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cussed more fully in the Triggered Measurements section
below.
Range Hold may be selected (see page 4-6) to limit dy
-
namic range and prevent small range change distur
-
bances on very high speed signals. Use Range Hold 1 for
measurements down to –25 dBm, and Range Hold 2 up
to –25. If the display update is turned off via GPIB, only
the average is updated.
Triggered
Measurements
Since non-triggered measurements are of limited use in the PROFILE mode,
most applications require triggering. For example:
1. Provide a 1 kHz square wave modulated signal to sensor A, and set
TRIGGER|SETUP|MODE to Internal A (Int A). This causes the PROFILE sweep
to wait until a certain power level is present on the sensor before starting the
sweep.
2. The DELAY and WIDTH parameters, as discussed above, are the positions of
the two CURSORS. These can be set to specific locations; for example, if the sig-
nal is a 1 kHz square wave, setting the DELAY to 250 µs places the cursor in the
first cycle at the midpoint of one of the phases. Setting the WIDTH to 500 µs sets
the other CURSOR to exactly one half-cycle later, thus allowing display of the
power levels in the two phases of the signal.
NOTE
If the modulation is turned off, then the trigger conditions
will not be met and the sweep will not continue to be up-
dated. This is useful to ‘freeze’ a display. To display a CW
signal again, re-select CONTINUOUS trigger in TRIG
-
GER|SETUP|MODE.
In some conditions, it is useful to view triggered signals
independent of signal levels. In these cases, provide an
external trigger source into the rear panel TRIGGER input
to trigger such a measurement.
3. The dynamic range in PROFILE mode should extend to the maximum specifi
-
cation of the meter, to approximately –40 dBm (diode sensors only). If the dis
-
played range is restricted, check that RANGE HOLD is not applied.
NOTE
If RANGE HOLD 1 is applied, the lower limit will be ap
-
proximately –30 dBm. If RANGE HOLD 2 is applied, the
maximum level will be limited to approximately –10 dBm.
In most triggered situations, range hold should be set to
AUTO.
ML2430A OM 5-13
PROCEDURES PROFILE OPERATION MODE