ISS at 437.025 MHz?

[fredy]

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:

ISS Deployment (JAXA) J-SSOD#32 - 2025-09-19

Here is an interesting reception SatNOGS Network - Observation 12410418. The signal seems to fit the ISS TLE but not the new ones we generated for GHS-01. The signal is at 437.081, instead of the 437.090 and it is very faint and not visible in other high pass observations at the same time. Also the signal looks like voice. I’m not sure how to interpret this and in my mind run different scenarios: The signal comes from ISS, then why is so faint and why in this unexpected frequency. The signal…

Not exactly at 437.025 but near.

@K4KDR

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

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.