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Sync word questions

ECH12
Expert 1195 points

Other Parts Discussed in Thread: CC1120, CC1200

Hi,

Few questions about sync word:

1. How to select the correct sync word which will give the best sensitivity. Is there a correct value?

2. Does the preamble have any affect on the Sync word value? meaning, if I select 0xAA preamble, should the sync word be different if I change the preamble to 0x55?

3. How to select correct values for dual sync sync word?

4.Is the max SYNC_THR (which is 5 bits value) different if I use 16 / 32 bit sync word?

Thx

  • 0
    TI__Guru**** 317180 points
    1) For CC1200 and CC1120 the sensitivity is not limited by the sync word. If the sync word is poor the probability to get false sync increases but the sensitivity is not affected as such.

    To see if the sync word is poor:

    -Convert the sync word to a binary vector
    -Run xcorr(2*sync_vector - 1) in Matlab or equivalent
    -Plot the result
    •A good sync word has no side lobes

    2) No

    3) If you keep the default sync word given in SmartRFStudio this is also a good option for dual sync use
    4) No. The threshold should be set differently between FSK and GFSK. If the sync word is poor the threshold in some cases has to be set higher.