Manual - 8500A Series Peak Power Meter - Giga-tronics

Operation
Single pulse measurements cannot be made with the same accuracy as repeating pulse trains. This is
primarily due to the fact that there is no way to eliminate noise that might be present in the test setup.
For repetitive pulse trains, averaging can be used to eliminate errors due to noise.
The procedure for making a single pulse measurement is as follows:
1. Allow the PPM to warm up for 30 minutes, then conduct a Self-Cal.
2. Select the Peak Mode of operation. If there is no pulse at the detector input there will be no
trigger. If this is the case, the display will either be blank or frozen with the last data that was
taken. The Ready light should be lit, the New Data light will be dark.
3. Set the Trigger Mode to Internal, and then set the trigger level as desired.
4. Set the Cursor Delay to the desired time following the trigger that the measurement is to be
taken. Press [GRAPH]. Move the cursor to CSR DLY. Enter the desired delay (for this example,
use 5 µs) through the keypad, and terminate with the ms, µs, or ns key. Then press [PEAK].
5. Set the Peak Pulse Averaging number to 1.
6. Connect the detector to the RF source to be measured.
7. When a pulse of sufficient amplitude to cause a trigger enters the detector input, the PPM (in this
case) will take a reading 5 µs later. The Peak power being measured at the time of the Cursor
Delay will then be frozen on the display until the next pulse or trigger occurs.
2.13.4 Single Pulse Measurement With an External Trigger
Making a single pulse measurement using an External Trigger is done with the same limitations as with
the Internal Trigger. However, it is possible to control exactly when the power reading is taken by
supplying a TTL trigger to the PPM’s rear panel trigger input at the appropriate time.
The PPM is set to External Trigger by pressing [MENU] (1) [F2].
The trigger signal must arrive coincident with or before the RF pulse to be measured when measuring
with the External Trigger. If the power reading needs to be taken exactly at the time that the trigger
occurs, then the Cursor Delay is set to 0.0000 ns. If the pulse to be measured arrives after the trigger,
then set the Cursor Delay so that the power reading will be taken at the desired point on the pulse.
Manual No. 20790, Rev C, November 1998 2-41
Superceded by Revision D, March 2009