The function of the block in demodulation part?

[SUSTC2013]

I am studying your gr-ieee802-15-4 code now. But I was a little puzzled. How do you demodulate the received signal? Why do you use single_pole_iir_filter block, subtract block and Clock recovery MM block? Regards,

Thank you!

MarxWolf

[bastibl]

I think you should do some research on the functionality of the blocks. The GNU Radio documentation is very good.

Then there is the paper GNU Radio 802.15.4 En- and Decoding by Thomas Schmid that gives an overview and CMOS RFIC architectures for IEEE 802.15. 4 networks by Notor et al. that describes the receive algorithm.

The general idea is to regard O-QPSK as frequency modulation:

• Quadrature demod extracts the phase of the complex symbols
• the IIR filter calcualtes the average phase
• that is subtracts it to center around zero
• the bits are extracted with the MM clock-recovery block