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CC1310 Receiver sensitivity at 433 MHz

Tianyu May
Prodigy 130 points
Other Parts Discussed in Thread: CC1310

in the cc1310's datasheet,all the parameters are at 868 MHz. How to measure the Receiver sensitivity at 433 MHz? I try to do this,but the RSSI view from SmartRF studio 7 is larger 6dBm than the value at Signal generator。

  • 0
    TI__Mastermind 39860 points
    You are correct, SmartRF Studio does not give the correct RSSI reading when operating at 433 MHz.

    At 868 MHz operation the measured input power level is corrected by -5 dB (RSSI offset) internally. At 433 MHz operation the correct RSSI offset is +1 dB. Since 433 MHz operation is not fully characterized, the settings (including RSSI offset) use the the "868 MHz values". Thus, when changing the RF frequency from 868 to 433 MHz the displayed RSSI will be 6 d too high.

    We will correct this when we have the final 433 MHz settings. For the time being simply subtract 6 dB from the displayed RSSI readings.
  • 0 in reply to Sverre
    Intellectual 415 points

    Sverre said:
    You are correct, SmartRF Studio does not give the correct RSSI reading when operating at 433 MHz.

    At 868 MHz operation the measured input power level is corrected by -5 dB (RSSI offset) internally. At 433 MHz operation the correct RSSI offset is +1 dB. Since 433 MHz operation is not fully characterized, the settings (including RSSI offset) use the the "868 MHz values". Thus, when changing the RF frequency from 868 to 433 MHz the displayed RSSI will be 6 d too high.

    We will correct this when we have the final 433 MHz settings. For the time being simply subtract 6 dB from the displayed RSSI readings.

    Now i used the 433MHz setting in SmartRF studio 7 v2.3.1, i change "txPower\centerFreq\loDivider"in smartrf_setting.c in rfPacketTX, but can't receive anything in SmartRF studio. Is this modify right?

  • 0 in reply to Sverre
    Intellectual 405 points
    Has TI finalized the 433 Mhz Settings and done a correction for this yet? It's June.
  • 0 in reply to nowell outlaw
    TI__Guru**** 317180 points
    June has just started. The work will be finalized this month.
  • 0 in reply to TER
    TI__Expert 3515 points

    Hi TER,

    Is there any update to this ?  The RSSI measured by software is also 5dB ~ 6dB higher? What suggested to walk around? Thanks.

  • 0 in reply to LLouis
    TI__Guru**** 317180 points

    Please download SmartRF Studio 2.4.3 to get settings for 433 MHz. 

  • 0 in reply to TER
    Intellectual 645 points
    TER,
    RF studio still says 433Mhz settings may not be correct. I am evaluating one 433Mhz module, can I trust these settings?
    -D
  • 0 in reply to Dh Sh
    TI__Guru**** 317180 points
    Note that the settings are correct for rev2.1 of CC1310 (you get this settings if you are in offline mode). If you have a rev2.0 device connected to SmartRF Studio you will still get a warning.
  • 0 in reply to TER
    Intellectual 645 points
    Thanks TER. I am using a hardware with 433Mhz support. So having rev B is absolutely must for 433Mhz support or rev A would work but not optimally? The reason I am asking this question is, I have imported 2 launchpads (looks like Rev A as studio throws warning) with 433Mhz and they are behaving really nasty. RSSI of -80 even when 1 mtr apart and worst if 2 meters apart.
    Also should I assume if I take latest TI RTOS and 15.4 stack, they both would support 433Mhz revB seamlessly? What kind of RSSI should I expect if placed next to each other (-110?)?
  • 0 in reply to Dh Sh
    TI__Guru**** 317180 points

    Revision: 

    Both SmartRF Studio and Flash Programmer 2 reports the version of the chip when connected. Rev 2.0 = rev A, rev 2.1 = rev B.

    Note that the Lauchpads are designed for 868 MHz. 

    - The match/ filtering are tuned for 868/ 915 MHz meaning that when used on 433 MHz the PA will see far from the optimal impedance. Also the harmonics could be too high from a regulation standpoint since the filtering is designed for 868 MHz.

    - The antenna is tuned for 868/ 915 MHz meaning that the efficiency on 433 MHz will be very poor.

    To use the LP on 433 MHz and get good results you have to change the BOM to comply with the 433 MHz reference design and use an external 433 MHz antenna.

    You will not get a different RSSI with a different TI-RTOS/ TI Stack since this is a fundamental hardware limit.