Distortionmeter (or more precisely distortion factor meter) is an electronic measuring instrument which displays the amount of distortion added to the original signal by an electronic circuit.
Distortion is equivalent to adding harmonics to a signal. When a purely sinusoidal signal is distorted, a series of harmonics is superimposed on the original signal.
If the input is
The normalized output is
The Total harmonics distortion (THD) is defined as the ratio of the harmonics to the fundamental;  i.e.,
This ratio can be given in dB or in percentage.
The distortionmeter is actually a levelmeter with two switchable parallel circuits at the input. The first circuit measures the total signal at the output of a system. (For low distortion levels this is almost equal to fundamental). That is calibrated to 100% or equivalently to 0 dB. The second circuit is a highpass filter which attenuates the fundamental, with negligible attenuation at harmonic frequencies. So when the instrument is switched for harmonics measurement the displayed level is the level of the harmonics only.
Analogue television broadcasting topics Systems Color systems VideoBack porch and front porch • Black level • Chrominance • Chrominance subcarrier • Colorburst • Color killer • Color TV • Composite video • Frame (video) • Horizontal scan rate • Horizontal blanking interval • Luma • Nominal analogue blanking • Overscan • Raster scan • Safe area • Television lines • Vertical blanking interval • White clipper Sound Modulation TransmissionAmplifiers • Antenna (radio) • Cavity amplifier • Differential gain • Differential phase • Diplexer • Dipole antenna • Dummy load • Frequency mixer • Intercarrier method • Intermediate frequency • Output power of an analog TV transmitter • Pre-emphasis • Residual carrier • Split sound system • Superheterodyne transmitter • Television receive-only • Television transmitter • Terrestrial television • Transmitter station • Transposer Frequencies & Bands Propagation TestingDistortionmeter • Field strength meter • Vectorscope • VIT signals • Zero reference pulse Artifacts Electrical and electronic measuring equipment
Ammeter · Capacitance meter · Distortionmeter · Electric energy meter · LCR meter · Microwave power meter · Multimeter · Network analyzer · Ohmmeter · Oscilloscope · Psophometer · Q meter · Signal analyzer · Signal generator · Spectrum analyzer · Transistor tester · Tube tester · Wattmeter · Vectorscope · Video signal generator · Voltmeter · VU meter
Wikimedia Foundation. 2010.
Look at other dictionaries:
Ammeter — Amperemeter redirects here. For the unit of measurement, see Ampere meter. Demonstration model of a moving iron ammeter. As the current through the coil increases, the plunger is drawn further into the coil and the pointer deflects to the right … Wikipedia
Chrominance — (chroma or C for short) is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal (or Y for short). Chrominance is usually represented as two color difference components: U =… … Wikipedia
NTSC — This article is about the television system. For the Indonesian government agency, see National Transportation Safety Committee. Television encoding systems by nation; countries using the NTSC system are shown in green. NTSC, named for the… … Wikipedia
PAL — For other uses, see PAL (disambiguation). Television encoding systems by nation; countries using the PAL system are shown in blue. PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast… … Wikipedia
SECAM — SECAM, also written SÉCAM (Séquentiel couleur à mémoire, French for Sequential Color with Memory ), is an analog color television system first used in France. A team led by Henri de France working at Compagnie Française de Télévision (later… … Wikipedia
Voltmeter — Demonstration voltmeter from a physics class A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit. Analog voltmeters move a pointer across a scale in proportion to the voltage… … Wikipedia
Ohmmeter — An ohmmeter An ohmmeter is an electrical instrument that measures electrical resistance, the opposition to an electric current. Micro ohmmeters (microhmmeter or microohmmeter) make low resistance measurements. Megohmmeters (aka megaohmmeter or in … Wikipedia
Multimeter — A digital multimeter A multimeter or a multitester, also known as a VOM (Volt Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability … Wikipedia
Distortion — This article is about technology, especially electrical engineering. For other uses, see Distortion (disambiguation). Distort redirects here. For other uses, see Distort (disambiguation). A distortion is the alteration of the original shape (or… … Wikipedia
Colorburst — Horizontal sync and color burst of PAL videosignal Colorburst is a analog video, composite video signal generated by a video signal generator used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an… … Wikipedia