RU2263323C2 - Method and device for determining position of objects on basis of alarm radio signals - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: signal in client transmitter of object is subjected firstly to time-pulse, then to phase modulation. At receipt stations signal is subjected to autocorrelation processing. On basis of differences in time delays of radio signal receipt object coordinates are determined. Signal is sent to space in the moment necessary for client by packets of 10 pulses with temporary shift of position of each pulse of packet. Each pulse consists of fixed binary phase-manipulated 512 digit M-series of elements, picked with consideration of minimal level of side leafs in frequencies band 5MHz. radio receipt is performed only by three stationary base stations. Temporary delays of radio signal receipt are determined at same stations. Time-pulse modulator is connected to code series generator via Gauss filter.

EFFECT: higher efficiency, broader functional capabilities.

2 cl, 1 dwg

Description

The invention relates to the field of radio engineering and can be used to determine the location and identification of various objects in order to ensure their integrated security in the region.

Various radio navigation systems are known, as well as alarm transmission and reception systems for, for example, determining the coordinates of stolen cars (See. Proceedings of the scientific and technical conference “Planning global radio navigation”. M. 1995). The disadvantages of many of these systems are their autonomy or complexity and the large dimensions of the equipment associated with the type of coding.

Closest to the proposed invention and adopted as a prototype is a system for recognizing the location of objects (Shorin OA, Pantikyan RT "Optimization of the signal structure in a radio engineering system for transmitting alarm information. Telecommunications, 1996, No. 6, p.31) , consisting of a subscriber radio transmitter of the object whose location is estimated, three sensor stations located at known points in space and the processing center. The transmitter of the object emits a phase-coded radio signal received by the sensors and the processing center. At sensor stations, a decision is made about the presence of a signal from the object and its own phase-code signals are formed, which differ in code sequences that are emitted towards the processing center. In the three-channel unit for detecting the processing center, the presence of signals from the object and sensors is recorded, and the coordinates of the object are calculated from the measured differences in the delay time of the arrival of signals using a digital computer. The disadvantages of the prototype are:

- a high degree of dependence of the accuracy of determining the coordinates of the location of the object from fluctuations in the values of the parameters of the subscriber’s transmitters and receivers of the base stations-sensors;

- servicing only one subscriber;

- lack of information about the identification of the subscriber and the type of danger;

- system synchronization is forced - by timer;

- the subscriber’s location is determined only at strictly specified, fixed points in time;

- the lack of binding of the receivers of the base stations-sensors and the processing center to a single time system;

- the lack of high-precision clocks in the base stations-sensors and the processing center, which makes it impossible for the subscriber to send a signal at the required time.

The problem to which the present invention is directed, is the creation of a system for determining the location of objects by alarming radio signals, firstly, devoid of the disadvantages indicated in the prototype, and secondly, having higher technical, functional and operational characteristics.

This problem is solved by achieving a technical result, namely:

- to minimize the sensitivity of the coordinate determination system to the instability of the frequencies of the transmitter and local oscillators of the receivers;

- in the development of the structure of a high-frequency, broadband phase-shifted signal with time-pulse modulation, its formation, radiation, reception and processing.

This technical result in the implementation of the present invention is achieved by the fact that in the method of determining the location of the object, in which the signal in the subscriber’s radio transmitter of the object, in addition to phase modulation, is also subjected to pulse-time modulation, and then emitted into space by bursts of ten pulses. This radio signal is received by three stationary base stations, at each of which it is subjected to autocorrelation processing, and also the moments of the signal arrival are recorded by comparison with the exact time signals. The received information in the form of coded messages is sent to the processing and control center, where the location of the subscriber, his individual number and message code are determined.

In the event of an emergency, the subscriber presses a button on the miniature radio transmitter. A radio transmitter emits a high-frequency phase-shift complex signal to the air. The signal is a sequence of 5 packs. Each packet consists of 10 complex phase-manipulated pulses, the base of which is 512.

Signal Characteristics:

- the subscriber number and the alarm message code is transmitted using a ten-element code with a code base number of 11;

- the code element (impulse) is a binary phase-manipulated (0 °; 180 °) 512-bit sequence with a total duration of 100 μs;

- average pulse repetition period - 1 ms;

- coding of the number and code of the subscriber’s alarm message is achieved by temporarily shifting the position of each of the burst pulses relative to the conditional zero by one of the discrete values that are multiples of 100 μs, ranging from -500 μs to +500 μs (code base 11).

For this radio engineering system, a complex binary phase-manipulated signal based on a fixed M-sequence is used. The base of this signal is equal to the number of elementary pulses τ ₀ , that is, B = N = 512.

The choice of a fixed M-sequence as a code sequence is due to the low level of side peaks of the autocorrelation function. The code sequence is obtained based on the characteristic polynomial. For N = 512, a polynomial was chosen that gives a code sequence with a minimum level of side peaks. To minimize out-of-band radiation when forming a code sequence in a subscriber radio transmitter, a Gaussian filter is used.

The high-frequency phase-shift complex signal emitted by the radio transmitter is received by the radio receiver path of the base station receiver.

