# Mode of determination of coordinates of unknown transmitter in system of satellite communication

FIELD: the invention refers to radio technique means of determination of a direction, location, measuring of distance and speed with using of spaced antennas and measuring of a phase shift or time lag of taking from them signals.

SUBSTANCE: the proposed mode of determination of coordinates of an unknown transmitter is based on the transmitter's emitting of a tracing signal to the satellite, on receiving of signals of an unknown transmitter and legimite transmitters which coordinates are known, on forming a file of clusters, on selection of the best clusters out of which virtual bases are formed for calculating coordinates of legimite and unknown transmitters according to the coordinates of legimite transmitters and the results of calculation of their coordinates one can calculate mistakes of measuring which are taken into account at calculating the coordinates of the unknown transmitter.

EFFECT: increases accuracy of determination of coordinates of an unknown transmitter in the system of a satellite communication with a relay station on a geostationary satellite.

2 dwg, 1 tbl

The invention relates to electronic means of determining the direction, location, dimensions, distance, or speed using diversity antennas and measuring the phase shift or time-delay retiring signals (system determination of the difference between the paths traveled by the signal) and, in particular, to a method of determining the coordinates of the transmitters in the satellite repeater in the geostationary Artificial Satellite of the Earth.

The known method described in U.S. patent No. 5008679, N 04 7/185 (G 01 S 5/02), publ. 16.04.91.

The method of determining the coordinates of the unknown transmitter is in reception and re-radiation signal transmitter whose coordinates will define the repeaters located on Board two closely located in a geostationary orbit of an Artificial Earth Satellites (AES), the reception pereizluchennykh signals two Earth Stations and the calculation of desired coordinates in the point of intersection of the curve of constant time delay of received signals with a curve of constant Doppler frequency offset of received signals.

The disadvantage of this method is the low accuracy of determination of coordinates of the unknown transmitter.

The closest to the technical nature of the proposed solution is described in U.S. patent No. 5570096, 01 S 5/02, publ. 29.10.96.

The method of determining the coordinates of the unknown transmitter in the satellite communication system is the radiation transmitter tracer signal to the satellite and receiving at least one Terrestrial receiver signal relayed by the satellite equipment to determine the speed and position of the satellite according to the signal and then determining the coordinates of the unknown transmitter at the crossing point on the Earth's surface curve of constant time difference of arrival of signals from the unknown transmitter with two satellites and a curve of constant values of the Doppler frequency offset.

The disadvantage of the prototype method is characterized by low accuracy of determination of coordinates of the unknown transmitter due to the truncation error, which increases with the removal of the unknown transmitter from the sub-satellite point [Spearco, Sun. The phase direction finding in satellite communications. Electronic journal "Investigated in Russia", 35, str-388, 2003, http://zhumal.gpi.ru], and the error associated with diurnal, seasonal and other izmenenie electromagnetic characteristics of the propagation of signals.

The invention is achieved technical result - increasing the accuracy of determining the coordinates of the unknown transmitter in the satellite communication system with retranslate the rum in the geostationary Artificial Satellite of the Earth.

To obtain this result, the proposed method of determining the coordinates of the unknown transmitter in the satellite communication system with a relay in the geostationary Artificial Satellite of the Earth, including a radiation transmitter tracer signal to the satellite and Terrestrial reception by the receiver tracer signal relayed by the satellite equipment, determining the position of the satellite according to the signal, according to the invention form an array of clusters, each consisting of 3+n elements, the first, second and third elements of each cluster represent, respectively, the coordinates of the satellite: distance, elevation and azimuth, the fourth element represents the value of the phase of the signal is unknown to the transmitter at the time of determining the coordinates of the satellite and subsequent elements of each cluster are phase signals legitimate transmitters, the coordinates of which are known, also at the time of determining the coordinates of the satellite, choose at least four of the best cluster, grouped in pairs of which form at least two virtual base, respectively, to calculate the coordinates of the legitimate and unknown transmitters at known coordinates legitimate transmitters and results calculation calculate their coordinates measurement error that consideration is given to the t when calculating the coordinates of the unknown transmitter.

Distinctive features of the proposed method are as follows: form an array of clusters, each consisting of 3+n elements, the first, second and third elements of each cluster represent, respectively, the coordinates of the satellite: distance, elevation and azimuth, the fourth element represents the value of the phase of the signal is unknown to the transmitter at the time of determining the coordinates of the satellite, and the subsequent elements of each cluster are phase signals legitimate transmitters, the coordinates of which are known, also at the time of determining the coordinates of the satellite, choose at least four of the best cluster, grouped in pairs of which form at least two virtual base, respectively, to calculate the coordinates of the legitimate and unknown transmitters at known coordinates legitimate transmitters and results calculation calculate their coordinates measurement errors, which take into account when calculating the coordinates of the unknown transmitter.

