I’ve created a separate topic topic for this as you suggested to discuss it a little more.
The only known transmission around that frequency was from the Russian satellites deployed by hand Tanusha 1 and 2 and Tomsk-TPU-120.
I’m wondering what is the source of this signal.
A weak signal, it seems to be broken or not connected antenna.
I’ll create a new transmitter for ISS and try to watch if we can get more observations.
As still close, I’ll share the time of the stations between the ISS and the deployed satellites.
While it seems unlikely, I believe that there are some not-yet-deployed cubesats on the ISS from NG-23 that are scheduled to downlink in the lower 437 MHz range:
EagleSat-2: 437.165
SilverSat: 437.175
I think the first step should be to verify that this transmission is 100% coming from ISS, so we need observations from other stations to verify it.
@EU1SAT don’t get me wrong I believe you and I’m 99% sure is coming from ISS, but I have this 1% that we may miss something.
In parallel there was also a similar finding near this frequency we are talking about:
Not exactly at 437.025 but near.
To be honest I’m finding it unlikely given that the observed frequency is more than 100KHz away from these satellites’ frequencies. But it doesn’t hurt to keep it as a scenario.
@EU1SAT Did you noticed any other transmission than the ones you shared?
From the Network’s observations there isn’t anything observed until now. But I’ve scheduled a couple more observations for the next days to see.
Within 3 days, I observed this signal on several pass every day.
Now I am on a short -term vacation and I can’t observe satellites.
The signal is very weak and a high performance antenna is required.
It seems that my observations are a signal transfer from 437.800 MHz due to ADC overload!!!
I think the topic can be closed or even deleted.
I apologise to everyone in your lost time.
To @fredy :
The transmitter and observation must be cancelled!
No worries (:
It is always something to learn.
I’m guessing youre running the rtlsdr at 1.536MHz ? I think that could explain the 768kHz difference giving 437.032MHz
Thank you for letting us know! Another mystery solved! 
No need to apologize, RF observations can be tricky, so everything is a lesson for our community!
I’m going to invalidate the transmitter in the next hour.
