Many thanks to SWLing Post contributor, Tom (DF5JL), who writes:
At the end of last year it appeared for the first time: a telemetry transmitter in CW on 7039.60 kHz. It always transmits at the 2nd, 22nd and 42nd minute of every hour. Every day.
Reception reports are available from Germany, the Netherlands, France and Greece. Three numbers and a V are transmitted ten times in succession, as follows:0522 UTC: 121V
0542 UTC: 121V
0622 UTC: 122V
0722 UTC: 123V
0822 UTC: 125V
0842 UTC: 127V
0902 UTC: 128V
0922 UTC: 129VDuring the day the values increase, in the afternoon they decrease. It is assumed that voltage values are transmitted here, i.e. “121V” would correspond to 12.1 volts. You can listen to a recording here:
Any idea?
73 Tom
Thank you, Tom.
Post readers: If you can shed some light on these transmissions, please comment!
Thanks all. After reporting the mysterious transmitter stopped. Those signals started in November 2020 and were reported many times. Direction finding wasn’t that easy because of short periods when transmitting, max. 20 seconds, and that in a crowded band segment of the 40m amateur radio band.
Can it be the battery charging state of some solar-powered installation?
Definitely the Morse (CW) section of 40 meter amateur band (which is in constant use). I suggest it’s reporting battery level powered by a solar panel, as it increases during the early hours, could be a remotely powered Raspberry Pi performing some other function.
It is on 40 mgs.I imagine someone has rigged up a morse key tone on their computer to play automaticly. and continuely probably only the person concerned will know what it means if anything, Sometimes we do hear morse code at this end of the band,but normaly it will be “Hams” communicateing via morse. If it is only since Covid,it could well have something to do with covid to the person doing it. The Values could have meaning , to do with Covid.
what about using the kiwisdr network to triangulate the transmitter ?
Just to be clear, I’m referring to
https://hackaday.com/2018/07/16/global-radio-direction-finding-in-your-browser/
https://www.rtl-sdr.com/kiwisdr-tdoa-direction-finding-now-freely-available-for-public-use/
now, while the above won’t tell “who” is sending those signals, it will allow to understand “where” those signals are coming from, and may allow to gather further informations