DE29607766U1 - Signal distribution system - Google Patents

Description

29607766.6 29 July 1996

Televes, S.A. T 22072 GBM Ds/hi

Signal distribution system

The present invention relates to a system for distributing signals, in particular a community antenna system for distributing television signals of different channels according to the preamble of claim 1.

At present, two main systems are used for this purpose, which are shown schematically in Figures 9 and 10:

In the first state-of-the-art system, which is shown in Figure 9, signals received by the antenna are frequency demodulated for each channel after being amplified and converted by known units (low-noise amplifier LNA, low-noise block converter LMB). The channel-specific frequency-demodulated signals are then amplitude-modulated in a conventional UHF television channel.

This system consists of an antenna 1 that receives television signals of one polarity, a converter 2, in particular an LNA/LNB block, and cables 3 that connect the LNA/LNB block to a signal processing unit 400. This signal processing unit 400 consists of a plurality of channel-specific FM demodulators/AM modulators 19, a switching element 18, a power supply 17, connecting bridges 7, load components 8. A single distribution cable (output cable) 13 with output couplers 14 and user or antenna sockets 15 is connected to this.

The system has the disadvantage that it requires a channel-specific FM demodulator/AM modulator 19 for each satellite channel received. If the number of satellite channels to be received is to be increased, the number of FM demodulators/AM modulators required must also be increased. Each individual FM demodulator/AM modulator, which is used for both frequency demodulation and amplitude modulation, has a relatively complex circuit design and is therefore expensive. The costs of the system according to Figure 9 increase considerably if the number of satellite channels to be distributed is increased. Even in relatively small community antenna installations with a small number of users, considerable costs arise even if just a few satellite channels are received.

Such a system is known, for example, from EP-A-0 2 888 928, which discloses a device with an internal unit that implements an amplifier and signal converter function. This internal unit has several converters, each with a tuner-demodulator and an encoder-modulator.

In the second system according to the state of the art, which is shown in Figure 10, the distribution of television satellite channels to the system user takes place without the signals being frequency demodulated and amplitude modulated beforehand. The signals of the television satellite channels are therefore distributed in a frequency modulated manner (e.g. in the frequency range between 950 MHz and 2050 MHz). In contrast to the system according to Figure 1, this system according to Figure 10 does not require any channel-specific FM demodulators/AM modulators connected downstream of the LNA/LNB blocks; however, this system has the disadvantage that more than one distribution cable 13 has to be installed to distribute the satellite channels that come from two different polarities or from more than one satellite. The installation of additional distribution cables 13 in existing systems can be made possible due to spatial conditions in the buildings in which the additional

chen distribution cables would be very complex or possibly impossible. Furthermore, this system according to the state of the art requires several switching devices 16 in order to select different distribution cables and to tap signals transmitted on the selected distribution cable. The use of these switching devices, which are connected to the distribution cables, is also associated with the risk that electrical switching pulses generated by the switching devices reach the distribution cables and deteriorate the transmission quality of the signals transmitted there.

US Patent 5,073,930 discloses a method and a system for receiving and distributing television signals transmitted by satellites. This previously known system is structured in such a way that low-noise amplifiers (LNA) and low-noise block converters (LNB) are followed by so-called power splitters, whereby each transmission line is split into 8 transmission lines at the output of a low-noise block converter (LNB). These transmission lines are routed to eight satellite transponder processors via a connecting bus network. The satellite transponder processors each convert signals from a channel into a new frequency position. On the output side, the satellite transponder processors are connected to transponder combination devices. The transponder combination devices then combine the signals formed by the satellite transponder processors. Furthermore, the transponder combination devices are followed by power inserters, which are connected to several distribution cables on the output side. The known system is therefore designed with complex circuitry.

From DE-OS 41 17 208 Al a device for satellite television reception devices is known, whereby television signals are processed that are received by a parabolic antenna and have horizontally polarized channels and vertically polarized channels. To avoid complex cabling, the horizontally polarized channels and the vertically polarized channels are

polarized channels are separated from each other and converted into separate frequency bands in blocks. The blocks of channels separated in this way are switched to a common line. The known device only enables the conversion of channels in blocks. A similarly structured system is also known from European patent application 0 597 783.

Based on this prior art, the invention is based on the object of specifying a system for distributing signals of the type mentioned at the beginning, which enables the distribution of a larger number of channels and is designed in a simple manner in terms of circuitry.

