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CC1101: Preamble/sync setup at receive mode

Taba Imre
Prodigy 20 points
Part Number: CC1101


I am trying to record a signal from one of my RF transmitter. Picture from the signal Preamble/sync field:

 

After the highlighted part, there comes the payload which i want to go into the RX FIFO. As you can see before that, there is 11 bit of preamble and an 8 bit long sync field with high bits.

My config are set with RF studio, with the values of:

-433 MHZ

-58kHZ rx filter BW

-ASK/OOK modulation

-1250 baud rate, which i calculated, because 1 pulse is 800 microseconds as i inspected

-no manchester encoding / no data whitening

I am confused about the 11 bit long preamble, and only 8 bit sync field. I saw that in the cc1101 datasheet that with the MSB 3 bits of the PKTCTRL1 register i can set preamble detection, but i dont really see how that is work, and after that, i only have 8 bits of sync field, at 16 is minimal for the chip as long as i can see.

So my question would be how can i set up properly the packet control registers, so the receiver would start at the end of that 8 bit long High syncfield. Is it possible?

  • 0
    TI__Mastermind 36395 points
    Taba,

    The CC1101 needs as much sync word as possible, so I suggest setting up the CC1101 to use 16 bit sync word and then use some of the preamble as syncword.

    Preamble = 2 bytes long (even though you do not have enough bits)
    Syncword = 0b1010101111111100

    Regards,
    /TA
  • 0 in reply to TA12012
    Prodigy 20 points

    Thank you for the fast answer,

    I got it working now, the only problem what i have left, that my receiving is not trustable. It misses bits here and there, after i captured a signal and looked into it like 5-10% of the bits was not syncroized with the original signal. Sometimes it misses digital 1s. What could cause this, do you have any suggestions for me?

    Best Regards,
    Taba Imre