RoyalTek REV-2000 User Manual

Page 43

RoyalTek GPS Receiver REB-2000/REB-12R REV-2000 Operational Manual

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

Trickle Power

200

Trickle Power

200

Trickle Power

300

Trickle power

500

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