This object is achieved according to the invention by a system according to claim 1.

is The system according to the invention is characterized by a number of advantages. According to the invention, the user is provided with predefined channels via just one distribution cable, which are individually selected from signals that come from one antenna or from several antennas. With the individual selection of channels, the demand of system users with regard to the reception of predefined channels can be individually met. The channel-specific converters provided according to the invention, which convert a predefined channel into another channel, but also the system as a whole, are implemented in a simple manner in terms of circuitry. The channel-specific converters can be set to any frequency in a predefined frequency band. The system according to the invention thus makes it possible to flexibly meet a changed demand of system users with regard to the reception of predefined channels.

The system according to the invention can be used, among other things, in cases where a single distribution cable has already been laid or in cases where

where the laying of an additional distribution cable would be complicated or impossible due to the same circumstances.

The system according to the invention, in which channels of two polarities 5 or from two or more satellites are transmitted to user sockets via a single distribution cable, also has no switching devices on the distribution cable. This means that no electrical switching pulses are coupled to the distribution cable, so that corresponding interference is excluded.

&iacgr;&ogr; An advantageous embodiment of the invention is characterized in that the channel-specific converters of the head device are integrated in at least one converter module, the converter module being connected at its input to down converters and at its output to the distribution cable. Preferably, the converter module has at least two converters, the converters in the converter module being connected to one another in a chain connection (an input of a first converter module is connected to the input of a second converter module that is adjacent to the first converter module; an output of the first converter module is connected to the output of the second converter module).

This chain connection structure is characterized by the important advantage in practice that not every channel-specific converter has to be connected to a down converter via a separate cable and that, in addition, not every channel-specific converter has to be connected to a mixer or adder that is connected upstream of the distribution cable via a separate cable. By using the chain connection structure, both the separate cables and the costs of installing them are saved.

In particular, the channel-individual converters or their inputs and/or their outputs can be connected to one another using known connecting bridges.

The system according to the invention enables the processing and distribution of signals from a large number of television channels. In this way, several converter modules, into which a variable number of channel-specific converters can be integrated, can be connected to one another, e.g. via a mixer ("9").

The system according to the invention can have a further mixer ("5") with at least two inputs. One of the inputs is connected to the output of a converter module, while another input is connected directly to a downconverter of an antenna. This mixer, which is possibly connected to the distribution cable on the output side via an amplifier, makes it possible to couple further channels into the distribution cable, namely from first channels or signals that are emitted by satellites and received by parabolic antennas, as well as from second channels or signals that are emitted by terrestrial transmitters and received by conventional antennas, as well as from first and second signals.

The channel-specific converters can each have a microprocessor that controls at least one oscillator. The microprocessor makes it possible to detachably connect an input device external to the converter to the microprocessor and to enter data into the converter or the microprocessor that designates a predeterminable input channel frequency and a predeterminable output channel frequency. In this way, the channel-specific converters can be set in a particularly simple manner to a predeterminable input frequency and a predeterminable output frequency, by which the frequency conversion of a channel is determined. The

The converter-external input device can also be designed as a remote control transmitter.

Furthermore, the invention provides that the channel-specific converter has an amplifier with controllable gain, whereby signals from different channels of the same frequency with different signal levels are fed to a mixer ("5") with at least two inputs. This makes it easy to superimpose different channels on the distribution cable. With the signal level difference of

With a minimum of 15 dB, the overlapping channels can be displayed in good reception quality in the terminal devices connected to the user sockets.

The properties of the invention shown as well as further properties and advantages are now described with reference to the drawings in which embodiments of the invention are shown.

It shows:

Fig. 1 a first embodiment of the signal distribution system

according to the invention;

Fig. 2-4 Embodiments of signal processing units

a signal distribution system according to the invention according to Figure 1;

Fig. 5 an embodiment of a channel-specific con

verters in a signal processing unit according to Figures 1-4;

Fig. 6 an embodiment of a mixer which is used in a

Signal processing unit according to Figures 1-4 at least one channel-specific converter according to

is switched on;

Fig. 7 shows an embodiment of a Si according to the invention

signal distribution system with selected switching points,

Figure 8 Diagrams of channel signal frequencies at the switches

points of the inventive signal distribution system

stems according to Figure 7 and

Fig. 9 and 10 Signal distribution systems according to the state of the art.

&iacgr;&ogr; The signal distribution system shown in the drawings, as also shown in Fig. 1, consists of three blocks A, B and C. Block A is a signal transmitter device, block B is a head device with a signal processing unit and block C represents the distribution network.

