RU2498344C2 - Correlation device for measuring height and ground velocity vector components - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: result is achieved owing to presence of a range of new units with interconnections thereof within the disclosed measuring device, as well as owing to radiation towards the underlying surface and receiving short radio pulse packets reflected from the underlying surface, which are converted in the receiver to bipolar video pulses whose amplitude fluctuates with a frequency defined by the Doppler frequency shift of signals, and ground velocity vector components are determined from the maximum of the cross-correlation function of spaced apart signals reflected from the underlying surface that are received by spaced apart antennae located on an aircraft, taking into account the shape of the antenna system.

EFFECT: broader functional capabilities, high accuracy of measuring the ground velocity vector of aircraft.

3 cl, 10 dwg

Description

The invention relates to the field of radar and can be used in airborne navigation systems.

A device [1] is known that implements a method of measuring the speed of an aircraft relative to the underlying surface, which consists in determining the correlation time delay by equalizing the autocorrelation coefficient in one of the receiving channels, the mutual correlation coefficient of the signals of two receivers, calculating the autocorrelation coefficient in the second receiving channel and finding the temporary position the maximum cross-correlation function of the signals of these receivers. In this case, the average value of the autocorrelation coefficients is used to calculate the speed.

The main disadvantage of this device is the use of two receiving antennas, which does not allow measurements to be made with a given accuracy when the object evolves over a wide range of surface types (sea, forest, etc.). The location option of the receiving antennas proposed in [1] does not allow measurements at small drift angles (in the absence of drift), because in this case, the maximum cross-correlation coefficient is determined by the spacing of the antennas along the transverse axis of the aircraft. At small drift angles, the cross-correlation coefficient is small, which leads to increased measurement errors of the components of the path velocity vector. It is possible to increase the cross-correlation coefficient by approaching the receiving antennas, however, the minimum distance between the antennas is limited by their geometric dimensions.

In addition, the design of the proposed antenna system does not allow the device to be placed on relatively narrow and long sides of aircraft.

Known correlation meter for flight speed and drift angle [2], which contains four antennas, two receivers, two time discretizers, a delay line, a switch, two multipliers, a directional coupler, a clock, two low-pass filters, a transmitter, an engine, an indicator paths, subtraction unit, tracking unit, three double-sided limiters, wind speed and drift angle indicators, two coincidence units and a divider.

The main disadvantage of this device is the use of spatially separated signals of the fork method for determining the transport delay, which does not allow for high accuracy of measurements of the components of the ground speed vector, to estimate the position of the maxima of the cross-correlation functions (CCF).

The closest in technical essence is the device [3], which relates to means for monitoring and measuring the thickness of the layers of liquids heterogeneous in the electrophysical properties, as well as their relative changes. The device contains a synchronizer, a computing device, an analog-to-digital converter, a phase shifter, a pulse modulator, a controlled attenuator, a video amplifier, a BOSU, a gain control unit, an attenuation control unit, a voltage-controlled current source, an exchange controller, a series-connected antenna system, a circulator, a low-noise UHF phase detector, directional, coupler, discretely controlled microwave generator, the output of which is connected to the input of a directional coupler, the second output of which is dined with the second input of the phase detector, the first input of which is connected to the low-noise amplifier output, the input of which is connected to the output of the circulator, the input / output of which is connected to the antenna system, and the first output of the directional coupler is connected to the first input of the pulse modulator, the second input of which is connected to the second synchronizer output, the output of the pulse modulator is connected to the second input of the phase shifter, the first input of which is connected to the first output of the synchronizer, and the output to the first input of the controlled attenuato a, the output of which is connected to the input of the circulator, and the second input - to the output of a voltage-controlled current source, the input of which is connected to the output of the attenuation control unit, all the first inputs of which are connected via the data bus to all the first inputs of the gain control unit, all six of the inputs of the BOS , all the first inputs / outputs of the exchange controller, all the third inputs / outputs of which are the inputs / outputs of the meter, as well as all twelve inputs of the computing device, the second, third, fourth, fifth outputs of which They are connected respectively to the second inputs of the attenuation control unit, gain control unit, exchange controller, BOSU, and the sixth, seventh, thirteenth outputs, respectively, with the third, fourth, seventh inputs of the BOSU, eighth, ninth outputs, respectively, with the second and third inputs of the synchronizer, the tenth, eleventh outputs, respectively, with the second and first inputs of a discretely controlled microwave generator, the first input is with the fourth output of the synchronizer, the first input of which is connected to the first output of the BOSE, the first input otorrhea connected to the third output of the synchronizer and the second ADC input, all the outputs of which are connected to all inputs Bozu fifth, and the first ADC input - with the output of the video amplifier, a first input coupled to an output of the phase detector, the second input - to the output gain control unit.