Technical characteristics of the radio receiving path of the base station receiver:

- received frequency - 886 MHz;

- bandwidth of the main selection path - 8 MHz (at the level of 3 dB);

- input path resistance - 50 Ohms;

- sensitivity - not worse than 2.5 μV;

- frequency stability - 2 · 10 ^-5 ;

- suppression of side channels of reception - not less than 70 dB.

The signal from the output of the receiver is fed to the input of the autocorrelation demodulator.

Technical characteristics of the autocorrelation demodulator:

- the demodulator works from the output of the last intermediate frequency of the receiving path of the receiver of the base station;

- provides demodulation of the binary phase-shifted (0 °; 180 °) signal at a speed of 5.0 Mbit / s;

- provides the addition of 512 discrete demodulated pulse signal;

- the signal is provided to the special processor for processing the pulse sequence after receiving the pulse;

The signal from the output of the autocorrelation demodulator is fed to the input of a special processor for processing a pulse sequence.

Technical characteristics of the special processor for processing a pulse sequence:

- the special processor receives a demodulated signal having the structure of the signal characteristics described above;

- the special processor performs the function of digitally matched filtering of the received signal in order to calculate the maximum of the autocorrelation function of the signal;

- the special processor temporarily binds the maximum of the autocorrelation function of the signal to the single-time system to identify the transmitter number and calculate the location of the transmitter in the processing and control center;

- the special processor provides decoding of signals overlapping in time from various subscribers.

The signal from the output of the special processor for processing the pulse sequence via communication lines is fed to the input of the processing and control center.

In the processing and control center, consisting of a number of digital computers integrated into a local computer network, joint processing of information received from all base stations is performed. Based on this information, the location of the subscriber, his individual number and the code of the alarm message are calculated in the processing and control center.

The invention is illustrated by the figure, which presents a block diagram of the proposed device. It consists of a small-sized subscriber radio transmitter 1, three base radio receiving stations 2, located in clearly defined places in the space, and a processing and control center 3, which is connected to the base stations by wired communication lines 4. The small-sized transmitter 1 includes a frequency synthesizer 5, a code generator sequence 6, Gaussian filter 7 and time-pulse modulator 8. The input of time-pulse modulator 8 is connected to the output of the control unit 9, and the output to the input of the phase modulator 10. The output of the phase the radiator 10 is connected to a power amplifier 11 and through a microwave filter 12 with a pin antenna 13. The transmitter 1 is equipped with a power source 14. The main blocks of the receiving base stations 2 are antenna 15, the receiver 16 with a mixer, a local oscillator and amplifiers, an autocorrelation demodulator 17, the output of which connected to a special processor for processing a pulse sequence — an autocorrelation matched filter 18, and a comparison unit with a threshold 19. In addition, base stations 2 are equipped with blocks for evaluating the delay time of receiving a signal 20 from a receiver mi reference signals of a single time 21. The outputs of the blocks 20 are the outputs of the stations 2 and are connected to the processing center and control 3 communication lines 4.

The device operates as follows. If necessary, the subscriber presses a button on the radio transmitter 1. Radio transmitter 1 emits signals that are received by base stations 2. At each station 2, the time delay of the signal with respect to the signals of a single time is estimated. Delay data is transmitted via communication lines 4 to the processing and control center 3, where the coordinates of the subscriber are calculated and their identification occurs, based on which control commands are generated.

Claims (3)

1. A method for determining the location of an object from alarming radio signals, in which the signal in the subscriber’s transmitter of the object is phase-modulated, then radiated into space in the form of an electromagnetic wave of the radio range, receive this radio signal by stationary radio receiving base stations located in known places of the space where the signal is demodulated, subjected to autocorrelation processing, compared with a threshold value and, if the threshold value is exceeded, the maxim is linked and the autocorrelation function to a single-time system, after which the results are transmitted to the processing and control center, where the coordinates of the object are determined by the differences in the time delays of the reception of the radio signal by the stationary base stations, characterized in that the signal is modulated before phase modulation, and the signal is emitted into space at a point in time necessary for the subscriber in bursts of 10 pulses with a time shift of the position of each of the burst pulses, and each of the pulses consists of a fixed binary phase-shifted 512-bit M-sequence elements selected considering the minimum level of side lobes in the frequency band is 5 MHz, the reception is performed only three fixed base stations and radio reception delay time determined at the same stations by comparing the signals of a single time. 2. A device for determining the location of objects by alarming radio signals, consisting of a processing and control center, at least three radio receiving base stations located at known points in space that contain signal receiving blocks, including matched filters that perform the functions of digital matched filtering of the received signal to calculate the maximum autocorrelation function of the signal, and the subscriber’s radio transmitter, including a phase modulator radio transmitter, a control unit and a power supply, characterized in that the subscriber’s transmitter includes a code sequence generator and a time-pulse modulation of the code sequence, a time-pulse modulator, the input of which is connected to the output of the control unit, and the output - to the input of the phase modulator, moreover, matched filters that record the fact of signal arrival and carry out the binding the maximum of the autocorrelation function of the signal to the single-time system for identifying the transmitter number and calculating its location in The processing and control center is contained only at the base radio receiving stations, while the inputs of the matched filters are connected to the outputs of the autocorrelation demodulators. 3. The device for determining the location of objects by alarming radio signals according to claim 1, characterized in that the time-pulse modulator is connected to the code sequence generator via a Gaussian filter.