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Lassen-SK8 Embedded GPS Module 3-1
3 Software Interface
This chapter describes the Lassen-SK8 software interface, the start-up characteristics for
the interface protocols, a description of the receiver operating modes, and a brief
discussion of the interface protocols.
3.1 Start-up
ACE GPS is a complete 8-channel parallel tracking GPS receiver designed to operate with
the L1 frequency, standard position service, Coarse Acquisition code. Using two highly
integrated Trimble custom integrated circuits, the receiver is designed in a modular format
especially suited for embedded applications.
When connected to an external GPS antenna, the receiver contains all the circuitry
necessary to automatically acquire GPS satellite signals, track up to 8 GPS satellites, and
compute location, speed, heading, and time. The receiver will automatically begin to
search for and track GPS satellite signals at power-up.
The performance of a GPS receiver at power-on is determined largely by the availability
and accuracy of the satellite ephemeris data and the availability of a GPS system almanac.
Refer to Chapter 4 for additional information. The first time the receiver is powered-up, it
is searching for satellites from a cold start (no almanac). While the receiver will begin to
compute position solutions within the first two minutes, it actually takes the receiver about
15 minutes to download a complete almanac. This initialization process should not be
interrupted. With a complete almanac and back-up power, the time to first fix can typically
be shortened to less than 20 seconds. The receiver will respond to commands almost
immediately after power-up.
3.2 Software Tool Kits
Trimble provides a Software Developers Tool Kit to support the TSIP and TAIP
protocols. The Kit contains a user-friendly program to communicate with the receiver and
includes sample C source code and reusable routines to aid in developing applications.
The following Appendices provide additional information:
• TSIP
- Appendix A, Trimble Standard Interface Protocol
- Appendix B, TSIP User's Guide
• TAIP
- Appendix D, GPSSK User's Guide (TAIP)
- Appendix E, NMEA 0183.