RU2389040C1 - Query method of measuring radial velocity and system for realising said method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: system which realises the said method has two objects. The first object (request unit) has a driving generator, shift register, phase keying device, first and second heterodynes, first and second mixers, first intermediate frequency amplifier, first and second power amplifiers, first duplexer, first transceiving antenna, third intermediate frequency amplifier, phase doubler, phase halver, two narrow band-pass filters, fourth mixer, Doppler frequency measurement device, correlator, range indicator and differentiator connected to each other in a defined way. The correlator is made in form of a multiplier, low-pass filter, low frequency amplifier, controlled delay unit. The second object (transponder) has a second transceiving antenna, second duplexer, third and fourth power amplifiers, third heterodyne, third mixer and second intermediate frequency amplifier.

EFFECT: increased accuracy of measuring distance to an object by using the derivative of a correlation function.

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Description

The proposed method and system relates to radar technology and can be used to ensure flight safety of aircraft, to control the proximity and docking of spacecraft (SC).

Known methods and systems for measuring the radial speed of moving objects (ed. Certificate of the USSR No. 293175, 926611, 1300531; RF patents No. 2111505, 2124760, 2126797, 2131622, 2134910, 2150752, 2309431; US patents No. 3714654, 4400780, 482521313 , 4495580; UK patent No. 2232316; French patent No. 2037222; German patent No. 1917140; EP patents No. 0283723, 0707220; TG Anodina et al. Automation of air traffic control. - M .: Transport, 1992, p.145 -147 and others).

Of the known methods and systems closest to the proposed are the "Request method for measuring radial velocity and a system for its implementation" (RF patent No. 2309431, G01S 13/78, 2006), which are selected as the base objects.

The specified method is based on the emission of the request signal and relaying it. To isolate the Doppler frequency, the relayed signal is compared in frequency with the interrogated one. The decoupling of the request and relay signals is achieved by spacing them in frequency.

A system that implements the known method consists of two objects, each of which contains a request block and a relay. One or both objects can be movable.

For accurate measurement of the distance to the object, it is necessary to more accurately determine the time delay τ _{3 of the} relay signal relative to the interrogation signal, corresponding to the maximum of the correlation function R (τ).

However, in the region of the maximum, the correlation function R (τ) has a very small slope and changes insignificantly with changes in τ (Fig. 5, a). Much more favorable for the search for the maximum is the form of the derivative of the correlation function dR (τ) / dt (Fig. 5, b). At the point τ = 0, the derivative has a significant steepness and, in addition, changes sign depending on the position relative to the zero point.

Thus, finding the maximum of the correlation function R (τ) (maximum principle) is replaced by the minimum measurement principle - stabilization of the zero value of the controlled variable τ.

An object of the invention is to increase the accuracy of measuring the distance to the object by using the derivative of the correlation function.

The problem is solved in that the interrogation method for measuring the radial velocity of objects and the distance between them, which consists, in accordance with the closest analogue, in the use of two objects. Moreover, each object is equipped with a request unit and a repeater, in addition, one or both objects can be movable, at each object the request signal at a frequency ω _{s is} manipulated by a + 180 ° phase with a pseudo-random sequence of maximum duration, thereby forming a complex signal with phase manipulation, it is converted in frequency by using frequency ω _r1 of the first local oscillator is isolated voltage of the first intermediate frequency _pr1 ω = ω _c + ω ₁ = ω _r1 increase its power emit the broadcast at the frequency ω ₁ = ω _pr1, catch Relay Transmission insulator another object, increase in power is converted in frequency by using frequency ω _z3 third LO isolated voltage of the second intermediate frequency