Blocks A, B and C are designed as follows:

1. Block A is a signal generator device which consists of at least one antenna 1 and known downconverters 2 (low-noise amplifier LNA, low-noise block converter LNB). The received signals can come from various broadcast and/or telecommunications satellites and/or have different polarities (horizontal, vertical). The downconverters 2 convert the received signals in a manner known per se from the reception frequency range of e.g. 11.7 12.5 GHz; 10.7 - 11.7 GHz; 12.5 - 12.75 GHz or preferably 10.7 - 12.5 GHz into an intermediate frequency range of e.g. 950 1760 MHz or preferably 950 MHz and 2050 MHz;

2. Block B is a head device with a signal processing device 400 in which channel-specific converters 4 are arranged. The channel-specific converters 4 will be described in more detail, in particular with reference to Figure 5. Various embodiments of the signal processing device 400 are shown in Figures 1, 2, 3 and 4;

3. The distribution network C has a single distribution cable 13, over which the signals are transmitted via tapping or diverting devices 14 to user sockets 15.

Block A of the system according to the invention, i.e. the signal generator device, as shown for example in Fig. 1, consists of antennas 1 which receive the signals from television channels transmitted via satellites. If the antennas are parabolic antennas, a down converter 2 is arranged at the focal point of each antenna 1,

&iacgr;&ogr; which convert the received signals in a manner known per se from the satellite television reception frequency range of e.g. 10.7 - 12.5 GHz into the intermediate frequency range between 950 MHz and 2050 MHz (usually referred to as "first intermediate frequency"). Such downconverters 2 with an amplifier LNA and a channel block converter LNB are

is known and available on the market.

Each antenna 1 has one or two downconverters 2 (or one downconverter with two outputs) depending on whether signals of one or two polarities (horizontal, vertical) are to be received per antenna. If the antenna 1 receives signals of one polarity, one downconverter 2 is provided; if the antenna 1 receives signals of two polarities, two downconverters 2 are provided.

The downconverters 2 are each connected to a cable 3 on the output side. In different embodiments of the invention, one or more cables 3, as shown in Figures 1, 2, 3, 4 and 7, lead to the signal processing unit 400 with at least one channel-specific converter 4. It can also be provided that one or more cables 3, as shown in Figures 1, 4 and 7, lead to a ("second") mixer 5, which is connected downstream of a channel-specific converter 4 or a converter module 40 with at least one channel-specific converter 4.

The channel-specific converters 4 of the head device B are preferably integrated into at least one converter module 40, whereby the converter module 40 can be connected at its input via a cable 3 to a down converter (LNA/LNB) 2 and at its output to the distribution cable 13 (coaxial cable). Preferably, the distribution cable 13 is connected to the output of an amplifier 6, which can be connected downstream of the ("second") mixer 5.

Each channel-individual converter 4, the circuit design of which will be explained in detail in Figure 5, has two inputs and two outputs.

As shown in Figures 3, 4, 5, 6 and 9, the channel-specific converters 4 of a converter module 40 are connected to one another in such a way that

is that an input (e.g. ECl in Figure 5) of a first converter module is connected to the input (e.g. EC2) of a second converter module (not shown in Figure 5) that is adjacent to the first converter module. An output (e.g. SCl) of the first converter module is also connected to the output (e.g. SC2) of the second converter module (ladder connection).

This chain connection structure is characterized by the practically important advantage that not every channel-specific converter 4 has to be connected to a down-converter 2 via a separate cable 3 and that, in addition, not every channel-specific converter 4 has to be connected to a ("second") mixer (5) which is connected upstream of the distribution cable 13 via a separate cable.

It can be provided that each of the two inputs is connected, for example, via a known connecting bridge 7 to an input of an upstream channel-specific converter 4 or to the input of a downstream channel-specific converter 4.

I · · · DCt * *

·♦

With regard to the outputs, it can be provided that each of the two outputs is connected, for example, via a known connecting bridge 7 to an output of an upstream channel-specific converter 4 or to the output of a downstream channel-specific converter 4. Preferably, an identical housing is provided for each channel-specific converter 4, that is to say a housing with the same spatial dimensions on which the input and output connections are arranged at the same locations. This enables the use of identical connecting bridges 7, with which an electrical connection is established either between two inputs or between two outputs.

Furthermore, it can be provided that an input of a converter 4 (first converter 4 of a converter module 40, which is shown on the right in each converter module in Figures 2 and 3) is connected to a cable 3, which transmits the signals generated by the down converters 2 or converted into the intermediate frequency range. An input of a converter 4 (last converter 4 of a converter module 40, which is shown on the left in Figures 4 and 5) is connected to a power source 11, which supplies the converters 4 and an amplifier 12 provided for each signal processing unit 400.

