RU2459350C1 - Method of filtering and detecting fluctuating radiopulse packet - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: for each radio pulse, a primary adaptive robust estimate of the carrier frequency of the radio pulse is generated; an in-phase long sequence of radio pulses is generated in form of a quasi-harmonic signal; parts of the long sequence that are in-phase for the radio pulses and out of phase for noise are summed; the obtained quasi-harmonic signal is interpolated and based on the smoothed quasi-harmonic signal, using narrowband inertial phase-locked-loop frequency control, both the initial phase and the final estimate of the carrier frequency of the corresponding radio pulse of the packet of the observed mixture are estimated; coherent delay of the processed radio pulse of the observed mixture is carried out until the steady-state condition of the interpolation process is achieved; the processed radio pulse is detected via synchronous detection.

EFFECT: high noise-immunity.

Description

The invention relates to radio engineering and can be used in radio communication systems, radar systems, in diagnostic, as well as various other information systems for transmitting, receiving and extracting information, namely, the invention can have a wide class of applications as in the reception, detection of single radio pulses and their various sequences, as well as measuring their unknown carrier frequencies. The invention can also be applied in information systems with increased noise immunity, using complex signals with a large base with varying carrier frequencies, to form databases.

Known methods of processing against the background of noise of a radio pulse and its sequences: 1. The theory of signal detection. / P.S. Akimov, P.A. Bakut, V.A. Bogdanovich and others, edited by P.A. Bakut. - M.: Radio and Communications, 1984 - 440 p. 2. Nevolin V.I. Robust information systems. Synthesis and analysis methods. - M .: Radio and communications, 2008. - 312 p.: Ill .; 3. Tikhonov V.I., Mironov M.A. Markov processes. - M .: Soviet Radio, 1977; 4. Levin B.R. The theoretical foundations of statistical radio engineering in 3 books. - M.: Soviet Radio, 1976. - Book 3. - 285 p .; 5. Interference immunity of radio communication systems with the expansion of the spectrum of signals by modulation by a pseudo-random sequence. // V.I. Borisov, V.M. Zinchuk, A.E. Limarev, N.P. Mukhin, G.S. Nakhamson; under the editorship of V.I. Borisov. - M .: Radio and communications, 2003.

Using these known methods for processing a radio pulse when receiving against a background of noise, the problems of filtering and detecting a radio pulse whose distribution of the carrier frequency ω belongs to some limited non-parameterized family in the frequency range [ω ₁ ÷ ω ₂ ] can be solved. Those. valid random process observed

- вектор как известных, так и неизвестных параметров огибающей так, что

∈A₀ - множеству соответствующего эвклидова пространства, например, для прямоугольной огибающей

и

- соответственно начальное положение и длительность радиоимпульса); θ=0,1 - случайная величина, n(t) - может быть БГШ с нулевым средним и интенсивностью N₀ или какой-либо другой шум, τ_u≤Т - время наблюдения.Here, A ₀ is a known amplitude factor that determines the power of the radio pulse; φ is a random initial phase with a uniform distribution on the interval [0.2π], f (•) is the envelope function of the radio pulse, and || f (•) || = 1;

is a vector of both known and unknown envelope parameters so that

∈A ₀ - the set of the corresponding Euclidean space, for example, for a rectangular envelope

and

- respectively, the initial position and duration of the radio pulse); θ = 0.1 is a random variable, n (t) can be a BGS with zero mean and intensity N ₀ or some other noise, τ _u ≤T is the observation time.

In specific representations, against the background of noise by known methods, the following radio pulses are usually processed with a known amplitude and unknown initial phase and (or) frequency

s (t) = A ₀ cos (ωt + φ), t∈ [t ₀ , t ₀ + τ _u ],

where A ₀ , t ₀ , τ _u are the amplitude, initial position, and duration of the radio pulse, respectively, ω, φ are the frequency and initial phase, respectively unknown, the form and distribution parameters of which in the general case, as noted above (2), are not specified or are not specified parametrically. As a rule, known methods usually use the maximum likelihood method, which in many practical cases is quite acceptable. However, these methods become ineffective, namely, they are not sufficiently noise-resistant at small signal-to-noise ratios approaching single.

