Real Time Acquisition - Fluke CombiScope PM3370B User Manual

USING THE COMBISCOPE INSTRUMENTS
PROGRAM EXAMPLE:
CALL Send(0, 8, "SENSe:SWEep:TIME?, 1)
CALL Receive(0, 8, STIME$, 256)
CALL Send(0, 8, "TRACe:POINts? CH1, 1)
CALL Receive(0, 8, TPOINTS$, 256)
SWETIM = VAL(STIME$)
TRAPOI = VAL(TPOINTS$)
MTB = 50 * SWETIM / (TRAPOI-1)
PRINT "Main Time Base ="; MTB
In a similar way, the time value Ts that is associated with a trace sample point can
be calculated from the following expression:
Ts = <sample_index>
where <sample_index> is the point number of the sample in the trace.
3.8.3

Real time acquisition

Since there is a physical limit to the maximum sample rate of the ADC, traces with
a duration which is less than 200 ns cannot be sampled within one real-time
acquisition. To allow you to go below the 200 ns limit, the CombiScope instrument
uses particular random sampling techniques, where points in the requested trace
are collected from a number of successive acquisitions. The result returned is a
reconstruction of the original signal out of several acquisitions, which is not real
time.
When real time acquisition needs to be guaranteed, the command
SENSe:SWEep:REALtime[:STATe] must be set to ON. This disables the random
sampling techniques. The trade-off is that the SENSe:SWEep:TIME range is
limited to 200 ns. After
The "peak detection" function allows the Analog-to-Digital Converters (ADC) to
operate at their highest speed, even when a lower time base speed is selected.
The result is that maximum and minimum peaks of the signal are detected, even
at lower time
SENSe:SWEep:PDETection[:STATe] command allows you to switch peak
detection on or off.
PROGRAM EXAMPLE:
CALL Send(0, 8, " * RST", 1)
CALL Send(0, 8, "SENSe:SWEep:REALtime ON", 1)
CALL Send(0, 8, "SENSe:SWEep:PDETection ON", 1)
SENSe:SWEep:TIME / (TRACe:POINts - 1)
*
RST the :REALtime command is set to OFF.
*
base speeds.
'Requests sweep time
'Reads sweep time
'Requests number of trace points
'Reads number of trace points
'Converts string to variable
'Converts string to variable
'Calculates the MTB
'Prints the MTB
This is called
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oversampling.
'Real time mode off
'Real time mode on
'Sets peak detection on.
The