Re: [Discuss-gnuradio] sampling rate of tx_sampless.cc and rx_streaming_sampless.cc

[Per Zetterberg]

Krishna,

My understanding is that we can regard the sample rate of the DAC and 
ADC as 100MHz (although the DAC uses internally a larger rate, this is 
what I have read). Thus the rate at which samples are leaving or 
entering the RF sections at are 100MHz.   The maximum rate at the host 
side is 25MHz, then that rate is interpolated/decimated in the FPGA 
to/from the 100MHz. The tx_sampless.cc and rx_streaming_sampless.cc 
reads and writes from file and therefore 25MHz host sample-rate may not 
be possible. 

Thus you should typically use the same interpolation/decimation factor 
in the transmitter and receiver.

BR/
Per

Krishna S wrote:
> Hi,
>      So,  if i am setting interpolation rate 16 at transmitter 
> side(tx_samples.cc), according to the equation the program is sampling at
>
>    Sampling rate = 400/16 = 25M samples/sec.
>
> but, I am able to receive the data only at the same decimation rate 
> 16(rx_streaming_samples.cc) , for which the program is sampling at
>
> Sampling rate =100/16 =6.25M samples/sec 
>  
> But for me to transmit and receive data i have to send and receive at 
> 25M samples /sec right ??
>
> if i try to do that i.e., at receiver side samp rate = 100/4 = 25M 
> samples /sec
>
> I don't receive at all ...?
>
> everything boils down to one question ?
>
> the sampling rate what we are talking here is the sampling rate at 
> which the samples have been sampled before sending to RF as discussed 
> in COMMUNICATION THEORY (following the Nyquist Criteria)
>
> or the sampling rate calculated to find the allowed no.of samples/sec 
> the ETHERNET  can take  to connect the host to USRP2.  but inside the 
> sampling rate is different ?
>
> As i am dealing with RF communication i need to know exactly what 
> sampling rate the USRP2 is sampling the data and sending over the air ?
>
> Thanks
> KRISHNA S
>
> --- On *Wed, 7/4/10, Per Zetterberg /<address@hidden>/* wrote:
>
>
>     From: Per Zetterberg <address@hidden>
>     Subject: Re: [Discuss-gnuradio] sampling rate of tx_sampless.cc
>     and rx_streaming_sampless.cc
>     To: "Krishna S" <address@hidden>
>     Cc: "gnu" <address@hidden>
>     Date: Wednesday, 7 April, 2010, 7:52 AM
>
>     Krishna S wrote:
>     > Hi,
>     >     i am trying to calculate at what sampling rate does the
>     tx_sampless.cc and rx_streaming samples.cc  are sending the data
>     (file). from 1 USRP2 to another USRP2.
>     >
>     > i am setting interpolation as 16 at transmitter side
>     (tx_samples.cc) and decimation rate of 16 at receiver side
>     (rx_streaming_samples.cc)
>     >
>     > according to formula what i have learnt from WEB is
>     >
>     >
>     > Tx Side :  Sampling Rate =  DAC rate/ Interpolation rate;
>     > Rx Side : Sampling Rate =  ADC rate/ Decimation rate;
>     >
>     > are the above equation are correct for determining the sampling
>     rate ????
>     >
>     > Thank You
>     > Regards
>     > KRISHNA S
>     >
>     >
>     >
>     >
>     ------------------------------------------------------------------------
>     > Your Mail works best with the New Yahoo Optimized IE8. Get it
>     NOW!
>     
> <http://in.rd.yahoo.com/tagline_ie8_new/*http://downloads.yahoo.com/in/internetexplorer/>.
>
>     >
>     ------------------------------------------------------------------------
>     >
>     > _______________________________________________
>     > Discuss-gnuradio mailing list
>     > address@hidden </mc/address@hidden>
>     > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>     >   
>
>     Yes, it is the sample-rate on the host-side. DAC rate and ADC rate
>     is 100MHz.
>
>     BR/
>     Per
>
>
> Send free SMS to your Friends on Mobile from your Yahoo! Messenger. 
> Download Now! http://messenger.yahoo.com/download.php