[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] Sampling Freq

From: David Scaperoth
Subject: Re: [Discuss-gnuradio] Sampling Freq
Date: Fri, 23 Mar 2007 00:53:25 -0400

On Mar 22, 2007, at 5:11 PM, Jonathan Shan wrote:

On Thu, 22 Mar 2007, Johnathan Corgan wrote:

Jonathan Shan wrote:

When I send this to file_sink, I see correctly 16 samples from peak to peak. However, when I transmit this using 'usrp sink' and receive at the
other end, I see about 32 samples from peak to peak.. double what I
expected. What is happening?

What do you have the transmitter interpolation and receiver decimation
set to?

interp_rate = 64, decim_rate = 16.


16 samples per cycle and interp = 64 (2MSps over the USRP) means sinwave freq = 2MSps/16 = 125kHz 32 samples per cycle and decim = 16 (4MSps over the USRP) means sinwave freq = 4MSps/32 = 125kHz

I saw the formulas
usb_sample_rate1 = 64e6 / decim_rate
usb_sample_rate2 = 128e6 / interp_rate

Using current values, usb_rate1 = 2 * usb_rate2. I'm assuming.. to
get the correct sampling freq, usb_sample_rate at both ends should be

Jonathan Shan

Discuss-gnuradio mailing list

reply via email to

[Prev in Thread] Current Thread [Next in Thread]