User guide

Model 577 Operating Manual 13
Duty Cycle: Allows T
0
rate to be a sub-multiple of the Clock Source.
On: Sets the number of pulses to be generated during each “On” cycle when in Duty Cycle
mode.
Off: Sets the number of pulses to skip during each “Off” cycle when in the Duty Cycle mode.
*NOTE: Any mode may be started by the RUN/STOP key when the Trigger Input is disabled. Any mode may be
armed by the RUN/STOP key, and then started by an external trigger when the Trigger Input is enabled. When in
Single Shot or Burst modes (and if the Trigger Input is disabled) the unit disarms itself at the end of the pulse
train. Pressing the RUN/STOP key after the unit has been disarmed will generate a new pulse train. If in triggered
mode the unit will not disarm so that multiple sets of pulses may be generated without user intervention.
7.2.3 Setting the Internal Reference Source and Rate
Not only does the 577 have the ability to be timed by using the internally generated clock, it also has the ability to
be timed by an externally connected Clock Source within a range of common frequencies. If the user frequency is
not listed a different frequency can be used, but the user cannot put in a faster frequency than the selection made
on the soft key. In other words if you have a 35 MHz signal you must tell the 577 to look for a 40 MHz or higher,
any choice below that will result in unpredictable results.
.
Osc: Selects the internal or external Clock Source from which the unit will operate.
To: Sets the T
0
period (or rate) which determines the fundamental output frequency of the unit.