RU2335781C1 - Method of signal reciprocal delay measurement with program operating frequency tuning (poft) - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: substance of method of signal reciprocal delay measurement with program omnirange operating frequency tuning implies application of stage-by-stage reciprocal signal phase spectrum reconstruction, except that within address signal set at the first stage, and detection of delay time based thereof. At the second stage reciprocal signal phase spectrum is reconstructed within frequency range 0÷f_n, where f_n is width of address signal set. At the third stage disambiguation of two previously reconstructed reciprocal phase spectrum is provided alongside with calculation of reciprocal signal delay with margin error inversely proportional to radio signal carrier frequency value.

EFFECT: higher measurement accuracy of reciprocal signal delay.

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Description

Application area

The invention relates to the field of radio navigation and can be used in differential ranging and other systems for determining the location of sources using the mutual delay of received radio emissions as a coordinate-informative parameter.

State of the art

The known method [2, p. 48], [3, p. 253] measuring the mutual delay of discrete frequency broadband signals (RF SHPS or PPRCH), implemented in phase radio navigation systems and phase direction finding methods. The error in determining the navigation parameter in radio navigation systems is defined as

where c is the speed of light;

Δ _φ is the error in determining the phase difference (phase incursion);

f ₀ - carrier radiation frequency,

or the measurement error of the mutual delay Δ _τ , taking into account Δ _rnp = s · Δ _τ [4, p.234]:

The error in determining the mutual delay is inversely proportional to the carrier frequency of the signal. However, with the phase method, the measurement of the phase difference Δφ is unambiguously associated with the radio navigation parameter only when the phase advance between the points of reception of the radio signal is less than 2π. In particular, in direction finders, a base restriction is introduced for this. If this condition is not met, the phase difference Δφ includes an unknown number N of complete phase cycles [4, p. 282]. To simultaneously satisfy the requirements for the accuracy and uniqueness of phase measurements, one of the known methods for eliminating the ambiguity of measurements is required [4, p. 285], [5, p. 19-28]. In this case, the multiscale method was most widely used. For its implementation, it is necessary that the signals are emitted at several frequencies that are interconnected in a certain integer ratio. A multiscale meter allows an unambiguous measurement within the wavelength of the lowest difference frequency with scale accuracy at the fundamental frequency. This method is successfully implemented in radio navigation systems of the super-long and long-wave range. But it is hardly possible to use signals with frequency hopping for the formation of multiscale measurements in the VHF range under conditions of a priori parametric uncertainty.

Closest to the invention is a method (selected as a prototype), which is proposed in [6].

Its essence is as follows: dividing the working frequency range into bands corresponding to the width of the spectrum of individual emissions; detection and reception of single radiation signals from frequency hopping in spatially separated points of reception (PRPP); calculation of mutual correlation functions (VKF) of the corresponding radio pulses received in different PRPP; determination of complex mutual spectra of radio pulses and their arguments; interpolation of the mutual phase spectrum (VFS) between the received radio pulses; estimation of the mutual delay by the slope of the entire VFS.

Interpolation, conjugation or disambiguation of the mutual phase spectrum is ensured by determining an integer number of transitions through 2π between the components of the VFS.

Multi-frequency processing is characterized by the VFS conjugation index of single radio emissions received at different frequencies.

At the frequencies f _k and f _i (with f _k > f _i and Ф _ki = f _k -f _i ), two single RF emissions of a frequency hopping signal belonging to one IRI S ₁ (t, f _k ), S ₁ ( t, f _i ), S ₂ (t + Δτ, f _k ) and S ₂ (t + Δτ, f _i ), where Δτ is their mutual delay.

(Δτ) и B_fi(Δτ), и затем аргументы их комплексных взаимных спектров:

(f) и Δφ_fi(f) (фиг.1). Аргументы комплексных взаимных спектров и есть взаимные фазовые спектры.The signals are relayed to a single processing point, where their VKF are defined:

(Δτ) and B _fi (Δτ), and then the arguments of their complex mutual spectra:

(f) and Δφ _fi (f) (Fig. 1). Arguments of complex mutual spectra are mutual phase spectra.

The VFS of each individual radio emission is determined by:

- the initial phases Δφ _k and Δφ _i ;

- estimates of the mutual delay Δτ _k and Δτ _i .

Secondary grades and standard deviations are determined by:

,provided that

,

The value of the mutual delay of the signals from two single radio emissions is obtained by correlating the increment of the phase of the VFS to its width, that is:

where m _ki is the number of integer transitions of the VFS through 2π between the frequencies f _k and f _i .

