NAVIOR-24S
™
CHAPTER III
Software Interface
45
NAVIOR-24S ™
Revision
V1.00 20.05.2008
Start-up
NAVIOR-24S GPS/GLONASS receiver module is a complete 24-channel parallel tracking
GPS/GLONASS receiver designed to operate with the L1 frequency, standard position service,
Coarse Acquisition code (GPS) and CT code (GLONASS). When connected to an external
GPS/GLONASS antenna, the receiver contains all the circuitry necessary to automatically acquire
GPS/GLONASS satellite signals, track up to 24 GPS/GLONASS satellites, and compute location,
speed, heading, and time. The receiver will automatically begin to search for and track
GPS/GLONASS satellite signals at power-up.
The performance of a GPS/GLONASS receiver at power-on is determined largely by the
availability and accuracy of the satellite ephemeris data and the availability of a GPS and
GLONASS system almanac. The first time the receiver is powered-up, it is searching for satellites
from a cold start (no almanac). While the receiver will begin to compute position solutions within
the first 90 seconds, it must continuously track satellites for approximately 15 minutes to download
a complete almanac. This initialization process should not be interrupted. With a complete almanac
and back-up power, the time to first fix can typically be shortened to less than 50 seconds. The
receiver will respond to commands almost immediately after power-up (see Warning below).
Note –
See Chapter 4 for further detail on ephemeris data and the GPS and GLONASS almanac.
Warning – The NAVIOR-24S GPS/GLONASS Receiver is ready to accept any commands
approximately 6 seconds after power-up. If a command is sent to the receiver within this 6
second window, the receiver will ignore the command. The NAVIOR-24S GPS/GLONASS
Receiver will not respond to commands sent within the 6 second window and will discard any
associated command data.
