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CC1120 Coding Gain

Alberto Villa
Prodigy 130 points
Other Parts Discussed in Thread: CC1120

Hello to everybody,

New to this forum, I am looking for more details about the interesting "Built-in Coding Gain" support of the CC1120 transceiver.The info in the datasheet is minimal, and the swru295e User's Guide doesn't mention this parameter.

Thank you very much, and best regards.

Alberto

  • 0
    TI__Guru**** 317180 points

    If you mean coding gain in DSSS mode this is covered in the UserGuide.

  • 0 in reply to TER
    Prodigy 130 points

    Thank you very much, I've found this topic in section 5.2 of the User Guide, where it is stated that the DSSS pseudo-noise spreading mode (with its error-correction capabilities) is to be used when higher RX sensitivities are required.

    But I am looking for detailed info about the expected performance improvements (coding gain) under different operating modes. For instance, with 2 and 4-GFSK running at different symbol rates, deviations and receiver BW.

    Thanks again,

    Alberto

  • 0 in reply to Alberto Villa
    TI__Guru**** 317180 points
    We have done some measurements in the lab in in those measurements the fain of using DSSS have been limited. The reason is as follows:

    If you want a throughput of 50 kbps and a coding gain equal to 4 you have to send 200 kbps over the air. To be able to receive 200 kbps the Rx BW needs to be increased and hence the noise floor increases. You will increase the sensitivity by using DSSS but the sensitivity is reduced by increasing the RX BW so in the end the sensitivity is close to the same.

    That said, our measurements have been done conducted. It could be that is some environments (high noise floor due to a lot of RF noise) you gain using DSSS due to the redundancy in the data.