Multiswitch

A satellite block distribution is a commonly used variant of the building cabling in which a broadcasting receiving system enables the operation of multiple community satellite receiver at one or more satellite antennas. The main task is the signals supplied to each participant in the distribution of the LNB (and possibly existing terrestrial antennas). A satellite block distribution is characterized in that each satellite receiver (eg Digital Receiver) connected to its own antenna cable. The wiring is so star-shaped. Alternatively, the cable system and the improved variant unicable apply.

• 3.1 distinction between analogue and digital reception technology
• 3.2 Other functions of the multiswitch
• 3.3 multiswitch LNB
• 3.4 multi-switch for multiple satellites
• 3.5 Cascadable Multiswitch
• 3.6 Trade names for multi-switch

• 5.1 advantages
• 5.2 disadvantages
• 5.3 alternatives 5.3.1 unicable
• 5.3.2 unicable

Principle of operation

Modern television satellites receive signals from the ground station to the uplink frequency and implement them by means of so-called transponders on board the satellite in a new downlink frequency to. In this Astra downlink frequency is from 10.70 to 12.75 GHz. The signals are amplified in the transponders, and then sent back via directional antennas at a particular region on the earth's surface. The geographic area where the satellite signal is to be received, is called illumination zone. Because of their high frequency, these signals obstacles such as trees, house walls and roofs can not penetrate so on. Therefore, at the receiving facility a clear view of the satellite is always necessary.

Signals at such high frequencies can not be distributed in a building wiring with ordinary coaxial cables; the signal attenuation would be too high. Therefore, the received frequencies are first downconverted by the LNB to a lower intermediate frequency range. It is not implemented the full frequency band of 10.70-12.75 GHz, but halved the tape into two approximately equal segments and converted into the same, lower IF band. The automatic switching of the LNB internal mixing frequencies is controlled by the satellite receiver. The conversion of the very high transmission frequencies of the satellite transponder into a deeper band reduces the losses due to cable attenuation, which are highly frequency and cable type dependent. The use of a typical coaxial cable for antenna engineering at 10Ghz / 12GHz instead of 1Ghz - 2Ghz would mean that hardly anything would arrive at the receiver, which was received at the antenna before. However, the transpose alone may not be sufficient to provide an adequate level for the satellite receiver. Therefore, the converter stage ( mixer) and follows the same is a potent amplifier which provides a strong enough signal for the subsequent cable distribution. LNB which consists essentially of a small level per antenna, an input amplifier, a mixer, a line amplifier and a switchable oscillator for each channel ( horizontal / vertical), is supplied via the coaxial cable to power and control signals.

Since the broadcast from the satellite signals are both horizontally and vertically polarized, there are four possible switching states are produced:

• Horizontal polarization, the upper frequency range ( high band ) 11.70 to 12.75 GHz
• Horizontal polarization, the lower frequency range ( low band ) 10.70 to 11.70 GHz
• Vertical Polarization, upper frequency range ( high band ) 11.70 to 12.75 GHz
• Vertical polarization, lower frequency range ( low band ) 10.70 to 11.70 GHz

The down-converted by the LNB reception frequencies are then passed through an ordinary coaxial cable in the frequency range of 950-2150 MHz to the satellite receiver. Usually these downmix is done with 9.75 GHz and 10.6 GHz in the low band in the high band ( called local oscillator frequency, short LOF ). Since the local frequency range is 1,200 MHz great, but the standard Satblöcke use only 1,000 ( low band ) or 1.050 MHz ( high band ), this gives a range, which is by default not used by the receiver. One can but the boundary between the low and high band ( LOF switch called ) from the standard 11.7 GHz with many receivers and TV cards set depending on a value from 11.55 to 11.9 GHz.

Switching between polarization and frequency range

The receiver is required depending on which station is to be received, another plane of polarization and / or a different frequency range (see the oblong diagram right). To switch the receiver transmits via the antenna cable to the LNB ( or, if present, to the multi- switch) various control signals:

The switching of the plane of polarization is performed by changing the height of the remote supply voltage is present between the inner conductor and outer shield of the coaxial cable. 18 V signal horizontally, 14 V vertical.

The change of the frequency range ( low band or high band ) via a modulated 22 kHz audio frequency signal. If this signal is output from the receiver, the LNB (or multi-switch ) switches to high - band. Missing it, he falls back to the low band.