Closest to the claimed is a method of synchronous detection (6. Tikhonov V.I. Optimal reception of signals. M: Radio and communication, 1983, p.30), i.e. A method for synchronously processing the observed mixture of a radio pulse (quasi-harmonic signal) with additive noise. Moreover, in the synchronous detection method, the observed additive mixture of the radio pulse with noise is synchronously and in-phase processed (filtered) by a synchronous detector (in conjunction with an integrator with a reset included in the synchronous detector) using the reference oscillation, and if it is detected, a binary decisive test is carried out for alternative hypotheses by the rule. And then for Gaussian noise in the interval of the duration of the radio pulse for the known observation conditions and the given parameters of the radio pulse for this pulse, the optimal Bayesian processing with maximum noise immunity is realized. However, with unknown frequency and initial phase, both in the synchronous detection algorithm and in other methods, the real noise immunity can be significantly lower than the maximum.

The technical task of the invention is to increase the noise immunity of the synchronous detection method when filtering and detecting a received highly fluctuating burst of radio pulses on the background of noise.

This problem is solved in that the method of filtering and detecting a fluctuating burst of radio pulses, including observing an additive mixture of radio pulses with unknown frequencies and initial phases against a background of noise, synchronous and in-phase filtering of each radio pulse, is characterized by the fact that initially for each radio pulse an initial adaptive robust carrier estimate is formed frequency of the radio pulse, then, based on the initial estimate of the frequency, a in-phase long sequence of radio pulses in the form of quasigars is created onicheskogo signal later in this phase the long RF pulse sequence organize constant or variable intervals between each radio pulses long sequences are in phase to the radio pulses and not in phase noise, and can also arrange for the summation of in-phase RF pulse and not-in-phase noise for a long sequence pieces,

then, for the in-phase long sequence of radio pulses organized in this way, the obtained quasiharmonic signal is interpolated over the long sequence interval by linear, by narrow-band linear filtering, and non-linear, by phase-locked loop or robust narrow-band filtering, methods, and by a smoothed quasi-harmonic signal using narrow-band in-phase auto-tuning of the frequency, the evaluation of both the initial phase and the final evaluation carried the frequency of the corresponding radio pulse of the packet of the observed mixture, then, after evaluations, the processed radio pulse of the observed mixture is coherently delayed until the interpolation process is stationary, the processed radio pulse is detected by synchronous detection, and finally, after the detection of each radio pulse of the packet, the entire fluctuating packet is detected by the in-phase method summation of radio pulses and / or by the method of coherent su ming for strongly fluctuating synchronously detected burst corresponding video pulses.

согласно общей концепции робастного подхода (2) в задачах непараметрического обнаружения на фоне шумов. На основе этих первоначальных оценок, которые могут быть и смещенными, однако, с приемлемой первоначальной погрешностью, реализуются дальнейшие процедуры заявляемого синхронного робастного способа. Если же по условию решаемых задач частота является известной (заданной, т.е. в случае флуктуирующей пачки радиоимпульсов), то тогда в заявляемом способе процедуры реализуются только со второго раздела и вместо оценок

используются непосредственно заданные частоты.This problem is solved by the fact that in the case of unknown both the initial phase and frequency (i.e., in the case of a strongly fluctuating burst of radio pulses), adaptive robust estimates of the unknown frequency are made -

according to the general concept of the robust approach (2) in problems of nonparametric detection against a background of noise. Based on these initial estimates, which may be biased, however, with an acceptable initial error, further procedures of the claimed synchronous robust method are implemented. If, by the condition of the problems being solved, the frequency is known (given, i.e., in the case of a fluctuating burst of radio pulses), then in the claimed method the procedures are implemented only from the second section and instead of estimates

directly set frequencies are used.

на основе наблюдаемых реализаций радиоимпульса и шума конструируется длинная синфазная последовательность радиоимпульсов (синфазная пачка радиоимпульсов), длительность которой определяется выбранным методом вынесения оценок начальных фаз. Снижение влияния помех кроме синхронной обработки достигается также методами робастной нелинейной фильтрации при проведении реализуемых или нереализуемых робастных оценок частоты, а так же в процессе конструирования длинных последовательностей. Данные последовательности могут быть как с постоянными, так и переменными интервалами между импульсами, а также с суммированием отдельных участков синфазной пачки, что является синфазным для сигнала - радиоимпульса и произвольным для помеховой составляющей. Таким образом, как непосредственно, так и в дальнейших сглаживающих алгоритмах отдельные импульсы пачки будут суммироваться синфазно, а помехи - случайно, так как конструирование длинных последовательностей производится по параметрам радиоимпульсов. В спектральном представлении подобное конструирование длинной последовательности обуславливает подъем спектральных составляющих радиоимпульса в районе частоты