The disadvantage of the prototype of the device in question is that it does not measure the components of the ground speed vector.

The aim of the invention is to expand the functionality of the device, improving the accuracy of measuring the vector of the ground speed of the aircraft.

This goal is achieved by the fact that in the device [3], containing a synchronizer, a computing device, an analog-to-digital converter, a phase shifter, a pulse modulator, a controlled attenuator, a video amplifier, a BOZU, a gain control unit, an attenuation control unit, a voltage controlled current source, a controller exchange, circulator, series-connected low-noise UHF, phase detector, directional coupler, discretely controlled microwave generator, the output of which is connected to the input of the directional coupler, the second output of which is connected to the second input of the phase detector, the first input of which is connected to the output of the low-noise amplifier, and the first output of the directional coupler is connected to the first input of the pulse modulator, the second input of which is connected to the second output of the synchronizer, the output of the pulse modulator is connected to the second input of the phase shifter, the first the input of which is connected to the first output of the synchronizer, and the output to the first input of the controlled attenuator, the output of which is connected to the first input of the circulator, and the second input to orogo connected to the output of the current source, the voltage controlled oscillator having an input coupled to an output attenuation control unit, all first inputs of which are connected by. data bus with all the first inputs of the gain control unit, all six inputs / outputs of the BOZU, all the first inputs / outputs of the exchange controller, all of the third inputs / outputs of which are the inputs / outputs of the meter, as well as all twelve inputs of the computing device, the second, third, fourth , the fifth outputs of which are connected respectively to the second inputs of the attenuation control unit, gain control unit, exchange controller, BOSE, and the sixth, seventh, thirteenth outputs, respectively, with the third, fourth, the seventh inputs of the BOSE, the eighth, ninth outputs, respectively, with the second and third inputs of the synchronizer, the tenth, eleventh outputs, respectively, with the second and first inputs of a discretely controlled microwave generator, the first input with the fourth output of the synchronizer, the first input of which is connected to the output of the BOSU, the first the input of which is connected to the third output of the synchronizer and the second input of the ADC, all the outputs of which are connected to all fifth inputs of the BOZU, and the first input of the ADC is connected to the output of the video amplifier, the first input of which is connected to the output of a gas detector, the second input - with the output of the gain control unit, an antenna switch, an antenna switch control unit, an antenna system [4] are introduced, the middle of which can be used as a transceiver antenna, while the second input / output of the circulator is connected to the second input / the output of the antenna system, the first and third outputs of which are connected to the fifth and sixth inputs of the antenna switch, the output of which is connected to the input of a low-noise UHF, the output of the circulator is connected to the first input of the antenna switch A second, third, fourth, inputs of which are connected to first, second, third antenna switch outputs of control unit, first, second and third inputs connected respectively to the first, second and fifth outputs of the synchronizer.

To measure extremely low heights, the transmitting antenna can be made in the form of a separate unit connected to the output of the controlled attenuator and spaced with the receiving antenna system at a certain distance to ensure high isolation from the “direct” signal induced at the time of radiation to the receiver. At the same time, a matched load is connected to the first input of the circulator.

The inventive correlation meter height and components of the vector of ground speed radiates in the direction of the underlying surface and receives short packets of radio pulses. In this case, the radio pulses in the receiver are converted into bipolar video pulses, the envelope of which fluctuates in amplitude with a frequency determined by the Doppler frequency shift of the signals reflected from the underlying surface.

The components of the path velocity vector are determined by the maximum of the cross-correlation functions of the spatially spaced signals reflected from the underlying surface, received by the spaced antennas located on the aircraft, taking into account the geometry of the antenna system [5].

Comparative analysis with the prototype shows that the inventive device is characterized by the presence of new blocks and their relationships with each other and with other blocks of the prototype.

Thus, the claimed device meets the criterion of "novelty."

Comparison of the proposed solution with other technical solutions shows that the introduced blocks are known [3, 4, 6]. However, their introduction into the inventive correlation height meter and components of the ground speed vector in the indicated set of signs were not found and leads to the expansion of functionality and increase the accuracy of measurements, which allows us to conclude that the technical solution meets the criterion of "significant differences".