These channel-specific converters 4 receive on the input side the signals or channels in the intermediate frequency range emitted by the downconverters 2 and transmitted via the cables 3 and convert the signals or channels in the intermediate frequency range, as will be described with reference to Figures 7 and 8.

Inputs of the channel-specific converters 4, which are not connected to the input of a neighboring converter or to which no cable 3 is connected, can be terminated with an ohmic resistor 8 of 75 ohms (see Figure 1, Block B, reference number 8 above the

Converter 4; right converter module 40 in Figure 3; Figure 7, reference number 8 above the converter 4).

Likewise, outputs of the channel-specific converters 4 can be terminated with an ohmic resistance 8 of 75 ohms (cf. Figure 3, block B, reference numeral 8 below the converters 4; right and left converter modules 40 in Figure 3; Figures 4 and 7, reference numeral 8 below the converters 4). These are in particular the output of a first converter 4 (with regard to the signal flow) in a first converter module (right

&iacgr;&ogr; converter module in Figure 3) and the output of a last converter 4 (with regard to the signal flow) in a last converter module (left converter module in Figure 3).

With each channel-specific converter 4, a channel is selected and converted from an input frequency in the intermediate frequency range to a predeterminable output frequency in the intermediate frequency range.

As already described, a plurality of channel-specific converters 4, at least two, preferably four converters 4 can be integrated in a converter module 40. Two adjacent modules can be combined with one another via a (“first”) mixer 9.

The output of the first mixer 9 is introduced into the arrangement of the power source 11 and amplifier 12 by means of a connecting cable 10. The amplified signal is fed to the second mixer 5.

The channel-specific converter 4 is preferably designed as follows:

Input side

so Frequency range: 950 ... 1950 (or 2050) MHz

Input level: - 50 ... -30 dBm

Mirror selection

(image frequency rejection): > 40 dB

Intermediate frequency: 479.5 MHz

Bandwidth: 27 MHz

Loop-through input losses: < 1.2 dB s

Output side

Frequency range: 950 ... 1950 (or 2050) MHz

Max. output level: - 25 ± 5 dBm

Output level control range: 15 dB

&iacgr;&ogr; Bandwidth: 27 MHz

Loop-through output losses: < 1.2 dB

Noise level: > - 20 dBc

The power source 11 is preferably designed as follows: Mains voltage: 230V ±15%

Output voltage: 15V/5V

Intermediate frequency loop-through losses: < 1.2 dB

The amplifier 12 is preferably designed as follows: Bandwidth: 950 ... 2050 MHz

Gain: 23 ... 33 dB

Max. output level for two channels: 115 dB/t V/6 dBm

The first mixer 9 is preferably designed as follows: Bandwidth: 950 ... 2050 MHz

Insertion loss: < 4 dB

Rejection between inputs: 15 dB

As shown in Figure 4, first signals generated by a converter module (input El), as well as second signals generated by the down converters 2 (input E2), as well as third signals generated by antennas

fet ·« ■* Ir ·· t«

which receive signals from terrestrial transmitters are fed to the second mixer 5. The distribution cable 13 is connected to the output side of this mixer 5. Alternatively, it is provided that an amplifier 6 is connected downstream of the mixer 5, to which the distribution cable 13 is connected on the output side.

As shown in Fig. 1, the distribution network C consists of a single distribution cable 13 on which all channels that are FM modulated are transmitted. The distribution cable 13 is formed by a coaxial cable and leads to diverting devices 14 which couple the signal to various user sockets 15.

Figure 2 shows a signal processing unit 400 with a converter module 400, which consists of four channel-specific converters 4,
while Figure 3 shows a signal processing unit 400 with two converter modules 400, each consisting of four channel-individual converters 4.

In the system according to the invention, the number of channel-specific converters 4 is equal to the number of channels that are coupled into the distribution cable 13 and transmitted to the user sockets 15 via the discharge devices 14. The channel-specific converters can be set to predeterminable input frequencies in the intermediate frequency range and to predeterminable output frequencies in the intermediate frequency range.

Figure 5 shows an embodiment of a channel-specific converter 4. Two inputs EC1 and EC2 are electrically connected to one another and to an amplifier 42 via a directional coupler 41. The inputs EC1 and EC2 are mechanically designed in such a way that known connecting bridges (7 in Figure 2) are used to connect to one input of an adjacent channel-specific converter.

