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Trigger position
8us
Fig. 3.11 Trigger delay of 8 us
3.7 Test Methods for Stability of Pulse Strings in Different Periods
The pulse strings can be measured through “HoldOff”
After trigger is performed each time, it is necessary to add a certain time interval during which pulse trigger is prohibited.
This time period should be shorter than the period of the pulse string but longer than the “Pulse Width Excluding the
Maximum Period in the Pulse String”. For example, if a pulse string includes five pulses with the periods of “2us, 4us,
6us, 8us, 10us” respectively, then “HoldOff” should be set between 20.1 us and 29.9 us so that the pulse sequence can be
triggered stably.
In this section, the methods for measurement of the pulse strings in different periods through the trigger holdoff function
are described in detail by taking the Channel A of the S2438 microwave power meter connected to a S81702D peak
power sensor for example.
The signal generator is set with a frequency of 1 GHz and a power of 10 dBm, the pulse modulation mode is adopted,
and the output signal is a pulse sequence including five pulse with the periods of 2 us, 4 us, 6 us, 8 us and 10 us
respectively and a duty cycle of 50%.
The specific settings are as follows:
1) Connect the zeroed and calibrated S81702L power sensor to the signal generator output port;
2) Set [Menu]>[Trigger] >[Trig Pos] >[Trig Slope] >[+], [Trig Source Chan A] and [Trig Level -5dBm];
3) Set [HoldOff 21us];
4) Set [Menu]>[Display] >[Disp Mode] >[Trace A];
5) Set [Channel]>[Trace Ctrl] >[Trace Set] >[X Scale 10us/], [Trig Pos Mid], [Vert Scale 10.00dB/];
The pulse strings in different periods can be stably displayed on the screen through the above steps.
