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Old 21-01-2005, 13:54   #541
dk8cb
Roland
 
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Hi,

today, Rampisham's signal was weaker than on the last two days. There seeemed to be some interference underneath the DRM signal.

Roland
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Old 21-01-2005, 14:45   #542
jbriggs
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Here is a combination of the transmitter site log and Simones:
There was a Transmitter fault at 13:36, and Simone stopped logging for a period. It's obvious when you look at the file!
James
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Old 21-01-2005, 15:06   #543
dk8cb
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Hi,

I can't really believe that the antenna feedline in Rampisham is 18 kilometres long!

Roland
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Old 21-01-2005, 15:13   #544
G8JQW
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Quote:
Originally posted by dk8cb
Hi,

I can't really believe that the antenna feedline in Rampisham is 18 kilometres long!

Roland
lol
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Old 22-01-2005, 16:14   #545
dk8cb
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Hi,

today, there was a period during which the signal lost strength and when dropouts were quite common. Later signal strength recovered again.
I also noticed large differences in signal strength during fading periods.

Roland
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Old 22-01-2005, 18:19   #546
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Hi all,
pretty good results besides two dips probably caused by problems at the Tx site, see attachment
73, Simone
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Old 23-01-2005, 16:30   #547
simone
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Hi all,
quite good concerning audio decoding, but the Tx tuning problem occured again for a period of 40min, see attachment
73, Simone
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Old 23-01-2005, 18:11   #548
dk8cb
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Hi,

Dream with bandpass filter and modified metrics switched on yielded a much better result than the DRMSWR in the presence of interference.

Roland
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Old 25-01-2005, 11:03   #549
dk8cb
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Hi,

all ionospheric paths from England to my location seem to be weak now. Orfordness was terribly weak last night and so is Rampisham today.
So many dropouts that it is just unbearable to listen to.

Roland
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Old 26-01-2005, 10:58   #550
dk8cb
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No fun to listen

Hi,

today reception is hampered by problems:

- the ionospheric conditions are poor and the signal is weak, such that the slightest local noise peak as well as any interference signal causes a dropout

- there were many incidents in which the encoder did not produce the correct DRM signal but when it switched to the well-known P23S state.

No fun.
A normal listener would have switched off within minutes...

Roland
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Old 27-01-2005, 10:52   #551
jbriggs
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We have identified and fixed 2 problems:

1. Recent modifications to the transmitter to make operation easier (addition of some electrically operated co-axial switches) introduced some attenuation, and a slight change in level meant that some compensation circuits stopped working. This explains the step in SNR/MER observed by many people over the last few weeks.

2. The problems yesterday were caused by a monitoring PC here at the transmitter station & Multicast set up. In some more detail a PC was monitoring the DRM (MDI) stream coming into the transmitter site, but it was on a different subnet. Because we used multicast, sometimes the PC (rather than the DRM exciter) would reply indicating membership of the multicast group. The DRM exciter would see this reply as valid, and so would not reply itself. However the Satellite receiver/router did not accept the reply from the monitoring PC as valid. Therefore, sometimes the Sat Rx/router would stop sending packets and we then get the P23S state.

This problem was fixed by putting the monitoring PC onto the same subnet. I think we had a similar problem last year.


James
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Old 27-01-2005, 11:04   #552
dk8cb
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Hi James,

thanks for the information and congratulations on finding the faults.

But wasn't the MDI monitor originally switched on because there are also sometimes MDI packet loss incidents that occur out of the blue?
Have these also been eliminated?

Roland
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Old 27-01-2005, 11:17   #553
dk8cb
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Hi,

signal is again weak today and there are occasional dropouts.
Signal strength seems do decrease even more over time.

Roland
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Old 28-01-2005, 10:26   #554
jbriggs
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Hi Roland, yes you are correct there is still the original occasional packet loss, and we are continuing to look at this. We have monitoring software on the local network here looking at the incoming MDI stream.
James
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Old 28-01-2005, 21:01   #555
dk8cb
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Signal strength was better than yesterday but not yet back to normal.
There was also again a P23S incident.

Roland
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