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Re: [Discuss-gnuradio] voice over digital moduation
From: |
Marcus Müller |
Subject: |
Re: [Discuss-gnuradio] voice over digital moduation |
Date: |
Fri, 10 Nov 2017 09:55:30 +0100 |
Hi Atif,
nice question!
so, I'm a bit bit confused by your resampling and your "multiply with
signal source". Can you explain what the sampling rates of your USRP
is?
And: if you resample something to 200 kS/s, then the unambiguously
representable frequencies are -100kHz to + 100kHz.
Since your OFDM signal doesn't have 0Hz bandwidth, I'm almost certain
that it's then a very bad idea to shift it by 100 kHz. Add some Qt GUI
frequency sinks throughout your flowgraph to see why!
Best regards,
Marcus
On Thu, 2017-11-09 at 20:22 -0800, Atif Javed wrote:
> Hi
>
> I have been working with Gnuradio and USRP N200 for about a month now and
> about all this time I have never succeeded in transmitting digital voice via
> USRP. My Proposed approach is like
>
> audio source--->CVSD encoder---->OFDM mod------>rational resample to
> 200k------->multiply with signal source (100k)------>USRP sink
>
> on the receiver side
>
> USRP source------> multiply with signal source (100k)----------..rational
> resample to 48k ------->low pass filter----->OFDM demod------>CVSD decoder
> ------->audio sink
>
>
> I have also used a built in flowgraph of OFDM voice attached within where i
> get zero output with encoder (codec 2). If the encoder is disabled, the
> output works just fine.
> Any kind of assistance in this regard would be much appreciated.
>
> Regards
> ATIF JAVED
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> Discuss-gnuradio mailing list
> address@hidden
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