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General Modem Features
This section contains information associated with the basic features that is offered by your HPD 1000 modem.
Location Services Offered
The personnel location tracking service allows the radio user and location application servers to determine the current location of a mobile HPD radio. Location alone or combined with other information about the environment (e.g. a map) enables value-added applications such as tracking of resources.
With the GPS feature, it is possible to enable or disable the location service of an Subscriber Unit using CPS. When completely disabled, no location services will be available. Any requests sent to the location information port on an Subscriber unit will result in a “port unreachable” message to the location application.
GPS Services are available only on HPD radios for which a customer has purchased the GPS feature.
Note: The location service feature is not available when the HPD radio is in 700MHz , APCO conventional interoperability mode.
Any requests sent to the location information while operating in
700MHz conventional interoperability mode will result in a “port unreachable” message to the location application.
The location service does NOT provide a way for the radio user to trigger a location update to a location application server.
Note: Location information from the HPD radio is not available to the mobile computer connected to the HPD radio in this release.
HPD™ 1000 Modem
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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
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General Modem Features successfully, and was shut down and re-started without disconnecting the radio from its power source.
The PGAM GPS hardware always operates in “ autonomous continuous acquisition mode ” when the HPD radio is powered on.
Autonomous implies that you do not need to supply any assistance data from an external source to the PGAM GPS hardware.
Continuous acquisition means that the PGAM GPS hardware is set up to acquire location information periodically.
When the HPD modem is powered OFF , the PGAM GPS hardware is put into low power mode. It stops attempting to acquire location information periodically. However, it retains GPS information that helps reduce the GPS signal acquisition time when the HPD modem is powered backed on (warm start conditions).
Note: Power is always supplied to the GPS hardware unless the modem is totally disconnected from it's power source. A small amount of current is drawn during this period.
HPD™ 1000 Modem
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General Modem Features
Notes
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