Tech Terms | Abbreviations A–Z
Qualcomm code-excited linear prediction (QCELP), also known as Qualcomm PureVoice, is a speech codec developed in 1994 by Qualcomm to increase the speech quality of the IS-96A codec earlier used in CDMA networks. It was later replaced with EVRC since it provides better speech quality with fewer bits. The two versions, QCELP8 and QCELP13, operate at 8 and 13 kilobits per second (Kbit/s) respectively.
In CDMA systems, a QCELP vocoder converts a sound signal into a signal transmissible within a circuit. In wired systems, voice signals are generally sampled at 8kHz (that is, 8,000 sample values per second) and then encoded by 8-bit quantization for each sample value. Such a system transmits at 64 kbit/s, an expensive rate in a wireless system. A QCELP vocoder with variable rates can reduce the rate enough to fit a wireless system by coding the information more efficiently. In particular, it can change its own coding rates based on the speaker's volume or pitch; a louder or higher-pitched voice requires a higher rate.
QNX (/ˌkjuː ˌɛn ˈɛks/ or /ˈkjuːnɪks/) is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market. QNX was one of the first commercially successful microkernel operating systems. As of 2020, it is used in a variety of devices including cars and mobile phones.
The product was originally developed in the early 1980s by Canadian company Quantum Software Systems, later renamed QNX Software Systems. The company was ultimately acquired by BlackBerry Limited in 2010.
As a microkernel-based OS, QNX is based on the idea of running most of the operating system kernel in the form of a number of small tasks, named Resource Managers. This differs from the more traditional monolithic kernel, in which the operating system kernel is one very large program composed of a huge number of parts, with special abilities. In the case of QNX, the use of a microkernel allows users (developers) to turn off any functions they do not need without having to change the OS. Instead, such services will simply not run.
To demonstrate the OS's capability and relatively small size, in the late 1990s QNX released a demo image that included the POSIX-compliant QNX 4 OS, a full graphical user interface, graphical text editor, TCP/IP networking, web browser and web server that all fit on a bootable 1.44 MB floppy disk for the 386 PC.
QNX Neutrino (2001) has been ported to a number of platforms and now runs on practically any modern central processing unit (CPU) family that is used in the embedded market. This includes the PowerPC, x86, MIPS, SH-4, and the closely interrelated of ARM, StrongARM, and XScale.
QNX offers a license for noncommercial and academic users.
The BlackBerry PlayBook tablet computer designed by BlackBerry uses a version of QNX as the primary operating system. Devices from BlackBerry running the BlackBerry 10 operating system are also based on QNX.
In recent[when?] years QNX has been used in automated drive or ADAS systems for automotive projects that require a functional safety certification. QNX provides this with its QNX OS for Safety product.
The QNX operating system also contained a web browser known as 'Voyager'.
Under the Microsoft Windows operating system, a quick way to format data media without prior checking.
A QR code (an initialism for Quick Response code) is a type of matrix barcode (or two-dimensional barcode) invented in 1994 by the Japanese automotive company Denso Wave. A barcode is a machine-readable optical label that contains information about the item to which it is attached. In practice, QR codes often contain data for a locator, identifier, or tracker that points to a website or application. A QR code uses four standardized encoding modes (numeric, alphanumeric, byte/binary, and kanji) to store data efficiently; extensions may also be used.
The Quick Response system became popular outside the automotive industry due to its fast readability and greater storage capacity compared to standard UPC barcodes. Applications include product tracking, item identification, time tracking, document management, and general marketing.
A QR code consists of black squares arranged in a square grid on a white background, which can be read by an imaging device such as a camera, and processed using Reed–Solomon error correction until the image can be appropriately interpreted. The required data is then extracted from patterns that are present in both horizontal and vertical components of the image.
A query string is a part of a uniform resource locator (URL) that assigns values to specified parameters. A query string commonly includes fields added to a base URL by a Web browser or other client application, for example as part of an HTML, choosing the appearance of a page, or jumping to positions in multimedia content.
A web server can handle a Hypertext Transfer Protocol (HTTP) request either by reading a file from its file system based on the URL path or by handling the request using logic that is specific to the type of resource. In cases where special logic is invoked, the query string will be available to that logic for use in its processing, along with the path component of the URL.
Typical URL containing a query string is as follows:
When a server receives a request for such a page, it may run a program, passing the query string, which in this case is
name=ferret, unchanged to the program. The question mark is used as a separator, and is not part of the query string.