Evening listening of Radio Delta International on 6020 kHz in Eastern Europe is usually accompanied by interference from FSK utility station on the adjacent frequency of 6022 kHz.From the RDI's reply on my reception report:
"…In the East we have some problems with the strange digital interference on 6022. Hopefully in the future it will disappear, it is not normal that they use this frequency…"
This QRM is not a trouble at all in the case of reception with some SDR, where low and high sidebands of the "filter" can be adjusted independently, and splashes from Chinese high-power transmitters on 6015 and 6025 kHz are much more considerable and annoying. However, this signal makes reception on 6020 kHz uncomfortable or even impossible (depending on its strength) for DXers with simple portable receivers, where rich selection of IF filters is absent.
Protocol of this utility station is identified as CIS-36-50 (also known as BEE-36 or T-600) with 200 Hz shift and 50 Bd rate FSK modulation. It is being widely used by russian navy. Tentative location of the transmitter is Autonomous Republic of Crimea or Sevastopil, occupied and annexed by russia. Results of the TDoA analysis point at the same direction:
From 17.00 till 18.00 UTC 6022 kHz channel is completely blocked by superstrong DRM signal of Radio Romania International on 6025 kHz, and the reason for such a stupid choice of frequency for the utility station is unknown. Anyway, if you hear utility interference on 49 mb, be sure that in 95 per cent of the cases the source of interference is the russian military.
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