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A - 2 APPLICATION PROGRAM EXAMPLES
A.1 Measuring Signal Characteristics
Measuring signal characteristics can be done in either of the following ways:
1) Using the measurement instructions. Example A.1.1 shows how to do that
automatically by letting the CombiScope instrument select the best possible
settings. Example A.1.2 shows how to do that after programming your own
instrument settings.
2) Using the DISPlay:WINDow:TEXT<n>:DATA? query to read signal values as
measured by the MEAS1 & MEAS2 features of the CombiScope instrument
(refer to example A.1.3).
A.1.1 Making automatic measurements
In the following example the frequency, amplitude, period, positive and negative
pulse width of the Probe Adjust signal are measured and displayed 10 times. This
is done automatically by using the CONFigure, READ?, and FETCh?
measurement instructions.
Application summary:
•
Connect a 10:1 probe between channel 1 and the Probe Adjust signal (2000 Hz,
600 mV).
•
Configure for measuring the Probe Adjust voltage of 600 mV and frequency
of about 2000 Hz by sending:
CONFigure:VOLTage:FREQuency (0.6),2000,(@1)
•
Send the following queries 10 times and read the corresponding responses:
READ:FREQuency? Initiates and fetches a frequency measurement.
FETCh:AMPLitude? Fetches the measured amplitude.
FETCh:PERiod? Fetches the measured period.
FETCh:PWIDth? Fetches the measured positive pulse width.
FETCh:NWIDth? Fetches the measured negative pulse width.
•
Print the received signal characteristics. Notice that the sum of the positive
and negative pulse width equals the period, and that the inverse period equals
the frequency.
Application program:
Note: The program is also supplied on floppy under file name EXAPPA11.BAS.
REM $INCLUDE: ’QBDECL.BAS’
DECLARE SUB errorcheck ()
DIM res AS STRING * 100 ’
Dimension response string
DIM cmd AS STRING ’
Declare command string
EndEOI% = 1 ’
Termination Send on LineFeed & EOI