Re: [Discuss-gnuradio] Frequency Hopping

[Firas A.]

Hi,

Your quote is not being distributed to the community at all. I  can only
found them at www.nabble.com. 

Regards,

Firas


Attari wrote:
> 
> Hi,
>  I have solved this error by proper connection between signal processing
> blocks in self.connect method
>  as:
> 
> Cosine = gr.sig_source_f(250e3,gr.GR_COS_WAVE,self._mix_freq,1,0)
>       Sin    = gr.sig_source_f(250e3,gr.GR_SIN_WAVE,self._mix_freq,1,0)
> 
>       self.expjw = gr.float_to_complex()
>       self.connect(Cosine,(self.expjw,0))
>       self.connect(Sin,(self.expjw,1))
> 
>       self.mixer = gr.multiply_cc()
> 
>         self.connect(self, self.bytes2chunks, self.symbol_mapper,
> self.diffenc,
>                      self.chunks2symbols,self.rrc_filter )
>         self.connect(self.rrc_filter ,(self.mixer,0))
>       self.connect(self.expjw ,(self.mixer,1))
>         self.connect(self.mixer,self)
> 
> I am shifting my baseband spectrum a little bit like between  -120kHz to
> +120kHz [like four hopping freq's are -90kHz ,-40kHz 40kHz,90kHz] as my
> sampling freq is 250kHz and my signal bandwidth is 68kHz on the rate of
> 50kbps with Bpsk modulation. Rest my USRP is operating on same 900MHz
> (fc). as it takes 32MHz signal as baseband (dueto 64MHz sampling freq at
> receiver),so it will give me the margin of shifting spectrum to only few
> kHz treating it same as baseband.
> 
> Now I have problem of getting my packets recovered at receiver side in
> dbpsk demode class.where i have added a demixer (with negative freq's)
> before RRC filtering and demodulation in its connect method chain.
> 
> I am doubtful at RRC filtering parameters specially in its interpolation
> method of RRC taps ,where it takes "1" in place of "_samples_per_symbol".
> I have tried to set its parameters same as they are at transmitter side
> but it doesn't work.Out of 1000 packets i get only 5 or 6 packets and are
> in error.
> 
> Help me in solving this problem!
> Thanks in advance,
> Attari. 
> 

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