I am using GNURadio to send and receive a limited number of modulation symbols. I have constructed the following flow chart:random source(no repeat)->chuncks to symbols(file sink1)->polyphase arbitrary resampler->channel model-polyphase clock sync->file sink2 enter image description here

This flowchart is modified from the example that comes with gnuradio, and the parameter settings should be correct. I checked the two files and found that their numbers are not the same, and there is a lot of difference between them. I don’t know how to recover the transmitted modulation symbols. My channel module does not set the clock offset and frequency offset. There is no multipath effect and no sampling clock deviation. I have the following questions:

  1. Why is the number of these two files different? If the sent and received data are not the same, then this cannot be used to transmit data.
  2. How to ensure that the symbols sent and received are the same, or the error is small? I know that there are more forward operations, such as the upper layer protocol PDU, etc., but if the symbols in this part of my place cannot be completely received correctly, how do I perform the subsequent operations?
  3. Modules such as "polyphase clock" and "costas loop" are used to restore symbols, but they need a certain amount of time to lock the loop. In this case, some data symbols will always cause errors? Can it be used for actual communication?

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