Instruction manual

Introduction Page 3
Introduction
broadcasts almanac and ephemeris information every 30 seconds, and the sensor
automatically records this information in its non-volatile memory.
The sensor has an L1/L2-band radio frequency (RF) port and three RS-232 serial
input/output (I/O) ports. Ports A and B are capable of two-way communication with
external equipment. Port C is capable of RTCM operation.
With external power removed from the non-volatile part of the RAM, data storage is
maintained using an internal battery.
The RF circuitry receives satellite data from a GPS antenna and LNA via a coaxial
cable, and can supply power to the antenna/LNA by means of that cable. No separate
antenna power cable is required. Power consumption is approximately 12 watts even
when powering an LNA.
The sensor incorporates a two-color LED which lights red to indicate the power
status, and flashes green to indicate the number of SVs locked.
The sensor collects Coarse Acquisition (C/A) code-phase (pseudo-range) and full
wavelength carrier phase measurement on L1 frequency (1575 MHz), Precise (P)
code phase (pseudo-range) and full wavelength carrier phase on L1 and L2 frequency
(1227 MHz). The sensor permits uninterrupted use even when Anti-Spoofing (AS) is
turned on. When AS is on, the sensor automatically activates Ashtech patented Z-
tracking mode that mitigates the effects of AS. The performance when AS is on is the
same as when AS is off.
Real-Time Differential
One of the most important functions of the sensor is providing real-time position
solutions with accuracy ranging from centimeter level to 100 meters. Table 1.1
summarizes the positioning modes and expected accuracy.
Table 1.1: Accuracy as Function of Mode
Positioning Mode
Tyhpical Horizontal
Accuracy (rms), 5 SVs,
PDOP<4
Maximum
Update Rate
Maximum Operating
Range
Autonomous 16 meters with SA off 1 Hz Anywhere
RTCM differrential <1 meter 1 Hz Several hundred kilome-
ters
Real-time kinematic (RTK)
carrier phase differential
in RTCM-RTK format or
DBEN format
0.01 meter or better 5 Hz <15 kilometers