RU2030755C1 - Radio-navigation system - Google Patents

Abstract

FIELD: radio navigation. SUBSTANCE: radio-navigation system includes transmitting stations 1, 2, 3, receiving station 4, transmitters 5, 6, 7 of pulse radio signals, transmitters 8, 9, 10 of continuous radio signals, receiver of pulse radio signals, phase meters of pulse radio signals, reference generator, meter of phase difference, channels of measurement of phase of continuous signal, receiver of continuous signal, meters of phase of continuous signal. EFFECT: simplified design, improved reliability of system. 3 dwg

Description

 The invention relates to radio navigation and can be used to determine the location of mobile, including highly maneuverable objects.

 Known phase radio navigation system with frequency selection of signals "Decca" (see Kinkulkin I.E., Rubtsov V.D., Fabrik N.A. Phase method for determining coordinates. M .: Sov. Radio, 1979, p. 71-90 )

 The system consists of a leading, three driven coastal transmitting stations and airborne transceivers. The length of the base lines (the distance between the master and slave stations) is 100-220 km. The range of the system is 400 km. The error in determining the coordinates is from 16-60 m during the day to 1000 m at night.

;

;

. В бортовых приемоиндикаторах эти частоты приводятся к одной частоте сравнения для каждой пары станций и определяют разности фаз принятых непрерывных сигналов.The system’s principle of operation is based on the emission of unmodulated coherent oscillations at coastal transmitting stations at frequencies that are in relation to the frequency of the leading station in simple integer relations

;

;

. In airborne receiver-indicators, these frequencies are reduced to one comparison frequency for each pair of stations and determine the phase differences of the received continuous signals.

 The disadvantages of this radio navigation system is the need to resolve the ambiguity of phase measurements, as well as an increase in the errors of phase measurements at night.

 Also known is the pulse-phase radio navigation system "Laurent-S", which we have chosen as a prototype.

 Pulse-phase radionavigation system (IFRNS) consists of a group of ground-based transmitting stations, one of which is the leading, the rest (at least two) - slaves, and an unlimited number of receiving stations.

 The length of the baseline is from 600 to 800 miles. Range 900-1480 miles with a measurement error of 0.1 μs.

Each transmitting station consists of a transmitter of pulsed radio signals at a frequency f ₁ = 100000 kHz with hardware synchronization, which ensures synchronous operation of all transmitting stations.

 In the Loran-S system, transmitting stations emit a series (packets) of pulses with a time resolution of signals from ground stations. To do this, at the slave stations, the generation of a series of pulses is performed with the code delay set for each station relative to the moment of emission of the series of pulses of the master station. In this case, a predetermined time diagram of pulsed radio signals is formed in the working area.

 The receiving station consists of a receiver of pulsed radio signals, at least three channels for measuring the phase of the pulsed radio signals, a reference generator and a meter of the difference coordinates of the object.

At the receiving station of the known radio-navigation pulse-phase system for determining the differential coordinates:
- receive pulsed radio signals from the master and slave stations;
- form the reference frequency f ₁ *;
- carry out an automatic search for received signals against atmospheric interference, for example, according to a quadrature scheme in which signal and noise mixtures are compared in phase with two reference channels;
- measure in the measuring channels the phases of the high-frequency oscillations of the signals of each transmitting station;
- eliminate the ambiguity of the phase measurement by additionally searching for a characterizing point (CT) at the leading edge of the pulsed radio signals;
- determine the difference coordinates as the difference in time delays received in the corresponding channels of the phase measurement.

 To reduce noise errors in the search channels, ambiguities and phase measurements are eliminated; long-term accumulation of the useful signal is necessary, which is equivalent to a decrease in the passband of the tracking system.

 A decrease in bandwidth during the evolution of a moving object leads to the appearance of dynamic errors and a decrease in the accuracy of the radio navigation system.

