Identification of unknown signals?

Hi all,

While scanning some frequencies, I came across some digital signal in
the 166-168MHz region that I would like to identify.
The baseband signals are narrow (5/10 kHz) using an unknown modulation.
I had a look at the constellation diagram and all I could see is a quite
flat ellipse.

The spectrum at the beginning of the burst has 5 harmonics spaced by ca.
1.6KHz, and at the end of the bust it’s just a single spike (and the IQ
signals are almost pure sinus)

I would be grateful if someone could share tips about signal


Christian G.,
Embedded systems engineer.
Techworks Marine
1 Harbour road
Dun Laoghaire
Co. Dublin
Tel: + 353 (0) 1 236 5990