A goniometer is often included in

analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analo ...

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum * Digital audio, representation of soun ...

equipment to display a

Lissajous figure A Lissajous curve , also known as Lissajous figure or Bowditch curve , is the graph of a system of parametric equations : x=A\sin(at+\delta),\quad y=B\sin(bt), which describe the superposition of two perpendicular oscillations in x and y dire ...

which shows the amount of

stereo Stereophonic sound, or more commonly stereo, is a method of sound reproduction that recreates a multi-directional, 3-dimensional audible perspective. This is usually achieved by using two independent audio channels through a configuration ...

(that is, phase differences) in a dual-channel signal. It allows the sound technician to adjust for optimal stereo and determine the makeup of errors such as an inverted signal. Many goniometers also provide a VU or PPM as a secondary function. A goniometer adapted for surround metering is called a 'jellyfish display'. This term was coined by DK-Technologies A/S from Denmark.

Function

Its function is to plot a signal on a two-dimensional area so that the correlation between the two axes (audio channels, or phases) becomes apparent. The channels are plotted on diagonal axes; a left-channel-only signal would form a diagonal line running top-left to bottom-right and a right-channel-only signal would form the opposite diagonal running top-right to bottom-left. A signal on both channels would provide components on both axes and thus expand the plot into two dimensions: a

mono Mono may refer to: Common meanings * Infectious mononucleosis, "the kissing disease" * Monaural, monophonic sound reproduction, often shortened to mono * Mono-, a numerical prefix representing anything single Music Performers * Mono (Japanese ...

signal would produce a straight line angled according to balance; whereas a stereo signal, being asymmetrical, would produce a highly volatile image with a concentration of lines towards the center of the goniometer (see image). An audio technician would typically begin a session by adjusting the equipment (usually with a 1

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one h ...

tone) so that the output produces a vertical plot line. If one channel were phase-inverted, it would result in the plot line being a horizontal instead of vertical, a sure sign of problems. As for mono signals, a half-inverted signal would be reduced to (near) silence. The persistence of a CRT display is a desired effect on goniometers because the signal display is very dynamic, and the overall shape or envelope of the signal is the object of interest. In fact, good digital and software goniometers provide artificial and even user-adjustable persistence. The goniometer proves useful because it provides very dense information in an analog and surprisingly intuitive form. From the display, one can get a good feel for the audio levels for each channel and the amount of stereo and its compatibility as a mono signal.

References

{{Reflist Audio engineering

Function

See also

References