:
http://www.drmrx.org/forum/showpost....6&postcount=21
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Old 07-06-2007, 09:15   #30
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Hi digitalradiotec,
after having a look at your website I wonder about your question here, the missing 0.6 kbps would probably not help you!
quote from your website:...they're using a bit rate as ridiculously low as 23 kbps, it is inevitable that the audio quality would be very poor
Although I can not listen live on this transmission, I agree with James (see post from May 23rd) that the mode/ bitrate are a good choice, two of our ARD stations are using the same configuration for audio (not the dataservice) and sound quite good.
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