ZOE-M8B - System Integration Manual
UBX-17045131 - R04
Contents
Page 8 of 42
Production Information
to receive data for current GNSS time and information of at least four satellites (red points in Figure
1). The receiver continues searching for more satellites in the acquisition state (yellow dots in Figure
1) until it has enough information for proper low-power operation. By default, this search lasts for five
minutes after the receiver start-up, but can be adjusted if, for instance, AssistNow data is used.
After the initial acquisition state, the receiver enters the power-optimized tracking state (shown by
the green dots in Figure 1). This is the low-power state of the Super-E mode. If the set of available
satellites gets too small, the receiver again enters acquisition or tracking state for a short period until
it has enough satellites to track. This is shown by the brief peaks in current consumption during the
power-optimized tracking state in Figure 1.
The state of the receiver is given in the psmState field in the UBX-NAV-PVT message.
Figure 1: Current consumption in different states in Super-E mode.
1.2.2.2
Super-E power consumption examples
The sensitivity, accuracy, and power efficiency of a GNSS receiver depend heavily on the availability,
strength and quality of the GNSS signal. If the signal is attenuated, blocked or reflected, the power
consumption, acquisition speed, and positioning accuracy suffer. Application design, including
antenna performance, also contributes to the signal quality. Use of assistance often helps to improve
both performance and power consumption.
In the following examples, current consumption in Super-E mode is shown for open, forest and urban
environment over a 30-minute period. The results are presented for the default mode, i.e., 1 Hz Super-
E “performance” setting with GPS, GLONASS and QZSS enabled. A wrist-worn sports watch with
weak and constantly changing reception was used to receive the GNSS signal.
Current consumption in an open environment is shown in Figure 2 and Figure 3 for continuous and
Super-E mode, respectively. The average tracking current in continuous mode is 45.7 mA whereas in
Super-E mode the average current drops to 13.3 mA after the (adjustable) initial acquisition period.
Use of assistance improves TTFF but also further reduces average current consumption by
approximately 15% (Figure 4).
The effect of environment on current consumption can be seen in Figure 3 (open), Figure 5 (forest)
and Figure 7 (urban). The power optimization in Super-E mode performs best in an open environment,
with the current consumption increasing with deteriorating signal conditions. Under heavy multipath
and blocking of satellites, the receiver may need to briefly exit power-optimized tracking to acquire
