Telecommunications terms starting with Q

57 terms

QA Quality Assurance.
QAM Abbreviation for quadrature amplitude modulation.
QC Quality Control.
QCIF Abbreviation for quarter common intermediate format.
QOS Quality of Service. The performance level defined for a data communications system.
QPSK Abbreviation for quadrature phase-shift keying.
QRS (1) Quartz Resonant Sensor. (2) Quick Reaction Software.
QRSS Abbreviation for quasi-random signal source.
QRTS Abbreviation for quasi-random test signal.
QRW Abbreviation for quasi-random word.
Quad One quadrillion Btu. (1,000,000,000,000,000 Btu)
quadded cable A cable formed of multiples of quads, paired and separately insulated, and contained under a common jacket.
QUADRANT The District of Columbia is divided into four quadrants: Northwest, Northeast, Southwest and Southeast.
quadratic profile Synonym parabolic profile.
Quadrature The component of the complex signal that is 90 degrees out of phase with the inphase component.
quadrature amplitude modulation (QAM) Quadrature modulation in which the two carriers are amplitude modulated. 2. In analog communications, the representation (i.e.
quadrature modulation Modulation using two carriers out of phase by 90° and modulated by separate signals.
quadrature phase-shift keying (QPSK) Phase-shift keying in which four different phase angles are used. Note: In QPSK, the four angles are usually out of phase by 90°.
quadriphase Synonym quadrature phase-shift keying.
quadruple diversity In radio communication, diversity transmission and reception in which four independently fading signals are used.
quadruply clad fiber A single-mode optical fiber that has four claddings. Note 1: Each cladding has a refractive index lower than that of the core.
Quality Assurance (QA) The process of identifying problems in service delivery, designing activities to overcome these problems, and following up to ensure that no new problems…
quality control (QC) A management function whereby control of the quality of (a) raw materials, assemblies, produced materiel, and components, (b) services related to…
quality factor In a reactive circuit, the ratio of the reactance in ohms divided by the resistance in ohms.
Quality of Service (QoS) The performance level defined for a data communications system.
Quantization A process in which a continuous signal is converted to a series of points at discrete levels.
quantization error Synonym quantizing distortion.
quantization level In the quantization process, the discrete value assigned to a particular subrange of the analog signal being quantized.
quantization noise Synonym quantizing noise.
quantized feedback In a digital feedback loop, the digital signal that is fed back. Note 1: Several forms of analog-to-digital converters contain a quantized feedback loop…
quantizing distortion Distortion that results from the quantization process. Synonym quantization error.
quantizing levels In digital transmission, the number of discrete signal levels transmitted as the result of signal digitization.
quantizing noise Noise caused by the error of approximation in quantization. Note: Quantizing noise is dependent on the particular quantization process used and the…
quantum efficiency In an optical source or detector, the ratio of the number of output quanta to the number of input quanta.
quantum noise Noise attributable to the discrete and probabilistic nature of physical phenomena and their interactions.
quantum-limited operation Synonym quantum-noise-limited operation.
quantum-noise-limited operation Operation wherein the minimum detectable signal is limited by quantum noise. Synonym quantum-limited operation.
quarter common intermediate format (QCIF) A video format defined in ITU-T Recommendation H.261 that is characterized by 176 luminance pixels on each of 144 lines, with half as many chrominance…
quartz clock A clock containing a quartz oscillator that determines the accuracy and precision of the clock.
quartz oscillator An oscillator in which a quartz crystal is used to stabilize the frequency. Note: The piezoelectric property of the quartz crystal results in a nearly…
quasi-analog signal A digital signal that has been converted to a form suitable for transmission over a specified analog channel.
quasi-analog transmission Transmission in which a special-purpose modulator is used to convert digital signals into an analog form suitable for transmission over an analog…
quasi-associated mode of signaling A limited case of the nonassociated mode of signaling in which the path taken by a message through the signaling network is predetermined and fixed at a…
quasi-lossless compression In video and multimedia applications, the bit-rate reduction of an image signal, by an algorithm that recognizes the high degree of correlation…
quasi-random signal (QRS) See QRS.
quaternary phase-shift keying Synonym quadrature phase-shift keying.
quaternary signal A digital signal having four significant conditions.
Query A request for identification of a set of assets, expressed in terms of a set of criteria, which the identified item must satisfy.
query call In adaptive high-frequency (HF) radio, an automatic-link-establishment (ALE) call that requests responses from stations having connectivity to the…
queue A system where if a realm is overloaded, subsequent players trying to log on will be queued up in a first come first serve basis and allowed to log on…
queue traffic A series of outgoing or incoming calls waiting for service. 2. In a store-and-forward switching center, the outgoing messages awaiting transmission at the…
queuing The process of entering elements into or removing elements from a queue.
queuing delay In a switched network, the time between the completion of signaling by the call originator and the arrival of a ringing signal at the call receiver.
queuing theory The theoretical study of waiting lines, expressed in mathematical terms--including components such as number of waiting lines, number of servers, average…
quiet zone With respect to the rf spectrum, an area in which emissions are restricted for the purpose of minimizing possible impact on the operations of radio…
quieting In an FM receiver, the phenomenon that results in less noise when an unmodulated carrier is present than when there is no carrier present.
quincunx sampling 1. In a digital video system, a sampling structure where the luminance and color-difference samples are generated from pixels arranged on one of two…