Philips PM3320 Operating Manual page 138

4-122E
Conversion and processing section
In the conversion and processing section the vertical input signals are digitised, processed and
stored in a digital memory. This is done by an Analog to Digital Converter, which receives the
vertical input signals via a MULTIPLEXER from the VERTICAL CHANNEL SWITCH AND PEAK
DETECTORS.
This MULTIPLEXER is provided with track and hold circuits, which can hold samples that are
taken from both channels at the same moment.
The samples are converted then in sequence by the ADC.
Data from the ADC is processed by the DATA PROCESSING CIRCUIT, which performs e.g. the
softkey selectable AVERAGE function.
Data from the DATA PROCESSING CIRCUIT is transported to the STORAGE SECTION.
The PEAK DETECTORS, MULTIPLEXER and ADC are controlled by the TIME BASE LOGIC,
which on its turn is controtled by the ACQUISITION AND CONTROL LOGIC.
The ACQUISITION AND CONTROL LOGIC performs the following functions:
- Time base setting, controlled by the TIME/DIV switch
— Horizontal mode selection by means of the softkey functions under the HORIZONTAL MODE
pushbutton.
RECURRENT
~ MULTIPLY
- SINGLE
- ROLL
~ Trigger delay selection by means of the softkey functions under the TRIGGER DELAY
pushbutton.
- TIME
- DIV
— EVENTS
- Selection of EVENTS or EXT CLOCK via the frontpanel EXT CLOCK pushbutton.
- Control! of pilot lamps ALIASED, REP ONLY and NOT TRIG'D.
The ACQUISITION AND CONTROL LOGIC is controlled by the microprocessor system, which
also controls the DATA PROCESSING circuit.
The DELTA-t circuit is used for the random sampling mode (time base range 100 ns/div - 5
ns/div).
The delta-t output signal is fed to the microprocessor system via the MICROPROCESSOR
MANAGEMENT INTERFACE for dot position calculation.