Daqarta
Data AcQuisition And Real-Time Analysis
Scope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!
The following is from the Daqarta Help system:

Features:

Oscilloscope

Spectrum Analyzer

8-Channel
Signal Generator

(Absolutely FREE!)

Spectrogram

Pitch Tracker

Pitch-to-MIDI

DaqMusiq Generator
(Free Music... Forever!)

Engine Simulator

LCR Meter

Remote Operation

DC Measurements

True RMS Voltmeter

Sound Level Meter

Frequency Counter
    Period
    Event
    Spectral Event

    Temperature
    Pressure
    MHz Frequencies

Data Logger

Waveform Averager

Histogram

Post-Stimulus Time
Histogram (PSTH)

THD Meter

IMD Meter

Precision Phase Meter

Pulse Meter

Macro System

Multi-Trace Arrays

Trigger Controls

Auto-Calibration

Spectral Peak Track

Spectrum Limit Testing

Direct-to-Disk Recording

Accessibility

Applications:

Frequency response

Distortion measurement

Speech and music

Microphone calibration

Loudspeaker test

Auditory phenomena

Musical instrument tuning

Animal sound

Evoked potentials

Rotating machinery

Automotive

Product test

Contact us about
your application!

Screen Zero controls

Controls: Zero Dialog >> Cursor
Macro: ZeroCurs, ZeroScrn

The Screen Zero controls are at the top of the Zero control dialog. The Screen Zero button is a duplicate of the main toolbar Zero; clicking either (or ALT+Z) toggles both.

Below the button is an edit control to set the desired Screen Zero position. It can be set either as a percentage of full-scale, or, if your system is calibrated, in volts or arbitrary User Units. You select the entry/display mode via the Units button, midway down on the right side of the dialog.

For example, in percent mode (Units not depressed) if you enter 25 (and the Screen Zero button is active), the waveform display will be shifted down such that a point that was formerly at 25% of full scale will now be at zero.

Note that at high trace magnifications (typical in Histogram display mode) the little up/down scroll button steps will be too big... you'll need direct entry in such cases. (In Histogram mode the Y-axis is in percent, so you can enter those values directly.)

To the left of the edit control is a small Curs button. Clicking this (or using ALT+SHIFT+Z causes the edit control to take the true value of the waveform under the solid trace cursor. This is usually more convenient than direct entry if you want to examine fine details in the waveform.

Just drag the cursor to the location of interest and hit Curs; you can then increase the display magnification (PgUp) as much as desired. Otherwise, if the area of interest was not near true waveform zero, it would tend to be driven off the screen at high magnifications.

If the display shows multiple channels, they are all shifted by the same amount. You can click the small color button next to the solid cursor readout to select the channel you are interested in, before clicking Curs to capture a value.

The ALT+SHIFT+Z option is particularly handy when the Zero control dialog is not visible.

Screen Zero affects only the vertical position of waveforms on the screen; it does not change the cursor readouts, the Y axis, Trigger operation, nor the data saved to a file. It has no effect (and is disabled) in Spectrum, Spectrogram, and Pitch Track (Sgram/PT) modes.

Since for Triggered operation the Trigger Level threshold and Hysteresis are applied prior to any Screen Zero adjustment of the Display, you may want to toggle Zero off while adjusting the trigger.

Note that the state of the Zero toolbar button shows whether Screen Zero is active, but the button text shows if any Data Zero mode is active:

Screen Zero state and value are not saved when exiting Daqarta, to prevent possible confusion in the next session.


Macro Notes:

Zero=1 activates Screen Zero, Zero=0 turns it off, and Zero=x toggles between on and off.

ZeroScrn=25 sets the Screen Zero position to 25% of full scale if the Zero Units button is off.

If Units is active, this same command will attempt to set Screen Zero to 25 volts (or 25 User Units), limiting the value to the actual full-scale range as needed. You can use ZeroScrn=25m to set 25 mV (or 25 milli-units for User Units).

ZeroCurs= (value ignored) sets Screen Zero to the true value of the waveform under the solid trace cursor.

Note that attempts to use either command when disabled in Spectrum, Spectrogram, or Pitch Track modes will result in "Control disabled. Aborting macro."

Macros can read the current value of ZeroScrn in units determined by the Screen / Data Zero Units button state, and the current User Units state.

Alternatively, you can read the current value in percent via ZeroScrn?%, regardless of the units mode. This is particularly useful for macros using Buf0-Buf7 arrays to display computed waveforms, where you want the screen position to respond to Screen Zero the same way in all modes.


See also Zero (Screen and Data)

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