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30 :WAVeform Commands
The high resolution (smoothing) mode is used to reduce noise at slower
sweep speeds where the digitizer samples faster than needed to fill
memory for the displayed time range.
Data Conversion
Word or byte data sent from the oscilloscope must be scaled for useful
interpretation. The values used to interpret the data are the X and Y
references, X and Y origins, and X and Y increments. These values are
read from the waveform preamble. Each channel has its own waveform
preamble.
In converting a data value to a voltage value, the following formula is
used:
voltage = [(data value - yreference) * yincrement] + yorigin
If the :WAVeform:FORMat data format is ASCii (see page 639), the data
values are converted internally and sent as floating point values separated
by commas.
In converting a data value to time, the time value of a data point can be
determined by the position of the data point. For example, the fourth data
point sent with :WAVeform:XORigin = 16 ns, :WAVeform:XREFerence = 0,
and :WAVeform:XINCrement = 2 ns, can be calculated using the following
formula:
time = [(data point number - xreference) * xincrement] + xorigin
This would result in the following calculation for time bucket 3:
time = [(3 - 0) * 2 ns] + 16 ns = 22 ns
In :ACQuire:TYPE PEAK mode (see page 195), because data is acquired in
max- min pairs, modify the previous time formula to the following:
time=[(data pair number - xreference) * xincrement * 2] + xorigin
Data Format for Transfer
There are three formats for transferring waveform data over the interface:
BYTE, WORD and ASCii (see ":WAVeform:FORMat" on page 639). BYTE,
WORD and ASCii formatted waveform records are transmitted using the
arbitrary block program data format specified in IEEE 488.2.
When you use the block data format, the ASCII character string
"#8<DD...D>" is sent prior to sending the actual data. The 8 indicates how
many Ds follow. The Ds are ASCII numbers that indicate how many data
bytes follow.
For example, if 1000 points will be transferred, and the WORD format was
specified, the block header "#800001000" would be sent. The 8 indicates
that eight length bytes follow, and 00001000 indicates that 1000 binary
data bytes follow.
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Agilent InfiniiVision 2000 X-Series Oscilloscopes Programmer's Guide