AFC measurement

Syntax:

%XRFTEST=<test>,<operation>,<param0>,<param1>,<param2>,<param3>

The AFC measurement command parameters and their defined values are the following:

<test>

4 – AFC

<operation>

1 – ON (measure).

Note: OFF <operation> is not needed due to automatic stop. Mode is always LTE-M. The stored value is reset when the device is booted.

4 – Calibration. Measures frequency error. The measured value is stored to Non-volatile Memory (NVM) with the %XFSSYNC command.nRF9131

<param0>

3GPP band number. Use 24 for Global Navigation Satellite System (GNSS) reception.

DECT NR+ bands 1, 2, 9, and 22 are supported when <param3> is 10. See ETSI TS 103 636-2 V1.4.1 Table 5.2-1.

<param1>

Frequency 100 kHz.

Valid range 6000–22000 (corresponds to 600.0 MHz–2200.0 MHz).

In DECT NR+, the valid range is 18800–19300 (corresponds to 1880.0 MHz–1930.0 MHz) depending on the DECT NR+ band selected in <param0>.

Note: If Carrier Wave (CW) is used, an offset of about 45 kHz for Narrowband Internet of Things (NB-IoT) and 300 kHz for LTE-M is recommended.

<param2>

RX signal power at the System in Package (SiP) antenna port in dBm.

<param3>

System mode.

0 – NB-IoT.

1 – LTE-M.

10 – DECT NR+.

Response syntax:

%XRFTEST: <AFC_error_value_Hz>,<AFC_error_value_Q30>,<antenna_power>,<result_status>

The response parameters and their defined values are the following:

<AFC_error_value_Hz>

Measured AFC error value in Hz format. 0 if <result_status> is 1 (fail).

<AFC_error_value_Q30>

Measured AFC error value in relative signed Q30 format. 0 if <result_status> is 1 (fail).

<antenna_power>

Measured signal power at the SiP antenna port in q8 dBm. q8 means dividing the result by 2⁸ = 256 gives dBm.

<result_status>

Status of the AFC measurement.

0 – OK.

1 – Fail.

Failure is caused if the measured <antenna_power> (converted to dB from dB Q8) is not within –3 ... +5 dB of the input <param2>. This is to ensure result quality.

The following command example successfully measures the AFC error value for band 1, 2140.0 MHz, -40 dBm in LTE-M mode:

AT%XRFTEST=4,1,1,21400,-40,1 
%XRFTEST:349,175,-10240,0
 OK