Remote Control. Business Technologist. Experience Information Technology conferences Join your peers for the unveiling of the latest insights at Gartner conferences. View Conferences.
Gartner Webinars Expert insights and strategies to address your priorities and solve your most pressing challenges. View Webinars. Free Newsletter for Executives Get objective, actionable insights — plus invitations to events. Cancel Report. Create a new account. Log In. Know what is QAM? Got another good explanation for QAM? Don't keep it to yourself! Add it HERE! Still can't find the acronym definition you were looking for? Use our Power Search technology to look for more unique definitions from across the web!
Search the web. Citation Use the citation options below to add these abbreviations to your bibliography. Powered by CITE. Prisoner Of War. Persons Of Wars. Private Of War. Prisoner Of World. Browse Abbreviations. Get instant explanation for any acronym or abbreviation that hits you anywhere on the web!
It is able to provide a highly effective form of modulation for data and as such it is used in everything from cellular phones to Wi-Fi and almost every other form of high speed data communications system. Quadrature Amplitude Modulation, QAM is a signal in which two carriers shifted in phase by 90 degrees i.
The resultant overall signal consisting of the combination of both I and Q carriers contains of both amplitude and phase variations. In view of the fact that both amplitude and phase variations are present it may also be considered as a mixture of amplitude and phase modulation. A motivation for the use of quadrature amplitude modulation comes from the fact that a straight amplitude modulated signal, i.
This is very wasteful of the available frequency spectrum. QAM restores the balance by placing two independent double sideband suppressed carrier signals in the same spectrum as one ordinary double sideband supressed carrier signal. Quadrature amplitude modulation, QAM may exist in what may be termed either analogue or digital formats. The analogue versions of QAM are typically used to allow multiple analogue signals to be carried on a single carrier.
Here the different channels enable the two channels required for stereo to be carried on the single carrier. Digital formats of QAM are often referred to as "Quantised QAM" and they are being increasingly used for data communications often within radio communications systems. Quadrature amplitude modulation, QAM, when used for digital transmission for radio communications applications is able to carry higher data rates than ordinary amplitude modulated schemes and phase modulated schemes.
Basic signals exhibit only two positions which allow the transfer of either a 0 or 1. Using QAM there are many different points that can be used, each having defined values of phase and amplitude. This is known as a constellation diagram. The different positions are assigned different values, and in this way a single signal is able to transfer data at a much higher rate.
As shown above, the constellation points are typically arranged in a square grid with equal horizontal and vertical spacing.
0コメント