Symmetricom 5071A, Operating And Programming Manual

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Preface
Operating and Programming Manual xix
Operating The 5071A
Local operation of the 5071A is performed on the control panel located
behind the front panel door. Here you will find the 5071A's controls and
Liquid Crystal Display (LCD). The LCD is backlit for better visibility
whenever any key is pressed.
There are four sinusoidal outputs available on the 5071A: two fixed
frequency outputs of 1 MHz and 100 kHz, and two programmable output
ports. Each programmable output port can be set to emit a 5 or 10 MHz
signal. These ports are isolated from each other so that noise or impedance
changes on one port can not significantly effect the amplitude or phase of
the signal on any other port. An additional property of these outputs is that
they are phase consistent. That is, when the frequency on a port is changed
then returned to the original frequency, the original phase is restored.
The clock functions use the large six-digit LED display, the 1pps outputs,
and their control circuits. The 1pps outputs are movable in time and can be
automatically synchronized with other 1PPS sources. Clock adjustment
procedures can be found in Chapter 2.
Clock display: On power up, the clock display is OFF so the clock will
not display incorrect time. The display may be set and turned on using the
front- panel controls or the RS-232C interface. If you plan to use the
Modified Julian Day (MJD) date system, the time should be set to
Coordinated Universal Time (UTC). See below for more information
about the MJD.
1pps outputs: There are three 1pps outputs on the 5071A, one on the front
panel and two on the rear panel. All are synchronous (pulses occur at the
same time) and isolated from each other so that a short circuit or other
disturbance on one, can not effect the amplitude or timing on the others.
All 1pps outputs are TTL compatible and are designed for 50
termination. You can automatically synchronize the 1PPS signals to an
external 1PPS, or manually change their timing by up to ±500 ms in 50 ns
steps. For automatic sync, there are two reference inputs: one on the front
panel and one on the rear panel. You select either input using the front-
panel controls.
Leap second: The 5071A can be easily set to add or delete a leap
second on a designated day. The leap second is automatically added-to
or subtracted-from the last minute of the day. There is no need for
operator intervention when the actual leap-second alteration occurs.
Signal Outputs
Clock Functions