_np2 ω = ω -ω _{z3 pr1} = ω _2, increase its power emit broadcast at frequency ω ₂ = ω _np2, capture unit request of another object, increase in power is converted in frequency by using frequency ω _r2 of the second local oscillator is isolated voltage of the third intermediate frequency ω _PR3 Ωq = ± ω _z2 -ω _2, multiply and divide it into two phase, is isolated harmonic oscillation at frequency ω _PR3 ± Ωq, compare it with a frequency interrogation signal at frequency ω _s, the Doppler frequency ± isolated Ωq and the magnitude and sign of the Doppler frequency determine the magnitude and The pressure of the radial velocity, while the composite signal with a phase shift keying _with a frequency ω is passed through the adjustable delay unit is different from the closest analog by the fact that the voltage of the third intermediate frequency ω _PR3 ± Ωq = ω _z2 -ω ₂ is differentiated with respect to time, multiplied with a complex signal with by phase manipulation at a frequency ω _c passed through an adjustable delay unit, a low-frequency voltage is isolated, thereby forming a derivative of the correlation function:

dR (τ) / dt,

where τ is the current time delay,

by varying the delay τ, the derivative correlation function dR (τ) / dt is maintained at a zero level, the time delay τ ₃ between the request and relay signals corresponding to the zero value of the derivative of the correlation function is fixed, and the distance between the objects is determined by its value.

The problem is solved in that a system for measuring the radial speed of objects and the distance between them, containing, in accordance with the closest analogue, a request block located on each object, including a serially connected master oscillator, a phase manipulator, the second output of which is connected to the output of the shift register, the first mixer, the second input of which is connected to the output of the first local oscillator, the amplifier of the first intermediate frequency, the first power amplifier, the first duplexer, the input-output of which is connected to a second transceiver antenna, a second power amplifier, a second mixer, the second input of which is connected to the output of the second local oscillator, a third intermediate frequency amplifier, a phase doubler, a phase divider by two, a first narrow-band filter, a fourth mixer, the second input of which is connected to the output of the master oscillator, the second a narrow-band filter and a Doppler frequency meter, connected in series to the output of the phase manipulator, an adjustable delay unit, to the second output of which a range indicator is connected, a cutter and a low-pass filter, and a repeater including a second duplexer connected in series, the input-output of which is connected to the second transceiver antenna, a third power amplifier, a third mixer, the second input of which is connected to the output of the third local oscillator, a second intermediate frequency amplifier and a fourth power amplifier, the output of which is connected to the input of the second duplexer, differs from the nearest analogue in that it is equipped with a differentiator and a low-frequency amplifier, and the output of the amplifier of the third gap full frequency through a differentiator is connected to the second input of the multiplier, the output of the low-pass filter through a low-frequency amplifier is connected to the second input of the adjustable delay unit.

The system that implements the proposed method contains two objects. The block diagram of the feather object (query blocks) is presented in figure 1. The structural diagram of the second object (repeater) is presented in figure 2. A frequency diagram illustrating signal conversion is shown in FIG. 3. The correlation function and its derivative are shown in Fig.4.

The first object (request block) contains a serially connected master oscillator 1, a phase manipulator 3, the second input of which is connected to the output of the shift register 2, the first mixer 5, the second input of which is connected to the output of the first local oscillator 4, an amplifier 6 of the first intermediate frequency, the first amplifier 7 power, the first duplexer 8, the input-output of which is connected to the first transceiver antenna 9, the second power amplifier 10, the second mixer 12, the second input of which is connected to the output of the second local oscillator 11, the amplifier 13 of the third intermediate of the second frequency, phase doubler 14, phase divider 15 into two, the first narrow-band filter 16, the fourth mixer 17, the second input of which is connected to the output of the master oscillator 1, the second narrow-band filter 18 and the Doppler frequency meter 19 connected in series to the output of the amplifier 13 of the third intermediate frequency, differentiator 33, multiplier 21, low-pass filter 22, low-frequency amplifier 23 and adjustable delay unit 24, the second input of which is connected to the output of the phase manipulator 3, the first output is connected to the second input Yelaya 21, and the second output is connected to the indicator 25 range. The multiplier 21, the low-pass filter 22, the low-frequency amplifier 33 and the adjustable delay unit 24 form a correlator 20.