The number of integer transitions of the VFS through 2π m _ki is defined as:

- операция выделения целого числа. СКО числа переходов через 2π определяется:Where

- the operation of extracting an integer. The standard deviation of the number of transitions through 2π is determined by:

A confidence interval is introduced for Δm _ki / σ _m (Δm _ki must be less than 0.5):

возможна интерполяция ВФС между радиоимпульсами:the expression for Φ _ki is determined, for which with confidence probability

VFS interpolation between radio pulses is possible:

where I _{P dov} (Δm _ki / σ _m ) is the value of the confidence interval Δm _ki / σ _m at a confidence probability of P _dov . The MAX index in expression (10) means that this is the maximum frequency spacing between the EPI. Interfacing the VFS is possible under the condition Ф _ki ≤Ф _k-iMAX .

The accuracy of the estimation of the mutual delay in the case of the restoration of the VFS between two ERIs, according to expression (5), will be determined:

Thus, in the prototype, the error of the mutual delay is inversely proportional to the width of the spectrum of the signal with frequency hopping.

As a disadvantage of this method, it should be noted that in the absence of ambiguity in the measurement of a signal with frequency hopping, the mutual delay error depends on the width of the spectrum of the signal, and not on its carrier frequency. A comparative analysis of the analogues of the invention shows that in the case of a priori uncertainty of the signal parameters, it is possible to increase the accuracy of measuring the mutual delay of the signals with frequency hopping due to removal of the restriction on the dependence of the measurement error on the signal spectrum width in the prototype.

The purpose of the invention is to increase the accuracy of measuring the mutual delay of the signals from the VHF frequency hopping due to the restoration of the mutual phase spectrum to zero.

Brief Description of the Drawings

Figure 1 shows the mutual phase spectrum of the ERI at different frequencies;

In figure 2. shows a graph of the recovery of the VFS signal with frequency hopping within the address group of frequencies f _ki ;

In figure 3. the dependence of the measurement error of the instrumentation on the width of the address group of frequencies f _ki (q = 3, ΔF = 25 kHz, T = 0.1 s) is shown;

In figure 4. Shown is the transfer of the reconstructed VFS signal to the zero frequency region;

In Fig.5. shows a graph of the restoration of the VFS signal to zero;

In Fig.6. the dependence of Φ _kMAX on the width of the address group of frequencies Φ _{ki of the} reconstructed VFS for various signal-to-noise ratios (ΔF = 25 kHz, T = 0.1 s) is shown;

7 shows a block diagram of the principle of the method.

SUMMARY OF THE INVENTION

The essence of the method for measuring the mutual delay of signals with software tuning the operating frequency of the VHF range is that they use phased reconstruction of the mutual phase spectrum of the signals, and at the first stage, within the address group of the signal and determine the delay time from it, at the second stage, the mutual a phase spectrum at a frequency plot 0 ÷ f _n, where f _n the width of the address signal group, the third step is conducted to eliminate the ambiguity between two mutual phase previously recovered spectra and performing the calculation of the mutual delay signal with an error is inversely proportional to the value of the radio frequency carrier.

At the first stage, the mutual phase spectrum is conjugated within the address group of the signal using the multi-frequency processing apparatus.

As a result of this procedure, the ambiguity of the number of transitions through 2π in the frequency interval f _k ÷ f _{i is} eliminated (Fig. 2). The error in measuring the delay time is calculated in accordance with (11).

The graph of σ _Δτ × s for q = 3 is shown in FIG. 3.

Recovery of VFS to zero is possible if the condition:

For the VHF range (λ = 1 m), the ambiguity condition is fulfilled with some margin of measurement accuracy. Based on this, it is possible to eliminate the ambiguity in the number of transitions through a 2π VFS signal in the frequency range 0 ÷ f _i . The graph of σ _Δτ × s for q = 3 is shown in FIG. 3.

At the second stage of the VFS recovery method, we measure the delay time of the arrival of radio signals in accordance with the formula

Knowing that the delay time is related to the VFS ratio

calculate the VFS signal in the frequency range 0 ÷ (f _i -f _k ).

As a result, we obtain two identical VFS restored in the frequency range 0 ÷ f _n and f _i ÷ f _k (Fig. 4).

At the third stage, we use the multi-frequency processing procedure and eliminate the ambiguity of transitions through 2π between two previously reconstructed VFS.

The root-mean-square number of transitions through 2π is determined by:

By entering the confidence interval for Δm _k / σ _m :

, возможна интерполяция между двумя восстановленными ВФСwe get an expression in which, with confidence

, interpolation between two reconstructed VFS possible

.where I _{P dov} (Δm _ki / σ _m ) is the value of the confidence interval Δm _ki / σ _m at confidence probability

.

