RX functionality test

The %XRFTEST RX test enables the RF receiver with the given parameters and returns the result of the antenna power measurement or Signal-to-Noise Ratio (SNR). The reported parameter is set by the <test> parameter following the %XRFTEST AT command. OFF <operation> disables the RF receiver.

The recommended signal level for RX testing is -90 dBm. The expected SNR with this signal level is normally more than 16 dB.

AFC correction can be performed to increase the accuracy of the SNR measurement. AFC correction can compensate the frequency error between nRF9160 and the used test equipment. AFC measurement and setting are supported by modem firmware v1.2.x and later.

Note: The reported SNR is very sensitive to external RF disturbance that may be present in the test environment. An RF shielded chamber is recommended as a stable test environment. A known device, such as a golden unit, can be used as a reference to confirm the validity of the test result.

The value of the power measured at the antenna port is given in the q8 (dBm) format. Dividing the result by 2⁸= 256 gives the dBm value of the antenna power.

The following command example executes an RX signal level (RSSI) test:

%XRFTEST=0,1,1,21400,−65,0	// RX ON (B1,2140.0MHz,-65dBm,NB1 mode)
%XRFTEST: -17002			// Result: -17002/256 = -66.4dBm
OK

%XRFTEST=0,0			// RX OFF
OK

The measured SNR is given in the q4 (dB) format. Dividing the result by 2⁴ = 16 gives the dB value of the antenna power. This measurement reports both the SNR and RSSI values.

The following command example executes an RX SNR test:

%XRFTEST=3,1,1,21400,-65,1,1 // RX ON (B1,2140.0MHz,-65dBm,M1 mode, AFC correction enabled)
%XRFTEST: 496,-17002 // Res: 496/16=31dB, -17002/256=-66.4dBm 
OK

%XRFTEST=0,0	// RX OFF 
OK

The input parameters of the RX functionality test are described in the following table:

Table 1. Input parameters of RX functionality test
Parameter name	Parameter description	Value	Value description
<param0>	3GPP band number	1–66	Bands supported by nRF9160
<param1>	Frequency 100 kHz raster	6000–22000	Corresponds to 600–2200 MHz
<param2>	Signal level at antenna	–127 to –25	Signal level at the nRF9160 antenna input (dBm)
<param3>	System mode	0–1	NB1 = 0 M1 = 1
<param4>	Enabling AFC correction during SNR test	0–1	Enable and disable AFC correction

The signal level at antenna <param2> is used to set the receiver gain. It is recommended to set it to equal to the expected signal level at the nRF9160 antenna input.

For bands supported by nRF9160, see nRF9160 Product Specification.

For more information on RX testing with the %XRFTEST AT command, see RX test %XRFTEST in nRF91 AT Commands Reference Guide.