Sample receive time in benchmark

GNU Radio
1

Hi,
My last question
([Discuss-gnuradio] tx_tag's time VS. USRP time)
seems no answer.But I get another question.
I wanna know the actual receive time of a sample. If I get the rx
tag(sample count 100), I can calculate the any sample’s receive time.
For example,sample 1600’s receive time: (1600-100)*sample_rate.
Is it correct?
In my last question, the sender transmit data every 3 second and the
uhd_fft shows it’s true.But the above formula give the result about 1
second.
I think the sample_rate is wrong. I’m using benchmark_rx(gmsk) in
narrowband and the UHD shows the sample_rate is 200ksample/s.
Sample_rate wrong or my formula,which is wrong?
Any suggestion is appreciated.

2

On Wed, Sep 18, 2013 at 11:32 PM, Harry Z. [email protected]
wrote:

Hi,
My last question
([Discuss-gnuradio] tx_tag's time VS. USRP time)
seems no answer.But I get another question.
I wanna know the actual receive time of a sample. If I get the rx
tag(sample count 100), I can calculate the any sample’s receive time.
For example,sample 1600’s receive time: (1600-100)*sample_rate.
Is it correct?

Yes, as long as you are using the right sample rate.

In my last question, the sender transmit data every 3 second and the
uhd_fft shows it’s true.But the above formula give the result about 1
second.
I think the sample_rate is wrong. I’m using benchmark_rx(gmsk) in
narrowband and the UHD shows the sample_rate is 200ksample/s.
Sample_rate wrong or my formula,which is wrong?
Any suggestion is appreciated.

Make sure you are using the sample rate and not the symbol rate. Each
symbol is transmitted using some number of samples per symbol. I’m
sure you already know that, but just to make sure as that’s a likely
cause of confusion when setting things up.

–
Tom
Visit us at GRCon13 Oct. 1 - 4
http://www.trondeau.com/grcon13

3

于 2013/9/19 21:56, Tom R. 写道:

cause of confusion when setting things up.

If I’m using the symbol_rate, the actual sample_rate must be more that
that I’m using now. Thus the formula gives result even less than 1
second, which is still not coming to 3 second.