 The aim of the present invention is to improve the accuracy and reliability of measuring the coordinates of a moving object by a receiving station by introducing into each transmitting station an additional low-power transmitter of a continuous or quasicontinuous radio signal synchronized with the signal of a pulsed radio transmitter, and three channels of measuring the phase of a continuous signal in each receiving station. The output signals of these channels after appropriate conversion are used in the channels for measuring the phase of the pulsed radio signal as reference signals, which leads to compensation of the dynamic error in these channels and, accordingly, to an increase in the accuracy of the radio navigation system.

The essence of the invention lies in the fact that the radio navigation system contains at least three transmitting stations and an unlimited number of receiving stations. Each transmitting station contains a transmitter of pulsed radio signals at a frequency f ₁ , and each receiving station contains a receiver of pulsed radio signals and at least three channels for measuring the phase of the pulsed radio signal, a phase difference meter and a reference generator.

 The input of each channel for measuring the phase of the pulsed radio signal is connected to the outputs of the receiver, and the output of the channel of the phase meter is connected to the corresponding input of the phase meter.

The proposed radio navigation system differs from the known one in that in order to improve the accuracy and reliability of measuring the phase of pulsed radio signals, a transmitter of a continuous or quasi-continuous radio signal at a frequency f _i ≠ f _i (where i = 2, 3, 4 is the number of the frequency channel) is introduced into each transmitting station . The input of the continuous radio signal transmitter for synchronization is connected to the transmitter of the pulsed radio signals.

At least three channels for measuring the phase of a continuous radio signal are additionally introduced into each receiving station, each channel containing a receiver of a continuous radio signal at a frequency f _i connected to a phase meter of a continuous radio signal. The output of each channel for measuring the phase of a continuous radio signal is connected to the second input of the corresponding phase meter of the pulsed radio signal.

 The output of the reference generator is connected to the second inputs of the phase meters of the continuous radio signal.

 Thus, by introducing an additional transmitter of continuous radio signals at each ground station and phase measurement channels of these signals at the receiving station, it is possible to correct the reference frequency by an amount corresponding to the rate of change of the phase of the pulsed radio signals. Thus, the search, determination of the characteristic point and direct phase measurements are carried out in a mode equivalent to quasistatic. This eliminates dynamic errors and thereby improves the accuracy and reliability of IFRNS.

 In FIG. 1 shows a structural diagram of the proposed radionavigation system; in FIG. 2 is a block diagram of a receiving station; in FIG. 3 - time diagrams of signals emitted by three stations of the proposed radio navigation system (a - continuous mode of additional radiation, b - quasi-continuous mode).

Designations in the drawings:
1 - transmitting station "A"(leading);
2 - transmitting station "B" (first slave);
3 - transmitting station "B" (second slave);
4 - receiving station (receiving indicator);
5 - transmitter of pulsed radio signals of station "A";
6 - transmitter of pulse radio signals of station "B";
7 - transmitter of pulse radio signals of station "B";
8 - continuous radio transmitter station "A";
9 - continuous radio transmitter station "B";
10 - transmitter continuous radio signals of the station "B";
11 - receiver of pulsed radio signals;
12 - phase meter of pulsed radio signals (first channel);
13 - phase meter of pulsed radio signals (second channel);
14 - phase meter of pulsed radio signals (third channel);
15 - reference generator;
16 - phase difference meter;
17 - the first channel for measuring the phase of a continuous radio signal;
18 is a second channel for measuring the phase of a continuous radio signal;
19 is a third channel for measuring the phase of a continuous radio signal;
20 - receiver f ₂ ;
21 - receiver f ₃ ;
22 - receiver f ₄ ;
23 - phase meter continuous signal f ₂ ;
24 - phase meter continuous signal f ₃ ;
25 - phase meter continuous signal f ₄ .

 The proposed radio navigation system (see Fig. 1) can, for example, consist of three transmitting stations synchronized with each other: one leading 1 and two slave 2 and 3 and a receiving station (receiver indicator) 4. Each transmitting station contains a transmitter of pulsed radio signals 5, 6 , 7 and an additional low-power transmitter of continuous or quasi-continuous radio signals 8, 9, 10, the input of which is connected to a transmitter of pulsed radio signals.

