User Manual

Asset-Link 250 User Manual July 19, 2004
970-00047 Rev. 1.2
CSI Wireless©2004 Specifications subject to change without notice Page 2-2
2.2 Mechanical Dimensions
The Asset-Link enclosure for the product will be approximately 5.8” x 3.4” x .9” to
the outside of the connectors.
2.3 GPS Receiver
The Asset-Link incorporates a low power integrated twelve-channel GPS receiver.
The GPS receiver is designed by CSI-Wireless utilizing the SiRFstarII LP GPS
architecture, which includes acquisition accelerator and multi path mitigation
hardware. The GPS receiver complies with ICD-GPS-200C.
The Asset-Link Global Positioning System (GPS) receiver shares the ARM7
processor with the FCP to determine position and provide control functions. The time
to position determination and the accuracy of position determination are dependant
upon the GPS LNA antenna performance as well as the GPS Antenna.
The frequencies used for the GPS receiver are centered on 1574 MHz, which are
referred to as L1. Other GPS frequencies are not supported by the Asset-Link . The
Asset-Link does not support WAAS.
Parameter Min Nominal Max Units
GPS Receive Frequencies 1569 1574 1579 MHz
Tracking capabilities 4 7 12 Satellites
Solution Update Rate -- -- 1 seconds
Satellite Reacquisition 45 80 100 milliseconds
“Snap” Start time 8 8 20 Seconds
“Warm” Start time 26 35 38 Seconds
“Cold” Start time 40 45 120 Seconds
Signal Level -155 -141 -108 DBm
Maximum position speed 0 -- 999 knots
Position accuracy SA off -- 10 14 meters 2D rms
Position accuracy SA on -- 100 120 meters 2D rms
Velocity determination -- 1 -- meter/sec
Table 2-1 GPS Receiver Characteristics
2.3.1 GPS Position/Velocity Fix
The GPS receiver establishes a position fix with a 95% certainty as shown in Table
2-2. The following data provided by SiRF assumes a full view of the sky (360°
azimuth), actual field data will vary with antenna installation.
If the satellites are not equally distributed around the horizon as often happens in
urban canyons, and in covert vehicle installations, the fix circular error is more like a
large oval. The result is a large “DOP” (dilution of precision) and a lower fix
accuracy, as well as an increased time to first fix. Increased DOP (HDOP –horizontal