DiSEqC

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DiSEqC logo, indicating DiSEqC 2.0 compliance

DiSEqC switch

DiSEqC (Digital Satellite Equipment Control), pronounced "Die-Sec", is a special communication protocol for use between a satellite receiver and a device such as a multi-dish switch or a small dish antenna rotor. DiSEqC was developed by European satellite provider Eutelsat, who which now acts as the standards agency for the protocol.

DiSEqC relies only upon a coaxial cable to transmit both bidirectional data/signals and power. DiSEqC is commonly used to control switches and motors, and is claimed to be more flexible than 13/18 volt and 22 kHz tone or ToneBurst/MiniDiSEqC techniques. DiSEqC is also compatible with the actuators used to rotate large C band dishes if used with a DiSEqC positioner. Despite its name, it has been used on fully analogue or only partially digital-capable (Astra Digital Radio) satellite receivers.

A number of variations of DiSEqC exist:

DiSEqC 1.0, which allows switching between up to 4 satellite sources
DiSEqC 1.1, which allows switching between up to 16 sources
DiSEqC 1.2, which allows switching between up to 16 sources, and control of a simple horizontal-panning satellite motor
DiSEqC 2.0, which adds bi-directional communications to DiSEqC 1.0
DiSEqC 2.1, which adds bi-directional communications to DiSEqC 1.1
DiSEqC 2.2, which adds bi-directional communications to DiSEqC 1.2

All four variations were standardised by February 1998, prior to general use of digital satellite television. The later versions are backwards compatible with the lower revisions, but the lower revisions are, somewhat obviously, not forward compatible with the higher revision numbers. 1.x and 2.x versions are both backwards and forwards compatible. This table shows what works and what doesn't:

	1.0 switch	1.1 switch	1.2 motor	2.0 switch	2.1 switch	2.2 motor
1.0 receiver	yes	no	no	yes	no	no
1.1 receiver	yes	yes	no	yes	yes	no
1.2 receiver	yes	yes	yes	yes	yes	yes
2.0 receiver	yes	no	no	yes	no	no
2.1 receiver	yes	yes	no	yes	yes	no
2.2 receiver	yes	yes	yes	yes	yes	yes

Do note that a 1.x receiver will not be able to receive communication from a switch or motor. Usually this is not important, as the switch or motor can be controlled by the receiver without problems.

Eutelsat apparently developed the system to allow satellite users in Continental Europe to switch between the more popular SES Astra 1 block of satellites and Eutelsat's own Hot Bird system. As a result, the vast majority of European satellite receivers support DiSEqC 1.0 or higher, with the notable exception of all set top boxes manufactured under the Sky Digibox name. All supporting receivers have received certification to carry a logo specifying which variation of DiSEqC they support.

Also often found are the terms DiSEqC 1.3 and 2.3 used by manufacturers and retailers to refer to the use of DiSEqC with other protocols. For example, 1.3 usually refers to a receiver which uses USALS in conjunction with the DiSEqC 1.2 protocol. Such terminology has not been authorised by Eutelsat.