Threshold Signal

threshold signal

[′thresh‚hōld ‚sig·nəl]
A received radio signal (or radar echo) whose power is just above the noise level of the receiver. Also known as minimum detectable signal.

Threshold Signal


a signal at the input of a receiving device; its magnitude is the minimum that provides the required probability of registering a signal for a specified probability level of false registration, or operation caused by noise.

The concept of a “threshold signal” is used in analyzing the quality of systems of communication, sonar, radar, radiogoni-ometry, and optical location. The magnitude of a threshold signal can be evaluated in terms of energy, power or field intensity at the aperture of an antenna in radio-receiving devices, quantity of photons in optical receivers, current or voltage, or pressure or temperature at the input of relay systems. When applied to radio receivers and solid-state photodetectors, the threshold signal is often assumed to be equal to the optical density referred to the input of a receiver.

For a given noise level the power of the threshold signal can be as small as desired— for instance, in cases where it is possible to store the signal coherently and for an infinite length of time. In the optical range the magnitude of the threshold signal for a given observation period is sometimes determined not only by the external background noise and by the noise orginating in the receiver itself but also by the quantum fluctuations of the signal that is being registered. Current state of engineering (as of 1975) makes it possible to obtain threshold signals in the optical range that correspond to several dozens or even several units of quanta.


Porogovye signaly. Edited by A. P. Sivers. Moscow, 1952. (Translated from English.)
Horton, J. W. Osnovy gidrolokatsii. Leningrad, 1961. (Translated from English.)
Voprosy statisticheskoi teorii radiolokatsii, vols. 1-2. Moscow, 1963-64. Kuriksha, A. A. Kvantovaia optika i opticheskaia lokatsiia. Moscow, 1973.


References in periodicals archive ?
Readings above the 50 threshold signal a growth in the manufacturing sector, while readings below 50 show deterioration in the industry.
The robot's active participation through its assistance is dictated by the electromyography (EMG) threshold signal level in which this signal can be measured using the mean EMG signal (mV).
An electronic filter on the gripping threshold signal compensates for vibration of the parts on the vacuum cups during fast movements.
I can still hear out to 11 kHz, but my ability to hear a threshold signal at that frequency is limited.
When I did my series, I noticed that even the slightest bit of extraneous noise made it difficult to detect some of those threshold signals.
The company even has an on-line hearing test you can take, although it will not be as convenient to do as the CD version or as defining if your computer's cooling fan is loud enough to mask some of the threshold signals.
Also included in the set are Crystal Rectifiers, Microwave Mixers, Components Handbook, Vacuum Tube Amplifiers, Waveforms, Electronic Time Measurements, Electronic Instruments, Cathode Ray Tube Displays, Microwave Receivers, Threshold Signals, Theory of Servomechanisms, Radar Scanners and Radomes, and Computing Mechanisms and Linkages.