Voice of Russia on 15780 kHz

[simone]

Hi Andrew,
still bad results here this morning, last year I achieved the highest SNR of all transmissions on this one, and like Carsten I have not sent reports lately because it is impossible here to listen anymore.
73, Simone

[Andrew]

Hi Manuel, Carsten and Simone,

many thanks for your replies. I completely agree with you, I also prefer a clear frequency and high bitrate but not all depends on us, sorry. I have already spoken about the problem of interferences from AM-stations on a meeting of technical committee of DRM consortium, which was held in Moscow on June 17, 2004... It seems the interference is a main problem for DRM reception of our signal at the moment, isn't it?

Thanks to dk8cb for your nice report, probably the reception in the morning is better (without interferences?). I have got the the similar information from Munich and from Rostock with about 100% audio decoding, but for the periods of 7:50 - 10:58 UTC.

Hi Per,
I think the SNR in Sweden has so big variations because our radiation sector direction is south-west (the edge of a zone covered and, in addition, unstable ionosphere). And the interference "cuts" our signal as "she wants".

And what are your opinions?

At the moment we prolong our test with changed settings for weekend.

Kind regards,

Andrew.

[CT1ADT]

Hi Andrew.
Hi all

I listened DRM about two years ago and I think that big
problem off DRM are the interferences that caused down
SNR --> dropouts.
For low bit rate < 17 kbs, i like more AM mode !
at the moment this is your´s bigger problem on 15780 kHz in my location.
"tacitus-ms" made a realistic exposition about this on

http://www.drmrx.org/forum/showthread.php?threadid=785

and I am in agreement one hundred percent.

[simone]

Hi Andrew,
in my location the problem is not only the interference, it is just that the DRM signal is so much weaker than last year.
73, Simone

[carknue]

Hi Andrew,

I totally agree with Simone. The main problem on 15780 khz this year is the very weak and unstable signal. It is mostly just around S5.

[Per]

Aug 7

Originally posted by Andrew


Hi Per,
I think the SNR in Sweden has so big variations because our radiation sector direction is south-west (the edge of a zone covered and, in addition, unstable ionosphere). And the interference "cuts" our signal as "she wants".

And what are your opinions?

Kind regards,

Andrew.

Hi Andrew + all,

Yes, if I look at the coverage map I'm clearly not in the target area. So I persume that the signal in my location is much weaker than in beam center.
Today provided a similar result as previous days: 70%. Listening time: 08:00 - 09:10 UTC.

[simone]

Hi Andrew,
I tuned in again this morning, better than last time, at least I could listen to the German service in the last 15min, see attachment
73, Simone

[lmaes]

The big variations are also present here in Belgium, and we think we are in the main transmission lobe.

Reception of signals from Portugal in the 15 MHz band are much more stable and the distance is comparable to Taldom.

Is the performance of the transmitter stable or are there perhaps variations in power, SWR or other factors? Is a different type of transmitter in use compared to the transmitters in Portugal. Might that be the reason?

In our opinion, if the performance of transmitter and antenna is more constant and less variable, then reception would be much better. We do not think that propagation is the main factor that causes not so good reception.

It would be good if Andrew and his team could work out a step by step analysis of the complete chain to determine the weak part and trying to fix that.

Ludo

[simone]

Hi Ludo,
I don´t know when you started listening to the transmissions from VOR, but if I compare with last year: I always had a very strong signal S9+20 and more, it never was as stable as the transmissions from Sines, the situation concerning interferences is comparable to last year, here in Germany we had the best SNR of all transmissions back then, the main problem now is definitely that signal strength is way too low compared to last year.
73, Simone

[Andrew]

Hi all DRMrs,

Thank you for your replies.

Ludo and Simone, the modern transmitter from Sines is significantly more powerful, than our one, so I think their transmissions must be received better almost in all cases when the distance is comparable. We try to use existing SSB transmitters with some modernisation in DRM mode, while another DRM transmitters are preparing.

This year the output power was a little less than in June-August of last year, but almost the same one as in October-December. The mode of operations of our transmitter during transmission sessions were stable.
Of course, we are analyzing what takes place actually in complete chain and what is the most significant for reception. Today we have returned the output power up to earlier level and with antenna settings as last days.
Let's see, what it gives.


Best regards

Andrew.

[simone]

Hi Andrew,
unfortunately no improvement of the results, see attachment
73, Simone

[lmaes]

Hi Andrew,

We did not read your message earlier, so we only tuned in the last half hour today. And the result is much better then it has been these past few weeks. If you look at the SNR you will see that it reaches almost 32!

Ludo

[dk8cb]

Hi Andrew,

here is a spectrum plot showing the heavy interference from 15785 kHz at 08:15 UTC today.

Very bad reception as a result.

Even the new bandpass filter in Dream does not help.

dk8cb

[lmaes]

Hi Andrew,

We had our receiver monitor your frequency a full 12 hours and enclosed is the result.

During the period 0814-1200 UTC the signal was quite acceptable with a 71% audio, but during other times, reception was nil, also in the afternoon transmission. A big difference to yesterday's early evening reception.

Hope the log is of some use.

Ludo

[CT4RK]

Taldom signal

Hi all


About Taldom signal streng, and to compare it with Sines signal, First we can look to the slow go down into 11 years minimum sun spot number, and efecttively last year the propagation conditions was much better than now. What will do happen in the next 2 or 3 years, when the propagation will be praticlly closed? Second, Taldom are in hight latitude and in this latitude, the disturbances F/F2 layer during the day light and F during the night are more sensitive to the solar wind, and this year the sun have a great activity, with a big flares (remember that Taldom is in the auroras area). About the power Idont see a big diference between 35Kw and 80Kw, because it is more or less ...only 3dBs in the signal streng!! And of course 3 dBs is absolutly nothing in short wave. Much more diference have we with the fading that some times go up to 40dB, and 40dB is from 80kw to...8watts. Finally I can`t beleave that Andrew can`t see any trouble in the transmitter / antenna, that cause the great changes we can see in the signal streng in the receiver side.