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3 - 36 USING THE COMBISCOPE INSTRUMENTS
3.5 Averaging Acquisition Data
Acquired traces and measured signal characteristics can be averaged over a
number of acquisitions. The preprocessing AVERAGE function of the
CombiScopes instruments can be enabled by using the SENSe:AVERage[STATe]
command. When this function is set to ON, averaging is done according to the
following formula:
In the expression,
n
specifies the number of acquisitions that is averaged. This
parameter can be programmed by using the SENSe:AVERage:COUNt
command.
X
represents the acquisition result to be averaged.
Example:
Send
→ SENSe:AVERage:COUnt 16 ’ This sets the average count factor at
16, which means 16 sequential
acquisitions are averaged.
Send
→ SENSe:AVERage ON ’ This enables the AVERAGE function.
When SENSe:AVERage is set to ON and an acquisition is initiated, the
CombiScope instrument takes n (SENSe:AVERage:COUNt) successive
acquisitions, as shown in the figure on the next page. When sufficient acquisitions
are taken, the final averaged result is returned. Intermediate results cannot be
queried.
PROGRAM EXAMPLE:
Acquire the trace of the actual signal on channel 1 and measure the amplitude
and frequency (averaged over 4 acquisitions).
DIM trace AS STRING
*
1033 ’
Dimensions trace string
DIM amplitude AS STRING
*
10 ’
Dimensions amplitude string
DIM frequency AS STRING
*
10 ’
Dimensions frequency string
CALL Send(0, 8, "CONFigure:AC (@1)", 1) ’
Configures for AC-RMS
CALL Send(0, 8, "SENSe:AVERage:COUNt 4", 1) ’
Average factor = 4
CALL Send(0, 8, "SENSe:AVERage ON", 1) ’
Averaging is turned on
CALL Send(0, 8, "INITiate", 1) ’
Initiates the averaging acquisition
CALL Send(0, 8, "
*
WAI;TRACe? CH1", 1) ’
Queries for channel 1 trace
CALL Receive(0, 8, trace$, 256) ’
Enters channel 1 trace
’
The trace samples are averaged over 4 sequential trace acquisitions.
CALL Send(0, 8, "READ:AMPLitude?", 1) ’
Reads the amplitude
CALL Receive(0, 8, amplitude$, 256) ’
Enters the amplitude
CALL Send(0, 8, "FETCh:FREQuency?", 1) ’
Fetches the frequency
CALL Receive(0, 8, frequency$, 256) ’
Enters the frequency
’
The amplitude and frequency are averaged over 4 sequential measured values.
AVG
n
X
1
.. X
n
++
()n⁄
∑
=