A satellite television receiver (often satellite receiver, engl. "Receiver " for " receiver " ) is a device from the consumer electronics, television and radio programs broadcast satellites can be received via a satellite dish with the. Compared with the terrestrial reception via antenna more programs are essential receivable. In contrast to the reception via cable television there are no additional fees for many satellite programs.
- 2.1 Analog satellite receiver
- 2.2 Digital Satellite Receiver
Principle of operation
A satellite receiver receives from the low noise block converter (LNB ) ( low-noise signal converter ) received and in the frequency range of 950-2150 MHz converted signals and converts a TV program this frequency range into a video signal that can be reproduced by a television. Usually he also takes on the power to the LNB, by communicating to him about the reception power cable.
Upon receipt of all existing in a satellite positioning frequencies, the problem occurs that four intermediate frequency (IF) bands are available from 950-2150 MHz, via a coaxial antenna cable but only one frequency band to the receiver (receiver) can be transferred.
Thus two antenna cables to your receiver In the early days of satellite reception to receive two planes of polarization, a receiver needed so compelling two IF inputs. A simplification brought so-called polarization rotors who selected the desired SAT level on a cable routed separately control cable to the LNB LNB feed a small rotor or an electromagnet; a receiver requires this special control outputs.
With the advent of affordable reception facilities in Europe, the industry was looking for workable solutions to their now sold in hardware stores satellite reception systems. By means of a so-called Marconi LNB to switch between the two supplied by the LNB SAT -IF polarisations was realized by different remote supply voltages 14/18 volts, which in turn necessitated the use of new satellite receiver, but quickly fell by corresponding numbers in the price. A remote supply voltage of 14 volts corresponded to the reception of the vertical plane of polarization, a voltage of 18 volts to the horizontal.
A further extension brought a use of the former only for telecommunications services and Direct Broadcasting Satellite ( DBS ) used frequency range from 11.7 to 12.75 GHz, which two additional from the receiver to receiving frequency ranges meant; switching to these third and fourth receiving plane was realized by superimposing the remote supply voltage with a 22 kHz frequency. A satellite receiver could now (on / off 14/18 volt, 22 - kHz signal ) switch provided between all four from a satellite polarization and frequency levels alone by the remote power control signals. To change to other satellites but turning the entire satellite dish by a complex rotation systems control ( Polar Mount) was still necessary.
To allow without rotary system switching to another satellite, developed by Philips, (Digital Satellite Equipment Control) DiSEqC protocol, the satellite operator Eutelsat developed to the specification for an extension of the 22 kHz control signal by pulse modulation, called DiSEqC protocol. Philips then sold the rights to Eutelsat.
The DiSEqC protocol is available in versions 1.0, 1.1 and 1.2. Although backward compatibility should exist, DVB-S receivers with DiSEqC 1.2 rarely compatible with DiSEqC 1.1 and therefore only limited multi-feed -aware, it can control up to 4 LNBs, while 1.1 up to 64 LNBs allows. When you purchase the receiver for use by more than 4 LNBs should therefore be taken to ensure that the technical data is specified explicitly DiSEqC 1.1.
- Most satellite receivers are external add-on devices ( set-top boxes). Advantage of this solution is the low by the mass production price. A disadvantage is that you need two remotes ( for TV and satellite receiver).
- A television with built-in satellite receiver is more comfortable, because only one remote control is needed. Such devices are currently only offered by a few manufacturers. The recording programs with a VCR in the context of such an integrated solution is more complicated and generally only possible when the TV is turned on. TV with integrated satellite receivers are not much more expensive than a television and external satellite receiver together. Meanwhile, so-called triple tuner (triple tuner ) are available from several manufacturers. With the receivers can be received on cable, antenna and satellite.
- There are also receivers with built-in hard disk drive. So you can record programs directly to the hard disk and transferred on demand via a USB or network interface to a PC and burn there, for example, on DVD. In addition, such receiver enable timeshifting; the program can, for example, in a telephone call to be interrupted, then you can at this point look further easy.