• Horizontal polarization, the upper frequency range ( high band ): 18 V 22 kHz
• Horizontal polarization, the lower frequency range ( low band ): 18 V
• Vertical Polarization, upper frequency range ( high band ): 14 V 22 kHz
• Vertical polarization, lower frequency range ( low band ): 14 V

Here it becomes clear why it is not possible without restrictions to operate multiple satellite receivers to a single antenna cable (eg with a distributor or through sockets ): Gives example of one of the receiver the 22 kHz signal, provides the LNB ( or multi-switch ) the High band. Another receiver who just needs the low band at the moment, could then receive nothing. Exceptions are the frequencies from 11.55 to 11.9 GHz the same polarization, which can in principle always be available, but require a situational configuration if the hardware does not recognize itself. Similarly, only without exceptions, it behaves horizontally and vertically with the switching between the polarizations. A parallel connection of multiple receivers is technically possible in principle, if one restricts oneself to a common frequency band and a plane of polarization, since the tuner itself indeed function independently. The horizontal plane of polarization behaves in their higher switching voltage to the vertical "dominant"; a parallel-connected second receiver then receives despite setting " vertical" only the stations with horizontal polarization plane. The series connection is possible if each device (except possibly the last ) with a loop through output ( also RF Out ) has. What attitude dominates this depends on the hardware and can not generally be said.

In practice, to observe and not to be confused are:

• A quad LNB has four ports. Each port is controlled to output one of the four possible reception areas. The control is usually via a satellite receiver or multi-switch. Also, a single and a dual LNB, with appropriate control output by the satellite receiver all four reception areas on each output. A Quattro Switch LNB, as it is commonly found in commercial matters, the quad LNB, as it has a built in multi-switch and so has four terminals, each of which is controllable to play one of the four reception areas.
• A Quattro LNB has four ports. About every port a predetermined reception area is output controllability of the assignment of a reception area to a port in the current operation is not possible. Will these four terminals connected to the inputs of an external multiswitch, all satellite receiver connected to the outputs (eg, 16 when 16 outputs are available on the multi- switch) received by appropriate control of the multi-switch all four reception areas.

The connection of multiple receivers to a coaxial cable with full range of programs but is now made ​​possible by a unicable system.

DiSEqC

DiSEqC makes it possible to receive multiple satellites on one or more satellite antennas with a receiver. The following cases are possible:

• Driving a motorized rotation satellite antenna to focus on different satellites ( only suitable for a receiver ).
• Activation of a switch ( multi-switch ), which is associated with various fixed antenna LNB, received respectively different satellites (eg Astra, Eutelsat's receiving system, suitable for multiple receivers ).
• With newer receiver systems also can switch between low-and high - band as well as horizontal and vertical polarization in the LNB DiSEqC signals take place, as an alternative to switching voltage and 22kHz signal.
• Use of special LNB, loop through the satellite block - intermediate frequency (IF ) when they themselves are not turned on. A complete multi-switch logic is to be integrated in each LNB. Several such LNBs are connected in cascaded one behind the other; the selection of a desired frequency range and LNBs then ( only suitable for a receiver ) via DiSEqC signal.

Structure of the cabling

The LNB located at the focal point of a parabolic reflector are in satellite block - distribution depending on the control signal emitted by the receiver a certain band ( intermediate frequency range 950-2200 MHz) of four per satellite emitted from transmission ranges. Is issued because of the control signals and there is always a whole spectrum block from the LNB to the receiver, each receiver is an exclusive coaxial required (cabling in a star topology).

If more receivers are operated at a receiving system, as an LNB outputs offering, which is accomplished by installing a downstream multi-switch. From the LNB to the multiswitch typical four exclusive antenna cables are then required each satellite. After the multi-switch wiring is again typical run in a star topology.

Unused outputs on the multiswitch or LNB be terminated with a 75 - Ω termination resistor. The use of antenna cans is not required, as long as no feeding of terrestrial or cable TV signals takes place. For long coaxial line, an IF amplifier may be used. It should be noted that this must reach through a remote voltage without voltage drop and superimposed control signals.

It may be problematic for very large plants also recommended to mount small cascadable multiswitch for each floor in the stairwell or distribution of the SAT - Master cable directly into the apartment to where the satellite signal from the LNB's flexible in the desired number per unit exclusively for each connected satellite receiver input, to provide a short path. So also many different satellite positions can be made individual participants is available upon request, without the will bear the additional cost of the more complex multi -DiSEqC capable switches shared by all participants need.

