Symmetricom XL-GPS User Manual

5: Function Reference
F5 – Time-Quality Setup
Use function F5 to enable/disable time quality reporting, and to set the thresholds of the four
time-quality flags.
How time quality reporting works: If the GPS timing reference becomes unavailable to
discipline or steer the oscillator, the oscillator begins to drift and gradually accumulates time
error. The XL-GPS estimates time error based on the oscillator-type and on the degree of
steering (the DAC value) that was being applied to the oscillator before the timing reference
became unavailable. As the estimated time error grows, exceeding the threshold of the four
Time Quality Flags set in F5, the XL-GPS outputs four corresponding time quality characters
in text outputs of F8. (See “F8 – Continuous Time Once-per-Second” on page60)
In addition, a time quality indicator is encoded in the time codes that carry time quality
information (i.e. IRIG, IEEE 1344). (see “F90 – Code Output Configuration” on page105).
The XL-GPS accepts threshold values from 200 nS to 40000000000 nS.
The factory settings for F5 are as follows:
• Time quality reporting - enabled
• First time quality flag 1,000 ns
• Second time quality flag 10,000 ns
• Third time quality flag 100,000 ns
• Fourth time quality flag 1,000,000 ns
See "Factory Default Jumper and Switch Settings for Options" on page 166
Related topics (Time Error):
• “F13 – Time Error” on page67 displays the current time error
• “F71 – Oscillator Statistics” on page92 provides the DAC value
Command Line
To determine if the time quality characters are enabled and what the thresholds are, enter:
F5<CR>
XL-GPS responds:
F5<S><STATE><SEP><FLAG><SEP><FLAG><SEP><FLAG><SEP><FLAG><CR><LF>
where:
Page 56 of 221 .................................098-00116-000 Rev. A

Symmetricom XL-GPS Specifications

General

Brand	Symmetricom
Model	XL-GPS
Category	Receiver
Language	English