Re: [Discuss-gnuradio] tx frequency changing by clk_divider

[Yan Nie]

Hi Johnathan,


I'm doing something similar as you did in gr-sounder project, sending a code modulated as BPSK with the suppplied center frequency, but different code (which contains 1 and -1 also), and bandwith for the code, which is 32kHz instead of 32MHz. I used the clk_divider block to down the frequency to 32kHz, then I monitored the signal from the antenna part on daughterboard by an oscilloscope. The waveform of the signal is a nicer sinusoid wave, but it doesn't show the phase shift for -1 part in the sequence.


I'm not sure if it's clear. If not, I will post some photos of the oscilloscope, but it just a continued sine wave without any phase shift for BPSK modulation.


Thank you so much!


Regards,
Yan

----- Original Message -----
From: Johnathan Corgan <address@hidden>
Date: Thursday, January 28, 2010 7:19 am
Subject: Re: [Discuss-gnuradio] tx frequency changing by clk_divider
To: Yan Nie <address@hidden>
Cc: address@hidden

> On Wed, Jan 27, 2010 at 15:08, Yan Nie <address@hidden> wrote:
> 
> > The major problem of the frequency decreasing is the 
> transmitting signal
> > from the antenna doesn't show the result of BPSK modulation in 
> the waveform
> > of the signal. Could you please give some suggestions about 
> what the
> > problem?
> 
> I'd like to help you out with this, as I wrote the original gr-sounder
> FPGA code, but to be honest I have no idea what you've done or what
> issue you are seeing with it.
> 
> Could you perhaps elaborate with the kinds of extensions you have
> written to it, maybe a description of your signal flow, post 
> links to
> screenshots of your lab equipment displays, or something more concrete
> than what you have written above?
> 
> What is it doing that it shouldn't be, or what isn't it doing 
> that it should?
> 
> Johnathan