The proposed method of determining the coordinates of the unknown transmitter is carried out in the following sequence: radiation transmitter tracer signal to the satellite in order to accurately determine the current coordinates of the satellite (azimuth, elevation and range), Terrestrial receiver tracer signal, retranslation is the satellite equipment to measure the current distance of the satellite, the signal is unknown to the transmitter and the legitimate transmitters, the coordinates of which are known, form an array of clusters, each consisting of 3+n elements, the first, second and third elements of each cluster represent, respectively, the coordinates of the satellite: distance, elevation and azimuth, the fourth element represents the value of the phase of the signal is unknown to the transmitter at the time of determining the coordinates of the satellite, and the subsequent elements of each cluster are phase signals legitimate transmitters, the coordinates of which are known, also at the time of determining the coordinates of the satellite, choose at least four of the best cluster, grouped in pairs of which form, at least two virtual base, respectively, to calculate the coordinates of the legitimate and unknown transmitters at known coordinates legitimate transmitters and results calculation calculate their coordinates measurement errors, which take into account when calculating the coordinates of the unknown transmitter.

Figure 1 shows the block diagram of the device that implements the inventive method. Figure 2. the calculated dependence of the errors in the determination of coordinate ΔY (C) from the values of the Y coordinates (degrees).

The device in figure 1, implements the inventive method contains: primemover is giving the antenna 1,
controller antenna 2, the filter reception/transmission 3, an amplifier 4, a modulator 5, the frequency synthesizer 6, the pseudo-random sequence generator 7, the receiving unit tracer signal 8, the correlator 9, receiving the block signal of the unknown transmitter 10_{1}foster blocks signals legitimate transmitters 10_{2}...10_{n}unit measurement range 11, a data buffer 12, the block selecting at least 4 clusters 13, the computing unit coordinates legitimate transmitters 14, site permanent storage of coordinates legitimate transmitters 15, block calculate the coordinates of the unknown transmitter 16.

The method of determining the coordinates of the unknown transmitter is implemented as follows. Transmitting-receiving antenna 1 is used for transmission and reception of the tracer signal, and the signal is unknown and legitimate transmitters. For tracer signal determines the distance of the satellite. The measurement range of the satellite is performed by estimating the time delay of the signal generated by the pseudo-random sequence generator (SRP) 7. In the prototype this signal is called dressirovochnyy. SRP is modulated in the modulator 5 carrier frequency generated by the frequency synthesizer 6. The modulated signal is amplified in the power amplifier 4 and through the filter of the reception/transmission 3 is radiated by using a transmitting antenna in the direction of the IP is.
The signal SRP, relayed by satellite equipment, converted transceiver antenna 1 passes the filter, the reception/transmission 3 and is picked by the receiving unit tracer signal 8. In the correlator 9 compares the time of the emitted and received the SRP, which allows us to calculate the time delay adopted SRP relatively emitted SRP and later in the unit of measurement range 11 to measure the distance of the satellite. Transceiver antenna 1 operates in the tracking mode for the movement of the satellite. This is because the angular beam width of the antennas for satellite communications, as a rule, much smaller than the angular size of the trajectory of the daily movement of the satellite, which shaped like a figure "8". Tracking transceiver antenna for moving the satellite controller provides antenna 2, which thus provides a measurement of the azimuth and elevation of the satellite relative to the Earth Station. Data about the azimuth angle and range exhaustively describe the position of the satellite. These data are entered in the data buffer 12. The unknown signal from the transmitter arrives at the receiving unit signal of the unknown transmitter 10_{1}. Signals legitimate transmitters are received at the receiving units 10_{2}...10_{n}. The functions of all the receiving units 10_{1}...10_{n}are receiving signals, compensation Dopplers is who is the offset frequency,
assessment and memorizing the instantaneous phase of the carrier frequencies of the signals at the inputs of the receiving units, i.e. signals of the unknown and legitimate transmitters. The values of the three coordinates of the satellite, as well as the phases of the signals of the unknown and legitimate transmitters are grouped into clusters. The parameters of the elements of each cluster are determined at the same time. On the receiving units 10_{1}...10_{n}do heterodyne signals from the frequency synthesizer 6. In the data buffer 12 is the accumulation of a sufficiently large number of clusters, the values of the elements are changed in the process of motion of the satellite. The frequency of formation of clusters is determined by the required accuracy of the estimates of the coordinates of the unknown transmitter. Having accumulated in the data buffer 12 a large number of clusters in the unit 13 selects at least 4 clusters, grouped in pairs. Both pairs represent two equivalent virtual base. The coordinates of the two ends of the virtual database is set to the first three elements (angular position and range of the satellite at the time of work measurement) in the selected clusters. Knowing these coordinates, it is easy to calculate the spatial location of the virtual base relative to the Equatorial meridional plane and the length of the base. The criterion for selecting clusters from the cumulative array is the tsya the degree of proximity of the intersection angle of the virtual database to the 90°
when that minimizes the error in the determination of the coordinates of the unknown transmitter and coordinates legitimate transmitters. Of the elements of the selected clusters in the unit 14 calculates the coordinates of the legitimate transmitter error caused, in particular, the state of the propagation path of signals and methodical error. Node persistent storage 15 stores the exact values of the coordinates legitimate transmitters. This allows us to calculate the block 14 is also the current value of the real error by calculating the difference between the exact and the measured value. In block 16 calculates the coordinates of the unknown transmitter and ignored the error value from the output unit 14.

