Transmitter Backend Options

Backend Selection

  • --backend <gpio\|si5351>
    Select RF output method.

    • gpio: Direct RF from Raspberry Pi GPIO (limited models).

    • si5351: External clock generator via I2C.

  • --power-level <level>
    Set transmit power for the active backend:

    • GPIO: 0–7

    • Si5351: 1–4

  • --gpio-power-level <0-7>
    Explicitly set GPIO drive strength.

  • --si5351-power-level <1-4>
    Set Si5351 output drive strength.

GPIO Backend

  • --transmit-gpio <4\|20>
    Select GPIO pin used for RF output.

  • --transmit-pin <4\|20>
    Legacy alias for transmit GPIO.

  • -n, --use-ntp
    Enable NTP-based frequency calibration.

  • --no-use-ntp
    Disable NTP calibration and use manual PPM.

  • -p, --ppm <value>
    Apply manual frequency correction (-200 to 200 ppm).

Si5351 Backend

  • --si5351-i2c-bus <bus>
    Select I2C bus (default: 1).

  • --si5351-i2c-address <addr>
    Set device address (decimal or hex).

  • --si5351-reference-frequency <hz>
    Define reference oscillator frequency.

  • --si5351-tx-output <CLK0\|CLK1\|CLK2>
    Select output clock. This option is not exposed in the Web UI.