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RoyalTek GPS Receiver REB-2000/REB-12R REV-2000 Operational Manual
26
Computation of Duty Cycle and On
Time.
The Duty Cycle is the desired time to be
spent tracking.The On Time is the duration
of each tracking period (range is 200 - 900
ms). To calculate the TricklePower update
rate as a function of Duty cycle and On
Time, use the following formula:
Off Time = (On Time - (Duty Cycle * On
Time)) / Duty Cycle
Update rate = Off Time + On Time
Note –
On Time inputs of > 900 ms will
default to 1000 ms
Following are some examples of
selections:
Table 37 Example of selections for Trickle Power Mode of Operation
Mode On Time (ms) Duty Cycle (%) Update rate (1/Hz)
Continuous 1000 100 1
Trickle Power 200 20 1
Trickle Power 200 10 2
Trickle Power 300 10 3
Trickle power 500 5 10
See Table 38 for supported/unsupported settings.
Table 38 Trickle Power Mode Settings
Update Rate (second) On Time
(ms)
1 2 3 4 5 6 7 8
200 Y Y N N N N N N
300 Y Y Y Y Y Y N N
400 Y Y Y Y Y Y Y Y
500 Y Y Y Y Y Y Y Y
600 Y Y Y Y Y Y Y Y
700 Y Y Y Y Y Y Y Y
800 Y Y Y Y Y Y Y Y
900 Y Y Y Y Y Y Y Y
Y = Yes (Mode supported)
N = No (Mode NOT supported)
Push-to-Fix
In this mode the receiver will turn on every
30 minutes to perform a system update
consisting of a RTC calibration and
satellite ephemeris data collection if
required (i.e., a new satellite has become
visible) as well as all software tasks to
support SnapStart in the event of an NMI.
Ephemeris collection time in general this
takes 18 to 30 seconds. If ephemeris data
is not required then the system will
re-calibrate and shut down. In either case,
the amount of time the receiver remains
off will be in proportion to how long it
stayed on:
Off period = (On Period*(1-Duty Cycle) /
Duty Cycle)
Off Period is limited to 30 minutes. The
duty cycle will not be less than
approximately On Period/1800, or about
1%. Push-to-Fix keeps the ephemeris for
all visible satellites up to date so
position/velocity fixes can generally be
computed within SnapStart times (when
requested by the user) on the order of 3