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CC113L: About the frequency offset compensation behavior after the auto calibration done

Sinsan
Prodigy 120 points
Part Number: CC113L

Hi there,

I have a question about the frequency offset compensation behavior after the auto calibration done.

According to the CC113L datasheet, when FOCCFG.FOC_BC_CS_GATE=1 is set and the receiver is in no signal condition (the CS signal is low), the frequency offset compensator will freeze and the offset information obtained is maintained.

In this situation, if state change operation below inclusive the calibration is done, is the offset information in (1) taken over to (4) or reset to the center frequency?

(1)RX state with CS signal low --> (2)IDLE state --> (3)Calibration --> (4)RX state with CS signal low

If it is reset to the center frequency, is there any way to take over the offset information to (4)?

Best regards,

Sinsan

 

  • 0
    TI__Guru**** 317180 points

    Restarting RX will reset all loops. 

    This may be of help (from the datasheet):

    "The estimated frequency offset value is available in the FREQEST status register. This can be used for permanent frequency offset compensation. By writing the value from FREQEST into FSCTRL0.FREQOFF, the frequency synthesizer will automatically be adjusted according to the estimated frequency offset. More details regarding this permanent frequency compensation algorithm can be found in DN015 SWRA159."

    Not sure if this is a real practical problem. If you have the part in continuous RX the estimate may slide to one side due to noise. But when you get a wanted signal on the air the estimate should start slide back to the correct frequency. Have you done some tests on this to see the practical impact?  

  • 0 in reply to TER
    Prodigy 120 points

    Hi TER,

    Thank you for your help.

    Please refer to the attached file. When FOCCFG.FOC_BS_CS_GATE=0 is set, data error occurs at the beginning of the received packet. On the other hand when FOCCFG.FOC_BS_CS_GATE=1 is set, no data error occurs even though the state change RX --> IDLE --> RX was performed before CS signal high. The frequency offset information which obtained in the old RX state looks to be taken over to the new RX state. At the moment, it seems to be no problem executing the state change.

    CC113L RX output.pdf

    Best regards,

    Sinsan