Falcon NAVI-B - Manual (Page 8)

NAVI-B VERSION 1.01
When the required data are completely collected, then satellite signals are
tracked continuously and the position is calculated from time to time. When
the received data from satellites is considered valid then the FALCOM
NAVI-B is available for navigation. The validity of these data stored in
SRAM is kept due to RTC keeps running from external battery and these
data may still be valid form the previous operation.
As above the initial state of the NAVI-B GPS receiver refers to the last
status of the receiver in memory (SRAM). This primarily determines the
length of time it will take for your FALCOM NAVI-B to obtain a GPS fix.
Your position can be extremely quick fixed within 4 seconds from a "hot-
start" state, and within 45 seconds from a "cold-start" state. The FALCOM
NAVI-B stores data about where the satellites are located at any given time.
The data is called almanac. Occasionally, when the FALCOM NAVI-B has
been turned off for a long time, the almanac may get out-dated or “cold” so
the NAVI-B performs a cold start. Otherwise, if the time and position are
known, as well the almanac data are also valid then the FALCOM NAVI-B
performs a Hot start.
The NAVI-B uses the satellite signals to calculate its exact current location
by calculating its distance from the satellites. The position data within the
receiver is then converted into latitude and longitude coordinates which are
usually provided in the geodetic datum on which the GPS is based (WGS84)
and transmitted via integrated Bluetooth™ transceiver direct to the
Bluetooth™-enabled device (PC, laptop or Pocked PC).
2.1.1 Software interface
The NAVI-B evaluation receiver is capable of outputting data in the
NMEA-0183 format as defined by the National Marine Electronics
Association (NMEA), Standard for Interfacing Marine Electronic Devices,
Version 3.00, January 1, 1997.
2.1.1.1 NMEA output messages
The table below shows all NMEA output messages supported by NAVI-B
as well as a brief description of each output message.
For more detailed information about the output message list, please refer to
the SiRFstarII message set specification available in section
“service/downloads/manuals” on Falcom’s Website
: www.falcom.de .
Option Description
GGA Time, position and fix type data.
GLL Latitude, longitude, UTC time of position fix and status.
GSA GPS receiver operating mode, satellites used in the position solution and DOP
values.
GSV The number of GPS satellites in view satellite ID numbers, elevation, azimuth
and SNR values.
RMC Time, date, position, course and speed data.
VTG Course and speed information relative to the ground.
Table 1: NMEA Output Messages
Info: Please note that all supported NMEA messages of the NAVI-B can be
configured via the SiRFdemo software (See chapter 4.2.1 ). All user
defined settings are kept into the SRAM memory and available on
each power up.
This confidential document is the property of FALCOM GmbH and may not be copied or circulated without permission.
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