Re: [Discuss-gnuradio] what is the rate(sampling) of the impulse response using usrp_sounder.py ?

[Johnathan Corgan]

On Fri, 2008-12-05 at 23:42 +0100, Bruhtesfa Ebrahim wrote:

> I am using usrp_sounder.py to see channel impulse response. I used
> just the default parameters(length=4095) using:
>  
> usrp_sounder.py -t -f 2.40e9  -v 
> usrp_sounder.py -t -f 2.40e9 -v  -F 1st_Record.dat
> 
> 1.  could someone tell me what the sampling rate of the recorded
>  impulse response recorded will be?

The impulse response bins are separated by 1/32MHz, or 31.25 ns.

> 2. on which  parameters will the sampling rate depend? 

This is fixed.  The sounder transmitter sends a repeating PN sequence at
32 Mchips/sec.  The receiver correlates the received data against all
possible offsets of the PN sequence and outputs the resulting
correlation vector.

> 3. and if I contine the sounding for some time and stop, does it mean
> i will have N different impulse responses or N*4095 samples ?  -Thanks

You will have a repeating sequence of impulse responses of length 4095
samples, corrupted by noise.  You may coherently sum these to reduce
noise, however, the gr-sounder receiver does *not* perform any
frequency/phase synchronization, so the vectors will need
post-processing if you want to do this.

-Johnathan