Tech Terms Glossary
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Radio frequency (RF): Signals with a repetition rate above audible range, but below the frequencies associated with heat and light.
Random Interlace: A scanning technique commonly used in CCTV systems in which there is no external control over the scanning process. That is, there is no fixed relationship between adjacent lines and successive fields.
Range Finder: Used to determine the focal length needed and what the picture will look like on the monitor. The user looks through the device and adjusts the range finder to the desired picture. Numbers on the outside of the range finder indicate the focal length needed.
Raster: The rectangular pattern of scanning lines upon which the picture is produced. The illuminated face of the TV monitor without the video information present.
RCA Connector: Also known as "line-level", "A/V" and "phono" connector. Very commonly used in line-level audio applications as connectors for cables. Coaxial connector with a center pin and surrounding ring.
Re: The DC resistance of a speaker driver's voice coil.
Reflected Light: The scene brightness or the light being reflected from a scene. Usually it represents 5 to 95 percent of the incident light, and it is expressed in foot-lamberts.
Resolution: A measure of the ability of a camera or television system to reproduce detail. That is the number of picture elements that can be reproduced with good definition. It is a factor of the pickup device or the TV CRT characteristics and the video signal bandwidth.
Resonant Frequency [Fs]: The free-air resonant frequency of a speaker driver. The frequency at which an object tends to vibrate. For example, although a bell can be externally driven to vibrate at different frequencies, it will always naturally tend to vibrate at it's given tuned tone, or resonant frequency.
Retained Image: (image burn) A change produced in or on the target of the pickup device which remains for a large number of frames after the removal of a previously stationary light image and which yields a spurious electrical signal that corresponds to that light image.
RF (Radio Frequency): Range of frequencies (10 kHz - 10 GHz) received through antennas.
RF Modulator: In auto sound, a device included with CD changer RF packages that converts the CD changer's audio signal to an FM radio station frequency for pickup by the car radio's tuner section. DSS systems with multi-room distribution unit use dual RF modulators to distribute two separate signals (from the receiver or another video source) so two separate programs can be viewed at the same time on two TVs in different rooms of the house.
RG-6: The number of the coaxial cable recommended when installing a DSS system. RG-6 is a larger cable with less signal loss and greater high-frequency transmission than the ordinary RG-59 coaxial cable.
Rms: The mechanical resistance of a loudspeaker's suspension losses.
RMS (Root Mean Square): Technically speaking, RMS=.707 X (peak measured power). Basically it can be considered the "average" operating wattage.
Roll: A loss of vertical sync which causes the picture to move up or down on the TV screen.
RPM: Number of times an object rotates in one minute.
RS232: A commonly used computer serial interface.
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