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GPS
Product series
4. Software Interface
The GR-82 interface protocol is based on the National Marine Electronics Association's
NMEA 0183 ASC interface specification, which is defined in NMEA 0183, Version 2.2 and the
Ⅱ
Radio Technical Commission for Maritime Services (RTCM Recommended Standards For
Differential Navstar GPS Service, Version 2.1, RTCM Special Committee No.104).
As soon as the initial self-test is complete, the GR-82 begins the process of satellite
acquisition and tracking automatically. Under normal circumstances, it takes approximately 42
seconds to achieve a position fix, 38 seconds if ephemeris data is known. After a position fix has
been calculated, information about valid position, velocity and time is transmitted over the output
channel.
The GR-82 utilizes initial data, such as last stored position, date, time and satellite orbital data,
to achieve maximum acquisition performance. If significant inaccuracy exists in the initial data, or
the orbital data is obsolete, it may take more time to achieve a navigation solution. The GR-82
Auto-locate feature is capable of automatically determining a navigation solution without
intervention from the host system. However, acquisition performance can be improved as the
host system initializes the GR-82 in the following situation:
Moving further than 500 kilometers.
Failure of Data storage due to the inactive internal memory battery.
4.1 NMEA Transmitted Messages
The default communication parameters for NMEA output are 4800 baud, 8 data bits, stop bit,
and no parity.
Table 4-1 NMEA-0183 Output Messages
NMEA Record
GPGGA
GPGLL
GPGSA
GPGSV
GPRMC
GPVTG
GPMSS
HOLUX Technology, Inc.
1F, No.30, R&D Road, Hsinchu 300, Taiwan (Hsinchu Science Industrial Park)
TEL: 886-3-6687000 FAX:886-3-6687111 E-mail:info@holux.com.tw Website:www.holux.com.tw
Description
Global positioning system fixed data
Geographic position- latitude/longitude
GNSS DOP and active satellites
GNSS satellites in view
Recommended minimum specific GNSS data
Course over ground and ground speed
Radio-beacon Signal-to-noise ratio, signal strength,
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