RU2760977C1 - Multifrequency phase automatic control system - Google Patents

Abstract

FIELD: satellite technologies.

SUBSTANCE: invention relates to satellite technologies for location determination and processing of radio navigation signals. For this digital system phase-locked loop, forming individual contour tracking, introduced m individual contours for tracking phases of received signals, where m=1…i, the general contour tracking for base frequency, containing vector multiplier, filters γ and α, the filter γ performed to determine the base frequency, to obtain estimates vector of received signals phase

and vector of frequencies estimates

of received signals, the unit of coefficients calculation α, β and γ for filters.

EFFECT: invention increases noise immunity of signal phase tracking system emitted by one navigation spacecraft (NSC) of satellite navigation systems, both at the same and at different carrier frequencies, to increase accuracy of signal measuring phases of received signals and to increase energy in phase tracking circuit of signals.

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Description

The invention relates to satellite technologies for determining the location and processing radio navigation signals.

Known digital phase-locked loop system, presented in RU 2431917 C1. Published on October 20, 2011 and containing a series-connected digital phase discriminator, an adder, a digital low-pass filter, a controlled digital harmonic signal generator and a 90 ° phase shifter, the output of which is connected to the quadrature control input of the digital phase discriminator, the first multiplier, the second multiplier and accumulator with reset, the output of which is connected to the second input of the adder, the input of the phase detector and the first input of the first multiplier are connected to each other and are the input of the digital phase-locked loop, the control input of the digital phase discriminator is connected to the second input of the second multiplier and is the control input of the digital phase-locked system autotuning, the output of the controlled digital harmonic signal generator is connected to the in-phase control input of the digital phase discriminator and the second input of the first multiplier, the second output of the digital low-frequency fil 4 is the output of a digital phase-locked loop.

The disadvantage of the known digital phase-locked-loop (PLL) system is the low accuracy of the signal phase measurement and low noise immunity, due to the fact that only received two-component signals emitted by other navigation spacecraft (NSC) are processed, both at the same carrier frequency and at different carrier frequencies and are processed in similar and independent PLL systems. This causes neglect of the general dynamics of the phases of signals at the same frequency and different NSCs, which leads to energy losses.

The closest one, taken as a prototype, is a digital phase-locked loop system described in the book GLONASS. Principles of construction and functioning / ed. A.I. Perova, V.N. Kharisova. - M .: Radiotekhnika, 2010, p. 507, fig. 13, fig. 14 and containing a series-connected digital phase discriminator, a digital low-pass filter, a controlled digital harmonic signal generator and a 90 ° phase shifter, the output of which is connected to the quadrature control input of the digital phase discriminator, the output of the controlled digital harmonic signal generator is connected to the in-phase control input of the digital phase discriminator, the control input of the digital phase discriminator is the control input of the digital phase-locked loop, and the second output of the digital low-pass filter is the output of the digital phase-locked loop.

The disadvantage of such a digital phase-locked loop system, taken as a prototype, is the low accuracy of the signal phase measurement and low noise immunity, due to the fact that each of the components of the received signals are processed separately, while the overall phase dynamics due to the movement of the consumer and the instability of the receiver's reference oscillator are not taken into account. leads to energy losses.

The technical result of the invention is to increase the noise immunity of the system for tracking the phases of signals emitted by one satellite of satellite navigation systems, both at the same and at different carrier frequencies, increasing the accuracy of measuring the phases of the signals of the received signals and increasing the energy in the signal phase tracking loop.

и вектора оценок частот принимаемых сигналов

The specified technical result is achieved by the fact that in a known digital phase-locked loop system containing a series-connected digital phase discriminator, a digital low-pass filter, a controlled digital harmonic signal generator and a 90 ° phase shifter, the output of which is connected to the quadrature control input of the digital phase discriminator, the output of the controlled of the digital harmonic signal generator is connected to the in-phase control input of the digital phase discriminator, forming an individual tracking loop, and the control input of the digital phase discriminator is the control input of the digital phase-locked loop, the second output of the digital filter is the output of the individual loop, m individual tracking loops are introduced for the phases of the received signals, where m = 1 ... i, a block for calculating the coefficients α, β and γ for filters, a common tracking loop for the base frequency, containing a vector multiplier and a sequential o connected filter γ and filter α in parallel, the input of the vector multiplier are the outputs of the discriminators of individual contours, the first output of the general circuit is the second control input of the individual circuits, the second output of the general circuit is the third control input of the individual circuits, while the filter γ is made with the possibility of determining the base frequency, to obtain a vector of estimates of the phases of the received signals

and the vector of estimates of the frequencies of the received signals

where

K = (K ₁ KK _m ) ^T - vector of coefficients of the ratio of the i-th frequency to the base frequency