 The receiving station (see Fig. 2) contains a pulse radio signal receiver 11, the output of which is connected to the first inputs of the three phase measurement channels of the pulse radio signals 12, 13, 14, a reference oscillator 15 and a phase difference meter 16, the output of each phase measurement channel of a pulse radio signal connected to the corresponding input of the phase difference meter.

 The receiving station includes three channels for measuring the phase of a continuous radio signal 17, 18, 19, each channel containing a receiver 20, 21, 22 connected to a corresponding phase meter 23, 24, 25, the second input of which is connected to a reference generator.

The proposed radio navigation system operates as follows. At the transmitting station "A" (master) in the radio transmitter, using a master highly stable generator, packets of 8 pulses with a period of T _about (Fig. 3) are formed and radio pulses are emitted at a frequency f ₁ = = 1000 kHz. The duration of the emitted radio pulses is 100-200 μs, the pulse repetition period in the packet is 1000 μs, and the pulse repetition period is 40-100 ms.

 To ensure the necessary level of the navigation signal relative to atmospheric interference, the pulsed power of the emitted signals must be at least 30 kW. In this case, the energy of the emitted pulses is concentrated in a band of the order of 25 kHz.

 At the transmitting slave stations "B" and "C", a series of the same pulsed radio signals is generated and emitted with predetermined time delays (Fig. 3). At the same time, synchronization of the radio signals emitted by all transmitting stations is supported, for which they use, for example, special control and synchronization equipment and a highly stable generator.

 Technical characteristics of a pulse radio transmitter of transmitting stations of the proposed radio navigation system are given in the book. Bykova V.I. and Nikitenko Yu.I. Ship radio navigation devices. M .: Transport, 1976, p.135-136.

Additionally, at each transmitting station, high-frequency narrow-band oscillations are emitted at a frequency f _i , where i is the number of the frequency channel (i = 2, 3, 4), which differs from the carrier frequency of the pulse signals f ₁ by a value specified for each station.

(2k-1), где Т_и - интервал между импульсами в пакете навигационного сигнала;
f₁ - несущая частота импульсного радиосигнала;
k - целые числа, выбираемые по числу станций из следующей последовательности 1, 2, ..., n

n =

;
i - номер частотного канала.So, for undistorted reception of pulsed and continuous signals in the frequency band Δ f ₁ allocated IFRNS, the choice of frequencies f _i can be carried out, for example, according to the following rule:
f _i = f ₁ ±

(2k-1), where T _and is the interval between pulses in the packet of the navigation signal;
f ₁ - carrier frequency of a pulsed radio signal;
k - integers selected by the number of stations from the following sequence 1, 2, ..., n

n =

;
i is the number of the frequency channel.

You can take, for example, K = 10, 15, 20. Then for f ₁ = 100 kHz and T _and = 1000 μs, we get: f ₂ = 109.5 kHz, f ₃ = 114.5 kHz, f ₄ = 119, 5 kHz.

 The radiation power of additional narrow-band signals, which ensures that the signal exceeds the interference by a factor of three (at the output of the filter with a band of 50 Hz) at a distance of 100-120 km, will not exceed 50 watts.

 Blocks of the Decca ground station can be used as a low-power additional transmitter (see Prince Kinkulkin I.E. et al. Phase method for determining coordinates, M .: Sov. Radio, 1979, pp. 71-72 and 82).

 Practically in the proposed radio navigation system, two emission modes of an additional narrow-band signal can be implemented: continuous (Fig. 3, a) and quasi-continuous (Fig. 3, b) modes.

In quasi-continuous mode, an additional radio signal is emitted in the interval T ₂ = T _o - T ₁ , where T ₁ is the transmission time of the packet of pulsed radio signals (T ₂ > T ₁ ).

