I am not familiar with raw IQ wave files. For tetra-1 signal, the bit rate is $36$ k bps (or $18$ k as the symbol rate). If the Fs saved in the .wav file is $48000$ Hz, what should be the SPS (sample per symbol)? Remember that if SPS is 4 for QPSK, then both I&Q components need to be upsampled by $4$. In this case, should it be calculated as $(48000/2)/18000$?

  • $\begingroup$ Is this a homework problem? $\endgroup$
    – MBaz
    Nov 20, 2020 at 14:18
  • $\begingroup$ It is a general question. If you are using GNU radio USRP to record the raw IQ data, you will need the upsampling rate (or sps) to process the recorded signal. $\endgroup$
    – Linda
    Nov 20, 2020 at 18:12

1 Answer 1


It is a unit conversion. You have the sampling rate given, $F_s$, and it has units of $\frac{\text{samples}}{\text{second}}$. You also have the symbol rate, $F_{sym}$, and it has units of $\frac{\text{symbols}}{\text{second}}$. You are trying to figure out what is the $\frac{\text{samples}}{\text{symbol}}$ so it is this division:

\begin{align} \frac{\text{samples}}{\text{symbol}} &= \frac{ F_s }{ F_{sym} } \\ &= \frac{ \big(\frac{\text{samples}}{\text{second}} \big)}{ \big(\frac{\text{symbols}}{\text{second}} \big) } \\ &= \frac{\text{samples}}{\text{symbol}} \checkmark \end{align}

  • $\begingroup$ That is what I am thinking as well. But should I put 1/2 here as I listed in the question area? How is the Fs defined for the .wav file? Is it the actual sample rate in the file or is it just Q(or I) sample rate individual? $\endgroup$
    – Linda
    Nov 23, 2020 at 14:07

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