α, β and γ are the coefficients of the tracking filter,

h is the integration interval,

d _t = (d _{1, t} , ..., d _{m, t} ) ^T is a vector of outputs of discriminators, the values of which are described by the expression

where

ξ _i is the NSC signal at the ith input of the discriminator,

- экстраполированное значение фазы i-го сигнала на шаг h, векторное произведение K^Td - взвешенная сумма выходов дискриминаторов, Im { } - определение мнимой части.

is the extrapolated value of the phase of the i-th signal to step h, the cross product K ^T d is the weighted sum of the outputs of the discriminators, Im {} is the definition of the imaginary part.

The essence of the proposed multifrequency phase-locked loop (MCHFAP) system is illustrated by the structural diagrams shown in the figures. These figures do not cover and, moreover, do not limit the entire scope of the claims of this solution, but are only illustrative material for a particular case of execution, where in Fig. 1 shows a block diagram of the MChFAP; fig. 2 is a diagram of an individual circuit; fig. 3 is a general circuit diagram.

MPFAP (Fig. 1) contains m individual loops for tracking the phases of signals (corresponds to the number of received signals), a common tracking loop for the base frequency and a block for calculating filter coefficients. At the input of the MFAP, which are inputs 1 of each of the individual circuits, a set of digitized ADC readings ξ _{i, t is} fed to different discriminators having different reference signals, different frequencies, ranges, where i = 1 ... m.

и

связанные с оценкой базовой частоты.In the common circuit, the increments in the phases of the signals are formed

and

related to base frequency estimation.

на основе приращений по фазам

и

а также определяются экстраполированные значения фаз

используемые для управления генераторами сигналов в индивидуальных контурах.In each individual circuit, estimates of the phases of the received signals from the NSC are formed

based on phase increments

and

and also the extrapolated values of the phases are determined

used to control signal generators in individual circuits.

Each individual circuit of the i-th PLL (Fig. 2) contains a serially connected digital phase discriminator D, a digital filter β, a controlled digital generator UG of a harmonic signal, the output of which is connected to the in-phase control input of a digital phase discriminator D.

At the output 2 of each individual circuit, a process d _{i, t is formed} , which is proportional to the magnitude of the phase mismatch of the carrier of the input and reference signals, which are fed to input 1 of the common circuit. The input 5 of each individual circuit receives G _{i, t} - the value of the symbol of the modulating sequence at time t.

соответствующая i-му частотному диапазону или компоненте принимаемого сигнала.At the output 1 of each individual circuit, a phase estimate is formed

corresponding to the i-th frequency range or component of the received signal.

A common tracking loop (Fig. 3), containing a vector multiplier (K ^T d process), a series-connected filter γ and a filter α in parallel, the filter γ being configured to determine the base frequency for calculating the phase increment for individual loops.

и вектор приращений фаз

пропорциональные базовой частоте, которые поступают на входы 2 соответствующих индивидуальных контуров. На выходе фильтра α формируются приращения фаз

пропорциональные взвешенной сумме K^Td выходов дискриминаторов и значениям частот принимаемых сигналов, которые поступают на входы 3 соответствующих индивидуальных контуров.The values of the processes d _{i, t} from the output 2 of each of the individual circuits are fed to the input 1 of the general circuit, to the vector multiplier, at the output of which the process K ^T d is formed, which is fed to the filter γ and the filter α. At the output of the filter γ, estimates of the frequency vector are formed

and the vector of phase increments

proportional to the base frequency, which are fed to the inputs 2 of the corresponding individual circuits. At the output of the filter α phase increments are formed

proportional to the weighted sum K ^T d of the outputs of the discriminators and the values of the frequencies of the received signals, which are fed to the inputs 3 of the corresponding individual circuits.

