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Appendix F 59551A Specifications
Specifications and Characteristics
Operating and Programming Guide F-3
1PPS Output
Specifications
Locked:
Jitter of leading edge: <750 ps
rms with at least one satellite in
view.
Time Accuracy:
<110 ns with respect to UTC
(USNO MC)—95% probability
when unit is properly installed,
calibrated, and locked to GPS.
Unlocked:
Accumulated time error: <8.6 µs
accumulated in 24 hours of
unlocked operation. (See Note 1.)
Supplemental Information
• Pulse Width: 26 µsec
• Amplitude: >2.4 volts into
50Ω load. (TTL compatible)
• Connector: BNC
•Rise time: <5ns
Additional Features
Alarm BITE Output:
Basic unit output: solid state relay
(normally open); closed contact
indicates system fault or loss of
satellite lock. Contact rating
200 Vdc @ 0.5 amps.
Connector: Twin BNC
IRIG-B123 Output Port
BNC connector
Note 1
This specification has a 95% probability,
and is based on availability of four or more
GPS satellites during three days locked
operation with a fixed antenna location.
The temperature must remain within a
10° C range between 10° C and 40° C.
Note 2
When a quartz crystal oscillator has not
been operated for a period of time, or if it
has been subjected to severe thermal or
mechanical shock, as might be
encountered during product shipment, the
oscillator may take some time to stabilize.
In most cases, the oscillator will drift and
then stabilize at or below its specified rate
within a few days after being turned on.
In isolated cases, depending upon the
amount of time the oscillator has been off
and the environmental conditions it has
experienced, the oscillator may take up to
one week to reach its specified aging rate
and to operate without significant
frequency “jumps.”
When a GPS Receiver is initially turned
on and locked to the GPS satellite
system, it will achieve GPS lock within
30 minutes of operation. It has a 95%
probability of meeting unlocked (holdover)
specifications after 24 hours of warmup,
followed by GPS lock for 48 hours. The
longer GPS Receiver (and its quartz
oscillator) operates, the better its stability
and unlocked (holdover) performance
becomes.
Three Time-tag Inputs
Received signal: TTL, 50Ω.
Time-tag accuracy: same as the
accuracy of the 59551A.
Quantization: 100 ns
Input Interface: BNC
Minimum Pos/Neg pulse width:
200 ns
Three time-tag buffers: 256 events
each, retrievable via RS-232C.
Minimum time between events:
1ms
Maximum stamp rate:
1 measurement per ms
Timer/Clock Output
Programmable Pulse Output:
Single pulse at the time
programmed via RS
-232C port,
or repetitive output pulse at a
programmable repetition period
from 1 second to 1 year.
Quantization: 100 ns
Accuracy: same as the time
accuracy of the 59551A.
Front Panel Indicators (LEDs):
Power
GPS Lock
Holdover Mode
Alarm
Remote Interface:
(Two RS
-232C Ports)
RS-232-C DTE configuration:
PRIMARY PORT
Complete remote control and
interrogation of all instrument
functions and parameters.
SECONDARY PORT
Interrogation of all instrument
functions and parameters.
Factory defaults: baud rate 9600—
8databits, 1startbit, 1stopbit,
no parity. Other settings are
programmable.
Connectors: 9-pin female
rectangular D subminiature
(DB-9) on front panel, 25-pin
female rectangular D
subminiature (DB-25) on rear
panel.
Time code output is available to a
computer immediately preceding
the 1 PPS signal for the current
second.