The application of this invention enables accurate positioning of the unknown transmitter situated at any point on the surface of the globe in the service area of communication satellites located in geostationary orbit.

Improving the accuracy of determination of coordinates can be proved as follows in the case of only one geographical coordinates of the unknown transmitter. Figure 2 shows the calculated dependence of the errors in the determination of coordinate ΔY (C) from the values of the Y coordinates (degrees) [see references cited above]. The value of Y=0 corresponds to p is sputnikovoi point,
when the distance between the satellite and the Ground surface is minimal. If you do not know the transmitter is located at the sub-satellite point, the truncation error is zero. The error caused by the condition of the propagation path of the signal is unknown and may be significant to any location of the unknown transmitter. Let also legitimate transmitters are located at positions Y_{1}, Y_{2}, Y_{3}. Since the coordinates legitimate transmitters are known, the measurement results easy to calculate the error ΔY_{1}that ΔY_{2}that ΔY_{3}. Most just use a stepped approximation of the curve of the real errors (bold line in figure 2) and calculate the desired coordinate according to the rules given in the table.

The measured value of Y_{ISM}belongs to the interval | The desired value of the UNP |

0<Y_{ISM}<Y_{1} | UNP=_{UiTM} |

Y_{1}<Y_{ISM}<Y_{2} | UNP=Y_{ISM}-Y_{1}+Y_{ISM} |

Y_{2}<Y_{ISM}<Y_{3} | UNP=Y_{ISM}-Y_{2}+Y_{ISM} |

Here Y_{ISM,}Y_{ISM}- the measured values of the coordinates legitimate transmitters.

Let the unknown transmitter is positioning at the position of the UNP. Then, as can be seen from figure 2, the error prototype 0.75°. The accuracy of determining the coordinates of the proposed method does not exceed 0,25°. The use of other methods of approximation, for example linear or spline function with knots at the points of placement legitimate transmitters will further increase the efficiency of the proposed method.

The method of determining the coordinates of the unknown transmitter in the satellite communication system including a radiation transmitter tracer signal to the satellite and terrestrial reception by the receiver tracer signal relayed by the satellite equipment, determining the position of the satellite according to the signal, wherein forming the array of clusters, each consisting of 3+n elements, the first, second and third elements of each cluster are respectively the coordinates of the satellite: distance, elevation and azimuth, the fourth element represents the value of the phase of the signal is unknown to the transmitter at the time of determining the coordinates of the satellite, and the subsequent elements of each cluster are phase signals legitimate transmitters, the coordinates of which known also at the time of determining the coordinates of the satellite select at least four of the best cluster, grouped in pairs of which form at least the ve virtual base to calculate the coordinates of the legitimate and unknown transmitters, on the known coordinates of the legitimate transmitter and the results of a calculation of their coordinates calculate measurement errors, which take into account when calculating the coordinates of the unknown transmitter.

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SUBSTANCE: the proposed mode of determination of coordinates of an unknown transmitter is based on the transmitter's emitting of a tracing signal to the satellite, on receiving of signals of an unknown transmitter and legimite transmitters which coordinates are known, on forming a file of clusters, on selection of the best clusters out of which virtual bases are formed for calculating coordinates of legimite and unknown transmitters according to the coordinates of legimite transmitters and the results of calculation of their coordinates one can calculate mistakes of measuring which are taken into account at calculating the coordinates of the unknown transmitter.

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