In this way, several channel-specific converters can be integrated into one converter module.

This type of connection therefore consists in that each of the two inputs ECl, EC2 is connected, for example, via a known connecting bridge, to an input of an upstream, channel-specific converter 4 or to the input of a downstream, channel-specific converter 4. Likewise, each of the two outputs SCl, SC2 of the converter 4 is connected, for example, via a known connecting bridge, to an output of an upstream, channel-specific converter 4 or to the output of a downstream, channel-specific converter 4. This type of connection has the advantage that distribution devices, which would otherwise have to be connected downstream of the downconverters 2, and connecting cables between these distribution devices and channel-specific converters are not required.

The amplifier 42 amplifies the supplied signals, e.g. in the frequency band from 950 to 2050 MHz. The signals are fed to an input-side tracking filter 43. This filter is a bandpass filter that is tuned to the selected input channel frequency by means of a voltage that is formed by a phase-locked loop (PLL) circuit 46. The circuit 46 is controlled by a microprocessor (MP) 49.

A mixer 44 connected downstream of the tracking filter 43 is controlled by a local oscillator (OL) 45, which in turn is controlled by the PLL circuit 46. The mixer 44 converts the frequency of the selected channel present at the inputs EC1 and EC2 to a frequency of 479.5 MHz.

The signal generated by the mixer 44 is fed to a low-pass filter 47, whose cut-off frequency is, for example, 600 MHz. This eliminates the signal from the local oscillator 45 and undesirable signals generated during the mixing process.

The signal is then filtered using a surface acoustic wave filter SAW 50, which has a bandwidth of 27 MHz at a center frequency of 479.5 MHz. The amplifiers 48 and 51 connected upstream and downstream of the surface acoustic wave filter SAW increase the signal level so that the losses caused by the SAW filter 50 are compensated.

The mixer 52 connected downstream of the amplifier 51 mixes the signal of the signal selected at the input of frequency 479.5 MHz with a signal formed by a local oscillator (OL) 53. The local

The oscillator is controlled by a PLL circuit 54. The PLL circuit 54 is also controlled by the microprocessor 49. The mixer 52 is followed by a tracking filter 55 on the output side, which is a bandpass filter just like the filter 43. The filter 55 eliminates the undesirable signals that are formed during the mixing carried out by the mixer 52. The signal of the frequency-converted channel is then available at the output of the filter 55 and is fed to an amplifier 56.

The gain of the amplifier 56 is controllable so that the levels of the frequency-converted channel signal can be set to predeterminable values (see, for example, channels 1 and 5 in Figure 6)

A downstream directional coupler 57 couples the amplified signal to the outputs SCl, SC2. The outputs SCl and SC2 are mechanically designed in such a way that known connecting bridges (7 in Figure 2) can be used to connect to one output of an adjacent channel-specific converter.

As shown in Figure 5, the converters 4 can include a microprocessor
49, which controls the PLL circuits 46 and 54 and determines the input and output frequency of the channel signal of the converter 4. Furthermore, the microprocessor 49 can control the amplifier 56. An input unit 16 can be connected to the microprocessor 49, for example via a 4-cable bus.

can be switched on, via which the data of a predeterminable input and output frequency and/or control data for the amplifier 56 (signal amplification parameters) can be entered into the microprocessor 49.

s The input unit 16 can have a control unit 162 (in particular a microprocessor MP), whereby a program assigned to the control unit 162 forms data, for example as a function of the limit frequencies of the respective intermediate frequency range (950 MHz, 2050 MHz), of channel bandwidths and channel spacings and signal levels of the channel signals, which correspond to predetermined technical specifications and which are entered into the microprocessor 49 of the channel-specific converter 4. The input unit 16 contains a keyboard 161, the control unit 162 and a display 163. The display shows data entered into the keyboard 161, operator guidance information and information which

is the state of the converter after it has been set using the entered data. The input unit 16 can be designed as a remote control transmitter with a transmitting device that transmits the data to be entered to a receiving device that is connected to the microprocessor 49 of the channel-specific converter.

Figure 6 shows a second mixer 5, which is also shown in Figure 1, block B. The second mixer 5 has, for example, three inputs El, E2, E3 and an output S to which the distribution cable 13 is connected. The distribution cable 13 is preferably a coaxial cable, but a glass fiber can also be provided.

The input El is directly connected by a cable to one or more converter modules 40; the input E2 is directly connected to a cable 3 with a down-converter (2 in Figure 1), while the input E3 is connected to a system for receiving terrestrial channels.

