01 Sept 2017 - double hop reception

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daveB
Posts: 1005
Joined: 07 Oct 2014 16:49

01 Sept 2017 - double hop reception

Post by daveB » 01 Sep 2017 22:33

Once again as the opening faded out some double hop reception was logged. At 1200 UTC a few transmitters from R. Rossii were still present on 66-74 MHz, three of which had an echo on the signal - not only evident from the doubling of the pips on the hour, but also on the programme itself.

This is the clearest example - https://app.box.com/s/9nsxfxcj8o9jtmdo17nf120052clvkjt

The primary station is Kozlovtsy/RTPS 2202 km / 61 degrees. Transmitters received on other frequencies at 1200 UTC ranged from 53 - 63 degrees and 1900 - 2300 km approx.

So my gut feeling is that the weak echo is from Radio Rossii, Kuybyshev/RTPS (NS) at 4890 km / 53 deg rather than Aleksandrov Gay/RTPS (SR) at 3306 km / 74 deg. Either way a double hop signal - and even if it is the closer one it would be almost on the Kazakhstan border.

The FMList log is here - http://www.fmlist.org/fm_logmap.php?dat ... &omid=2414 - and you can the other double hop signals logged as well. Both possibilities are on there for the time being. Half an hour earlier Band II yielded a few signals from Lithuania and Finland in the same general direction - once I've fully checked the logs I will know if any other single hop stations on a bearing around 75 deg were present.

If anyone has any thoughts - that would be great.

David
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

Maciek
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Joined: 04 Oct 2015 22:01

Re: 01 Sept 2017 - double hop reception

Post by Maciek » 08 Sep 2017 09:50

Clearly, there is only one signal.
But... modulated with two feeds at a time - main, which is the loudest and second - slightly delayed, in the background. Probably some kind of problem with the transmitter, which often happens to RR in the OIRT band.
Please note, that audio levels difference of both feeds is equal throughtout the whole recording and there is no carrier-clash effects, which would happed if there were two or more signals on one frequency.

daveB
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Joined: 07 Oct 2014 16:49

Re: 01 Sept 2017 - double hop reception

Post by daveB » 08 Sep 2017 10:58

Thanks for reply Marcus. I had same comment elsewhere. Checked backed earlier recording at 1129-1134 utc and same echo at constant level. Have deleted these from the log. When I have the chance I will check other frequencies to if the same thing was happening.
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

PFM907
Posts: 125
Joined: 19 Jun 2017 06:38
Location: GERMANY + MALTA

Re: 01 Sept 2017 - double hop reception

Post by PFM907 » 08 Sep 2017 18:45

I would also say regarding the excellent signal quality, this is only one station. There is no noise, disturbance or interference within the weaker, earlier beeps. My suggestion would be that this station is operating in the old Polar Stereo system and if the signal got strengthen up to stereo, these doubles are produced. I experienced sth. very similar regarding stations using Polar Stereo (and not only Mono or Western Stereo), their modulation gets a bit "higher" while stereo is received within a radio which is unable to decode Polar Stereo.

Double way signal or multi way signal reception is very difficult to identify. If the connection line towards the transmitter has no delay, a slight noise is being audible, which I would describe as susurration or whisper. If there is a delay, you can hear echoes that are not equal to the signal fading but going up and down in the background. This is a very rare catch which you can observe at some chains in Spain when two different transmitters come in at the same time. Multi way reception can be heard on 107.7 from France or 103.3 from Italy for example, where many transmitters of traffic radio operate. Some of them being sourced by satellite, others by line and few via LAN / ISDN.

I have once made a video of a transmitter 1700 k away and another one of the same station 1000 k away suddenly is coming in, best at 14 seconds (here you might think the delay is part of the jingle) / 22 seconds and even better 27 seconds / also 33 seconds / 54 seconds:
https://www.youtube.com/watch?v=sOdyvwqjeRw

But this is extremely hard to get as the cloud must be in position above an area between both transmitters and both may not be too far away from you.
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Paradisefm - Malta's N° 1 in dance and electronic
qths: Sliema MLT / Bavaria / Nth GER / Keitum-Sylt

daveB
Posts: 1005
Joined: 07 Oct 2014 16:49

Re: 01 Sept 2017 - double hop reception

Post by daveB » 09 Sep 2017 20:58

Just back from a nice week away in Suffolk - so it is only now that I can re-check the frequencies with an echo.

During the opening I've logged (so far) a dozen frequencies with Radio Rossii. Three of them had an echo - 66.38, 69.68, 71.24 - all three from GTRK Tver region. 69.68 was by far the strongest of the three but I can pick up the echo at the same points in the stream on the other two. At around 1130 UTC a drama programme was being transmitted across many regions - the one's I've received from txs in GTRK Pskov, Smolensk, and Slaviya were free of any echo. That must indicate a problem at regional level.
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

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