In a waveform designing i am getting this type of constellation(image_attached). Can anyone please tell me why i am getting this type of constellation? this constellation is after frequency correction.

enter image description here

  • $\begingroup$ Welcome to DSP.SE! Looks like your demodulation center frequency is off... but this isn't really my area of expertise. Let's see what answers we get. $\endgroup$ – Peter K. May 4 '16 at 11:50
  • $\begingroup$ Is this supposed to be QPSK? Fading or AWGN channel? Are you sure the transmitted signal is fine (e.g. the EVM is small)? $\endgroup$ – MBaz May 4 '16 at 13:47
  • $\begingroup$ @PeterK. is right, there is a bug in your frequency correction code (or circuitry). If you want more useful help, maybe you could explain how you are implementing frequency estimation/correction in your receiver. $\endgroup$ – vaz May 4 '16 at 13:50
  • $\begingroup$ Thanks to All for reply, but sir,i am also getting a fully moving Circle before frequency correction, i mean to say after symbol timing recovery which is also not correct. @vaz there is no bug in the frequency correction code beacuse i have tested and used this code in other waveforms also there is no issues. $\endgroup$ – kshitij goel May 5 '16 at 4:37
  • $\begingroup$ Is this with OFDM? Users here could help you a lot more if you gave a bit more details about what is going on, such as any digital filters or analog mixers involved in whatever this is? Also what bandwidth and channel? $\endgroup$ – portforwardpodcast Jun 30 '18 at 23:55

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