Boonton 4540 Peak Power Meter User Manual - Manual (Page 236)

Boonton 4540 Series RF Power Meter
Application Notes 6-8
6.3.3 Automatic Measurement Sequence
The automatic measurement process analyzes the captured signal data in the following sequence:
1. Approximately 500 samples of the waveform (equivalent to one screen width) are scanned to determine the
maximum and minimum sample amplitudes.
2. The difference between the maximum and minimum sample values is calculated and stored as the Signal
Amplitude.
3. The Transition Threshold is computed as one-half the sum of the maximum and minimum sample
amplitudes.
4. The processor locates each crossing of the Transition Threshold.
5. Starting at the left edge of the screen, the processor classifies each Transition threshold crossing according
to whether it is positive-going (– +) or negative-going (+ –). Because the signal is repetitive, only three
transitions are needed to classify the waveform, as follows:
Type Sequence Description
0 none No crossings detected
1 Not used
2 + – One falling edge
3
– +
One rising edge
4 + – + One falling, followed by one rising edge
5 – + – One rising, followed by one falling edge
6 + – + – Two falling edges
7 – + – + Two rising edges
Figure 6-5.
Step Waveforms
6. If the signal is Type 0, (No crossings detected) no measurements can be performed and the routine is
terminated, pending the next reload of the data buffers.