HP 8510, User Manual

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If y ou are viewing this with an oscilloscop e, notice ho w the measuremen t cycle time v aries
according to the pulse prole stop time. If the stop time is greater than the pulse width, the
measuremen t cycle time will extend past the end of the pulse dep ending up on the time v alue
of the data p oint b eing measured. Dep ending up on the pulse width, this can result in a low er
p ercen t dut y cycle tow ard the end of the time span.
External Trigger and Stop Sw eep Signals
Figure 8-3 sho ws the relationship b et w een the external T rigger Input and the HP 8510 Stop
Sw eep output for frequency domain p oint-in-pulse measuremen ts and for pulse prole domain
measuremen ts. F or external triggering, Stop Sw eep remains Busy (low) un til the measuremen t
cycle is complete. This information is imp ortant for sync hronizing the pulse mo dulation to the
external trigger.
It is easy to learn the timing b y using an oscilloscop e to view Stop Sw eep when the external
trigger is applied.
Press 4
STIMULUS MENU
5
NNNNNNNNNNNNNN
MORE
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
TRIGGER MODE
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
TRIGGERING EXTERNAL and apply a TTL pulse
train to the HP 8510 rear panel EXTERNAL TRIGGER INPUT. The trigger should stay low
for at least 100 nanoseconds. Excess triggers that o ccur while stop sw eep is busy (lo w) are
ignored. The next external trigger falling edge after stop sw eep is ready will initiate the next
measuremen t cycle and retrace is automatic.
Figure 8-3. External Trigger and Stop Sw eep Timing Diagram
General Timing Information 8-5