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Lassen-SK8 Embedded GPS Module 4-9
Operation and Performance
4.7.2 NMEA 0183
The NMEA 0183 protocol only supports LLA format and UTC time. Velocity is always
described as horizontal speed and heading; vertical speed is not output.
4.7.3 TAIP
The TAIP protocol only supports LLA position output. Timetags are GPS, except for the
TM time mark message.
4.8 Performance Characteristics
4.8.1 Update Rate
The Lassen-SK8 computes and outputs position solutions once per second, on the second.
NMEA outputs can be scheduled at a slower rate using TSIP command 7Ah. Refer to
Appendix A.
4.8.2 Dynamic Limits
The dynamic operating limits for the Lassen-SK8 are listed below. These operating limits
assume that the GPS module is correctly embedded and that the overall system is designed
to operate under the same dynamic conditions.
4.8.3 Re-Acquisition
Re-acquisition time for a momentary signal blockages is typically under 2 seconds.
When a satellite signal is momentarily interrupted during normal operation, the receiver
continues to search for the lost signal at the satellite's last known Doppler frequency. If the
signal is available again within 15 seconds, the receiver will normally re-establish track
within two seconds. If the lost signal is not re-acquired within 15 seconds, the receiver
initiates a broader frequency search. The receiver will continue to search for the satellite
until it falls below the elevation mask.
Table 4-2. Lassen-SK8 Operating Limits
Operation Limit
Acceleration 4 g (39.2 m/s
2
)
Jerk 20 m/s
3
Speed 500 m/s
Altitude 18,000 m