4.2.6 GPS Hardware for Surveying:

SOME INSTRUMENTATION (TRIMBLE)


 The Trimble company is the largest GPS receiver manufacturer in the world, boasting the widest range of products of any manufacturer. The company was established by Charlie Trimble (who until recently was the CEO) who is credited with bringing to market the first civilian receiver, the Trimble 4000A, a single-frequency, code-based GPS receiver. Although over the years the size of the receiver box has reduced, all Trimble receivers still are produced in the distinctive "yellow box" configuration.  
 The latest generation of dual-frequency, phase and code tracking Trimble receivers are all based on the core technology first released in the Trimble 4000SSi receiver. The basic "box" configuration for base stations (with choke ring antenna) and certain precise navigation receivers is as shown in the accompanying photograph. A similar configuration is used for the Trimble MS750 receiver intended for machine control/guidance applications.  

The two latest GPS surveying products are the Trimble Total Station 4700 and the Trimble Total Station 4800. The latter is a tightly integrated instrument in which all components (antenna, receiver and UHF radio link) are in one unit that sits atop a pole (which cleverly contains the batteries in its base). The GPSurvey software is a comprehensive program that rivals Leica's SKI-Pro software.

 
Trimble 4700.

 
Trimble 4700.

 
Trimble 4800.

 
Trimble 4800.

Trimble has always had a strong product line to support GIS mapping applications. The entry-level receiver is the Trimble GeoExplorer II. The top-of-the-line system is the Trimble PathfinderPro. The software that is used is known as Pfinder Office.

 
Trimble GeoExplorer.

 
Trimble PathFinderPro.



More details concerning products can be found on the Trimble web site. Other useful features of the Trimble web site include a basic tutorial on how GPS works and an ability to draw plots of satellite visibility/availability/skyplots/etc.

TRIMBLE 4000SSi

Manufacturer: Trimble Navigation, Sunnyvale, California, USA.
Applications: Geodesy, all survey & precise navigation applications.
Components: Separate pole-mounted kinematic antenna with backpack receiver, & optional handheld data logger/controller.
Alternative products include receiver box with LCD display & internal memory, with tripod-mounted geodetic microstrip antenna, or fully integrated "in-one-box" receiver.

Features:

  • Precision: ±(5-20mm + 1ppm) phase baseline solution, static or kinematic positioning mode. Supports "stop & go", "fast static", etc., modes.
  • 12 channels tracking both L1 & L2. P1 & P2 pseudo-ranges (AS off), P1-P2 (AS on). L1 phase tracked by reconstructing carrier using C/A code. L2 phase tracked by: (a) reconstructing carrier via P code (when AS off), or (b) Trimble proprietary codeless technique (when AS on).
  • RTCM capability, time-mark output, event mark input. RTCM I/O for real-time DGPS operations.
  • Internal RAM memory, or optional handheld data logger/controller.
  • Power consumption: external camcorder batteries (10.5-35V DC), & other power sources.
  • Otherwise physical characteristics and options are similar to earlier Trimble 4000 products (the "yellow box").

Comments: This is an improved dual-frequency Trimble receiver able to measure L2 carrier phase when AS is on, boasting Everest signal processing technology to suppress multipath, and allow low noise tracking. Several of the latest products are based on this core technology.

Software: GPSurvey suite, TRIMNET-plus network adjustment software, TRIMMAP topographic mapping software, other specialised software for real-time operations, etc.

Options: Trimble 4400 can operate as a base station, the Trimble 4700 and Trimble 4800 are the latest generations of field surveying systems. The Trimble MS750 is intended for machine guidance/control applications.

 

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© Chris Rizos, SNAP-UNSW, 1999