Motorola M12 Oncore User's Guide download pdf (Page 47)

Chapter 3 – Receiver Description

Motorola GPS Products - Oncore User’s Guide

Table 3.12: GT+, UT+, SL Oncore TTFF Information

INITIAL ERROR AGE TTFF

(GT+)

TTFF

(M12+)

POWER-UP

STATE

POS TIME ALMANAC EPHEMERIS TYPICAL 90% TYPICAL

Hot 100 km 3 min 1 month <4 hrs 15s 30s <15s

Warm 100km 3 min 1 month U/A 45s 65s <40s

Cold (default) N/A N/A U/A U/A 90s 210s <60s

U/A – This parameter is assumed to be unavailable.

N/A – Not applicable. Knowledge of this parameter has no effect on TTFF in this configuration.

Reacquisition time for all GPS satellite signals after signal obscuration is a function of

the obscuration time, as shown in the table below.

Table 3.13: Reacquisition Times

OPERATIONAL CONSIDERATIONS

When powered on, the Oncore Receiver automatically acquires and tracks satellites;

measures the pseudorange and phase data from each of up to eight satellites;

decodes and collects satellite broadcast data; computes the Oncore receiver's

position, velocity, and time; and outputs the results according to the current I/O

configuration selected.

TTFF is a function of position uncertainty, time uncertainty, almanac age, and

ephemeris age as shown in the table below. The following information assumes that

the antenna has full view of the sky when turned on.

TIME OBSCURED REACQUISITION TIME (Typical)

<15 s <1.0 s internal

15 s 2.5 s

60 s 3.6 s

30 min 300 s

First Time On

When the Oncore receiver powers up for the first time after factory shipment, the

initial date and time will be incorrect. This will force the Oncore receiver into a cold

power-up state (cold start), and it will begin to search the sky for all available

satellites. After one satellite has been acquired, the date and time will automatically

be set using the satellite. When three or more satellites are tracked, automatic

position computation is initiated. At power down, the Oncore receiver does not

remember its current configuration unless external battery power is applied.

Revision 5.0 08/30/02

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Motorola M12 Oncore User's Guide Page 47