RU2145151C1 - Satellite system for one-way transmission of short repeated messages - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: device has at least one transmitter, and at least one base station receiver, which receives signals from said transmitter through satellite communication channel. Receiver of base station provides reception and amplification of signal, its converting into quadrature video frequency, pre-detection filtration of manipulated signal in almost optimal mode with respect to each binary character, frequency detection, accumulation, making decision about each bit in frame, error correction. Each transmitter provides possibility of signal transmission in at least two frequencies from set of three. It has unit for reception of global satellite positioning system and unit for issuing contact broadcasting signal. Each base station receiver provides possibility of simultaneous reception of signals in three said frequencies. When unauthorized transmissions which run out of schedule are received, they are accumulated in sliding winding. Base station also has unit for reception of signals from global satellite positioning system and central computer. EFFECT: increased precision of transmitter position detection, increased speed of message delivery. 1 dwg

Description

 The invention relates to satellite communication systems, in particular to systems for one-way transmission and reception of low-speed information, which is intended for short repeating reports.

 Known satellite system "COSPAS-SARSAT" for transmitting and receiving short repeating signals (see Marine Fleet, 1982, N 2, p. 22-24. Satellite search system for emergency vessels, Yu.G. Zurabov and others), containing a transmitter short reports and receivers receiving transmitter signals relayed by satellites. The disadvantages of this system is a rough (several kilometers) determination of the location of the transmitter, local localization of the location is required, relatively high requirements for the power of the transmitted signal.

 A known satellite system with one-way transmission and reception of low-speed information (see CCIR IWP 8/7 SUB-GROUP WP-9 REV-2, 3 November 1983, Satellite EPIRB, FINAL REPORT, DORNIER SYSTEM GmbH, 1-22), which contains a transmitter with frequency manipulation of the information signal and a receiver, which includes a cascade-connected linear path, a detector path with pre-detector symbol-by-filtering, and a post-detector path made in the form of a decoder, to the output of which are connected the means of consumption and presentation of information. The disadvantage of this system is the inconsistency of the receiver with the spectrum of received signals due to the superposition of the spectrum of spurious frequency modulation on it and, therefore, either a non-optimal transmission speed or a long information transmission time will be chosen.

 A known communication system, including satellite, which is the closest analogue that eliminates these disadvantages (see US Pat. RF N 2107996 H 04 B 7/26 publ. 03/27/98) and containing at least one transmitting station having at least one transmitter digitally manipulated by an information signal for transmitting short repeating summaries, and at least one base station having at least one base station receiver receiving via a satellite communication channel, the receiver performing the following reception and amplification of the signal, its conversion to the video frequency in quadratures, pre-detector quasi-optimal filtering of the manipulated signal for each binary symbol, frequency detection, accumulation, decision making for each bit of the frame, error correction, conversion to binary and decimal forms and determination of subsequent processing steps and delivery information.

 The disadvantages of this system are the relatively low accuracy of determining the location of the transmitter, especially if it is mobile, the relatively high requirement for the power of the transmitted signal, the inefficient use of time-frequency resources and, consequently, the increased delivery time of the message.

 The technical result of the invention is the elimination or reduction of these disadvantages.

 The essence of the invention lies in the fact that in a satellite communication system containing at least one transmitting station having at least one transmitter, digitally manipulated by an information signal for transmitting short repeating reports, and at least one base station having at least at least one base station receiver receiving signals from said transmitter via a satellite communication channel, the base station receiver sequentially receiving and amplifying a signal, converted its frequency in quadratures, pre-detector quasi-optimal filtering of the manipulated signal for each binary symbol, frequency detection, accumulation, decision making for each bit of the frame, error correction, conversion to binary and decimal forms and determination of subsequent steps for processing and delivering information, each transmitter is executed also with the ability to transmit signals at least two of the three frequencies, one of which serves to transmit test signals, and the other two, respectively, for trans giving cyclic formats on a schedule and for unauthorized off-schedule transmissions, is equipped with a means for receiving global satellite navigation signals, which serves for supplying frequency, time and location signals to a transmitter, means for implementing a contractual transmission program that serves to turn on and control a transmitter and means for receiving global satellite navigation, each base station receiver is also configured to simultaneously receive signals at the three indicated frequencies, and when receiving unauthorized off-schedule transmissions, accumulation is carried out in a “sliding window”, the base station is equipped with a global satellite navigation signal receiving means, which serves to send frequency, time and location signals to the base station receiver, and a central computer that processes and distributes the received information, controls signal transmission time and frequency from the means for receiving global satellite navigation signals to the base station receiver according to a given program, registration, recording the terms of the contract and the control of the means of implementing the contractual program of transfers.

