[Hackrf-dev] PHASE CHANGE

[Ernest Matey]

Experts,

I have two hackrfs receiving the *same* voice transmission on FSK -1200bps
I expect and plan to see the same modulation signature from the two systems
of this same signal.
I did *Raw* IQ recording with SDRsharp with the following parametrs.

Tx Freq - 437 MHz
Rx Freq - 437 MHz
Bandwidth - 10 KHz
Samp - 12.5 MHz , 8bit
Black-Harris filter
Freq_correction - -2ppm

BUT, I do not see the same phase signature of the signal even though I
align the bursts in time. I expect to see same pattern

*See attached plots of same channel each from the two hackrf systems.*


*What could be done ?*

*Ernest*

[Cinaed Simson]

Recovering the information in a BFSK signal is a software problem on a SDR.

Also, they are typically noisy and use Manchester encoding to recover
the clock rate.

You should post this on the SDRsharp mailing list - and knowing the
transmitting device and a FFT of the resulting signal on the HackRF
would be helpful.

And did you use a low pass filter - what was the cut off frequency and
transition width - and did you avoid the DC offset on the HackRF?

And how did you determine it was a FSK and not a PSK signal?

The idea is to use the SDR to analyze the I/Q values captured by the
HackRFs.

-- Cinaed

Post by Ernest Matey
Experts,
I have two hackrfs receiving the *same* voice transmission on FSK -1200bps
I expect and plan to see the same modulation signature from the two
systems of this same signal.
I did *Raw* IQ recording with SDRsharp with the following parametrs.
Tx Freq - 437 MHz
Rx Freq - 437 MHz
Bandwidth - 10 KHz
Samp - 12.5 MHz , 8bit
Black-Harris filter
Freq_correction - -2ppm
BUT, I do not see the same phase signature of the signal even though I
align the bursts in time. I expect to see same pattern
*See attached plots of same channel each from the two hackrf systems.*
*
*
*What could be done ?
*
*
*
*Ernest*
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