Multiswitch

A multi-switch is a component of a receiving system in satellite block - distribution technology, which allows the common operation of multiple satellite receiver to a satellite antenna. The main task is to distribute the signals supplied from the LNB to the individual satellite receiver. In addition, he serves ( depending on design ) to feed terrestrial or cable television signals in the antenna cables to the participants.

Distinction between analogue and digital reception technology

The term " digital " or "analog " multiswitch or LNB is technically incorrect. Correctly it should read: "Analog Band - " or " Analog and Digital Band - " Level Multifinger switch or LNB hot.

Upon receipt of the first still analog channels in the low- band switching the frequency ranges (high or low band ) was not initially required. It is switched only between the horizontal and vertical polarization.

Analog Band -grade multi-switch and LNBs can also provide digital and HDTV channels available when they send in the low band. The first 200 MHz of high bands in which, for example, The first SD is capable of receiving, if you increase the limit for high band ( LOF switch) to 11.9 GHz, so that the receiver is not expected to have been down-mixed with the local oscillator frequency of the high band. Conversely, can provide the analogue channels are available as digital designated multi-switch and LNBs always.

The term "digital" was invented by the producers of the high- band -capable multi-switch and LNBs because all digital channels first sent to the dominant in Central Europe Astra satellite system at the start of digital television in the high- band analog channels in the low band. Today many digital channels and HDTV stations broadcast in the low band. During the switch-off of analogue TV stations the low band is more used for digital and HDTV channels in the future. Therefore, new satellite receiver should preferably be used as so-called HD receiver, as these usually allow also the reception of digital DVB-S standard.

Basically, you can see the difference between the analog and digital compatible multi switches on the number of inputs per LNB (two in analog, four in digital). Analog multi-switches are now but hardly to find in the trade, as well as a digital -compatible multi switches analog receiver can be operated. Analog -grade multi-switch will therefore only connected by two connecting cable to the LNB; usually twin or dual LNBs are used. The use of a digitally compatible Quattro LNB is also possible; then, however, only the two low-band outputs of the LNB are connected, the high-band connections remain unused.

The universal LNBs only the oscillator frequency of 9.75 to 10.6 GHz is switched to receive the high- band by the additional 22 - kHz signal on the basic operation of an LNB, frequency conversion, but nothing changes.

Other functions of the multiswitch

Since the multi-switch is usually installed in the attic, it is natural to feed the signals of a possibly extant terrestrial antenna system with in the house wiring, for example, for the reception of FM radio or DVB -T. Therefore, most multiswitches have an additional input for terrestrial signals. Preferably here an antenna switch or a so-called multi-range amplifier with the desired antenna is connected. In the same way also signals from the cable TV network can be fed.

Due to the multi-switch these signals are transmitted through the same cable to the aerial socket such as the satellite signals. With a suitable antenna socket (so-called three -hole socket) the different signals can be re- used separately.

When using services on cable television, the return channel capability require (such as Internet or telephone), and the return channel capability of the multiswitch is required.

Multiswitch LNB

These special LNBs have an integrated multi-switch with four or eight outputs. They are usually a quad LNB or Quad - LNB Switch ( four outputs ) or Octo LNB called ( eight outputs); the name varies depending on the manufacturer and is not necessarily uniform. Here, the receiver can be connected without additional Multiswitch directly to the LNB. Also monoblock LNBs for squinting installations ( multi-feed ) can have built-in multi-switch. Here you can run a receiver on each output; the receiver operate independently, that is, anyone can receive analog and digital TV programs without interfering with the reception of the other receiver.

Such multi-switch LNBs are useful for receiver sets with very few participants. At such LNB, a further multi-switch can be connected, provided that this once each 14 and 18 V, and outputs at its LNB inputs (at a suitable digital device) 22 kHz signal. Otherwise, the LNB would deliver on all outputs only the vertical low band. The use of a Quattro LNB (without built-in multi-switch ) is to be preferred. Better quality and an easier extendibility is to be expected with Quattro LNB and external multi-switch, since the electronics are less closely fitted (crosstalk ) is not exposed to the weather and the multiswitch has usually its own adequate power.

