Home Forums GENERAL Resample of Universal DSP

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    • #67141
      Fx Yang

      Hello all. There is a question about sample rate in “56Gbps Coherent 16QAM_B2B_detail with DSP”.

      In the Universal DSP, there are 262144 samples before [Resampling]. After [Resampling] sps = 2. Because there are 16384 symbols, the samples should be 32768 after [Resampling]. Why it is 32756? We can see this phenomenon in “Report->DSP for 16QAM->Constellation After Resampling”

      In the help document of Universal DSP we can see”Note: Between algorithm stages, the signals are up-sampled to their original rate (for the case of 16-QAM, 8 x Samples per bit). For 2 samples/symbol, the first half of the sampled signals are set to a and the second half to b. For 1 sample/symbol all sampled signals are set to c.” And there are 32768 points on the constellation of [QI Compensation][Timing Recovery][Adaptive Equalizer]. Is every algorithm upsample the data first and downsample the data before output to the next algorithm, and the next do the same thing?

      I find a phenomenon that the Universal DSP will make the signal power rise. Every algorithm except [Filter] will make the signal power rise. We can see the phenomenon by comparing the [RF Spectrum Analyzer] of the input and output of the DSP signal. I don’t know why. I use optisystem 15.

      Thanks for your help.

    • #67143
      Ahmad Atieh

      Hello FX,
      The Digital square and filter algorithm is used in the Universal DSP component. More details can be found in the datasheet of the component that can be accessed using the help button in the component properties.
      Please contact me at ahmad.atieh@optiwave.com to discuss further.

      The last paragraph on the signal power is not clear. Could you please elaborate on what do you mean by DSP make the signal power rise?


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