GPS receiver

The LPWA network processor supports GPS reception, if the onboard network protocol firmware supports it.

GPS receiver operation is time multiplexed with the LTE modem, and GPS and QZSS position can be received while the LTE modem is in RRC Idle mode, power saving mode (PSM), or completely deactivated.

The application processor is the system master and responsible for starting and stopping the GPS receiver. GPS can be run standalone or concurrently with QZSS. The GPS and QZSS reception can be configured through the GNSS interface API.

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

Key features of the GPS receiver are as follows:

GPS L1 C/A reception
QZSS L1 C/A reception
Optimized for low-power and low-cost IoT applications
Modes of operation:
- Single shot
- Position fix per fixed interval, configurable to a value between 10 s to 65536 s
- Continuous tracking
Power saving mode:
- Duty-cycled continuous tracking operation
One pulse per second (1PPS) signal:
- A pulse repeating once per second, 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, 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 minimum 27dB attenuation to out of band power to avoid blocking high power RF signals to GPS receiver input. This can be achieved by using a SAW filter, for example, at the external LNA output.

Electrical specification

The following is a 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 might lead to considerable variation in TTFF, positioning accuracy, 1PPS signal accuracy.

The figures in the following table assume the use of an external low-noise amplifier (LNA) with SAW filter.

Table 2. GPS electrical specification
Symbol	Description	Value	Unit
Sensitivity, cold	Acquisition sensitivity, cold start	-146.5	dBm
Sensitivity, hot	Acquisition sensitivity, hot start	-152.5	dBm
Sensitivity, tracking	Tracking sensitivity	-156.5	dBm
TTFF, cold	Time to first fix (TTFF), cold start	30.5	s
TTFF, hot	TTFF, hot start	1.3	s
TTFF, A-GPS	TTFF, A-GPS start	1.3	s
Accuracy, 2D, periodic	Positioning accuracy (CEP50), periodic tracking^¹	3.4	m
Accuracy, 2D, periodic, A-GPS	Positioning accuracy (CEP50), periodic tracking^¹ with A-GPS^²	3.1	m
Accuracy, 2D, continuous	Positioning accuracy (CEP50), continuous tracking	2.0	m
Accuracy, 2D, continuous, A-GPS	Positioning accuracy (CEP50), continuous tracking with A-GPS^²	1.8	m
1PPS accuracy	1PPS signal accuracy, continuous tracking	±35	ns

¹ Fix interval 2 min.

² Including NeQuick ionospheric model parameters.