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CC1101: PPM modulation decoding on the chip?

Eugene Dzhurynsky
Prodigy 40 points
Part Number: CC1101


Tool/software:

I have a transmitter that does PPM modulation / 915MHz. According to the specs, CC1101 can do ASK/OOK but not PPM.

As an experiment I took the known data packet, configured CC1101 to send it using the same settings from the transmitter ( preamble, sync words, bitrate etc ) and I was able to receive and decode the transmission on RTL-SDR dongle, so it looks like at least for transmitting CC1101 can somewhat match PPM.

But I have hard times doing receiving on CC1101 - with carefully selected bitrate it kinda gets fractions of packets fine but it constantly reads the remaining 50-60% as some gibberish, it looks like it mashes bits together.

I'd assume my best bet would be to use synchronous read and streaming signals from GDO0 / GDO2?

  • 0
    TI__Mastermind 33470 points

    Hi,

    As an intermediate step would recommend to connect CC1101 to CC1101 first with the selected bit rate, sync word, packet length etc.

  • 0 in reply to RGW
    Prodigy 40 points

    Hi! Thanks for the tip Slight smile

    What I did so far:

    - got the payload from RTL_433 packet decoder

    - send that payload from CC1101 to CC1101 using ASK/OOK modulation and 33kbps bitstream

    so far the results are:

    - CC1101 -> CC1101 = works well, packet is decoded

    - CC1101 -> RTL-SDR dongle and rtl_433 = works well, rtl_433 is able to decode the packet reliably

    - HackRF -> RTL_SDR dongle and rtl_433 = works well, rtl_433 is able to decode the packet reliably

    - HackRF -> CC1101 = no chance, the packet mode can't pick up the transfer, with async continuous mode the data on GDO2 doesn't make much sense as well ( I used logic analyzer with 2mbit sample rate and pulseviwe / sigrok for data capturing ). I can clearly see the packet boundaries but the pulse lenghths are far off 30 microseconds from what they should be.

  • 0 in reply to Eugene Dzhurynsky
    TI__Mastermind 33470 points

    Hi,

    Which chip is on the HackRF ?