RU2620131C1 - Method of measuring delays of radio signals - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to measuring equipment and can be used in radar, navigation, communication systems for locating emitters and synchronisation. Said result is achieved due to that, method includes receiving an analysed radio signal at a given time interval and receiving reference radio signal, formation of their correlation response and determination of position of its maximum, wherein reference radio signal begins with delay by an absolute value of minimum measured delay, and with advance by a value of maximum measured delay relative to beginning and end of reception of analysed radio signal.

EFFECT: technical result is wider field of application of method on class of continuous radio signals.

1 cl, 2 dwg

Description

The invention relates to radio engineering and can be used in radar, navigation, communication systems to determine the location of emitters and synchronization.

Known correlation methods for measuring delay are based on multiplying the analyzed signal by the reference oscillation and integrating the product for all possible time shifts between them. The specified set of transformations has a special name - convolution. The signals are received at a fixed observation interval, outside of it, with time shifts during the convolution process, they are further defined in various ways.

A known method for measuring delay, including analog-to-digital conversion of the analyzed and reference signal at a given observation interval, circular convolution of signals and determining the position of the maximum results of circular convolution [Took R., Enoxon L. Applied analysis of time series. The main methods: - M .: Mir, 1982, p. 273, 257-260].

Circular convolution is carried out according to the transformation formula

where m is the delay in sampling clocks, s _n , u _n are the samples of the analyzed and reference signals, n, N is the number and number of samples, <•> _N is the operation modulo N (the remainder of dividing the number in brackets by N) .

In this method, integration is replaced by summation, and the reference signal must be of a known shape. When performing the convolution, the time-shifted reference signal is determined beyond the observation interval by a periodic continuation. This is ensured by the application of the operation modulo N. For these reasons, the field of application of the method is limited to the class of periodic signals with respect to the observation interval of a known shape.

A known method of measuring delay, including analog-to-digital conversion of the analyzed and reference signal for a given time, the formation of doubled samples of signals by supplementing the missing samples with zeros, a circular convolution of the extended samples and determining the position of its maximum [Took R., Enoxon L. Applied analysis of time rows. The main methods: - M .: Mir, 1982, p. 256, 266-274].

Performing circular convolution of the extended sample is performed according to the conversion formula given above, taking into account the doubling of the number of samples. Another option is to perform the inverse Fourier transform of the product of direct Fourier transforms of the extended samples of the analyzed and reference signals.

In this method, the signals are additionally determined by adding them with zeros in a section with a width equal to a given time, a linear non-circular convolution with a variable degree of overlap of the analyzed and reference continuous signal is formed. As a result, the amplitude of the correlation response decreases with an increase in the mutual shift of the signals, and the measured delays are shifted toward values smaller in absolute value, which is a disadvantage of the method. To reduce the bias, it is proposed to correct the results of the circular convolution ρ (m) =: ρ (m) ⋅N / (N-m), where equality with a colon =: denotes the redefinition operation. However, this is accompanied by a shift in the delay measurements of the pulsed signals.

Of the known methods, the closest to the proposed technical essence (prototype) is a method of measuring the delay time of radio signals, including receiving the analyzed and reference radio signals for a given time, forming their correlation response by possible delays and determining the position of its maximum [Falkovich S.E. Estimation of signal parameters. -M .: Soviet Radio, 1970, p. 43, 59-62, 90-91].

Modes and options for performing composite operations of the method vary depending on the conditions. With an unknown initial phase of the radio signals, quadrature reception is performed (using quadrature channels), and the correlation response is formed by determining the complex convolution module, which is obtained by the transformation formula

,

,

,

- анализируемый и опорный радиосигнал, звездочка - операция комплексного сопряжения.where τ is the possible value of the delay, T, t is the set and current time of observation,

,

- analyzed and reference radio signal, asterisk - complex conjugation operation.

When performing the convolution, the time-shifted reference signal is determined equal to zero outside the observation interval [0, T].

For signals of known shape, one-channel reception is performed with the convolution of complex quantities replaced by real ones in the above formula and with the exception of the operation of determining its module.

The disadvantage of the prototype method is to limit the scope of the class of pulsed signals that completely fall within the observation interval. Due to the variable duration of the radio signals during the convolution, the measurement of the delay of continuous signals leads to significant bias errors in the region of values smaller in absolute value.

An object of the present invention is to expand the scope of application to continuous radio signals.

The problem is achieved in that in a method for measuring the delay of radio signals, including receiving an analyzed radio signal at a given time interval and receiving a reference radio signal, forming their correlation response and determining the position of its maximum, receiving a reference radio signal begins with a delay of the absolute value of the minimum measured delay, and ends ahead of the maximum measured delay, respectively, relative to the beginning and end of the reception of the analyzed radio signal.

The proposed method differs from the known mode of performing the operation of receiving the reference signal. Initially, at the level of technical requirements, a measurement range is set in the form of a minimum and maximum measured delay. In accordance with the proposed solution, the reception is started with a delay of an absolute value minimally, and completed ahead of the maximum measured delay. In this case, a reference radio signal is generated, fixed, shortened by the width of the range of measured duration delays. This ensures the constancy of the lifetime of the reference radio signal in the observation interval for all its possible shifts in the range of measured delays, which eliminates the reason for the decrease in the amplitude of the correlation response with an increase in the mutual shift between the signals and the shift of the measured delays.

Thus, ensuring the constancy of the duration of the reference radio signal at the observation interval at all possible shifts in accordance with the proposed new condition for the operation of receiving the reference radio signal, eliminates the offset of the delay measurements and solves the technical problem: to expand the scope of the method for continuous radio signals.

In FIG. 1 shows a block diagram of a delay meter according to the proposed method;

in FIG. 2 - dependence of the measurement error on the delay value.

