Yes and no: the shifting is done right; however, you should make sure to
use a consistent sampling rate throughout the block.
The USRP sink interprets the samples that come into it as having a
sample rate of 5MS/s, whereas the nominal sampling rate in the signal
sources is set to 2MS/s.


On 12/22/2014 10:45 AM, Saul E. wrote:
> First of all, I want to thank you for your answer.
>
> Then, It is correct? (for a simple simulation of 1k, 2k and 3k Hz of
> doppler shift)
>
>
>
> ​
> Thank you.
> Saul E.
>
>
> 2014-12-22 10:26 GMT+01:00 Marcus Müller <[email protected]
> <mailto:[email protected]>>:
>
>     Hi Saul,
>
>     a doppler shift is, mathematically speaking, nothing more than a
>     multiplication with a complex sine, so use a multiply block and a
>     signal source per simulated sattelite.
>
>     Now, you might want to update your doppler shift according to a
>     simulated sattelite's position. I recommend having a look at
>     PyEphem[1], which offers you calculational routines for such
>     things, and writing your own python block[2] to generate the
>     complex sine.
>
>     Greetings,
>     Marcus
>
>     [1] http://rhodesmill.org/pyephem/
>     [2]
>     http://gnuradio.org/redmine/projects/gnuradio/wiki/Guided_Tutorials ;
>     go through tutorials 1, 2, 3
>
>
>     On 12/22/2014 10:14 AM, Saul E. wrote:
>>     Hi all!!
>>
>>     I am developing a SDR receiver and want to simulate the doppler
>>     of signal from several satellites.
>>     Any suggestions?
>>
>>     Signal1, signal2 and signal3 are BPSK signals and I use a USRP N200.
>>
>>
>>     ​
>>
>>
>>     Thank you very much in advance.
>>     Saul E.
>>
>>
>>
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>
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>

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