# How do I get voltage data after sending the CURVE? or WAVFRM? query?

### 問題：

How do I get voltage data after sending the CURVE? or WAVFRM? query?

### 答案：

Once you’ve collected a waveform in binary format and transferred it to your PC using either CURVE? or WAVEFRM? you can next convert the waveform data into volts. To do this, use the waveform preamble from the WAVFRM? or WFMOUT? Query.

Sample mode data contains 256 digitizing levels. Your program converts this to volts with the YOFF, YPOS, and YMULT values. Yoff defines the position of the waveform trace on the display. Ypos represents the DC offset.

For example, to convert RPBinary data format to voltage, the algorithm is:

Voltage = (Digitizing Level – YOFF) * YMULT

In most Tektronix each digitizing level represents one part in 256 if the data width is set to 1. The screen shows only 8 divisions of a total of 10.24 divisions. This results in 25 digitizing levels per division. For an  example of measuring the 5 volt probe compensation signal with the scope set to 1 volt per division we find that the peak amplitude will be represented by a value of 125. The YMULT should be 4.0e-2 or 40mV per digitizing level. If assume that no offset was selected and apply the scaling algorithm the results will be:

5 volts = (125 – 0 ) * 0.04