 The prior art does not reveal objects that would contain the entire set of features of the system, which indicates compliance of the invention with the condition of "novelty." The prior art does not reveal objects that would contain a combination of distinctive features, which indicates the compliance of the invention with the condition "inventive step".

The drawing shows a system of one-way transmission of short repeating reports, where it is indicated:
1i - transmitter with frequency manipulation of the information signal;
2i - means of implementing the contractual program of transfers;
3i is a means of receiving global satellite navigation,
4 - base station receiver;
5 - means for receiving global satellite navigation;
6 - a central computer;
7 - information consumer;
8 - satellite communication channel;
9 - channel for transmitting global satellite navigation signals.

 The system operates as follows.

 Each transmitter 1i, where i = 1, 2, ... N, is digitally manipulated with an information signal and emits a radio signal that is modulated by a binary digital sequence within a multiple repeating frame of a fixed message length within an established separate transmission cycle that includes a sync word , information part and part of direct error correction. The information part, as its component, includes data on the location of the transmitter and the time of its radiation, which come from the means for receiving global satellite navigation signals 3i, which can be used as a GPS receiver. The location and time data, as well as reference signals of frequency and time, are received from the global satellite navigation signal receiving means 3i, which receives the corresponding signals from the global satellite navigation signal transmission channel 9, to the transmitter 1i according to a predetermined program, which is pre-generated and recorded in the means of implementation a 2i transmission program contract, which is a chip card inserted in a 1i transmitter. The transmitter 1i contains means for reading from the chip card and generating appropriate control commands, for example, turning on and off the transmitter 1i and means for receiving global satellite navigation signals 3i, generating a frame of a desired length, number of frame repeats, turning on a desired transmission mode (transmitting test signals or information signals), taking location data, reference frequency and time signals for the transmitter 1i from the means for receiving global satellite navigation signals 3i, etc.

 The transmitter 1i is configured to emit either at two frequencies or at three frequencies depending on the terms of the contract concluded between the subscriber of the corresponding transmitting station and the base station operator, i.e. transmitter 1i can be performed either with independent two or three frequency channels, or single-channel, but with tuning to two or three frequency channels. In all cases, one of the frequencies serves for the transmission of test signals, and the other two, respectively, for the transmission of cyclic formats on a schedule and for unauthorized transmissions outside the schedule. This allows you to organize several types of services, i.e. several modes, namely services for determining the location of objects, including mobile, sensory data services, such as determining temperature, pressure, etc. in a given place, for which they use the transmission mode of cyclic formats on a schedule, force majeure services (urgent delivery of information, for example, in case of an accident), for which the transmission mode is unauthorized outside the schedule. These two modes can be provided as separate independent transmitters 1i, and one transmitter. The conditions for choosing the required modes are agreed upon by the subscriber of the transmitting station and the operator of the base station also upon conclusion of the contract.

 The information signal prepared for transmission is converted to a radio frequency and emitted by the corresponding transmitter 1i and, via satellite communication channel 8, organized by one or more satellite transponders, is received at a base station having at least one base station receiver 4, and receiver 4 provides a direct or indirect access to system resources and sequentially receives and amplifies a signal, converts it into a video frequency in quadratures, a pre-detector quasi-optimal signal ltratsiyu manipulated signal for each of binary symbols, frequency detection, accumulation, a decision on each bit of the frame, error correction, conversion to binary and decimal form and determination of subsequent processing steps and information delivery. The receiver 4 provides the reception of signals simultaneously at the three frequencies indicated above. If the corresponding channel of the receiver 4 receives a signal emitted by the transmitter 1i in force majeure mode, i.e. reception of unauthorized transmissions outside the schedule, then the above accumulation is carried out in a "sliding window", which allows to increase the energy of the system and the reliability of the message. The base station is equipped with a means for receiving global satellite navigation signals 5, similar to the means for receiving global satellite navigation signals 3i and a central computer 6, which processes and distributes the received information, controls the transmission of time and frequency signals from the means for receiving global satellite navigation signals to the receiver of the base station at a predetermined the program, registration, recording of the terms of the contract and control of the implementation of the contractual program of transfers.

