Mobitex-1200 462.325 MHz ?

 Mobitex-1200 462.325 MHz ?

In Finland frequency range between 462.2 - 462.5 MHz is reserved for paging. I found (location: Pori, Finland) a transmission at 462.325 MHz which looks and sounds like Mobitex-1200 (MSK, 1200 bps).




PDW only decodes Mobitex-8000, so I decided to try decoding with GNU Radio





Short Python code converted out.txt to file which contains '1's and '0's

f = open("out.txt", "rb")
d = f.readlines()
f.close()

d[0] = d[0].replace('\x00', '0')
d[0] = d[0].replace('\x01', '1')

f = open("out-d1.txt", "w")
f.write(d[0])
f.close()

print 'converted'



I examined converted files and found Mobitex BS 0xCCCC and MS 0x3333 frames preambles. Mobitex data maybe is scrambled (http://www.decodesystems.com/mobitex.txt)

"It's the output of a 9 stage linear-feedback shift register with taps */
/* at position 5 and 9 XORed and fed back into the first stage.

https://www.semtech.com/uploads/documents/AN1200.18_STD.pdf