[Discuss-gnuradio] airprobe xlating filter question

[HW Wong]

It's known that the channel band width is 200KHz

 

When looking into airprobe, gsm_receiver.py

 

the cutoff freq in xlating is 145KHz, Can anyone kindly to explain. Thanks!

filter_cutoff   = 145e3
filter_t_width  = 10e3
 
filter_taps     = gr.firdes.low_pass(1.0, self.input_rate, filter_cutoff, filter_t_width, gr.firdes.WIN_HAMMING)
       
filtr          = gr.freq_xlating_fir_filter_ccf(1, filter_taps, offset, self.input_rate)