Calibration and Transmitter Backends

Use these sections for frequency calibration and RF output-path settings. See Configure Transmitter, Configure Raspberry Pi I/O, Transmission Timing and Calibration, Transmitter Backend Options, and RF and Electrical Reference for the corresponding workflows.

Calibration

The [Calibration] section supplies the manual PPM correction used by the Si5351 backend and whenever GPIO NTP correction is disabled.

[Calibration]
; PPM:
; Frequency calibration in parts per million.
; Used directly by the Si5351 backend and whenever GPIO.Use NTP is false.
PPM = 0.0

GPIO

The [GPIO] section configures the supported direct RF pin, GPIO-backend power level, and NTP-derived correction.

[GPIO]
; Transmit Pin:
; BCM GPIO used for RF output when Transmit Backend = gpio.
; GPCLK0 is supported on BCM GPIO 4 or 20.
; Ignored by the Si5351 backend.
Transmit Pin = 4

; Power Level:
; GPIO backend RF output power setting.
; Valid range is 0 to 7.
Power Level = 7

; Use NTP:
; Apply NTP-based PPM correction for the GPIO backend.
; Ignored by the Si5351 backend, which uses Calibration.PPM only.
Use NTP = True

Si5351

The [Si5351] section configures the I2C device, reference frequency, transmit output, and drive strength. The excerpt preserves the distinction between the internal parked synthesis state and emitted RF.

[Si5351]
; I2C Bus:
; Linux I2C bus number for the Si5351 device.
; Bus 1 usually maps to /dev/i2c-1 on Raspberry Pi systems.
I2C Bus = 1

; I2C Address:
; 7-bit Si5351 I2C address.
; 0x60 is the common default for many Si5351 breakout boards.
I2C Address = 0x60

; Reference Frequency:
; Si5351 crystal or reference input frequency in Hz.
; Typical modules use 27000000.
Reference Frequency = 27000000

; TX Output:
; Si5351 clock output used for transmit RF.
; Valid values:
;   CLK0
;   CLK1
;   CLK2
; Unused outputs are held in a safe non-transmitting state by WsprryPi.
; The internal parked PLL is a synthesis state, not an emitted parked RF output.
; This setting is configurable in INI and CLI; it is not exposed in the web UI.
TX Output = CLK0

; Power Level:
; Si5351 backend drive-strength level.
; Valid range is 1 to 4.
Power Level = 1