SIM548C Hardware Design
SIM548C_HD_V1.01
09.05.2008
82
Figure 40: Push-To-Fix mode
The user can also save power by sending the “Push-To-Fix” command to the GPS part of the
module.
The Push-to-Fix mode puts the receiver into a background duty cycle mode that provides a
periodic refresh of position, GPS time, ephemeris, and RTC calibration every 10 seconds to 2
hours. Typical PTF operation is illustrated in Figure 39.
The PTF period is 30 minutes by default but can be anywhere between 10 seconds and 2 hours.
When the PTF mode is enabled, upon power on or a new PTF cycle, the receiver will stay on full
power until the good navigation solution is computed. The stand-by state will follow for the
remainder of the period. If it took 36 seconds to fix position and refresh ephemeris on the default
period of 30 minutes, the receiver will sleep for the 29 minutes and 24 seconds. When the
application needs a position report, it can toggle the GPS_M-RST pin to wake up the receiver.
When the receiver wakes up, it can produce a valid position in the normal hot-start time.
