Baseband Technologies Inc.
Title: Stamp-size Ultra Low-Power GPS Receiver Module User Guide Rev 1.0
Page 34
Update Rate
IQ data
Power
15 seconds
4 milliseconds
1.89 mW*
15 seconds
10 milliseconds
2.80 mW*
15 seconds
30 milliseconds
6.15 mW*
Table 1: Typical Measurement Results
NOTE: *Based on 8 acquired satellites and 2 unacquired satellites
4.3.2
Tips
The typical power consumption measurements illustrated in Table 1 includes all the
necessary electronics components that make up the Stamp Module. More specifically, the
measurements illustrated were based on the energy consumed by all the necessary
components such as the (i) RFIC, (ii) TCXO, (iii) Active antenna, (iv) MCU and (v) power
management IC.
By comparison, some chipset receiver manufacturers often claim very low power
consumption figures without explicitly mentioning or accounting for the additional
components such as LNA, TCXO, flash memory, power management IC, and RTC etc.
required in order for the receiver to operate. When these components are taken into
consideration, the aggregated BOM cost and energy budget often exceed the original
claims.
In addition, beyond the power management capability of the chipset-based receiver itself,
some customers may power cycle the receiver at various intervals to further save energy
and still meet position accuracy requirements. It has been found that some receivers may
require as high as 50% duty cycle to maintain 20 second update rate to meet specific
position accuracy requirements. For example, for a receiver to maintain 5m CEP position
accuracy and at an update rate of 20 seconds, it needs to be powered on for 10 seconds
(i.e. 50% duty cycle).
Finally, while some manufacturers claim impressive Time-to-First-Fix (TTFF) performance
(e.g. 1 second), they seldom clarify that the position accuracy could be in the 10’s – 100’s
of meters of errors at the 1 second mark. In order for the receiver to converge to an
acceptable accuracy (e.g. 5m), the receiver may take 10’s of seconds.
