Sect_4.2.5(Ashtech)

4.2.5 GPS Hardware for Surveying:

SOME INSTRUMENTATION (ASHTECH)

The Ashtech company was started by Javad Ashjaee in the late 1980s. (Javad had been a senior engineer with the Trimble company.) In 1997 the company (no longer headed by Javad Ashjaee) was purchased by the Magellan Corporation, a manufacturer of low-cost, handheld GPS receivers. The combined product range of Magellan-Ashtech now addresses almost all user applications and is one of the few companies that can rival the range of products manufactured by Trimble. (Javad has since established another GPS company, called simply Javad Positioning Systems.)

Although Ashtech have manufactured low-cost, navigation receivers (including boardsets) they are best known for their high precision GPS geodesy/surveying products. With the release of the Ashtech Z-12 in the early 1990s the reputation of Ashtech for innovative electronics was established. Many people consider the Z-12 to be one of the (if not THE best) of the new generation of dual-frequency, phase and pseudo-range measuring instruments. The "Z-tracking" technology has the highest signal-to-noise ratio of all the codeless L2 tracking techniques (section 4.2.3).

Although the Z-12 has now been superseded, the core tracking technology is incorporated in the new products such as the Ashtech Z-Surveyor, the Ashtech Z-SuperStation and the CORS line of receivers. The Ashtech Z-Surveyor is designed for survey applications, and is the direct competitor to Leica's System 500 (SR520/530) and Trimble's 4700/4800 GPS receivers. The real-time (RTK) version is known as the Ashtech Z-SuperStation.

Ashtech Z-Surveyor (receiver only).

The CORS ('Continuous Operating Reference Station') receiver is, as the name implies, a version optimised for base station operations, and is a competitor to Leica's CRS1000 product. Ashtech produces several systems intended for machine guidance/control, airborne applications, maritime applications (such as dredging), opencut mining operations, and precision agriculture.

A recent product known as the Ashtech Locus is a small, tightly integrated unit requiring minimal operator input. The Ashtech Reliance family of receivers is intended for GIS mapping applications.

Ashtech Locus.

Ashtech is one of the few companies that has manufactured and marketed an integrated GPS+Glonass receiver, known as the Ashtech GG24. The RTK version is known as the Ashtech GG-SuperStation.

The Ashtech GG24 integrated GPS+Glonass receiver (receiver only).

More details of the Ashtech product range can be obtained by visiting their web site.

ASHTECH Z-12

Manufacturer: Magellan, Santa Clara, California, USA.

Applications: Geodesy, all survey & precise navigation applications.

Components: Antenna, tripod-mounted.
Receiver box with LCD display and internal memory.

Features:

Precision: ±(5mm + 1ppm) for static GPS, ±(10mm + 1ppm) for kinematic GPS, cm-dm accuracies for baselines <100km for kinematic (resolved ambiguities).
Tracks up to 12 satellites, L1 & L2 phase, P1 & P2 pseudo-range measurements.
Size: 99x203x216mm, 3.9kg.
Microstrip antenna (with groundplane 292mm dia.), 1.7kg.
Power consumption: 18W, external batteries (10-32V DC), & other power sources.
Four RS232 ports for data communication.
Optional RTCM or Ashtech format DGPS I/O messages.
8x40 character LCD display.
Internal RAM memory (expandable).

Comment: The Z-12 model is especially versatile even when AS is on (full P1, P2, L1, L2 observables using Ashtech proprietary codeless technology). Also available in configuration as the Z-12 Surveyor and the real-time version known as the Z-SuperStation.

Software: GPPS post-processing software (old), or WinPRISM processing software (new) integrated within the Ashtech Office Suite for Survey (AOSS), plus several software packages for kinematic survey (PNAV), real-time DGPS, real-time surveying, etc.

Back To Chapter 4 Contents / Next Topic / Previous Topic