и вектора оценок частот принимаемых сигналов

(размерность вектора фаз

и вектора частот

соответствуют количеству сигналов m принимаемых от одного НКА), которые можно определить из системы выражений:Determination of the vector of estimates of the phases of the received signals

and the vector of estimates of the frequencies of the received signals

(the dimension of the phase vector

and frequency vectors

correspond to the number of signals m received from one satellite), which can be determined from the system of expressions:

(за базовую частоту может быть принята любая из принимаемых частот), α, β и γ - коэффициенты следящего фильтра, h - интервал интегрирования, d_t=(d_1,t, …, d_m,t)^T - вектор выходов дискриминаторов, значения которых описываются выражениемwhere K = (K ₁ KK _m ) ^T is the vector of coefficients of the ratio of the i-th frequency to the base frequency

(any of the received frequencies can be taken as the base frequency), α, β and γ are the tracking filter coefficients, h is the integration interval, d _t = (d _{1, t} , ..., d _{m, t} ) ^T is the discriminator outputs vector, whose values are described by the expression

ξ _i is the NSC signal at the ith input of the discriminator,

- экстраполированное значение фазы i -го сигнала на шаг h, векторное произведение K^Td - взвешенная сумма выходов дискриминаторов, Im { } - определение мнимой части.

is the extrapolated value of the phase of the i -th signal to step h, the cross product K ^T d is the weighted sum of the outputs of the discriminators, Im {} is the definition of the imaginary part.

In the block for calculating the filter coefficients α, β and γ, the coefficients α, β and γ are calculated by the iterative method. The calculation procedure is divided into 4 stages:

Stage 1. Set initial data:

q is the value of the signal-to-noise ratio in the readout of the correlator;

N _ϕ is the spectral density of the phase shaping noise;

N _ω is the spectral density of the shaping noise of the base frequency.

решая систему уравнений:Stage 2. Determine the values of the correlation matrix

solving the system of equations:

where

решая систему уравнений с начальными условиями

Step 3. Determination of the gain

solving the system of equations with initial conditions

используя выраженияStage 4. Determination of the coefficients α, β and γ from the calculated values of the coefficients

using expressions

The use of the invention makes it possible to increase the accuracy of measuring the phases of signals and the noise immunity of the phase-locked loop system as a whole, both when receiving signals at different quadratures of the signal of one carrier, and at different carrier frequencies of one NSA, optimal estimation of the phases of all received signals is carried out, due to the weighted summation of the outputs of the discriminators proportional to the ratio of the carrier frequencies of the received signals to the base frequency.

Claims (13)

A multifrequency phase-locked loop containing a series-connected digital phase discriminator, a digital low-pass filter, a controlled digital harmonic signal generator and a 90 ° phase shifter, forming an individual phase tracking loop, the output of a controlled digital harmonic signal generator is connected to the common-mode control input of the digital phase discriminator, and the control input of the digital phase discriminator is the control input of the individual circuit, and the output of the digital filter is the output of the individual circuit, characterized in that m individual loops are introduced for tracking the phases of the received signals, where m = 1 ... i, the block for calculating the coefficients α, β and γ for filters, a common base frequency tracking loop containing a vector multiplier and a series-connected filter γ, and a filter α in parallel, the input of the vector multiplier is the outputs of the discriminators of individual contours, the first output is common th loop is the second control input of the individual loops, the second output of the common loop is the third control input of the individual loops, while the filter γ is configured to determine the base frequency to obtain a vector of phase estimates

of the received signals and the vector of frequency estimates

received signals

where K = (K ₁ KK _m ) ^T is the vector of coefficients of the ratio of the i-th frequency to the base frequency

α, β and γ are the coefficients of the tracking filter; h is the integration interval; d _t = (d _{1, t} , ..., d _{m, t} ) ^T is a vector of outputs of discriminators, the values of which are described by the expression

where ξ _i is the NSC signal at the i-th input of the discriminator;

- extrapolated value of the phase of the i-th signal to step h; the vector product K ^T d is the weighted sum of the outputs of the discriminators; Im {} - definition of the imaginary part.

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