Multi switch for multiple satellites

It is possible to distribute the signals from several satellites with a multiswitch. For the multiswitch LNB additional ports ( ie another four inputs for each additional Quattro - LNB). Switching to the respective LNB controls in this case, the receiver itself by means of an additional digital DiSEqC signal. It is irrelevant whether the second LNB on the same satellite dish ( multi-feed ) or on a second mirror is installed. Satellite Pro you need an LNB. The use of motorized rotating antennas for multiple satellite is not logically possible for Shared receiving systems with multi-switch.

Cascadable Multiswitch

Here is multi-switch, on the one hand to distribute at least four reception areas of a LNB to individual participants, by directing other hand, the delivered signal at its inputs and make it to the next further outputs cascadable multiswitch available unchanged. Cascadable multiswitches are used in large buildings such as blocks of flats to flexibly offer and distribute the required connections per unit over a short distance can.

The typical installation consists of a satellite dish and a cascadable multiswitch on each floor. From this, the discharges of lead into the homes of the floor and four coaxial cables to the multiswitch to the next floor and so manufacturers like Spaun, Arcon, GTN, or Kreiling Kathrein offer such systems.

If desired, an additional satellite in only one floor, then cascadable multiswitch with eight inputs can be used. You can also switch by means of a DiSEqC relay on further also cascadable multiswitch or directly to the LNB.

Trade names for multi-switch

The type of multi-switch often includes two digits, eg 5 / 8th The first digit indicates the number of inputs from the LNB, the second the number of outputs to the receiver. If the number of inputs is odd, the multi-switch also has a terrestrial input.

A few examples:

• Multiswitch 3/8: 2 inputs from a LNB 1 input for terrestrial antenna, 8 outputs to 8 receivers (analog Level Multifinger switch)
• Multiswitch 5 /4: 4 inputs from a LNB 1 input for terrestrial antenna, 4 outputs for 4 receivers
• Multiswitch 5 /8: 4 inputs from a LNB 1 input for terrestrial antenna, 8 outputs to 8 receivers
• Multiswitch 9 /8: 4 inputs from the first LNB, 4 inputs from the second LNB 1 input for terrestrial antenna, 8 outputs to 8 receivers
• Multiswitch 5/16: 4 inputs from a LNB 1 input for terrestrial antenna, 16 points to 16 receivers

Historical development

The European satellite operator SES Astra allowed from December 11, 1988 based on good PAL technology and a modern slim satellite concept (GE Astra Electronics Astra 1A, only an EIRP of 50 dBW, but with already 16 KU transponders ) a certain variety of programs, in contrast to the later failed TV - SAT system. The application of proven technology of telecommunications satellites also included the concept for the efficient use of spectrum by dividing the 16 transponders on a horizontal and a vertical polarization plane ( frequency blocks ). The receiver therefore had to reach full Astra program diversity (first 16 TV programs to a satellite ) receives both polarities separately; a common transmitting both satellite IF blocks over a single coaxial cable (as in the terrestrial PAL or cable television) was not possible due to the polarization planes in two equal occupied frequency range. The industry soon developed for easy to install receiving equipment, a Marconi LNB -called change-over concept, which was switching by changing the remote supply voltage (14/ 18 V ) between the two planes of polarization. For operation of multiple satellite receivers to a common mirror, this technique has been used in multi-switches with multiple outputs.

A development of this supply voltage controlled 14/18-Volt-V/H-Umschalttechnik was through the use of the imaginary actually for telecommunications satellites DFS Copernicus the German Postal Service for a TV DTH necessary ( in competition with Astra). Switching to the so-called high- band ( 12.5 to 12.75 GHz) was achieved by overlaying the LNB supply voltage with a 22 KHz control signal, which thus for the first time four IF bands were for satellite reception. This concept enabled the subsequent extension of high- band around the formerly reserved for satellite TV DBS frequencies ( 11.70 to 12.5 GHz) to 11.70 to 12.75 GHz.

A new development to switch to other satellites brought the DiSEqC system by Philips and Eutelsat.

One technique " 14/18 volt, 22 kHz Tone Burst, DiSEqC " to the recipient ( satellite receiver ) is always an entire reception frequency block ( 950-2300 MHz ) are available from the term satellite block distribution is derived.