The second object (repeater) contains serially connected third local oscillator 29, third mixer 30, second intermediate frequency amplifier 31, fourth power amplifier 32, second duplexer 27, the input-output of which is connected to the second transceiver antenna 26, and the third power amplifier 28, the output of which connected to the second input of the third mixer 30.

Each object is equipped with a request block and a relay. One or both objects can be movable.

The proposed method is implemented by a system that operates as follows.

At the first object using a master oscillator 1, a high-frequency oscillation is formed:

U _c (t) = V _c cos (ω _c t + φ _c ), 0≤t≥T _c,

where V _c , ω _c , φ _c , T _c - amplitude, carrier frequency, initial phase and duration of high-frequency oscillations,

which is fed to the first input of the phase manipulator 3. The second input of the latter is fed with a pseudo-random sequence (PSP) M (t) of maximum duration from the output of the shift recorder 2, covered by logical feedback. Feedback is carried out by adding modulo two output voltages, two or more stages, and applying the resulting voltage to the input of the first stage. The repetition period (duration) of such a code sequence:

m = 2 ⁿ -1,

where n is the number of stages of the shift register.

The output of the phase manipulator 3 produces a complex signal with phase shift keying (PSK):

U ' _c (t) = V _c · cos [ω _c · t + ω _k (t) + φ _s ], 0≤t≤T _c ,

where φ _к (t) = {0, π} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the pseudo-random sequence M (t), and φ (t) = const for k · τ _е <t <(k + 1 ) · Τ _e and can change abruptly at t = k · τ _e , i.e. at the borders between elementary premises (k = 1, 2, ... N);

τ _e , N is the duration and number of chips that make up the signal of duration T _c (T _c = τ _e · N).

This signal is fed to the first input of the first mixer 5, the second input of which is supplied with the voltage of the first local oscillator 4

U _g1 (t) = V _g1 · cos (ω _g1 · t + φ _g1 ).

At the output of the mixer 5, voltages of combination frequencies are generated. Amplifier 6 distinguishes the voltage of the first intermediate (total) frequency:

U _npl (t) = V _CR1 · cos [ω _CR1 · t + φ _k (t) + φ _CR1 ], 0≤t≤T _s .

where V _pr1 = _^1/2 K ₁ · V _c · V _r1;

K ₁ - gear ratio of the mixer;

ω _pr1 = ω _s + ω _g1 = ω ₁ - the first intermediate (total) frequency;

φ _pr1 = φ _s + φ _g1,

which after amplification in the first power amplifier 7 through the duplexer 8 enters the transceiver antenna 9, it is broadcasted on the frequency ω ₁ , it is captured by the transceiver antenna 26 of the second object and through the duplexer 27 and the power amplifier 28 goes to the first input of the third mixer 30, to the second the input of which the voltage of the third local oscillator 29 is supplied:

U _g3 (t) = V _g3 · cos (ω _g3 · t + φ _g3 ).

At the output of the mixer 30, voltages of combination frequencies are generated. The amplifier 31 is allocated the voltage of the second intermediate frequency:

U _np2 (t) = V _CR2 · cos [ω _CR2 · t + φ _k (t) + φ _CR2 ], 0≤t≤T _s .

_np2 where V = _^1/2 K ₁ · V · V _{r3 pr1;}

_np2 ω = ω -ω _{z3 pr1} = ω ₂ - second intermediate (difference) frequency;

φ _pr2 = φ _pr1 -φ _{g3 ,}

which after amplification in the fourth power amplifier 32 through the duplexer 27 enters the transceiver antenna 26, is radiated by it at a frequency ω ₂ , is captured by the transceiver antenna 9 of the first object and through the duplexer 8 and the power amplifier 10 is supplied to the first input of the second mixer 12, to the second the input of which the voltage of the second local oscillator 11 is supplied:

U _g2 (t) = V _g2 · cos (ω _g2 · t + φ _g2 ).

