RU2189702C2 - Ground communication system - Google Patents

Abstract

FIELD: communication. SUBSTANCE: invention refers to ground communication systems securing audio, video, information and other types of communication within boundaries of definite geographical locality having great number of communication channels with simultaneous access at extremely low cost. Ground communication system includes at least one local ground relay station preferably mounted on mast or on any other supporting structure. Each relay station is fitted with high-frequency communication equipment basically corresponding to equipment of standard geostationary satellite for digital transmission of audio and video information or data sent in L-range ( 1.0-2.0 GHz ), S-range ( 2.0- 4.0 GHz ) or in range of higher frequencies with relatively weak input signal. Omnidirectional antenna is preferably used to carry out transmission mainly in horizontal plane. EFFECT: potential for usage of equipment transmitting signals via satellite for ground transmission of signals. 4 cl, 6 dwg

Description

FIELD OF THE INVENTION
The invention relates to terrestrial communication systems providing audio (audio), video, information and other types of communication within a certain geographic area with a very large number of communication channels with simultaneous access at extremely low cost.

State of the art
The field of audio, video and information communication is attracting increasing interest, and existing terrestrial communication networks, radio channels and satellite communication systems are used very widely. To cover small geographical areas, specialized cable systems with a large number of television channels are also used. These systems can also be used for data transmission.

 Digital data transmission technologies have been developed, and repeaters now provide digital transmission for commercial television. With the use of digital technologies, the number of programs transmitted from each repeater is no longer limited to one, since several programs can be transmitted from each repeater simultaneously.

 However, with regard to terrestrial transmission technology, a suitable system does not yet exist, although there is hope that such a specialized system will appear in the near future. Then there will be a need to develop appropriate encoders and decoders specifically designed for terrestrial digital transmission and for the frequency ranges that are currently used to transmit terrestrial television signal. Significant efforts and money are invested in the development of such technologies, but so far these attempts have not brought success.

SUMMARY OF THE INVENTION
The present invention is based on the discovery that satellite signal transmission technology can also be used for terrestrial signal transmission.

 Thus, a user having equipment for receiving digital satellite signals can use the same equipment for receiving terrestrial transmissions. Such reception is ensured by the installation of communication equipment similar to that used in satellites as local terrestrial repeaters (MPRs) on masts or some other suitable platform. The transmission from the MPR is based on one of the traditional digital transmission standards, such as MPEG-2 or MPEG-1, used today by conventional geostationary orbiting satellites, as well as any other standards used for audio, video and information transmission. Today, the frequency modulated MPEG-2 standard (also compatible with MPEG-1) is preferred, but you can use other, already well-known standards, or those that may appear in the future. Amplitude modulated transmission can also be used as an alternative to frequency modulated transmission. Each MPR transmits with a relatively weak output signal, while it is desirable that the directional effect of the antenna is minimal. Thus, it is possible to establish a sufficient number of MPRs to cover a small geographic area in order to provide its residents with access to separate communication channels for information, video (TV) and sound communication. The advantages of such a system will be discussed in more detail below.

 The terrestrial communication system in accordance with this invention includes at least one MPR, preferably mounted on a mast or other supporting structure. Each MPR is equipped with high-frequency communication equipment, basically corresponding to the equipment of a standard geostationary satellite, for digital transmission of visual, sound information or data transmitted in the L-band (1-2 GHz), S-band (2-4 GHz) or higher frequency range with a relatively weak output. To transmit, mainly in the horizontal plane, it is desirable to use an omnidirectional antenna.

 Several embodiments of the present invention, not limiting the scope of claims, will be described in more detail below with reference to the accompanying drawings.

List of drawings
FIG. 1 is a top view that schematically depicts a basic system according to this invention, consisting of one MPR and two users of the system;
figure 2 is a side view of the mast, with two MPR installed at different heights;
FIG. 3 is a side view schematically illustrating a system of the invention and showing how a large number of MPRs can be arranged in a circle;
FIG. 4 is a top view of four MPRs arranged in a square pattern showing a zone within which users can exchange information with any of these four MPRs;
FIG. 5 is a side view of several masts, on each of which an MPR is mounted, is shown to show how the masts or other supporting structures can be positioned closer to each other; and
FIG. 6 is a schematic plan view explaining how several MPRs can be connected together to provide internal communication.