 Quasi-continuous mode allows you to use one transmitting antenna at a ground station, and also simplifies the allocation of additional frequencies at the receiving station. At the same time, the continuous signal emission mode does not require the introduction of a transmitter switching unit at the transmitting station.

At the receiving station, the receiver of pulsed radio signals receives sequentially the signals of the master and two slave stations at a frequency f ₁ , and the receivers of the additional frequencies f ₂ , f ₃ and f ₄ continuous or quasi-continuous radio signals.

 The radio signals received at a highly maneuverable object differ in frequency from those emitted by transmitting stations by the magnitude of the Doppler shift.

f_i·cos(KУ-A_j); где V_пс - путевая скорость объекта, на которой размещены приемная станция;
С - скорость распространения радиосигнала;
f_i - несущая частота излучаемого радиосигнала;
КУ - курс объекта, на котором размещена приемная станция;
A_j - азимут на j-ю передающую станцию ИФРНС.The frequency shift is determined by the velocity of the receiving station relative to the ground transmitting stations and is equal to
Δf _ij =

f _i cos (KU-A _j ); where V _ps - the ground speed of the object on which the receiving station is located;
C is the propagation speed of the radio signal;
f _i - carrier frequency of the emitted radio signal;
KU - the course of the facility where the receiving station is located;
A _j - azimuth to the j-th transmitting station IFRNS.

 The maximum frequency shift at a ground speed of 3000 km / h reaches 0.3 Hz.

 The pulsed radio signals of the master and slave transmitting stations received by the receiver are fed to the first inputs of the phase measurement channels, where preliminary search and additional search of the corresponding radio signals is carried out. Continuous radio signals from the outputs of the respective receivers are fed to the first inputs of the measuring phase of these signals.

At the same time, using the reference generator, the reference frequencies f ₂ *, f ₃ *, f ₄ * are formed for phase meters of continuous signals.

In phase meters of continuous radio signals, the reference signals are monitored for a phase change in the received narrow-band radio signals. The frequency of the output signal of the phase measurement channels of continuous radio signals after filtering interference is
f $\genfrac{}{}{0ex}{}{\text{o}}{\text{i}}$ = f _i ± Δf _i By converting the frequency of the output signal of each continuous channel to the frequency of the reference radio signal f ₁ * taking into account the frequency shift Δ f _i and applying this reference signal to the second input of the corresponding phase meter, dynamic errors are compensated in the pulse phase meter, which ensures improving the accuracy of the radio navigation system.

 To build the proposed receiving station can be used schemes shown in the book. Kazarinova Yu.M. et al. Search, detection and measurement of signal parameters in radio navigation systems, M .: Sov. Radio, 1975, p. 188, 259 and 269.

 Let us evaluate the positive effect arising from the implementation of the proposed radionavigation system and expressed in a decrease in the instrumental error of phase measurement and, accordingly, difference coordinates.

(1) Инструментальная погрешность измерения фазы импульсных радиосигналов в предлагаемой радионавигационной системе (с учетом, что σ_д = 0) равно:
σ_и2=

(2) где σ_ш1 - шумовая погрешность канала измерения фазы импульсного радиосигнала;
σ_ш2 - шумовая погрешность измерителя фазы непрерывного сигнала.The instrumental error in measuring the phase of the radio signal in the known radio navigation system (σ _{and 1} ) is determined by noise errors (σ _W ) and dynamic errors (σ _d ). The total error is
σ _{and 1} =

(1) The instrumental error in measuring the phase of pulsed radio signals in the proposed radio navigation system (taking into account that σ _d = 0) is equal to:
σ _{and 2} =

(2) where σ _w1 is the noise error of the channel for measuring the phase of the pulsed radio signal;
σ _W2 - noise error of the phase meter continuous signal.

