An observation that is probably not a satellite

Hello community!
I’m analizing diverse bands of some spectrograms in the L band (specially, in between the 1200 to 1800 MHz band), and I’m now investigating other sources of misterious signals. In particular, I have found 3 strange signals, but I don´t think they are satellites and, most important, I don´t even know what kind of device they could be!
The signal has a central frequency of 1398.77 MHz, as you can see in the following picture:

The vertical bands at 0.5 and 5 minutes are the signals we are looking for, the upper-right plot is a zoom of the spectrum in the frequency mentioned up here (forget about the BW, I calculated it only for the main peak), and the one over the spectrogram is the power in dB, measured only in the corresponding spectral line. As you can see, the power is almost constant each time the signal repeats, which drives me to think it does not correspond to a satellite’s transit.
I hope someone know something, or at least confirm that it isn’t a satellite! Thank you all for your time!