Information confirming the possibility of carrying out the invention
As mentioned above, the present invention is based on the discovery that modern communication tools used for digital satellite communications can also be used for terrestrial communications. Since so far no one has thought about this, all research resources have been directed to the development of alternative means of providing digital transmission within the framework of the traditional system of television channels.

 In accordance with the present invention, communication equipment similar to that used in modern communication satellites operating in terrestrial orbit is mounted on a mast or corresponding structure, forming a local ground repeater (MPR). The transponders are connected to an omnidirectional antenna system, but it is desirable for users of the system to have parabolic antennas that can be oriented in the direction of the above antenna system.

 A simple system of the above type is presented as a schematic top view in FIG. 1, showing an MPR, approximately in a circle, covering a limited geographical territory, the border of which is indicated by the number 1, and a series of parabolic antennas, 2 and 2 ', each of which is connected to equipment 3 and 3', similar to that used to receive and decrypt such the same digital signals that are transmitted from standard satellites. The output from such equipment can be received by a computer, and the video signal is displayed on a monitor, television screen, or other device. An acoustic signal is converted to an audio signal that is heard through the speakers. As for data transmission, it can be multidirectional, i.e. a computer with appropriate equipment for receiving and transmitting signals can receive and transmit signals from the computer to the MPR and thus communicate either with other computers connected to the MPR or with other communication systems associated with the MPR.

 The system discussed above is basic, i.e. it includes only one MPR. However, the number of MPRs in a particular geographical region can be increased at will, and thus the number of communication channels can increase almost to infinity.

 This can be achieved by installing several MPR at a certain acceptable distance from each other vertically on the same mast or other supporting structure. A diagram of this arrangement is shown in FIG. In addition, such masts or supporting structures can be placed at a distance from each other horizontally (as shown in figure 3). If the user has an antenna with an appropriate orientation, for example, a parabolic antenna or a multi-beam antenna, it is only necessary that the antennas connected to the digital converters of the MPR used are located at a distance of several degrees relative to the user's location. This will reduce to an acceptable level the effect of interference with neighboring MPRs (while interference with unselected MPRs should disappear altogether).

 Data transmission between the transponders used by MPR and users implies transmission with a weak output signal. Typically, an output power of 2-5 watts is sufficient, although a more powerful output signal can be used. High-frequency transmission is also used, preferably starting from the S-frequency range (2-4 GHz), increasing to 400 GHz. However, the transmission can be performed outside these limits, for example in the L-band (1-2 GHz).

 The weak output power in combination with high-frequency transmission allows you to limit the transmission to the borders of the selected geographical area. By amplifying or attenuating the transmitted output signal, the area of the territory covered by the ground repeater can be varied as desired. Various modifications of the antenna system are also allowed, especially if interference arises between two or more MHRs located in different places, whereby it is possible to reduce the output signal in an undesirable direction as an alternative to reducing the output power.

 The problem of interference between the geostationary orbiting satellites of the Earth and the MPR proposed in this invention does not arise, because MPRs are located below the horizon defined by these satellites. Accordingly, the signals transmitted from these geostationary satellites can be received at the same frequency as the MPR signals without interference, since the receiving parabolic antenna, designed to receive the signal from the Earth’s orbiting satellite, is turned at an angle greater than the horizontal plane than the antenna tuned receiving signals from MPR.

The system implemented in accordance with this invention allows to obtain a significant number of communication channels within a single geographical area. It is known that in order to avoid interference between channels transmitted at the same frequency, geostationary satellites should be located at a distance of 2-3 degrees. Even if this angular difference is increased to 6 degrees in the case of the system described by us, this will give 60 (360 ^o / 6) points of installation of the MPR, arranged in a circular pattern, as shown in figure 3. If you place three separate MPRs on one mast or supporting structure (high, very high, and even higher), the number of MPRs covering the selected geographical area will increase to 180 (3-6), while the installation of two MPRs on the mast will increase their number is up to 120 (figure 2). Each specific MPR can provide broadcasting of approximately 5,000 television programs of acceptable quality, as a result of which the above system can simultaneously transmit 900,000 (180 • 5000) different television programs within a specific area without interference problems. This number can be increased further, since the MPR can be arranged with alternating heights relative to the surface of the Earth (as shown in FIG. 5), due to which location points can be even closer than shown in FIG. 3. The circular arrangement, as in FIG. 3, can be replaced by some other, one of which is shown in FIG.

