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A radiobeacon whose carrier wave is unbroken but which is modulated with the identification signal. The continuous carrier wave signal is not audible to the operator of an aural null direction finder not having a beat frequency oscillator. The use of the continuous carrier wave improves the performance of automatic direction finders. The marine radiobeacons on the Atlantic and Pacific coasts of the U.S. are of this type.



Related Terms

AURAL NULL

A null detected by listening for the minimum or the absence of an audible signal

LOCKING

  1. Controlling the frequency of an oscillator by means of an applied signal of constant frequency. 2. Automatic following of a target by a radar antenna.

CONTROL VARIABLE

One of the input variables of a control system, such as motor torque or the opening of a valve, which can be varied directly by the operator to maximize some measure of performance of the system.

SECONDARY PHASE FACTOR CORRECTION

A correction for additional time (or phase delay) for transmission of a low frequency signal over an all seawater path when the signal transit time is based on the free-space velocity. The Loran C lattices as tabulated in tables or overprinted on the nautical chart normally include compensation for secondary phase factor.

SEARCH AND RESCUE RADAR TRANSPONDER

An electronic device which transmits a homing signal on the radar frequency used by rescue ships and aircraft.

EQUIVALENT NOISE PRESSURE

In an electroacoustic transducer or sound reception system, the root-mean-square sound pressure of a sinusoidal plane progressive wave, which when propagated parallel to the primary axis of the transducer, produces an open-circuit signal voltage equivalent to the root-mean-square of the inherent open-circuit noise voltage of the transducer in a transmission band centered on the frequency of the plane sound wave. Also known as inherent noise pressure.

FREQUENCY MODULATION

Angle modulation of a sinewave carrier in which the instantaneous frequency of the modulated wave differs from the carrier frequency by an amount proportional to the instantaneous value of the modulating.

PERFORMANCE EFFORT RATING

A technique in work measurement used to determine the leveling factor to be applied to an operator or a group of operators by short, randomly spaced observations of the performance index.

GONG BUOY

A buoy fitted with a group of saucer shaped bells of different tones as an audible signal

DOPPLER RADAR

Any form of radar which detects radial motion of a distant object relative to a radar apparatus by means of the change of the radio frequency of the echo signal due to motion.

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