Screen 1 - Orbit Information; Orbit Information - ashtech ZY-12 Information Supplement

Screen 1 - Orbit Information

The receiver collects and displays the orbit parameters from each satellite it has
found. It computes and displays information, such as elevation and azimuth, on
Screen 1 (Figure 3.2). Screen 1 is display-only, you can not use it to enter
information. Table 3.3 describes the screen parameters.
Parameter
PRN The PRN number of each satellite being tracked by the receiver. An asterisk
(*) preceding it says it is currently locked. If the SV numbers are displayed in
reverse video (blue numbers in a white box), then that satellite is in Z mode.
CNT The number of epochs of continuous data collected from this satellite. It is
updated every second. It ranges from 0 to 99 and remains at 99 until a cycle
slip. If there is a cycle slip or loss of lock, the receiver resets CNT to 0.
If CNT often drops to 0, it indicates there are frequent cycle slips with this
satellite. However, if the satellite is high in the sky (elevation angle 20° and
above), cycle slips are rare unless obstructions exist in the line of sight to the
satellite.
S/N The signal-to-noise ratio, a measure of a satellite's signal strength. When less
than 20, the signal is weak; when over 50, the signal is strong. A satellite at
low elevation displays a weaker S/N.
ELV The satellite's angle above horizon, ranging from 0° to 90°.
AZM Geodetic azimuth of the satellite clockwise from 0° geodetic north in units of
10° (geodetic north according to WGS-84 coordinates). When it displays 12,
read it as 120°.
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Figure 3.2. Screen 1 - Orbit Information
Table 3.3. Screen 1- Orbit Parameters
Description
ZY-12 GPS Receiver