At the output of the mixer 12, voltages of combination frequencies are generated. The amplifier 13 is allocated the voltage of the third intermediate (differential) frequency:

U _np3 (t-τ ₃ ) = V _pr3 · cos [(ω _pr3 · ± Ω _d ) (t-τ ₃ ) -φ _k (t-τ ₃ ) + φ _pr3 ], 0≤t≤T _s .

_PR3 where V = _^1/2 K ₁ · V · V _{r2 np2;}

_PR3 ω = ω _z2 -ω _np2 = ω _s - third intermediate (difference) frequency;

_PR3 φ = φ _{r2 np2} -φ; _,

τ ₃ = 2R / C is the delay time of the retranslated signal relative to the request;

R is the distance between the objects;

C is the propagation velocity of radio waves;

± Ω _d - Doppler frequency shift,

which is fed to the input of the doubler 14 phase. As the latter, a multiplier can be used, on the two inputs of which the same voltage is supplied.

At the output of the phase doubler 14, a harmonic oscillation is formed:

U ₂ (t-τ ₃ ) = V ₂ · cos [2 (ω _pr3 · ± Ω _d ) (t-τ ₃ ) + 2φ _pr3 ], 0≤t≤T _c ,

wherein V ₂ = _^1/2 K ₂ · V ² _PR3;

K ₂ - transfer coefficient of the multiplier,

in which phase manipulation is already absent, since 2φ _k (t-τ ₃ ) = {0, π}.

The width of the spectrum Δf _{c of the} complex QPSK signal is determined by the duration τ _{3 of} its elementary premises:

Δf _c = 1 / τ ₃ .

Whereas the width of the spectrum Δf _{2 of} its second harmonic is determined by the signal duration T _s :

Δf ₂ = 1 / T _c .

Therefore, when doubling the phase of the broadband QPSK signal, its spectrum collapses N times:

Δf _c / Δf ₂ = N.

This oscillation enters the input of the phase divider 15 into two, at the output of which a harmonic oscillation is formed:

U ₃ (t-τ ₃ ) = V ₃ · cos [(ω _pr3 · ± Ω _d ) (t-τ ₃ ) + φ _pr3 ], 0≤t≤T _c ,

which is allocated by a narrow-band filter 16 and supplied to the first input of the fourth mixer 17. The second signal of the last one is supplied with a request signal U _c (t) from the output of the master oscillator 1. At the output of the mixer 17, the frequencies of combination frequencies are generated. The narrow-band filter 18 distinguishes the voltage of the Doppler frequency:

U ₄ (t) = V ₄ · cos (± Ω _d · t + φ ₄ ), 0≤t≤T _c ,

₄ where V = _^1/2 K ₁ · V _c · V _3,

φ ₄ = φ _with -φ _pr3 , which is fed to the input of the Doppler frequency meter 19, which provides a measurement of the Doppler frequency ± Ω _d . Moreover, the magnitude and sign of the Doppler frequency determine the magnitude and direction of the radial velocity.

At the same time, the voltage of the third intermediate frequency U _pr3 (t-τ ₃ ) is supplied to the input of the differentiator 33, the output of which produces a voltage proportional to:

dU _pr3 (t-τ ₃ ) / dt.

This voltage is supplied to the first input of the multiplier 21, to the second input of which, through the adjustable delay unit 24, a complex QPSK signal U ₁ (t) is supplied from the output of the phase manipulator 3. The voltage received at the output of the multiplier 21 is passed through a low-pass filter 22, at the output of which the derivative of the correlation function dR (τ) / dt is formed (Fig. 4, b). If the specified derivative is not equal to zero, then a constant voltage is formed at the output of the low-pass filter 22, the amplitude of which is proportional to the degree of deviation of the derivative of the correlation function from zero, and the polarity to the direction of deviation. This voltage through the low-frequency amplifier 23 affects the control input of the adjustable delay unit 24, changing the time delay τ so that the derivative of the correlation function is equal to zero. The range indicator 25, associated with the adjustable delay unit 24, allows you to directly read the measured value of the distance R between objects:

R = c · τ _3/2.

