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CC1101: Receiving data from FX919B

Rossen Michev
Prodigy 20 points
Part Number: CC1101
Other Parts Discussed in Thread: CC1310

Hello,

I am trying to build a receiver with a CC1101 chip from TI and have several concerns regarding my particular case:

- the base station (equipped with FX919B from CML Semiconductor Products) which sends the signal uses a preamble which is periodic every 8 bits, e.g. 11110101 11110101...

- the sync word, coming from the base station, has a length of 24 symbols (resulting in 48 bits with 4-FSK modulation)

Is it possible to realize a receiver with the CC1101 for this packet format? If not, is there another chip from your catalog which can solve the problem, e.g. CC1310?
Is it also possible to obtain the data without the sync word / preamble and to post-process the received signal efficiently?

The base station transmits in the 447 MHz band with 4-FSK modulation.

Thank you in advance!

  • 0
    TI__Guru**** 317180 points
    I took a quick look at the FX919B datasheet and it looks like this is a modem chip.

    CC1101 uses a 2-(G)FSK sync word so if the radio you use actually uses all 4 levels for the sync word you will not be able to receive the packet. All our radios uses 2 level sync word.

    The preamble should not cause any issues since if preamble is only used to do bit/ byte sync. If PQT is used it should be a '1010' pattern.
  • 0 in reply to TER
    Prodigy 20 points
    Thank you for the answer! So you mean that the 4-level sync word cannot be correctly demodulated due to hardware reasons?

    The fact that the number of sync bits is too large could otherwise perhaps be solved by considering only the first 32 bits of the sync word and deleting the rest of the bits from the received data afterwards. As far as I have understood, this is not a possibility, am I right?
  • 0 in reply to Rossen Michev
    TI__Guru**** 317180 points
    The sync search is 2-FSK based due to how the sync word.

    If you were working with 2-FSK (or 4-FSK with a 2-FSK sync word) you could have looked for the last 16 or 32 bit of the sync word.