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CC1120 + legacy OOK TX with broad carrier tolerance

Aleksander Miera
Prodigy 60 points
Other Parts Discussed in Thread: CC1120, CC1200

Hello everyone,


I am trying to use CC1120 as receiver for some old OOK transmitter. RFM TR3000 was used before to receive it.


The problem is, that the our transmitter's carrier frequency tolerance is up to +-100kHz. Is is even possible to use the CC1120 in transparent mode in order to receive data from such TXes?

Our prev. RX used 600kHz input filter + simple rectifier and lowpass demodulation.

Up till now the max. carrier frequency tolerance we were able to achieve in OOK mode using CC1120 was ca. 30kHz. Is it possible to achieve more "tolerance"?  The point is, that CC1120 seems (judging from block its schematic) to use coherent or some other carrier-multiplication dependent demodulation, and thus it's rather impossibe to broaden its tolerance, am I right? If I'm wrong, how to overcome this?


Regards

A. M .Miera

  • 0
    TI__Guru**** 317180 points

    Not with CC1120 but could be possible with CC1200. A OOK signal has a fairly wide spectrum. To be able to receive this you have to fit +/- 100 kHz carrier tolerance + the OOK spectrum within the RX bandwidth of the chip. Max RX BW on CC1120 is 200 kHz so this is at least some of the explanation for the results you see with CC1120.