- A receiver with a twin tuner allows two different programs at the same time to watch / record. It is then, however, also possible to connect two coaxial cables necessary.
Analog satellite receiver
The decision of the Australian- American media entrepreneur Rupert Murdoch, to send in 1989 as the first customer of the fledgling satellite company SES Astra, his TV programs in the conventional TV system PAL, he brought the connected to the TV - SAT satellite plans the introduction of specially developed for direct satellite reception part digital channel D2- MAC of the postal monopolies, public broadcasters and the equipment industry to falter, and procured and the private satellite operator Astra by simple and inexpensive and available primarily receiving technology rapid growth and thus the decisive market advantage. The analog PAL broadcasting had on the Astra satellite system then a total of 23 years in hand and only ended with the analogue switch-off on 30 April 2012.
An analog receiver could be connected to all kinds of LNB, even on the so-called universal LNB which the complete Ku-band 10.7 - 12.75 GHz receives, which was above 11.7 GHz mainly transmitted digitally.
Digital satellite receiver
Digital satellite receivers are also called digital receiver. You can only receive coded digital television signals, mainly in the so-called hi- band ( 11.7 to 12.75 GHz) are broadcast. Meanwhile, also in the low-band digital stations are broadcast, tagesschau24 for example, Eins Festival, etc.
Different frequency information
In the frequency lists there is always the five-digit or six-digit downlink frequency ( the frequency at which the satellite transmits). Add to that the polarization and digital broadcasts also the symbol rate and the FEC error correction shortly.
Because high line losses would allow transmission of signals in the high frequency range over only a few meters, these signals are already implemented in the LNB in a lower frequency range. For this purpose, in the LNB, the received signal with the LOF (local oscillator frequency ) is mixed to obtain the satellite intermediate frequency ( Sat-IF ), which is in the frequency range 950-2150 MHz. This is received from the satellite receiver.
Some analog and virtually all digital receivers are now showing at the frequency settings on the five-digit downlink frequency to facilitate the user to search for stations. Others, especially older analog receiver, point the four-digit satellite IF. This is calculated from the downlink frequency minus the LOF.
The LOF is the low band 9.75 GHz, the High band is 10.6 GHz.
ARD Das Erste on ASTRA 1H: 11836.5 MHz ( = downlink frequency ) Polarization: Horizontal Symbol Rate 27500 FEC 3/4 according to frequency list, Sat-IF: = 1236.5 11836.5 to 10,600 satellite IF For analog ( tripped):
RTL on Astra 1F: 11229 MHz ( = downlink frequency ) Polarization: vertical noisy frequency list, Sat-IF: 11229-9750 = 1479 Sat-IF Very old analogue LNB (before about 1995 ) had a LOF of 10 GHz, with such a LNB SAT -IF, "low " is displayed at 250 MHz.
11229-10000 = 1229 Sat-IF The SAT-IF is therefore always higher by 250 MHz on newer LNBs.
Satellite programs can be encrypted (encoded ) or unencrypted (uncoded ) are broadcast by the station. For reception of encrypted satellite programs a conditional access system in the satellite receiver is needed.
- Receivers that can only receive unencrypted satellite programs due to their construction, are marketed with the attribute " Free to Air ".
- Receivers that are marketed with an attribute " CI ", have a "Common Interface", a compatible PCMCIA to slot into which a so-called Conditional Access Module can be inserted. Variety of encryption standards that contains all the necessary for a decoding hardware, as can be supported by such a satellite receiver.
- Receivers that are marketed with an attribute "HD ", have a special "Common Interface". This " HD " module is not interchangeable with a " CI " module and supports only the encryption standard HD .
- Receiver with a fixed decoding block. Such devices supported only said one or more predetermined decoding standards.
Some pay- TV operators do not allow its encryption standard is sold via Conditional Access Module, as they fear that the CI interface represents a vulnerability. They put forward for a reception satellite receiver with built- decrypting module, which means that CI receivers such programs despite Common Interface can not receive.
D-box 2 (Nokia)