Q¶

Q.931¶

The ITU-T ISDN signalling protocol on the D channel, which sets up, maintains and clears calls between the user and the network. H.323 and QSIG reuse its messages.

QA Lead¶

QAL. The person responsible for the quality of a project’s process and product.

QAM¶

Quadrature Amplitude Modulation. Modulation that sends data by varying the amplitude of two carriers 90° apart, so that each symbol carries several bits. Higher orders, such as 256-QAM, carry more bits but need a cleaner signal. DSL, cable, Wi-Fi and mobile networks use it.

QoS¶

Quality of Service. The mechanisms that give different traffic different treatment in a network, through classification, marking, queuing and policing. They protect delay-sensitive traffic, such as voice, from loss, delay and jitter. The term also means the measured performance of a service.

QSIG¶

An ISDN-based signalling protocol between PBXs in a private network, standardised by Ecma and ISO. It supports basic calls and supplementary services across different vendors’ equipment.

Quality¶

How well a system and its artefacts meet their requirements and standards, and the activities that make sure they do.

Quality Assurance¶

QA. Activities that prevent defects, by making sure the right processes are in place and followed.

See also: Quality Control, Quality Plan.

Quality Assurance Plan¶

See Quality Plan.

Quality Control¶

QC. Activities that find defects, mainly reviews and testing.

Quality Plan¶

QP. A plan for the quality methods and practices a project will use, and which artefacts they cover. It often leaves the testing details to the test plan.

Quick Design Session¶

A short meeting, often at a whiteboard, where two or more developers settle a design choice that has wide consequences.