I’m working in a project in which we are receiving diverse kind of signals from the sky in frequencies between 1695 to 1710 MHz.
We need to identify the source of each signal. I have associated some of them to NOAA, Metop and METEOR satellites, but there is a particular signal with a BW ~ 3 MHz and central frecuency ~ 1704 MHz.
I made some research and I found there’s a meteorological satellite (FengYung 3A) which is active and its downlink transmissor operates in the corresponding received frequency, but when I use orbitron to track the corresponding orbit, the transit time does not match with the received signal time, which is strange because all the other satellites’s predictions were precise and at the correct time. Is there an explanation for this situation? I think there are 2 options:
I hope someone could please help us!!! ty for your attention.
Here’s a picture of one of the spectrograms for the satellite:
Interesting. That used to be close to the broadcast frequency of FY-3A… AND the bandwidth is about right.
We need to investigate this further. What is your antenna? I could try to take a look with my 1m dish.
okaay I just reread your post
FY-3A is not active, it was shut down a long time ago. Perhaps this is a dead sat come back to life but this is unlikely.
Paging @dereksgc for this
Looks like a classic case of a YunHai-1 intrusion:
These are three Chinese satellites transmitting on 1704 MHz with a massive bandwidth and unusually high power (will be clearly visible even on an omnidirectional antenna).
Data is said to be encrypted. Check your observation time against Yunhai 1-01 , Yunhai 1-02  and Yunhai 1-03 .
FengYun-3A and 3B are both inactive, and 3C only transmits when in view of China. I’m not aware of anything else that could produce this kind of signature.
Thank you for your help and time! That´s strange. If that is true, then it’s natural that there is no data of the corresponding transit.
I appreciate your info! Salutations!
Thank you! it seems like you’re right, i have made some predictions and all of them are showing transits of the YUNHAI satellites, though there’s a little error in the time of arrival, but I think that’s because of the error in the TLE predictions.
I’m extremely grateful for your help!