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!

Spectrum (Fourier Transform) Theory

The Fourier Transform is a mathematical method that converts an input signal from the time domain to the frequency domain. The time domain is displayed as a waveform of voltage versus time, whereas the frequency domain is shown as a spectrum of magnitude or power versus frequency. Daqarta uses the Spectrum button or ALT+S to toggle between the time and frequency domains.

This discussion of Fourier Transform methods will begin with the original "continuous" Fourier Transform, which is the basis for several types of analog instruments, then proceed to the Discrete Fourier Transform (DFT) needed for digital systems, and finally the Fast Fourier Transform (FFT), which is the streamlined version of the DFT in common use.

Unlike the usual "textbook" treatment of these subjects, there are no integrals or summations, no complex or imaginary numbers, and no "compact" notational tricks. No math is used beyond the high school level, yet nothing has been "watered down". Instead, the focus is on a deeper understanding of fundamental principles... the "gut-level" kind of knowledge that is often missing from academic engineering formalism.

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