Actual TX power different from set TX power in Raw LoRa mode



  • Why is the TX power set in on the device (for example 14 dBm) significantly higher than the actual power that is transmitted (more like -25 dBm)?

    Hi, I have done some tests with a LoPy4 configured in Raw LoRa and connected directly to a spectrum analyzer. The following shows how I configured the devices:

    lora = LoRa(mode=LoRa.LORA, region=LoRa.EU868, sf=7, frequency=868625000, bandwidth=LoRa.BW_125KHZ, preamble=8, coding_rate=LoRa.CODING_4_8, tx_iq=False, rx_iq=False, public=False, power_mode= LoRa.ALWAYS_ON, tx_power = 14)
    lora_sock = socket.socket(socket.AF_LORA, socket.SOCK_RAW)
    

    I set the tx_power to different values from 2 to 20 and observed the peak power and the total power of the signal. The observed power was much less than the power that was specified, for example: when set to 20, the peak power was -17 dBm and the total power was -8 dBm.

    I don't believe that the u.fl connector attenuates the signal enough to produce this result, so am I doing something wrong in the configuration?

    Thanks



  • @jcaron Hi, yes that is correct.



  • This post is deleted!


  • @jokr2 Just to be sure, you measured on the right u.FL connector?

    The one for 868 MHz LoRa is to the right of the LED when the LED is up (i.e. not the one next to the reset button or next to the ceramic antenna).


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