Digital Satellite Equipment Control
DiSEqC (Digital Satellite Equipment Control), is a special protocol for communication between a satellite receiver and such devices as small dish antenna rotor or multi-dish switch, usually used to control motors and switches. Using it with a DiSEqC positioner allows to apply it with the largeC band dishes rotation actuators. Relying only upon a coaxial cable to transmit both power and bidirectional data/signals, DiSEqC protocol is more flexible in comparison with other techniques like ToneBurst/MiniDiSEqC or 13/18 volt and 22 kHz tone.
Despite the presence of word “digital” in its name, this protocol is used only on fully analogue or partially digital-capable satellite receivers, just like the ones, produced by Prof Tuners Group.
There exist a number of different DiSEqC variations:
DiSEqC 1.0, allowing switch between up to 4 satellite sources
DiSEqC 1.1, allowing switch between up to 16 satellites
DiSEqC 1.2, allowing switch between up to 16 sources, and control the motor of single axis satellite
DiSEqC 2.0, DiSEqC 2.1, and DiSEqC 2.2, allows the one to add bi-directional communications to the correspondent protocols DiSEqC 1.0, DiSEqC 1.1 and DiSEqC 1.2, respectively.
The later versions of the protocol have backward compatibility with the lower ones, but the lower revisions are not forwards compatible with the higher revisions. Versions 1.x and 2.x are both backwards and forwards compatible. See the table below for detais:
| ||1.0 switch ||1.1 switch ||1.2 switch ||2.0 switch ||2.1 switch ||2.2 switch|
|1.0 receiver ||+ ||- ||- ||+ ||- ||-|
|1.1 receiver ||+ ||+ ||- ||+ ||+ ||-|
|1.2 receiver ||+ ||+ ||+ ||+ ||+ ||+|
|2.0 receiver ||+ ||- ||- ||+ ||- ||-|
|2.1 receiver ||+ ||+ ||- ||+ ||+ ||-|
|2.2 receiver ||+ ||+ ||+ ||+ ||+ ||+|
DiSEqC system uses a pulsed (tone-burst) 22kHz sine-wave at 0.5v peak to peak.
Eutelsat apparently developed the system allowing the users in Continental Europe to switch between the Eutelsat's own Hot Bird system at 13° east and more popular SES Astra satellites at 19.2° east. As a result, the vast majority of European satellite receivers support DiSEqC 1.0 or higher. All DiSEqC supporting receivers have to receive certification mark specifying which variation of DiSEqC do they support.
Often mentioned such terms as DiSEqC 1.3 and DiSEqC 2.3 which are used by manufacturers and retailers to refer to applying DiSEqC with other protocols, primarily USALS. For example, DiSEqC 1.3 usually refers to satellite receivers which are using USALS with the DiSEqC 1.2 protocol. Such terminology is not authorised by Eutelsat, that's why we prefer not to use this terms though all the Prof satellite receivers use the USALS with the DiSEqC.
Along with DiSEqC, all the Prof satellite receivers support the USALS which is an abbreviation for Universal Satellites Automatic Location System also known as DiSEqC 1.3 (unofficially). Go X or Go to XX is a protocol for satellite dish motor control designed to automatically create an available satellite positions list when setting up a motorised satellite dish. This complex was developed by STAB company – the motor manufacturer which is still producing the major part of USALS-compatible motors. System is used together with the DiSEqC 1.2 protocol.
Once the user has input an initial location, satellite receiver software calculates all available satellites position which is the latitude and longitude relative to Earth. Calculated positions can vary within ±0.1 degrees from the offset. All of this is being adjusted automatically and does not require an advanced technical knowledge.
In comparison with DiSEqC 1.2 alone, with USALS it is not required to search and store every known satellite position manually. Thanks to that, using the Prof satellite receivers you can just point to a known satellite position (for example 14.3?E) which will be accepted as central point, on a basis of which the USALS system software will calculate visible satellites position within the offset.
In the northern hemisphere, receivers are aligned to the satellite southernmost to their position, or the most northern in the southern hemisphere.