Pros and Cons

Benefits

Is scheduled generously for the construction of an object of the satellite from the outset, as arise in the satellite IF distribution (eg compared to cable TV) distinct advantages. Firstly, the diversity of programs with the satellite reception significantly higher (especially for multi- satellite reception ). Thus, the digital satellite channels a few hundred free TV programs can be received while in digital cable reception only about 60 free TV programs can be received ( as of 2009). Furthermore, already receive some free HDTV programming via various satellites, while currently available exclusively chargeable HDTV offers the DVB - C reception in some states.

A further advantage is the significantly larger selection of receiver models with digital satellite reception. Choosing a State other than the provided by the cable provider digital receiver is connected depending on the provider with monthly costs.

Finally, the satellite reception is currently free, so pay back the initial investment in a SAT receiver ( especially in multi-party stores) within a few years.

The satellite block distribution by means of multi-switches is simple and flexible feasible and can also be combined with the cable TV. The reception of several satellite positions and Satellitenantenen is easy and relatively inexpensive for multiple participants possible with this system.

Disadvantages

The technique of satellite block IF Distribution has historically emerged from a major drawback is derived: due to the practice of satellite block - switching may only have a DVB -S or DVB - S2 receiver is connected to an antenna line. This causes a large wiring with less flexibility when connecting additional receiver. In contrast, a Connecting Multiple DVB -C or DVB- T receivers on one antenna line was never a problem, so a satellite block distribution in very large residential complexes is rarely practiced today. The classic Cable TV offers there often, especially with the service and the Internet offer commercial landlords several advantages.

Another disadvantage of a satellite block - IF distribution is that the number of operable in an apartment satellite receiver is set indirectly by the number of connection lines for each apartment. Many are in the planning phase of a satellite broadcast receiving system do not realize that today each apartment quite a number of other satellite receiver (VCR, Kitchen TV, children's room, PC with DVB -S2 card, DVB-S radio reception on the hi-fi system ) be connected and operated. A satellite block - distribution system can not be compared with the comfort of a linear signal distribution ( cable TV connection or DVB -T) for this reason.

It can also satellite cable looped through or be connected in parallel. Many satellite receivers and some DVB- S cards have to loop through a so-called loop-through output ( also called loop out or RF Out ). You have to agree to a switching state for it however. On the typical position of 19.2 ° East to almost all digital German stations are in standard quality (SDTV ) in the horizontal high band (see the oblong diagram right). It lacks primary Phoenix, arte, Eins Festival, Eins Plus, tagesschau24 from the horizontal low band and DMAX, Sport 1, Tele 5, Comedy Central and the alternative program course of arte from the vertical high band. In many HDTV channels are in the horizontal low band. Here 3sat, KiKA and ZDFinfo missing from the vertical low band and again, Tele 5, WDR and the complete Sky package from the horizontal high band. Some receivers and TV applications offer users the ability to customize the standard 11.7 - GHz boundary between low and high band itself ( standard compliant values ​​from 11.55 to 11.9 GHz ), so that more stations are in the desired band.

If an additional connection or a satellite desired in only one apartment, then cascadable multiswitch can be used with 8 inputs. You can also switch via a DiSEqC relay on Multi -switch or directly to the LNB. However, this shift variants are always associated with a significant additional planning effort straight at community facilities.

Alternatives

Unicable

Since 2004, however, another standard for the operation of up to 8 satellite receivers to a coaxial cable, which can receive the full program offer a satellite ( eg ASTRA ) independently. This system is known under the name unicable. Exists in existing MDU in each apartment per a separate cable, even larger living systems can be expanded subsequently without a costly rewiring relatively inexpensive to satellite channels through a cascade of several such unicable matrices. For the reception of satellite programs, however, a so-called unicable capable Satellitenreciver is then usually required. The performance of this system is limited additionally by the use unicable matrices over the Satblockverteilung at several satellite locations. Also, the existing installation of the distributor and the coaxial cable sometimes not all of the eight unicable enabled Satellitenreciver are any operable due.

Unicable

Another very simple alternative is the so-called single cable system, with the many satellite receiver ( limited to approximately 200 satellite TV channels though) can be operated on an existing coaxial cable. This system can not be used the full range of the satellite operator. If satellite transponder transmitter to change, they can with the simple single cable systems may not (more ) are received, it is then an upgrade to a programmable single cable in the headend may be possible, which then causes further additional costs.