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I'm currently using two USRP X310, one for transmitting and another one for receiving. Programming is done using GNU Radio. I want to transmit a chirp signal to find the distance between both USRPs.

However, before I can do it, I need to find out the receiving time of the signal. Anyone know how to do it using GNU radio?

Marcus Müller
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user982209
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2 Answers2

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The GNU Radio UHD source will produce rx_time stream tags on streaming start and after every stream disruption, which will give you the device time for the first sample. After that, it's that time + n_samples_since_tag / sampling_rate to get the current time.

See

for details, which are not easy to explain here, but nicely covered in the official documentation.

Marcus Müller
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rx_time tag may give you the time when the USRP receives noise, not the time of reception of desired signal. The only way i can think of is calculate the FFT of the signal and get the time when the PSD of the FFT goes above certain level

user5801221
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