Therefore, the task of measuring the range (distance) R is reduced to measuring the time delay τ _{3 of the} relay signal relative to the request.

Thus, the proposed method and system in comparison with the basic objects provide an increase in the accuracy of measuring the distance to the object. This is achieved using the derivative of the correlation function, which can significantly increase the accuracy and sensitivity of the meter.

An alternating signal with a large slope is formed at the output of the correlator in the region of the maximum of the correlation function (the minimum of its derivative), which is used to automatically change the adjustable delay unit. The advantage of this scheme is the relative simplicity of obtaining the desired error signal.

Claims (2)

1. A request method for measuring the radial speed of objects and the distance between them, which consists in using two objects, each object having a request block and a repeater, in addition, one or both objects can be movable, at each object the request signal at a frequency ω _{s is} manipulated by phase by 180 ° maximum length pseudo-random sequence, thus forming a complex signal with phase shift keying, it is converted in frequency using a frequency ω _r1 of the first local oscillator is isolated tense e first intermediate frequency:
ω _pr1 = ω _s + ω _g1 = ω ₁ ,
amplify it in power, radiate it on the frequency ω ₁ = ω _pr1 , capture it with the repeater of another object, amplify it in power, convert it in frequency using the frequency ω _{g3 of the} third local oscillator, isolate the voltage of the second intermediate frequency:
_np2 ω = ω -ω _{z3 pr1} = ω _2,
amplify it in power, radiate it on the frequency ω ₂ = ω _CR2 , pick it up by the request unit of another object, amplify it in power, convert it in frequency using the frequency ω _{g2 of the} second local oscillator, isolate the voltage of the third intermediate frequency:
_PR3 ± Ω ω _d = ω _z2 -ω _2,
multiply and divide it by phase into two, isolate harmonic oscillation at a frequency ω _pr3 ± Ω _d and determine the magnitude and direction of the radial velocity by the magnitude and sign of the Doppler frequency, at the same time a complex signal with phase shift keying at a frequency ω _{s is} passed through an adjustable delay unit, which differs in that the voltage of the third intermediate frequency _PR3 ± Ω ω _d = ω _z2 -ω ₂ is differentiated with respect to time, multiplied with a complex signal with phase shift keying at frequency ω _s, passed through a variable delay unit, allocate nizkoch frequency stress, thereby forming a derivative of the correlation function:
dR (τ) / dt,
where τ is the current time delay,
by varying the delay τ, the derivative of the correlation function dR (τ) / dt is maintained at a zero level, the time delay τ ₃ between the request and relay signals corresponding to the zero value of the derivative of the correlation function is fixed, and the distance between the objects is determined by its value. 2. A system for measuring the radial velocity of objects and the distance between them, containing a request block located on each object, including a serially connected master oscillator, a phase manipulator, the second input of which is connected to the output of the shift register, the first mixer, the second input of which is connected to the output of the first local oscillator , an amplifier of the first intermediate frequency, a first power amplifier, a first duplexer, the input-output of which is connected to the first transceiver antenna, a second power amplifier, a second mixer , the second input of which is connected to the output of the second local oscillator, an amplifier of the third intermediate frequency, a phase doubler, a phase divider into two, a first narrow-band filter, a fourth mixer, a second input of which is connected to the output of the master oscillator, a second narrow-band filter and a Doppler frequency meter connected in series to the output of the phase manipulator, an adjustable delay unit, to the second output of which a range indicator, a multiplier and a low-pass filter, and a repeater including a follower are connected included a second duplexer, the input-output of which is connected to the second transceiver antenna, a third power amplifier, a third mixer, the second input of which is connected to the output of the third local oscillator, a second intermediate frequency amplifier and a fourth power amplifier, the output of which is connected to the input of the second duplexer, characterized in that it is equipped with a differentiator and a low-frequency amplifier, and the output of the amplifier of the third intermediate frequency through the differentiator is connected to the second input of the multiplier, the output of the filter is lower of these frequencies through a low-frequency amplifier is connected to the second input of the adjustable delay unit.

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