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CC2500: Packet Error Rate(PER) test on various condition

Part Number: CC2500
Other Parts Discussed in Thread: CC1101

Hello Experts,

We are evaluating CC2500 on MSK 500kbps by using SmartRF studio and EM. Other than below parameters, we are using the default register settings of SmartRF studio 7.

1. Changing MDMCFG2.SYNC_MODE shows below PER

   0x71 : PER 100%( all failed)

   0x72 : PER 15%

   0x73 : PER 0% ( all good)

Why does sync word length affect PER? We want to use 16 bit sync word if possible.

2. When should we use MDMCFG2.SYNC_MODE with larger than b'101 (15/16 + carrier sense above threshold)?

3. How to use PKTCTRL1.PQT?

 When setting PKTCTRL1.PQT to 3, PER described on above 1 shows almost 0% ( good result)

Best Regards,

Uchikoshi

  • The sync detect on CC1101 and CC2500 are strictly bit based meaning that they just compare the incoming bits with the selected sync word. Using a 16 bit sync word means that the probability for finding a valid sync word in noise is rather large, especially on the 2.4 GHz band where the radio traffic is high. when you select 15/16 you in addition allow 1 bit error in the sync word increasing the probability to find in noise.

    Using PKTCTRL1.PQT gate sync detection on a valid preamble. Meaning that before starting looking for a sync word a number of preamble should be received where the PQT setting sets how good quality the preamble has to have. Since a valid sync word is always preceded by preamble this reduced the probability for false sync detection since a pattern in noise that equals the sync word will most likely not be preceded by preamble.
  • Thank you for your explanation.
    So do you think it is better to use longer sync word and higher PQT generally?
    Regards,
    Uchikoshi
  • Yes, when you can use a 32 bit sync word and if required, add PQT. This is also to some degree dependent on where you use the device => you should test in the relevant environment and see what's required to get a good connection.