, так как сопрягаемые ВФС полностью коррелированы. Восстановление ВФС возможно (фиг.5), если разнос по частоте между ними удовлетворяет условию Ф_k≤Ф_kMAX (фиг.6).Expression (17) differs from the previously obtained (11) (prototype) in the absence of a factor

, since the conjugated VFS are completely correlated. Recovery of VFS is possible (Fig. 5), if the frequency spacing between them satisfies the condition Ф _k ≤Ф _kMAX (Fig. 6).

Determining the number of transitions through 2π VFS signal in the frequency range 0 ÷ f _i allows you to calculate the value of the mutual delay of the signals according to the formula (13) taking into account f _k = 0, φ _k = 0:

The error in calculating the delay is:

Thus, due to the phased restoration of the mutual phase spectrum at different frequency sections and the simultaneous elimination of the ambiguity of transitions through 2π, the value of the mutual delay of the signals is inversely proportional to the value of the carrier frequency of the radio signal, which leads to an increase in the accuracy of measuring the mutual delay.

The method can be carried out in the following way.

Signals (see Fig. 6) with programmed tuning of the operating frequency (frequency hopping) are received at the pin antennas (1) at spaced receiving points (2), then the received analog signal is converted into an ADC (3) in digital form, which in turn are synchronized subsystem of uniform time (PSEV) (4).

The digitized signals received at the separated points of reception are fed through the communication channel (5) to the processing device (6).

After preliminary processing of the signals (filtering, frequency down conversion, separation of the ERI), the calculation (7) of their correlation function is performed and then the Fourier transform (8) is performed.

Then, the separation (9) of the argument of the mutual spectral density of the signal and the construction (10) of the mutual phase spectrum of the ERI are carried out. Next, pairing (11) VFS URI within the address group of frequencies. After that, determination (12) is performed by the slope Δτ of the conjugated VFS of the mutual delay of the received signals.

Then, the fulfillment of the condition λ <σ _Δτ · s (13) of the VFS recovery to zero is carried out.

Based on the known delay, the VFS is constructed (14) in the frequency range from zero to the frequency corresponding to the width of the address group of frequencies.

Next, pair (15) (from 0 to f _n ) of the two recovered VFS.

And at the end, they calculate (16) the mutual delay along the slope Δτ of the recovered VFS.

INFORMATION SOURCES

1. Varakin L.E. Communication systems with noise-like signals. - M .: Radio and communications, 1985.

2. Principles and methods of direction finding. I.A. Butchenko. YOU, 1977.

3. Yarlykov MS Statistical theory of radio navigation. - M .: Radio and communications, 1985.

4. Radio engineering systems: Textbook. for universities for special. "Radio Engineering" / Yu.P. Grishin, V. P. Ipatov, Yu. M. Kazarinov and others. - M .: Higher. school., 1990.

5. Kinkulkin I.E., Rubtsov V.D., Fabrik M.A. Phase method for determining coordinates. - M .: Owls. Radio, 1979.

6. Timofeev E.V., Vagin A.I., Berezhny D.L., Demichev I.V., Shaidulin Z.F. The content and main indicators of multi-frequency signal processing with software tuning of the operating frequency. - Collection of abstracts of deposited manuscripts. Issue No. 76. - M.: TsVNI MO RF, 2006.

Claims (1)

A method for measuring the mutual delay of signals with software tuning of the operating frequency (frequency hopping) in the band of the address group of signals in the VHF band with the carrier frequency of the radio signal, namely, dividing the working range of the frequency hopping signal into bands corresponding to the width of the spectrum of single radio emissions (URI), take single the radio frequency signals of the frequency hopping signals in spatially separated points of reception, calculate the mutual correlation functions of the corresponding single radio emissions received in spatially separated nct, determine the complex mutual spectra of single radio emissions and their arguments, interpolate the mutual phase spectrum (VFS) between the received single radio emissions and measure the mutual delay by the slope of the VFS, characterized in that when measuring the mutual delay between the received EIRs, a phased recovery of the mutual phase spectrum of the signals is used moreover, the VFS recovery at the first stage is carried out within the band of the address group of the signal and the delay time between the URI is determined from it, at the second the stage, the mutual phase spectrum is restored in the frequency range 0 ÷ f _n , where f _{n is the} width of the address group of the signal, at the third stage, the ambiguity between the two previously restored mutual phase spectra is eliminated, and the mutual delay of the signals is calculated with an error inversely proportional to the carrier value the frequency of the radio signal.

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