Motorola HPD 1000, Руководство пользователя

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14
General Modem Features
The following list are some services provided to a Radio User and
Location Application Server:
• Location service on/off control.
• maximum number of stored location requests.
• location status indication via the front-panel LEDs.
• single location updates and periodic location updates.
For Location Status Indicators, refer to “GPS Status” on page 8 to
send your page.
GPS Functionality
The GPS signals are received by an external active antenna
connected to the HPD radio. The on-board PGAM GPS hardware
searches the satellite’s unique Coarse Acquisition (C/A) code in the
received signal by shifting and correlating the C/A code of a satellite
with the received signal. This is repeated for all the satellites until the
receiver has found at least 3 or 4 satellites.
The acquisition of location data is done by the PGAM hardware inside
the HPD radio. The acquisition is dependent on the PGAM hardware
receiving sufficient and proper signals from the Global Positioning
System (GPS) satellites.
Under cold start conditions, the firmware that executes on the PGAM
hardware has to be downloaded to the hardware.This takes 2
minutes. The PGAM hardware may take up to 5 additional minutes to
acquire a proper signal from the GPS satellites in open sky
conditions.Under warm start and open sky conditions, the PGAM
hardware may take up to 1 minute to acquire a proper signal from the
GPS satellites.
Note: Cold start conditions will apply if the HPD radio is being
turned on for the very time or if the HPD radio is disconnected
from its power source (usually a vehicle battery) and
reconnected. Warm start conditions will apply if the HPD
radio had previously acquired location information
96C67_Text.book Page 14 Monday, February 20, 2006 5:19 PM