Digital Satellite Equipment Control

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DiSEqC switch

Digital Satellite Equipment Control , DiSEqC for short [ daɪˈsɛk ], describes a digital control signal technology used in the building cabling of satellite reception systems ( satellite block distribution or Unicable technology). DiSEqC control signals enable an extended range of functions compared to the 14/18 volt and 22 kHz control signals for satellite reception.

history

With the introduction of the Astra satellite system in early 1990, there was also a need for easy-to-install satellite receiving systems. At that time, mechanical or magnetic polarizers were common in satellite reception . These required control lines laid separately from the coaxial cable; there were also coaxial cables that ran control lines in the shield. To select the desired polarization, an exact fine adjustment (the so-called skew ) was necessary on the receiver for each satellite program . Alternatively, it was also common practice to lay a separate (i.e. two separate) coaxial cable for each satellite block level.

  • Marconi LNB: At that time, satellite reception systems for do-it-yourself assembly appeared in English hardware stores in order to receive the English Astra programs. These realized the polarization switching by simply changing the LNB supply voltage; There was no need for separate control lines, which made installation of the receiving systems easy.
  • Marconi LNB with 22 kHz control: By superimposing a 22 kHz signal on the LNB supply voltage, four switching states can be implemented on the LNB . That was enough to switch to the two newly added digital satellite block levels (high level) in Astra reception systems.
  • Eutelsat and the DiSEqC standard: After the introduction of the upper frequency band, no other, second satellite could be received with a single receiver. However, since Eutelsat also wanted to supply German households directly with satellite signals, additional switching options had to be implemented in new receivers to control several satellite dishes. For this purpose, Eutelsat developed the DiSEqC standard in collaboration with Philips in the early 1990s.

DiSEqC also defines options for digitally switching the first two analog criteria mentioned. Satellite reception systems with integrated DiSEqC technology will therefore no longer need to change an LNB supply voltage. Conversely, there is an analog counterpart called a tone burst for switching between two satellite positions, which is similar to a one-byte DiSEqC command and is therefore often imprecisely called Simple-One-Byte DiSEqC or Mini-DiSEqC. The following table shows the logically equivalent criteria:

Analog criterion DiSEqC criterion conditions
22 kHz continuous tone DiSEqC v1.0 tape Low band or high band
LNB supply voltage DiSEqC v1.0 polarization horizontal or vertical (or counterclockwise or clockwise)
Tone burst DiSEqC v1.0 position a or B

Using DiSEqC, complex control commands can also be transmitted from the receiver to the LNB; DiSEqC is the basis for a SAT IF distribution technology (Unicable) that is an alternative to Sat block distribution.

In October 2011 the Federal Court of Justice rejected the appeal of the company SuperSat against the deletion of patent claims for the DiSEqC procedure before the Federal Patent Court (AktZ .: X ZR 94/09).

technology

DiSEqC is an open, license-free industry standard for everyone. The DiSEqC switching commands are transmitted serially as digitally coded data words. The DiSEqC data word consists of a start byte, an address byte and a command byte, which can be followed by an additional data byte. The words are transmitted by switching the existing 22 kHz switching signal on and off (modulating). In order to be able to use DiSEqC, all active components must be technically designed. The integrity of the data transmission is ensured by a parity bit after each transmitted byte. DiSEqC is unidirectional in version 1.x (commands only from the receiver to the functional part), in version 2.x it is bidirectional. The version number indicates the scope of the functions:

  • v1.0 offers switching processes for four satellite positions, two bands (low, high) and two polarizations (horizontal, vertical), so a total of 16 switching states. The four states for the satellite positions result from a combination of the two criteria position and option, which can each assume state A or B. Said combinations are therefore called PosAOptA, PosBOptA, PosAOptB and PosBOptB; More common, however, are the designations with the numbers 1 to 4 or the letters A to D.
  • v1.1 uncommitted introduces four additional, freely usable (hence the name uncommitted ) criteria. In combination with the DiSEqC v1.0 criteria, there are 64 possible satellite positions and a total of 256 switching states - however, the rarely available receivers with v1.1 only support the 16 satellite positions made possible by the four new criteria themselves when using v1.1 ( 64 switching states), which are then designated with the numbers 1 to 16, 0 to 15 or the hexadecimal digits 0 to F. DiSEqC v1.1 is downward compatible with v1.0.
  • v1.2: additional option for rotor control; not backwards compatible with v1.0 and v1.1, however almost all receivers with v1.2 support v1.0 in practice
  • v2.x: bidirectional communication with the switching states of the associated v1.x (does not automatically contain v1.1 and v1.2, as is widely assumed)
  • v3.0: additional programming options (still not widely used, however, with this standard, individual Unicable single-cable systems can be implemented without any problems in order to combine numerous ZF levels with each other without rewiring and expensive head-end stations )

There are so-called multi-protocol switches that understand the commands of several version numbers or tone bursts. Either they always react to all supported commands or the version or the criterion can be selected. The latter is done either using a slider on the switch or using a programmer . There are also switches that activate a certain input when receiving v1.2 commands and forward the command, since a rotor is to be connected to the input.

Cascading DiSEqC switches is basically possible if switches closer to the receiver do not respond to criteria with which switches remote from the receiver are to be controlled. Instead of a four-port v1.0 switch, three two-port switches can also be used, two of which respond to one and one to the other v1.0 criterion. If supported by the receiver, switches of different versions can also be combined.

Compatibility table

1.0 switch
2.0 switch
1.1 Switch
2.1 Switch
1.2 engine
2.2 engine
1.0 Receiver
2.0 Receiver
Yes No No
1.1 Receiver
2.1 Receiver
Yes Yes No
1.2 Receiver
2.2 Receiver
Yes No Yes

See also

Individual evidence

  1. cf. DiSEqC for technicians (web links), p. 7
  2. Patent DE4404978 : Antenna arrangement for satellite reception . Published on August 24, 1995 , inventor: Włodzimierz Wasiak.
  3. cf. DiSEqC for technicians (web links), p. 10
  4. cf. DiSEqC for technicians (web links), p. 8f

Web links