C-Nav C-NaviGator III, Руководство пользователя

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C-NaviGator III User Manual
Revision 2 Page 88 of 121 9/27/2013
L1-L2 Sig. Strength GNSS satellites transmit spread spectrum signals in two
frequency bands, L1 and L2 (1575.42 and 1223.6 MHz,
respectively). The satellite signals carry both time
information and a data strings, referred to as the GNSS
navigation message. This message is transmitted at a rate
of 50 bits per second. Using the data from 4 or more
satellites, a GNSS receiver can accurately determine local
latitude, longitude and height. Civilian applications are
confined to the L1 band for computing position. The C & C
Technologies and military receivers employ both L1 and L2
bands, offering a significant improvement in accuracy.
NMEA 0183 This guideline for Interfacing marine electronics devices is a
voluntary industry standard, first released in March of 1983.
NMEA 0183 defines electrical signal requirements, data
transmission protocol, timing, and specific sentence formats
for up to 38.4K-baud serial data bus.
PDOP P osition D ilution o f P recision is the most common
mathematical expression of the quality of solutions. It is
based on the geometry of the satellites with the best case
being a value of 1. Higher numbers indicate worse quality.
The best DOP would occur with one satellite directly
overhead and three others evenly spaced about the horizon.
PDOP has a multiplicative effect on range error. For
example, a range error of 32 meters with a PDOP of 1 would
give a user an assumed best accuracy of 32 meters. A
PDOP of 2 would result in an assumed accuracy of 64
meters. C-NaviGator III can be programmed to stop
providing position solutions above a specific PDOP level (6
is common).
Position Includes Current Latitude, Longitude, Geoidal Height,
HDOP, PDOP, Type of corrections, Current Station ID,
Differential Age, Velocity, UTC Time and UTC Date if
available.
PPS P recise P ositioning S ervice
– a positioning service that
includes velocity and timing information. PPS is
continuously available, worldwide to authorized users. PPS