 As for the equipment, for receiving signals from the MPR, it is possible to use the parabolic antennas used today and satellite receivers with digital decoders, provided that the frequencies of the channels transmitted from the MPR are within the same range as is used by modern geostationary satellites. Accordingly, users will not need any additional expensive equipment for receiving television or teletext. The only thing that needs to be done is to turn the parabolic antenna towards the MPR.

 As for the television programs transmitted through the system presented by the present invention, of course, it is possible to install MPR, which is used for television transmission and connected to parabolic antennas, as well as receiving equipment for programs transmitted from orbital geostationary satellites, and relay these programs through MPR. As a result, the user will have access to all these channels without the large-diameter parabolic antenna, which is usually required in such cases, and a control system that provides its rotation for searching and receiving signals from various geostationary satellites having different positions relative to each other. System users can request pay-per-time channel programs.

 Another interesting characteristic of the described system is the ability to create a real "video on demand". The use of digital transmission and “smart cards” today allows users of the existing system of geostationary satellites to be able to watch certain programs, such as feature films, on demand. However, existing systems imply broadcasting films only at a specific, predetermined time. The user can call the operator by phone, asking them to launch one of the films of the current rental at this time. The user receives a special signal, thereby activating a decoder (or smart card) to decrypt the requested film from beginning to end. The cost of watching this movie is paid by the user. However, such a system cannot be called a real video on demand, since the choice of the viewer is limited to a certain set of films, and, in addition, the user is forced to adapt to the appointed start time of the film.

 Due to the large number of channels in the presented system, it is possible to offer such a video on demand that meets the tastes of the user. It will be possible to order any film at will, for example by phone, at any time convenient for the user. When ordering, the user is called the channel number used, for example, 28F. The operator has access to a video library, for example using satellite communications. From any corner of the Earth, any film that can be converted into a digital format at high speed and saved by the operator using an appropriate recording device, such as a computer with a hard disk, can be obtained at will. This means that any user will be able to view any movie in the world at a convenient time, and then pay for the bill.

 As mentioned above, the present system can also be used to transmit data. Thus, a computer equipped with the necessary equipment for reception and transmission connected to the antenna system can be prepared for communication with MPR. For example, a message over the Internet can be established due to high-speed communications and types of communications not available through telephone networks. Communication with the MPR can be achieved through the geostationary orbiting satellite of the Earth, via cable, a single MPR system (which will be discussed below), or by any other suitable means. Such a computer can also be used as a television receiver or connected to a separate monitor, which is used as a television screen.

 As already mentioned, the present system can also be used with one or more MPRs, which are part of the terrestrial communication system. The connection between the MPR is created due to the fact that the antenna directed in the preferred direction is placed in the antenna system directed towards the second MPR; that, in turn, should be equipped, if possible, with an antenna of a similar type, directed towards the first MPR. The aforementioned second MPR can be set in the same way as the first to communicate with the third MPR, which in turn is equipped with equipment for communicating with the fourth MPR, etc. (see Fig. 6). Separate areas can thus communicate with each other, and / or a communication line can be established for transmitting data, video or audio information over long distances, and / or communication with appropriate centers providing access to cable communication systems, or satellite communication, or carry out any other functions as necessary.

 The present invention also allows the use of MPH for purely audio communication, i.e., the user can contact the MPH via a small transceiver to establish verbal communication with another user with similar communication equipment. Moreover, MPR can also be connected to a public telephone network, and thus a user with equipment similar to a cellular telephone can make and receive phone calls.

