External Frequency Setup; Pulse Generation Parameters - ashtech ZY-12 Information Supplement

External Frequency Setup

This option lets you input an external frequency to override the receiver's internal
oscillator. To configure an external frequency, go to Screen 4 and select EXT
FREQ (Figure 3.13). Table 3.13 describes the screen parameters.
Figure 3.13. External Frequency Setup Screen
Table 3.13. External Frequency Parameters
Parameter
External
Frequency
Auto-switch
Press [e] to save the parameters. A status display indicates when the external
reference is locked. When locked, pressing [e] exits that display. If you do not
have the external frequency option, you can not access this subscreen.

Pulse Generation Parameters

A one-pulse-per-second (PPS) output option is available. The PPS signal is a TTL
signal into a 75-ohm impedance. The signal is normally low and goes high 1 to 2
ms before the falling edge. The rising edge is synchronized with GPS time, as
shown in Figure 3.14. The signal is synchronized with GPS time. Access the
Screen Descriptions
Description
Sets the receiver to the input frequency of the external
reference source. Range is 1.00 to 21.00 MHz.
Toggles Y(es) or N(o). Y saves the external frequency
parameters after a power cycle. N resets the receiver to
its internal oscillator after a power cycle.
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