 Means of receiving signals of global satellite navigation 3i and 5 carry out the binding in frequency and time of the transmitter 1i and receiver 4 by receiving signals of the reference frequencies and time from the transmission channel of the signals of global satellite navigation 9. Signals of the reference frequencies and time are transmitted to the transmitter 1i and receiver 4 according to the commands received respectively from the means for implementing the contracted program of transfers 2i and the central computer 6, and synchronize the respective generators.

 The signal received by the base station receiver 4, which is expected to be scheduled at a known place in the time-frequency field, of the known cyclic format for transmitting reports, is transmitted from the transmitter 1i to the central computer 6, which uses the base station database information about the programmed elements of the cycle formats of the reports and assigned to them time windows of the beginning and end of the cyclic format for transmitting the summary and the nominal value of the center frequency (above the three frequencies indicated) of the frequency channel involved. These elements may include, in particular, the length and duration of its individual frame, their number in the loop, the structure of the frame, its fields, the manipulation speed used by the sync word and polynomial of the code with direct error correction, as well as the reliability criteria of the processed summary and the subsequent steps for delivery, archiving, commercial and operational-statistical accounting of the summary. Based on these data, the central computer 6 composes a processor channel that corresponds to the operational parameters of the expected cycles of the format of the summary given by the program, taking into account possible deviations of the frequency and time standards, which are corrected by the signals from the means for receiving global satellite navigation signals 3i and 5.

 The signal received at the base station receiver 4 of a randomly starting time signal of a known cyclic format for transmitting a summary, i.e. the signal for unauthorized transmissions outside the schedule, from the transmitter 1i, which in this case works in force majeure mode, enters the central computer 6, which uses the information of the base station database on the programmed cyclic transmission formats of the reports and the frequency channels assigned to them, allocated in The system is only for random, not fixed by the start and end time, cyclic formats of transmission of summaries. These frequency channels are organized mainly on the basis of duty monitoring.

 When transmitting by the transmitter 1i on a frequency channel intended for transmitting test signals, the receiver 4 receives these test signals and the received data is transmitted to the central computer 6, where they are compared with the given data and a decision is made on the further suitability of the transmitter 1i. Testing of each transmitter 1i is carried out upon its delivery to the subscriber of the transmitting station by the operator of the base station at the conclusion of the contract and is subsequently timed to replace the batteries, as well as negotiated by the contract and recorded in the means of carrying out the contracted transmission program 2i and in the central computer 6.

 Delivery of the message to the consumer of information 7 can be carried out on an electronic mail box via the Internet, or to his computer via a telephone line using modems, as well as via a Telex network or to a telephone set with a synthesized voice, or to a satellite communication terminal.

 When a base station operator concludes a contract, the means for implementing the contracted transmission program 2j, where j = 1, 2, ... i, ... N, of each transmitter 1j, all contract terms and conditions of operation of the corresponding transmitter 1i are entered. The base station operator can expand its service beyond its needs by providing surpluses of available time-frequency resources to unknown users, applying for a license to provide paid services and receiving a standard contract of a service provider.

Claims (1)

 A satellite communication system comprising at least one transmitting station having at least one transmitter with digitally manipulated information signal for transmitting short repeating reports and at least one base station having at least one base station receiver receiving signals from said transmitter through a satellite communication channel, and the base station receiver sequentially receives and amplifies the signal, converts it into a video frequency in quadratures, a pre-detector quas optimal filtering of the manipulated signal for each binary symbol, private detection, accumulation, decision making for each bit of the frame, error correction, conversion to binary and decimal forms and determination of subsequent processing and delivery of information, characterized in that each transmitter is capable of transmitting signals at least two of the three frequencies, one of which serves to transmit test signals, and the other two, respectively, for transmission of cyclic formats on a schedule and I unauthorized transmissions outside the schedule, equipped with a means of receiving global satellite navigation signals, which serves to send signals of frequency, time and location to the transmitter, and means of implementing a contractual program of transmissions, which serves to turn on and control the transmitter and means of receiving global satellite navigation, each base receiver the station is configured to simultaneously receive signals at the three indicated frequencies, and when receiving unauthorized transmissions outside the schedule, Accumulation is carried out in a "sliding window", the base station is equipped with a means of receiving global satellite navigation signals, which serves to supply frequency, time and location signals to the receiver, and a central computer that processes and distributes the received information, controls the transmission of frequency and time signals from the reception means signals of global satellite navigation to the base station receiver according to a given program, registration, recording of contact conditions and monitoring of contractual means th transmission program.