 The type of MPR used in the terrestrial communication system of the present invention is not described in detail because it includes communication equipment known to any skilled person that is suitable for orbiting Earth satellites, which are commonly referred to as geostationary. The antenna system is usually omnidirectional, but can, as mentioned earlier, also include special antennas with a more or less directed lobe. Equipment for receiving signals from MPR should ideally be similar to that used to receive signals from a geostationary satellite using digital communication technology. The advantage of this system is that the required directional parabolic antenna can be very small compared to the parabolic antennas used to receive signals from geostationary satellites. It is preferable to use MPEG-2 as the encoding algorithm, but, as mentioned above, any other known or future digital transmission media, including the earlier version of MPEG (MPEG-1), can be used. It is preferable to use frequency modulation (FM), but the use of amplitude modulation (AM) is also acceptable.

 It is assumed that the above examples of the use of the system represented by this invention should show only some of the possibilities of its application. However, the scope of its application is in no way limited to these examples, since this invention opens up new, still unknown opportunities due to the huge number of communication channels available in any geographical region without any problems associated with the interference of other channels or transmitters ( due to the short range of the signals and the directivity of the antennas used for reception). The MPRs that make up the system can advantageously use masts and support structures, and the low cost of MPR allows this system to be used at minimal cost. Receiving television programs requires only existing and widespread equipment that is used to receive signals from geostationary satellites.

 The possibility of two-way communication between the computer and the MPR opens up new communication opportunities for firms, local authorities and other entities. Individuals can contact stores and other local businesses, for example, to place orders and make purchases.

 All these goals are achieved through the use of inexpensive equipment and well-tested equipment, as a result of which there is unlimited access to a huge number of channels / frequencies within a certain geographical area.

Industrial application
This system solves the problem of transmitting digital video, audio and data signals. Existing satellite television sets can receive several thousand television channels from one or more MPRs that make up the system without additional equipment or configuration changes. Thus, there is no need for cable television systems due to the small number of programs that can be transmitted via cable, as well as because of the initial cost of creating a cable network. In addition, the problems of “shading” (reflections) characteristic of traditional terrestrial television systems disappear.

 In addition, this system can be used for data transfer, as a result of which the communication speed increases to the values characteristic of local area networks (LANs). For example, in cities, access to the local administration information system can be obtained from schools, rescue services and other local services without having to resort to a local high-speed cable system. Local television can be made available to all residents at a very low price.

 The local systems of the present invention can also serve as repeaters for television programs received from geostationary satellites or television programs transmitted on the ground, and can also be networked together.

 The presence and availability of such a large number of channels / frequencies at such a low cost opens up until now unknown opportunities for a new application of information technology (IT) for important areas such as education, shopping within a certain area, video on demand, work (at home) , high-speed Internet communications and many other applications.

Claims (5)

 1. Terrestrial communication system that provides one-way and / or two-way audio, video or information communications for users within a limited geographical area using microwave frequencies and a relatively low power output signal, containing at least two local terrestrial repeaters with high-frequency communication equipment mainly corresponding to that used in standard geostationary satellites with digital communications, with one local terrestrial retra in its range of frequencies used, frequencies used by another local ground repeater for similar or excellent communication tasks, and the antenna system of each local ground repeater is located at a certain distance from other local ground repeaters serving this geographical territory, while users of the system have directional antennas systems, characterized in that the said antenna systems of local ground repeaters are omnidirectional and installed with the ability to transmit signals mainly in the horizontal plane, and the user antenna systems are installed with the ability to select the appropriate local ground repeater from among those located within the limited geographical area by changing the direction of the antenna in horizontal (rotational) or vertical (with tilt) planes, while the number of communication channels received by the antenna system of the user within the boundaries of the specified geographic area with op edelennym number of allocated frequencies for communication depends on the amount of local terrestrial repeaters covering the aforementioned geographic area.  2. The system according to claim 1, characterized in that the local terrestrial repeaters are associated with a communication system with geostationary satellites and are installed as repeaters of signals received or transmitted from the said geostationary satellites.  3. The system according to claim 1 or 2, characterized in that the local terrestrial repeaters are connected with a video broadcasting system with the possibility of ordering for a user to individually view the system at any time convenient for him of any video available within such a system.  4. The system according to any one of paragraphs. 1-3, characterized in that the number of available communication channels is equal to the available number of frequencies multiplied by the number of local terrestrial repeaters.  5. The system according to any one of paragraphs. 1-4, characterized in that it has usable frequencies from the range of L-frequencies (1-2 GHz), S-frequencies (2-4 GHz) or frequencies below 25 GHz.

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