Operator's Manual

OM-E 2072-09689-00
2-23
2-9. USING THE GPS RECEIVER (OPTIONAL)
2-9.1 Overview of GPS Receiver Functions
The GPS receiver is an integral part of the Micom-Z transceiver, and can be used whenever the GPS
antenna supplied together with the Micom-Z transceiver is properly connected and installed.
The GPS receiver provides accurate time and navigation data. The navigation data includes the
geographical coordinates (position data) and the altitude. When the Micom-Z transceiver is moving,
you can also see the speed and direction (heading).
The format of the navigation data can be selected in accordance with your needs:
• LLA format: Latitude, longitude and altitude (LLA). The latitude and longitude are displayed in
degrees, with a precision of hundredths of arc minutes (1/100 min); the altitude is reported in
meters, relative to the mean sea level (MSL).
Velocity is reported as the change in the East, North, and Up coordinates, presented in meter/sec
with a precision of 0.001 m/sec.
• ECEF format: Earth-Centered, Earth-Fixed format for position and velocity. Provides your
position and velocity in a Cartesian (X, Y, Z) coordinate frame with its center at the Earth's
center, the Z-axis through the North Pole, and the X-axis through 0 degrees longitude, 0 degrees
latitude. The position is reported in meters.
Velocity for each axis (that is, is the change in the X, Y and Z coordinate) is displayed in
meter/sec, with a precision up to 0.001 m/sec.
The time is always presented on basis of the UTC (Universal Time Coordinated).
The information collected by the GPS receiver can be displayed on the Micom-Z display when using
the CH and FREQ modes. In the ALE and CCIR modes, the position data can be reported by means of
AMD messages; it can also be automatically reported in response to position queries (also sent by
AMD messages).
2-9.2 How to Get the Best Results from your Micom-Z GPS Receiver
The GPS receiver extracts the information it needs by analyzing the signals received from GPS
satellites. These satellite periodically transmit navigation messages, where the transmission of each
complete message requires almost 15 minutes. To calculate all the data your GPS receiver is capable
of providing, it must receive and decode navigation messages from at least 4 GPS satellites (the GPS
receiver can use as many as 8 satellites to improve accuracy).
Therefore, after turning a GPS receiver on for the first time after a long period of inactivity, it is
essential to let the GPS receiver operate continuously for at least 15 minutes, to enable it to collect
updated almanac data. After this initial 15-minute interval, a GPS receiver can relatively rapidly
acquire the satellites and calculate its position; thereafter, a GPS receiver must remain on only for a
few minutes in order to be able to provide navigation data.
The internal GPS receiver is always powered when the transceiver is turned on. Therefore, if the GPS
antenna is connected, the GPS receiver can start the acquisition process as soon as the transceiver is
turned on, and can then track the satellites continuously. Turning the Micom-Z transceiver off will
force the GPS receiver to reacquire the satellites.
2-9.3 Operating the GPS Receiver
2-9.3.1 GPS Menu
The GPS menu is displayed by selecting the GPS item on the FREQ or CH menu. The GPS menu
structure is shown in Figure 2-4.