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:



Spectrum Analyzer

Signal Generator

(Absolutely FREE!)


Pitch Tracker


DaqMusiq Generator
(Free Music... Forever!)

Engine Simulator

LCR Meter

Remote Operation

DC Measurements

True RMS Voltmeter

Sound Level Meter

Frequency Counter
    Spectral Event

    MHz Frequencies

Data Logger

Waveform Averager


Post-Stimulus Time
Histogram (PSTH)

THD Meter

IMD Meter

Precision Phase Meter

Pulse Meter

Macro System

Multi-Trace Arrays

Trigger Controls


Spectral Peak Track

Spectrum Limit Testing

Direct-to-Disk Recording



Frequency response

Distortion measurement

Speech and music

Microphone calibration

Loudspeaker test

Auditory phenomena

Musical instrument tuning

Animal sound

Evoked potentials

Rotating machinery


Product test

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your application!

Sine Wave Basics

Consider the second hand on an "old-fashioned" round clock face: The hand makes an angle relative to a horizontal line drawn through the shaft from 9 to 3. The sine of that angle is proportional to the height of the tip of the hand above this reference line. (Heights are negative if the tip is below this.) Start with the hand at 9, and measure the height as it passes each numeral on the face:

This is one cycle of a classic sine wave.

The amplitude of the clock sinusoidal wave is the length of the hand, which is the maximum height above or below the horizontal reference line.

The frequency of the wave is the number of cycles per unit time. On a clock, the second hand completes one cycle per minute. Although those who deal with rotating machinery use Cycles Per Minute (CPM), other users commonly refer to frequency in cycles per second, so we would say that the second hand completes 1/60 cycle per second. One cycle per second is called one hertz, abbreviated Hz and usually pronounced "hurts" (like the Hertz car rental agency), or "hairtz" in the native German of its namesake Heinrich Hertz.

We apply standard scientific prefixes to this, so 1000 hertz is 1 kilohertz (kHz) and 1/1000 Hz is 1 millihertz (mHz). Our second hand thus has a frequency of 1/60 Hz or 0.0166667 Hz or 16.6667 mHz. Note the small 'm' in 'mHz'. A large 'MHz' is used to refer to 1 million hertz or Megahertz. Small letters refer to prefixes less than one, capitals to those more than one. The exception to this is small 'k' for kilo... a tribute to the group wisdom of standards committees. Daqarta allows you to enter either 'K' or 'k', but always shows this as 'k'.

See also Sine Wave Phase, Magnitude via Vector Sum, Making Waves via Sine Wave Synthesis


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