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!

Trigger Auto Level Mode

Controls: Trigger Dialog >> Auto Level
Macro: TrigMode=Alevel

With Auto Level the operation is similar to Auto, in that the trace is updated after 1024 samples without a trigger event. The difference is that the effective Trigger Level is scaled according to the peak signal of the prior update. This mode is similar to Auto Trigger on a conventional oscilloscope, if you are already familiar with that.

Suppose, for example, that Level is set to +500 mV on a +/-1 volt input range, or half of positive full scale. Then the actual trigger level will be at half of the zero-to-peak amplitude of the signal, and it will self-adjust as the input level changes... if the signal level is only 42 mV, then the effective trigger level will be 21 mV. This allows a stable trace under changing input conditions.

The Auto-trigger logic scans 1024 samples waiting for a valid trigger, based upon the current effective level set by the previous frame. If a trigger is not found, those 1024 samples are displayed anyway and used to compute the trigger level for the next frame. The waveform display may thus "hiccup" for one frame when the level drops suddenly.

A powerful advantage of Auto Level mode is that you thus always get a more-or-less ongoing frame display. This allows you to see what is going on, even when things are not happening the way you assumed when you set the original trigger Level.


Macro Notes:

TrigMode=ALevel or TrigMode=1 sets the mode to Auto Level. See Macro Notes under Trigger Auto Mode for the complete list of mode names and numbers.


See also Trigger Toggle - Introduction, Trigger Control Dialog

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