, рад,
(3) где g_пр - отношение сигнал/шум на выходе приемника, т.е. на входе измерителя;
Δ F_сс - эквивалентная полоса следящей системы;
Т_и- период следования импульсов ИФРНС. (см. Быков В.И. и Никитенко Ю.И. Судовые радионавигационные устройства. М.: Транспорт, 1876, с.101-103).In relation to a meter with a temporary discriminator, the noise error of the phase measurement is equal to:
σ _φ =

, glad,
(3) where g _CR - the signal-to-noise ratio at the output of the receiver, i.e. at the input of the meter;
Δ F _ss is the equivalent band of the tracking system;
T _and - the pulse repetition period of IFRNS. (see Bykov V.I. and Nikitenko Yu.I. Ship radio navigation devices. M.: Transport, 1876, pp. 101-103).

, мкс,
(4) Приняв для известной радионавигационной системы Δ F_сс = 0,1 Гц, g_пр =

, f₁ = 10⁵ Гц, Т_и = 40000 мкс, получим σ_ш1 = 0,61 мкс.Taking into account the errors in two measuring channels, we obtain the error in determining the difference coordinates equal to
σ _w1 =

, μs,
(4) Taking for a known radio navigation system Δ F _ss = 0.1 Hz, g _CR =

, f ₁ = 10 ⁵ Hz, T _and = 40,000 μs, we obtain σ _w1 = 0.61 μs.

 A dynamic error for a second-order tracking system occurs if an object moves with acceleration.

Error
σ _d = 2a T $\genfrac{}{}{0ex}{}{\text{2}}{\text{c}}$ _c , μs, (5) where T _ss is the time constant;
a - acceleration of a moving object.

As a movable object, on which a receiving station is installed, a plane is selected that performs a coordinated U-turn with a roll β. Acceleration at such a U-turn
a = 9.8 tg β. (6) At β = 30, the acceleration is 5.76 m / s ² (0.019 μs / s ² ) and the dynamic error is 3.84 μs.

 The total instrumental error in the known radio navigation system reaches 3.89 μs.

где Δ f_ф - полоса пропускания полосового фильтра;
Δ F_сс2 - эквивалентная полоса пропускания измерителя фазы непрерывного сигнала;
g_ф - отношение сигнал/шум на выходе фильтра.For the proposed radionavigation system, σ _d = 0, but the noise error of the channel for measuring the phase of the continuous signal σ _w2 equal to
σ _w2 =

where Δ f _f - bandpass bandpass filter;
Δ F _ss2 - equivalent passband of the phase meter of the continuous signal;
g _f - the signal-to-noise ratio at the output of the filter.

, получим f_ф = 7,45 и σ_ш2 = 0,02 мкс.Taking Δ f _CR = 25 kHz, Δ f _f = 50 Hz, g _CR =

, we obtain f _f = 7.45 and σ _W2 = 0.02 μs.

The total instrumental error in the proposed radionavigation system for the specified conditions will be equal to σ _and2 = 0.62 μs, i.e. system accuracy increases by an order of magnitude.

 An additional positive effect can be obtained by increasing the time constant of the tracking systems while maintaining a zero dynamic error.

Claims (1)

A RADIO NAVIGATION SYSTEM containing at least three transmitting stations and receiving stations, wherein each transmitting station contains a transmitter of a pulsed radio signal at a frequency f ₁ , the receiving station contains a receiver of pulsed radio signals, at least three channels for measuring the phase of a pulsed radio signal, a phase difference meter and a reference generator, moreover, each channel for measuring the phase of the pulsed radio signal is connected to the receiver and the corresponding input of the phase difference meter, characterized in that, in order to improve accuracy measurements, a transmitter of a continuous or quasi-continuous radio signal at a frequency f _i ≠ f ₁ , where i = 2,3,4, is introduced into each transmitting station. .., the input of which is connected to the second output of the transmitter of pulsed radio signals, to each receiving station - at least three channels for measuring the phase of a continuous radio signal, each channel containing a receiver of continuous radio signal at a frequency f _i connected to a phase meter of a continuous radio signal, the output of which is connected to the second input of the corresponding phase meter of the pulsed radio signal, the output of the reference generator is connected to the second inputs of the phase meters of the continuous radio signal.

Images