Hi,
i try to analyse a sensor, from which I have no information. I used a GNURadio and to take a look at the sensors rf spectrum.
I think the modulation used here is 2-FSK. But i would expect 2 more clean peaks. And the waterfall diagaram shows a dotted spectrum. This confuses me. I am not very experiend in rf protocol analyses, what do you say?
Could it be FSK with carrier suppression ?
What happens if you demodulate it with FM ?
When i demodualted with FM i get the data i want. May i had to be more precise, what type of FSK modulation is it?
In an other case i had a sensor which modulated with 2-FSK but the spectrum was weird and finally someone gave me the hint that there was FHSS used.
Here i hope too, that some can give me a hint, what type of FSK-Modulation is used or what other machanism looks like this.
Its some kind of FSK.
The 2 peaks are a function of the carrier deviation, and the spectral components between the 2 peaks are a function of the transmitted data rate.
Most likely its just 2 state modulation , ie binary 1 shifts up, binary 0 shifts down, or vice versa.
I just noticed the time scale on the 'waterfall' picture. Can you stretch that 100 or 1000 times ?
Those are bursts of data of a transmitter or a transceiver. Could it be that an other module is answering ? Or are there two transmitters ?
Many of the newer protocols have more than just two frequencies. Since this is only two, it is something close to normal FSK. I think we need to know more about the signal to be able to say what exactly it is.