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I read about Time recovery (as an example, the Mueller&Muller algorithm); it is linked to when you should sample your signal.

I am currently working on a project with GNU Radio and there is some blocks that perform time recovery.

I don't get how those blocks actually perform a time recovery in the digital world because they can't change the sample that the USRP produces... I don't understand how such algorithm can be implemented on the digital side with out affecting the USRP itself which is the device sampling the signal.

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  • $\begingroup$ There are two kinds of sampling going on. The USRP turns a continuous signal into a discrete signal. After matched filtering (implemented in digital backend), the signal is sampled again at specific time instants, to get the transmitted bits. This second sampling is what M&M is about. $\endgroup$ – MBaz May 27 '16 at 16:18
  • $\begingroup$ @MBaz so the samp_rate only affect how you sample the already sampled stream of data that come from the USRP? So the samp_rate is a downsampling? $\endgroup$ – MathieuL May 27 '16 at 17:14
  • $\begingroup$ Depends on what you mean by samp_rate. If it is the number you give the USRP, then no, the USRP's sample rate is the rate at which the RF continuous signal is discretized. $\endgroup$ – MBaz May 27 '16 at 18:32
  • $\begingroup$ Well you are saying that the USRP sampling rate is constant what ever the samp_rate variable is set @MBaz $\endgroup$ – MathieuL May 27 '16 at 19:19
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    $\begingroup$ You must really understand what a pulse shaping filter does, @MathieuL; that's very important for understanding what timing recovery needs to do! $\endgroup$ – Marcus Müller May 30 '16 at 13:23

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