Boonton 4540 Peak Power Meter User Manual Manual do Utilizador descarregar pdf (Página 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.

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