GPS receiver

The GPS receiver supports GPS L1 C/A and QZSS L1 C/A reception. Operation is time multiplexed with LTE modem, and it is possible to use the GPS and QZSS receiver to obtain position either while the LTE is in RRC Idle mode or power saving mode (PSM), or when the LTE modem is completely deactivated.

The application processor is the master in the system and responsible for starting and stopping of the GPS receiver. GPS can be run standalone or concurrently with QZSS. GPS and QZSS receiver configuration is accessible to user through the GNSS interface API.

Note: For details regarding the GNSS API, please refer to nRF Connect SDK API documentation.

Key features of the GPS receiver are:

GPS L1 C/A supported
QZSS L1 C/A supported
Optimized for low-power and low-cost IoT applications
Modes of operation:
- Single shot (cold start mode by default)
- Position fix per fixed interval, configurable between 10 s - 0.5 hour: first start with cold start, sequential fixes with hot start if interval less than 0.5 hour and enough satellites have been found in the first start
- Continuous tracking
Power saving mode:
- Duty-cycled continuous tracking operation
One pulse per second (1PPS) signal:
- A pulse repeating once per second, extremely accurately synchronized to coordinated universal time (UTC) full seconds
- For more details on 1PPS programmability and power vs. accuracy trade-offs, see GNSS API documentation
- Available on device COEX1 pin
  - For more details, please see LTE modem, coexistence interface
Antenna interface:
- External low-noise amplifier (LNA) with SAW filter recommended on the GPS antenna input
- Dedicated GPS antenna, or shared antenna with LTE
- GPS antenna pin is DC grounded

Note: There must be minumum 27dB attenuation to out of band power to avoid blocking high power RF signals to GPS receiver input. This can be achieved for example by a SAW filter at the output of the external LNA.

Electrical specification

Summary of GPS receiver performance parameters.

Table 1. Common typical conditions
Condition	Value
Environment	Open sky
Temperature	25 °C
GPS sleep clock source	TCXO

Note: Local and temporal conditions may lead to considerable variation in TTFF, positioning accuracy, 1PPS signal accuracy.

Table 2. GPS electrical specification
Symbol	Description	Value	Unit
Sensitivity, cold	Acquisition sensitivity, cold start	-145.5	dBm
Sensitivity, hot	Acquisition sensitivity, hot start	-147	dBm
Sensitivity, tracking	Tracking sensitivity	-155	dBm
TTFF, cold	Acquisition time (time to first fix (TTFF)), cold start	36	s
TTFF, hot	Acquisition time (TTFF), hot start	1.3	s
Accuracy, 2D, periodic	Positioning accuracy (CEP50), periodic tracking	5	m
Accuracy, 2D, continuous	Positioning accuracy (CEP50), continuous tracking	3	m
1PPS accuracy	1PPS signal accuracy, continous tracking	±40	ns