The delay meter (Fig. 1) contains radio receivers 1.1, 1.2, a pulse generator 2, a key 3, a correlator 4, which includes correlation channels of processing 5.1-5.N and an N-tap delay line 6, and a device for determining the maximum 7, inputs 1 ... N connected to the outputs of respectively the correlation channels of processing 5.1-5.N. The radio receiver 1.1 is connected by an output to the first inputs of the correlation processing channels 5.1-5.N, to the second inputs of which the outputs 1 ... N of the delay line 6 are connected, the input of which is connected to the key output, the first input of which is connected to the output of radio receiver 1.2, and the second the input is with the second output of the pulse generator 2, the first output of which is connected to the zero inputs of the correlation channels of processing 5.1-5.N and the device for determining the maximum 7.

Radio receivers 1.1, 1.2 provide quadrature reception of radio signals with their presentation in an integrated form. Correlation processing channels are also quadrature type. The delay line 6 of the correlator 4 multi-tap, with a fixed pitch. Pulse generator 2 generates two types of pulses: output 1, and output 2, shortened by the width of the range of measured delays of the pulse duration, to output two types of pulses:

The principle of operation of the delay meter is as follows. The analyzed and reference radio signals are received using radio receivers 1.1 and 1.2. The start / end moment of reception of the analyzed signal is set by the signal from the output 1 of the pulse generator 2, which is fed to the zero control inputs of the correlation channels of processing 5.1-5.N and the device 7 for determining the maximum. At the moment of the beginning of the pulse, the work of the correlation channels of processing 5.1-5.N (the beginning of integration) begins, and the reception of the analyzed signal ends at the end of the specified T time. With delay relative to the beginning of reception of the analyzed signal by the absolute value of the minimum measured delay | τ _min | generator 2 at output 2 generates a pulse of duration T- (τ _max- τ _min ), where τ _max > 0 is the maximum measured delay, τ _min ≤0. Thus, the moment of the end of the pulse occurs ahead of the maximum measured delay relative to the moment of the end of reception of the analyzed radio signal.

On the interval of existence of the generated pulse coming from the output 2 of the pulse generator 2 to the second input of the key 3, the reference radio signal is received from the output of the radio receiver 1.2 along the first input of the key 3. Outside of this interval, the level of the key is set to zero.

The reference signal adopted in this way is supplied to the delay line 6 of the correlator 4. At its outputs 1-N, a reference radio signal shifted in time with a given delay quantization step is obtained. In the channels of correlation processing 5.1-5.N, a correlation response is generated from the analyzed radio signal arriving at their first inputs and the delayed reference radio signal arriving at the second inputs from the corresponding outputs of the delay line 6

- анализируемый и опорный радиосигнал, Т, t - заданное и текущее время наблюдения, Δτ - шаг квантования задержки, n=0, 1, …, N-1 - номер кванта, N - число квантов, причем N⋅Δτ=τ_max<T, звездочка - операция комплексного сопряжения.Where

is the analyzed and reference radio signal, T, t is the set and current observation time, Δτ is the delay quantization step, n = 0, 1, ..., N-1 is the quantum number, N is the number of quanta, and N⋅Δτ = τ _max < T, asterisk - complex conjugation operation.

Since the reference radio signal was obtained fixed, shortened by the width of the range of measured delays, durations, it completely falls within the integration limits of formula (1), and the amplitude of the correlation response does not change when the delay between the radio signals changes.

и тем самым измеряемую задержку

.In the device for determining the maximum 7 at the end of the specified time T, that is, the position of the maximum of the correlation response is determined by the trailing edge of the pulse from the output 1 of the pulse generator 2

and thus the measured delay

.

The effectiveness of the invention is expressed in the elimination of bias measurements of the delay of continuous radio signals. The formation of the reference radio signal shortened by the width of the measurement range of the duration achieves a constant time of its existence on the observation interval for all possible shifts in the process of correlation analysis, this eliminates the reason for the decrease in the amplitude of the correlation response with an increase in the mutual shift between the signals and the shift of the measured delays of the prototype method.

Quantitative assessment was carried out by simulation method for frequency-modulated according to the sinusoidal law radio signals with a modulation frequency of 1 kHz, frequency deviation of 5 kHz. Reception time T = 2.56 ms, range of measured delays ± 200 μs, delay quantization step Δτ = 10 μs. Refinement of measurements within a quantum was carried out using interpolation [Bronstein I.K., Semendyaev K.A. Math reference. - M.: Science, GRFML, 1986, p. 510].

от истинного значения τ, толстой линией с применением способа-прототипа, тонкой линией вблизи оси абсцисс - предлагаемым способом. Погрешности способа-прототипа, достигающие по модулю 0,8-0,9 мкс, в предлагаемом способе снижаются до среднего квадратичного значения 5,3⋅10^-3 мкс.In FIG. 2 shows delay measurement errors

from the true value of τ, a thick line using the prototype method, a thin line near the abscissa axis - the proposed method. Errors of the prototype method, reaching a modulus of 0.8-0.9 μs, in the proposed method are reduced to a mean square value of 5.3 × 10 ^-3 μs.

Thus, the proposed technical solution eliminates the bias of the delay measurements and allows you to expand the scope of the method to the class of continuous radio signals.

Claims (1)

A method of measuring the delay of radio signals, including receiving the analyzed radio signal at a given time interval and receiving the reference radio signal, generating their correlation response and determining the position of its maximum, characterized in that the reception of the reference radio signal begins with a delay by the absolute value of the minimum measured delay, and ends ahead of the curve by the value of the maximum measured delay, respectively, relative to the beginning and end of the reception of the analyzed radio signal.

Images