As shown in Figure 6 as an example, the input El is supplied with signals from channels 1, 2, 3, 4, 5 and 6, which originate from a satellite, have a bandwidth of 27 MHz and, as described, have been converted by channel-specific converters in the frequency band between 950 and 2050 MHz.

Input E2 receives signals from channels 7, 8, 9, 10, 11, 12, 13 and 14, which originate from a satellite, have a bandwidth of 27 MHz and, as described, have been converted by channel-specific converters in the frequency band between 950 and 2050 MHz.
to At input E3 there are 6 terrestrial television channels with 8 MHz bandwidth in the frequency band between 47 and 860 MHz.

The signals of the channels present at the input El are fed from the channel-specific converters 4, in which the frequency conversion is carried out and the respective levels are formed with regard to the coupling of the signals via the mixer output S into the distribution cable 13.

The channels 2, 4 and 6, which are present at the input El, have been frequency-converted in the channel-individual converters 4 in such a way that no channels of the same frequency are present at the input E2. The channels 1 and 3 at the input El are arranged in frequencies between the unwanted channels 7 and 8 or 9 and 10, which are present at the input E2. The signal or power level of channel 1 is set to a value of at least 15 dB above the corresponding level of channels 7 and 8; and the signal or power level of channel 3 is set to a value of at least 15 dB above the corresponding level of channels 9 and 10.

Channel 5 of input El is arranged at the same frequency as the unwanted channel 12 present at input E2, whereby the signal or power level of channel 5 is at least 20 dB above the corresponding level of channel 12.

The level difference (at least 15 dB or at least 20 dB) depends on the frequencies of the superimposed channel and the frequency of the channel(s) to be superimposed: if the frequencies are different (cf. channel 1, which superimposes channels 7 and 8), the level difference is at least 15 dB; if the frequencies are the same (cf. channel 5, which superimposes channel 12), the level difference is at least 20 dB.

The channels designed in this way in terms of frequency and level at the inputs El, E2 and E3 of the mixer 5 are coupled by the mixer at the output S into the distribution cable 13 in the arrangement &iacgr;&ogr; shown in Figure 6:

in the frequency band between 47 and 860 MHz, the same channels in the same frequency position and with the same levels are available at the output S as at the input E3;

In the frequency band between 950 and 2050 MHz, channels 7 and 8 of input E2 are superimposed on channel 1 of input El at output S. Since channel 1 is set to a signal level that is at least 15 dB above the levels of channels 7 and 8, only channel 1 is visible to the system user, without channels 7 and 8 generating interference.

Likewise, at output S, channels 9 and 10 of input E2 are superimposed by channel 3 of input El.

In addition, channel 5 of input El is coupled into the distribution cable 13 at output S in the frequency position of channel 12 of input E2, whereby channel 5 overlays channel 12, since the signal level of channel 5 is at least 20 dB above channel 12.

In addition, channel 4 (originally at input El) is coupled into the distribution cable 13 between channels 3 (originally at input El) and 11 (originally at input E2) and channel 6 (originally at input El) is coupled between channels 13 (originally at input E2) and 14 (originally at input E2).

Channels 4 and 6 are therefore inserted into free frequency positions at input E2.

·■

Overall, the channels in the frequency band from 47 to 860 MHz and the channels 1, 2, 3, 4, 11, 5, 13, 6 and 14 in the frequency band from 950 to 2050 MHz are made available to the system user. The channels 7, 8, 9, 10 and 12 are also transmitted on the distribution cable 13; however, these are superimposed so that they are not made available to the system user. With the signal level difference of at least 15 dB provided according to the invention, the superimposed channels can be displayed in good reception quality in the terminal devices that can be connected to the user sockets.

Fig. 7 shows an embodiment of the system according to the invention, which is also shown in Figure 1. It is assumed that
Signals from different television channels are received and processed, which originate from three satellites with different orbital positions with horizontal and vertical positions. In the system according to the invention shown in Fig. 7, circuit points d, e, f, g, h, i, j, k, 1, m, n, and γ are indicated.

Fig. 8 shows the channels at the circuit points d - O shown in Fig. 7.

At points d, e and f in Fig. 7, the signals are received by each satellite in a frequency band between 10.7 - 12.5 GHz with horizontal and vertical polarity.

