In telecommunications, the term channel noise level has the following meanings:
- The ratio of the noise in the communication channel at any point in a transmission system to an arbitrary level chosen as a reference.
- The noise power spectral density in the frequency range of interest.
- The average noise power in the frequency range of interest.
In telecommunication, a combat-net radio (CNR) is a radio operating in a network that (a) provides a half-duplex circuit and (b) uses either a single radio frequency or a discrete set of radio frequencies when in a frequency hopping mode.
In telecommunication, the term conditioning equipment has the following meanings:
- At junctions of circuits, equipment used to obtain desired circuit characteristics, such as matched transmission levels, matched impedances, and equalization between facilities.
- Corrective networks used to improve data transmission, such as equalization of the insertion loss-vs.-frequency characteristic and the envelope delay distortion over a desired frequency range.
In telecommunication, a four-wire circuit is a two-way circuit using two paths so arranged that the respective signals are transmitted in one direction only by one path and in the other direction by the other path. Late in the 20th century, almost all connections between telephone exchanges were four-wire circuits, while conventional phone lines into residences and businesses were two-wire circuits.
In telecommunication, the term interposition trunk has the following meanings:
In telecommunications, net gain is the overall gain of a transmission circuit. Net gain is measured by applying a test signal at an appropriate power level at the input port of a circuit and measuring the power delivered at the output port. The net gain in dB is calculated by taking 10 times the common logarithm of the ratio of the output power to the input power.
In telecommunication, the term noise power has the following meanings:
- The measured total noise in a given bandwidth at the input or output of a device when the signal is not present; the integral of noise spectral density over the bandwidth
- The power generated by a random electromagnetic process.
- Interfering and unwanted power in an electrical device or system.
- In the acceptance testing of radio transmitters, the mean power supplied to the antenna transmission line by a radio transmitter when loaded with noise having a Gaussian amplitude-vs.-frequency distribution.
In signal processing, phase distortion or phase-frequency distortion is distortion, that is, change in the shape of the waveform, that occurs when (a) a filter's phase response is not linear over the frequency range of interest, that is, the phase shift introduced by a circuit or device is not directly proportional to frequency, or (b) the zero-frequency intercept of the phase-frequency characteristic is not 0 or an integral multiple of 2π radians.
In telecommunications, attack-time delay is the time needed for a receiver or transmitter to respond to an incoming signal.
In telecommunication, relative transmission level is the ratio of the signal power, at a given point in a transmission system, to a reference signal power.
The signal-to-crosstalk ratio at a specified point in a circuit is the ratio of the power of the wanted signal to the power of the unwanted signal from another channel.
Single-frequency signaling (SF) is line signaling in which dial pulses or supervisory signals are conveyed by a single voice-frequency tone in each direction. SF and similar systems were used in 20th-century carrier systems.
A stopband is a band of frequencies, between specified limits, through which a circuit, such as a filter or telephone circuit, does not allow signals to pass, or the attenuation is above the required stopband attenuation level. Depending on application, the required attenuation within the stopband may typically be a value between 20 and 120 dB higher than the nominal passband attenuation, which often is 0 dB.
In telecommunication, a voice frequency primary patch bay (VF) is a patching facility that provides the first appearance of local-user VF circuits in the technical control facility (TCF).
In electronics, a limiter is a circuit that allows signals below a specified input power or level to pass unaffected while attenuating (lowering) the peaks of stronger signals that exceed this threshold. Limiting is a type of dynamic range compression. Clipping is an extreme version of limiting.
Secure voice is a term in cryptography for the encryption of voice communication over a range of communication types such as radio, telephone or IP.
A United States defense standard, often called a military standard, "MIL-STD", "MIL-SPEC", or (informally) "MilSpecs", is used to help achieve standardization objectives by the U.S. Department of Defense.
In telecommunication, a measuring receiver or measurement receiver is a calibrated laboratory-grade radio receiver designed to measure the characteristics of radio signals. The parameters of such receivers can usually be adjusted over a much wider range of values than is the case with other radio receivers. Their circuitry is optimized for stability and to enable calibration and reproducible results. Some measurement receivers also have especially robust input circuits that can survive brief impulses of more than 1000 V, as they can occur during measurements of radio signals on power lines and other conductors.
A reference tone is a pure tone corresponding to a known frequency, and produced at a stable sound pressure level (volume), usually by specialized equipment.
