GPS mode

Global Positioning System (GPS) testing is essential on the product level since the GPS RF front-end design, including Low-Noise Amplifier (LNA) and filtering, is the integrator's responsibility.

The following table shows recommended test cases for conducted GPS signaling mode. The expected results include the contribution of external GPS LNA.

Table 1. RF performance tests for conducted GPS signaling mode
Mode Test item Test specification/ID Band/Channel Temp/Voltage Signaling parameters Expected result Note
GPS RX GPS sensitivity / CN0 (SNR) NA GPS TYP/TYP GPS in receive mode

GPS signal level -135 dBm

CN0>34 dB1 ARB signal generator can be used for GPS signal. The GPS CN0 data can be recorded from Universal Asynchronous Receiver/Transmitter (UART) trace information. For details on CN0 data tracing, see nRF Connect SDK code examples.
Adjacent frequency band selectivity ETSI EN 303 413 v1.1.1 GPS in receive mode

GPS signal level -128.5 dBm

1 satellite min

CN0 degradation <1 dB (vs. w/o blocker) Requires GPS and blocker signal (AWGN) generators.
Spurious emissions GPS in receive mode Below emissions limit Limit: 30 MHz…1 GHz -57 dBm/100 kHz, 1 GHz…8.3 GHz -47 dBm/1 MHz

Receiver blocking tests verify the GPS filtering's compliance against GPS blocking requirements in ETSI EN 303 413 V1.1.1.

Since LTE TX may cause intermodulation or harmonics in the external GPS LNA input, the LTE TX signal may require filtering on the GPS signal path. Other active components, such as Integrated Circuit (IC)s or LEDs, that are located near the LTE antenna may cause similar disturbance. These signal components may cause LTE radiated spurious tests to fail in certification. LTE TX and GPS RX are not active at the same time, and therefore the LTE TX signal does not interfere with GPS receiving.

1 Assuming that an external LNA is used. The external LNA's Noise Factor (NF) is less than 2 dB, and minimum gain is 15 dB.