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!

DAT Skip Header Bytes

Controls: DD/Open >> DAT Format >> Skip
Macro: DATskip

Some files that Daqarta can't identify are simply raw data. Others may actually have a header, but if it isn't one of the supported types, Daqarta doesn't understand it and just treats the header as more raw data. You can use the Skip Header Bytes control to tell Daqarta to skip over a specified number of header bytes to find the actual data.

The default setting is 0 on the assumption that there is no header. If you know the header size, just enter that value here. But if you don't you may still be able to determine it. First of all, make sure you set any .DAT format parameters you are sure of, especially Bits and Signed/Unsigned. If you get these right and the waveform still looks like pure trash, it may indicate a "read frame error" due to an odd number of bytes in the header with 12-bit or 16-bit data. Just close and re-open the file, and set Skip Bytes to an odd number; if the waveform now looks basically correct, you have found the proper read frame.

Once you have the proper read frame, you still may see a lot of trash at the start, where Daqarta is trying to interpret header data as waveform data. Just look at how much of the initial part of the wave is trash, and add the corresponding number of Skip Bytes when you re-open.

This can be easily determined by scrolling the file ahead with the > key until the initial trash is gone, then looking at the DDisk Position readout below the right end of the trace area. Hit ALT+SHIFT+D as needed to get it to show Bytes (or hit CTRL+D and set that from the DDisk Controls dialog), then add that value to whatever you had set for Skip Header Bytes when you re-open the file.


See also File Menu, Open Existing Data File, .DAT File Format Dialog

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