HP 85108A, System Manual

Page: 60 / 136

Measuremen t Cycle Times
1 ms Next Av erage
4 to 8 ms Next P arameter
30 to 40 ms Next F requency P oint (F requency Domain)
3-4 ms Next Time P oint (Pulse Prole Domain)
Measurement Cycle Time
Con trols that can eect the measuremen t cycle time are:
Sw eep Time . When the analyzer is otherwise ready for the next measuremen t cycle, it ignores
triggering for an in terv al equal to (Sw eep Time (ms)/Numb er of P oints).
Pulse Width . The pulse alwa ys remains On for the user-sp ecied time.
Dut y Cycle Limit . When the analyzer is otherwise ready for the next measuremen t cycle, if
the dut y cycle p ercen t maxim um limit w ould b e exceeded, the pro cess ignores triggering un til
the dut y cycle limit is satised.
Pulse Prole Domain Stop Time . The time v alue of the curren t pulse prole data p oint
determines the measuremen t cycle time when it is greater than the PRP set b y the dut y cycle
limit.
F requency Domain T rigger Dela y . If the frequency domain trigger dela y is greater than the
dut y cycle limit, trigger dela y will con trol the minimum frequency domain measuremen t cycle
time.
The only additional considerations are:
1. Pulse Output is set to the active lev el during measuremen t of an y calibration standard.
2. Pulse Output is set to the inactive lev el during the sw eep retrace.
3. Pulse Output is set to the active lev el for less than 30 microseconds immediately prior to
the b eginning of the sw eep for the automatic p erio dic IF calibration sequence.
4. Pulse Output remains at the inactive lev el under all conditions when External T riggering is
selected.
The automatic p erio dic IF calibration sequence is transparent to the op erator except for the
less than 30 microsecond pulse output immediately prior to the b eginning of a sw eep. T o the
op erator, the IF calibration sequence will app ear to o ccur at random times, more frequen tly
just after the HP 8510 is turned on, then less often as the system temp erature stabilizes.
Pulse Repetition P eriod and Duty Cycle Considerations
F rom the measuremen t cycle information y ou can see that the pulse rep etition p erio d and
th us the dut y cycle of the pulsed-RF signal applied to the DUT can v ary dep ending up on
the instrumen t state. F or measuremen ts in whic h the PRP or dut y cycle is not imp ortant,
simply set the pulse width and the dut y cycle con trols to an appropriate v alue and make the
measuremen t. The sp ecied dut y cycle limit will not b e exceeded, but the actual dut y cycle
may b e less than exp ected.
F or example, Figure 3-20 sho ws the pulse output w a v eform for v arious conditions.
Figure 3-20a sho ws the pulse output when the pulse width is 500 microseconds, the dut y
3-24 Operation
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