As shown in Fig. 8, at circuit point d (parabolic antenna left in Figure 7) channels 70, 72, ..., 92 are connected in vertical polarity and channels 71, 93, ..., 93 are connected in horizontal polarity. At circuit point e (middle parabolic antenna in Figure 9) channels 65, ..., 69 are connected in only one polarity. At circuit point f (parabolic antenna right in Figure 7) channels 49, 51, ...63; 33, 35, ...47; 1, 3, ...31 are connected in

vertical polarity and channels 50, 52, ...64; 34, 36, ...48; 2, 4, ..., 32 in horizontal polarity.

Each down-converter 2 (Fig. 7) selects a polarity and converts the frequency band of 10.9 - 12.5 GHz into the frequency band of 950-2050 MHz in such a way that in each cable 3 at the switching points g, h, i, j, k the channels belonging to the same satellites and to the same polarity are present.

Î As shown in Fig. 8, the channels 70, 72, ...92, are connected to the circuit point g, the channels 71, 73, ...93 are connected to the circuit point h, the channels 65 - 69 are connected to the circuit point i, the channels 49, 51...63, 33....47, 1, 3, ...31 are connected to the circuit point j and the channels 50, 52 ... 64; 34, 36, ... 48; 2, 4 ... 32 are connected to the circuit point k.

Desired channels are selected from all available channels at switching points d - k. For example, channels 60, 36, 44, 2, 6, 12, 18 and 24 present at switching point k are not processed further, while instead channels 65, 72, 68, 82, 77, 17, 89 and 41 present at switching points g, h, i, j are processed further.

For this purpose, converter modules 40 are provided at the circuit points g, n, i, j, whereby the channel-specific converters 4 of the modules 40 are set to the input frequencies of each of the selected channels and to the output frequencies to which the channels are to be arranged. These output frequencies are occupied frequencies of unwanted channels to be superimposed or free frequencies.

According to the invention, channels are provided at the output of each converter module 40 which have a different frequency position compared to the frequency position at the input of the modules.

As can be seen from Fig. 8, at circuit point i, the channels 72, 82, 77 and 89 appear in a frequency position that differs from the frequency position of the channels at circuit points g and h. At circuit point m, the channels 65, 68, 17 and 41, which originate from circuit points i and j, also exist in different frequency positions. After the channels have been subjected to a mixing process in mixer 9, all selected channels originating from circuit points g, h, i and j are present at circuit point n, as shown in Fig. 8, in frequency positions that differ from the

ββ original frequency positions. These channels are fed via the feed source 11 into the amplifier 12, which amplifies the signal levels of the channels. Then, in the mixer 5, the channels present at the circuit point β are mixed with the channels present at the circuit point k. During this mixing process, the channels present at the circuit point β are superimposed on the channels of the same frequency present at the circuit point k.

The channels at circuit point η have a higher signal level of at least 15, but preferably 18 to 20 dB above the signal levels of the channels at circuit point k that are to be superimposed. This level difference ensures that the channel that is superimposed on another channel is received without interference from the channel that has been superimposed.

After the mixing process has been carried out in the second mixer 5, one obtains one or more channels, which are shown in Fig. 8, whereby these channels are then distributed via the single distribution cable 13. In this case, as shown by way of example in Fig. 8, channel 65 is superimposed on channel 60 (cf. larger amplitude of 65 compared to 60), channel 72 on channel 36, channel 68 on channel 44, channel 82 on channel 2, channel 77 on channel 6, channel 17 on channel 12, channel 89 on channel 18 and channel 41 on channel 24.

According to the invention, it is therefore provided that signals, in particular television signals of different channels transmitted via satellite, are distributed in a community antenna system. The signals are received in a signal generator device A and the received signals of a certain polarity (H, V) from a reception frequency band are converted into signals in an intermediate frequency band. The signals converted into the intermediate frequency band are processed and the processed signals are transmitted via a single distribution cable 13 in the intermediate frequency band to user sockets 15. Individual predeterminable channels in the intermediate frequency band are converted into other channels in the intermediate frequency band.

First channels converted in the intermediate frequency band are mixed with second channels in the intermediate frequency band and the first and second channels are transmitted via the distribution cable 13. In particular,
For two channels of the same frequency converted into the intermediate frequency band, different signal levels are formed, whereby the signal levels of the signals of different channels differ by at least 15 dB.