и подавление спектральных составляющих помех.When using frequency estimates

Based on the observed realizations of the radio pulse and noise, a long in-phase sequence of radio pulses (in-phase packet of radio pulses) is constructed, the duration of which is determined by the selected method for making estimates of the initial phases. In addition to synchronous processing, the influence of interference is also reduced by robust nonlinear filtering methods when realizable or unrealizable robust frequency estimates are made, as well as in the process of constructing long sequences. These sequences can be both with constant and variable intervals between pulses, as well as with the summation of individual sections of the in-phase burst, which is in-phase for a signal - a radio pulse and arbitrary for an interfering component. Thus, both directly and in further smoothing algorithms, individual burst pulses will be summed in phase, and interference will be randomly randomized, since the construction of long sequences is performed using the parameters of the radio pulses. In the spectral representation, such a construction of a long sequence causes the rise of the spectral components of the radio pulse in the frequency region

and suppression of spectral interference components.

Narrow-band linear or non-linear robust filtering operations are applied to the simulated long sequence of radio pulses, followed by a rather lengthy procedure for making estimates of the initial phases. At the same time, the channel for making estimates of the initial phases should have noise immunity significantly exceeding the noise immunity of the proposed method. This is achieved both by the narrow-band of this channel and, therefore, by the long time for making estimates of the initial phases, and by the use of narrow-band linear or non-linear robust narrow-band smoothing.

When making estimates of the initial phases, the frequency estimates as final can be refined. Thus, in this inventive method of filtering and detecting a strongly fluctuating burst of radio pulses against the background of noise, noise-resistant robust joint estimates of unknown frequencies and initial phases are also made.

The final procedure in the inventive method is a coherent synchronous processing of the observed mixture of radio pulses after transients in the previous procedures, i.e. synchronous detection is implemented after the corresponding observation delays. As a result of synchronous detection for a strongly fluctuating burst of radio pulses, a coherent sequence of video pulses is formed, which is finally processed by coherent accumulation. Thus, with the appropriate parameters of the noise immunity of the channels for estimating the frequency and initial phase, the noise immunity of the proposed method is close to maximum, which ensures the solution of the problem.

Industrial applicability

The method of filtering and detecting a strongly fluctuating burst of radio pulses with unknown frequencies and initial phases against the background of noise can be applied in various fields of radio engineering and other various information systems for transmitting, receiving, extracting information in radar systems, radio communications, synchronization systems, etc. And for a fluctuating burst of radio pulses, the noise immunity can be increased up to 10-20 dB, and for a strongly fluctuating burst of radio pulses more than 20 dB. This method can also be effectively used for various systems in the formation of noisy databases.

Claims (1)

A method for filtering and detecting a fluctuating burst of radio pulses, including observing an additive mixture of radio pulses with unknown frequencies and initial phases against a noise background, synchronous and in-phase filtering of each radio pulse, characterized in that initially, for each radio pulse, an initial adaptive robust estimate of the carrier frequency of the radio pulse is formed, then based on primary frequency estimates create a common-mode long sequence of radio pulses in the form of a quasi-harmonic signal, then in this in-phase long sequences of radio pulses organize constant or variable intervals between each long-cycle radio pulses that are in-phase for radio pulses and not in-phase for noise, and also summarize in-phase for radio pulses and non-in-phase for noise parts of a long sequence, then for the in-phase long sequence of radio pulses organized in this way interpolation of the obtained quasi-harmonic signal in the interval of long Using linear narrow-band linear filtering and non-linear phase-locked loop or robust narrow-band filtering methods and using a smoothed quasi-harmonic signal, using the narrow-band inertial phase-locked loop, both the initial phase and the final carrier frequency of the corresponding radio pulse of the packet of the observed mixture are estimated, then after of estimates carry out a coherent delay of the processed radio pulse of the observed mixture until These are the stationary state of the interpolation process, the processed radio pulse is detected by synchronous detection, and finally, after each radio pulse is detected, the entire fluctuating packet is detected by the in-phase summation of the radio pulses and / or by the coherent summation method for a strongly fluctuating burst of corresponding synchronously detected video pulses.