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[Discuss-gnuradio] Re: Frequency dependent problem after syncronizing ,
From: |
Bruhtesfa Ebrahim |
Subject: |
[Discuss-gnuradio] Re: Frequency dependent problem after syncronizing , Please help! |
Date: |
Thu, 12 Feb 2009 22:20:08 +0100 |
Johnathan Corgan wrote:
> On Thu, Feb 12, 2009 at 5:43 AM, Bruhtesfa Ebrahim
> <address@hidden> wrote:
> It sounds like, since you have perfect synchronization between
> transmitter and receiver, that what you have after downconversion in
> the daughterboard is DC + noise. That is, the transmitted carrier
> (plus noise and multipath from the channel) is being mixed with a
> synchronized local oscillator, resulting in only the noise components
> being left in the complex baseband signal GNU Radio is receiving.
> There will also be a DC component based on the path delay and
> wavelength causing a phase shift between the transmitted carrier phase
> and and the receiver LO phase.
>
> Johnathan
Thank you Johnathan!
What makes it strange is the dependence on gain.when the linear gain in
the spectrum panel(usrp_fft.py)is set to 0,the signal at the center(the
DC)is 5dB higher than the noise level.When I increase the gain, the
difference between the DC and noise level keeps decreasing and finally
the DC level is equal to the noise level.
Specifically, for a linear gain >=20, the signal around DC is not
visible(it is equal to the noise level).
is this gain dependence normal?
Bruhtesfa
--
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- [Discuss-gnuradio] Frequency dependent problem after syncronizing , Please help!, Bruhtesfa Ebrahim, 2009/02/12
- Re: [Discuss-gnuradio] Frequency dependent problem after syncronizing , Please help!, Johnathan Corgan, 2009/02/12
- [Discuss-gnuradio] Re: Frequency dependent problem after syncronizing , Please help!,
Bruhtesfa Ebrahim <=
- Re: [Discuss-gnuradio] Re: Frequency dependent problem after syncronizing , Please help!, Johnathan Corgan, 2009/02/12
- [Discuss-gnuradio] gnuradio mentioned in cnet article on phone snooping, ematlis, 2009/02/12
- Re: [Discuss-gnuradio] Re: Frequency dependent problem after syncronizing , Please help!, Eric Blossom, 2009/02/16
- [Discuss-gnuradio] Re: Re: Frequency dependent problem after syncronizing , Please help!, Bruhtesfa Ebrahim, 2009/02/16