Telev6s, S.A. 29 April 1996

T 22072 GBM Ds/hi

List of reference symbols

A , EC2 57 S ignal generator device B , SC2 Head assembly C 55 Distribution network EC1 52 Inputs of 4 SCl 53 Outputs of 4 OIL 54 local oscillator 45, 53 (in 4) 1 antenna 2 41, 51 Downconverter LNA/LNB 3 42 Cable 4 43, channel-specific converter 44, Directional coupler 45, amplifier 46, Follow-on filter 47 mixer 48, local oscillator OL 49 PLL circuit 50 Low pass amplifier microprocessor SAW feeder 40 Converter module 400 S ignal processing device 5 second mixer

6 161 amplifier 7 162 Connecting bridge 8th 163 load 9 first mixer 5 10 connection cable 11 Food source 12 amplifier 13 Distribution cable (outlet) 14 Discharge devices &iacgr;&ogr; 15 User sockets 16 Input unit Keyboard Control unit Display

Claims (15)

Televes, S.A. 29 April 1996 T 22072 GBM Ds/hi Protection claims 1. System for the distribution of signals, in particular a community antenna system for the distribution of television signals of different channels, which are transmitted in particular via satellite, the system &iacgr;&ogr; a signal generator device (A) with at least one antenna (1) which receives the signals, and at least one down converter (LNA/LNB 2) which converts received signals of a certain polarity (H, V) from a reception frequency band into signals in a &ugr; intermediate frequency band, a head device (B) which is connected downstream of the signal generator device (A) and which has at least one signal processing unit (400) which is connected on the input side via a cable (3) to the downconverter (LNA/LNB 2) and which can be connected on the output side to a single distribution cable (13) via which the processed signals in the intermediate frequency band are transmitted to user sockets (15),
characterized,
that the signal processing unit (400) of the head device (B) · has at least one channel-specific converter (4), and that it converts a predeterminable channel in the intermediate frequency band into another channel in the intermediate frequency band using channel-specific converters (4). 2. System according to claim 1, characterized in that channel-individual converters (4) of the head device (B) are integrated in at least one converter module (40), and that the converter module (40) is its input can be connected to the downconverters (LNA/-LNB 2) via the cable (3) and its output can be connected to the distribution cable (13). 3. System according to claim 2, characterized in that the converter module (40) has at least two channel-specific converters (4), and that the channel-specific converters (4) in the converter module (40) are connected to one another in such a way that an input (EC1) of a first converter module is connected to an input (EC2) of a &iacgr;&ogr; second converter module, which is adjacent to the first converter module and that an output (SC1) of the first converter module is connected to an output (SC2) of the second converter module. 4. System according to claim 3, characterized in that the connection of the inputs of two adjacent channel-specific converters (4) and/or the connection of the outputs of two adjacent channel-specific converters (4) is realized by connecting bridges (7). 5. System according to one of the preceding claims, characterized in that the channel-specific converter (4) has a tracking filter (43, 55) on the input side and/or the output side. 6. System according to one of the preceding claims, characterized in that the channel-specific converter (4) comprises a microprocessor (49) which controls at least one oscillator (45, 53) of the channel-specific converter (4) and/or an amplifier (56) of the channel-specific converter (4). 7. System according to claim 6, characterized in that the microprocessor (49) of the channel-specific converter (4) can be connected to an input device (16) external to the converter, via which data can be entered which designate a predeterminable input channel frequency and a predeterminable output channel frequency and/or signal amplification parameters for controlling the amplifier (56). 8. System according to one of the preceding claims, characterized in that the converter-external input device (16) has a control unit (162). 9. System according to one of claims 2-8, characterized in that &iacgr;&ogr; several converter modules (40) are connected to a first mixer (9) whose output can be connected to the distribution cable (13) via a power supply source (11). 10. System according to one of the preceding claims, characterized in that the system has a second mixer (5) with at least two inputs (El, E2, E3), that one of the inputs (El) can be connected to the output of the converter module (40), that a further input (E2, E3) can be connected to a down converter (LNA/LNB 2) and that the second mixer (5) has an output (S) to which the distribution cable (13) can be connected. 11. System according to claim 10, characterized in that signals of different channels of the same frequency in the intermediate frequency band, which are fed to different inputs (El, E2, E3) of the second mixer (5) have different signal levels. 12. System according to claim 10, characterized in that the signal levels of the signals of different channels differ by at least 15 dB. 13. System according to one of claims 2 - 12, characterized in that the distribution cable (13) can be connected to the output of an amplifier (6) whose input can be connected to the output of a channel-specific converter (4) or a converter module (40). 14. Channel-specific converter (4) for use in a system according to one of the preceding claims. 15. Input device (16) for use with a channel-specific converter (4) according to claim 14.