Odetics
Telecom
GPStar
plus
Model 365
365-8006
Display Menus and Controls 5 - 23
5.4.5
MENU 7 - FREQUENCY STATUS
This menu includes a display screen that indicates the frequency disciplining status of
the internal oscillator. Through the screen the unit's timing can be re-synchronized and
the disciplining can be restarted.
•
Press key 7 to view the status screen (
Freq Error and Std Error of Estimate
).
Freq Error:-2.53E-011 Samples:0036133
≡
Std Error of Est:3.00E-008 DAC:31264
Freq Error
- During the initial 24-hour period after application of input power, this
screen displays the computed frequency error averaged over the number of
measurement
Samples
shown. The sample count increments only when the unit is
Time Locked. After the first 24-hour period, the averaged frequency value shown is
stored on the display, and updated at the end of each following 24-hour measurement
period.
Std Error of Est
value represents the standard error of estimate. The value is updated
once per second when the unit is Time Locked. For example, if the displayed value is
3.00E-008, it indicates that 67% of the measured differences between the GPS
receiver's 1 PPS and the 1 PPS derived from the internal oscillator were less than or
equal to the estimated time solution of +/- 3.00E-008 (i.e. +/- 30.0 ns, 1 sigma). Ninety
five percent of all estimates occur within 2 sigma. The calculated value is cumulative for
the present measurement period, and will fluctuate more in the early part of the period.
As the estimation progresses (higher number of samples), the value will become more
stable. The value is higher while operating in either the Dynamic or Position Averaging
mode.
DAC
value is the control value sent to the digital to analog converter that controls the
internal oscillator. The number ranges from 0 to 65535.
To manually force the internal timing to re-synchronize to the GPS receiver 1 PPS
output and restart the oscillator disciplining process:
•
Press the Edit key.
Re-Sync/Start Discipline:No
≡
•
Use the arrow keys to select
Yes
. Press the Enter key to re-synchronize the
unit's timing output signals and restart the disciplining of the oscillator.
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