Figure 1 presents a block diagram of a correlation meter height and components of the vector of ground speed. Figure 2 presents a block diagram of an antenna switch. Figure 3 presents the control block diagram of the antenna switch. Figure 4 presents the block diagram of the synchronizer (differs from the prototype by the addition of wire 83). Figure 5 presents the algorithm of the routine of setting the mode of the transceiver module when emitting radio pulses and the accumulation of radio pulses reflected from the underlying surface. Figure 6 presents the timing diagrams of the operation of the control unit of the antenna switch. Figure 7 presents the antenna system of the correlation meter for speed and drift angle of the aircraft. On Fig presents the restoration of the reflected signal by the vernier method. Figure 9 presents the algorithm for programmatically adjusting the gain of the receiving path and the radiation power. Figure 10 presents the algorithm of the subroutine for calculating the longitudinal and lateral components Vx and Vz.

The correlation meter for height and components of the ground speed vector contains a discretely controlled microwave generator 1, a directional coupler 2, a pulse modulator 3, a phase shifter 4, a controlled attenuator 5, an antenna switch 6, an antenna switch control unit 7, a circulator 8, a low-noise UHF 9, a phase detector 10 , video amplifier 11, ADC 12, BOSU 13, synchronizer 14, computing device 15, exchange controller 16, gain control unit 17, attenuation adjustment unit 18, voltage-controlled current source 19, antenna system 70, as well as transmit antenna 71, matched load 72 when using transmit antenna as a separate unit.

The output of the discretely controlled microwave generator 1 is connected to the input of the directional coupler 2, the first output of which is connected to the first input of the pulse modulator 3, the second input of which is connected to the second input of the control unit of the antenna switch 7 and the second output of the synchronizer 14, the first and fifth outputs of which are connected respectively, with the first and third inputs of the control unit of the antenna switch 7 and the phase shifter 4, the second input of which is connected to the output of the pulse modulator 3, and the output to the first input autonomous attenuator 5, the output of which is connected to the first input of the circulator 8, the output of which is connected to the first input of the antenna switch 6, and the second input / output - to the second input / output of the antenna system 70, the first and third outputs of which are connected respectively to the fifth and sixth inputs antenna switch 6, the second, third, fourth inputs of which are connected to the first, second, third outputs of the control unit of the antenna switch (AP) 7, the output is to the input of low-noise UHF 9, the output of which is connected to the first input of the phase detector torus 10, the second input of which is connected to the second output of the directional coupler 2, and the output to the first input of the video amplifier, the second input of which is connected to the output of the gain control unit 17, and the output to the first input of the ADC 12, all outputs of which are connected. the inputs of the BOZU 13, the first input of which is connected to the second input of the ADC 12 and the third output of the synchronizer 14, the fourth output of which is connected to the first input of the computing device 15, the second, third, fourth, fifth outputs of which are connected respectively to the second the odes of the attenuation adjustment block 18, the gain control block 17, the exchange controller 16, the BOSE 13, the sixth, seventh, thirteenth outputs, respectively, with the third, fourth, seventh inputs of the BOSU 13, the tenth, eleventh outputs, respectively, with the second and first inputs of a discretely controlled microwave generator 1, the eighth, ninth outputs respectively with the second and third inputs of the synchronizer 14, the first input of which is connected to the output of the BOZ 13, all sixth inputs / outputs of which are connected via data bus to all twelve inputs / outputs of the calculator an adapter device 12, with all the first inputs / outputs of the exchange controller 16, all the third inputs / outputs of which are inputs / outputs of a correlation height meter and components of the ground speed vector, as well as with all the first inputs of the gain control unit 17, all the first inputs of the attenuation adjustment unit 18 the output of which is connected to the input of the voltage controlled current source 19, the output of which is connected to the second input of the controlled attenuator 5.

The transmitting antenna 71 can be made in the form of a separate unit connected to the output of the controlled attenuator 5. At the same time, a matched load 72 is connected to the first input of the circulator 8.

The composition of the antenna switch 6 includes the first microwave key 73, the second microwave key 74, the third microwave key 75. In this case, the first input of the first microwave key 73 is the first input of the antenna switch 6, the second input of the first microwave key 73 is the third input of the antenna switch 6, the output of which is connected to the outputs of the first microwave key 73, the second and third microwave keys 74 and 75, the first inputs of which are the fifth and sixth inputs of the antenna switch 6, and the second inputs are the second and fourth inputs of the antenna switch 6.

The structure of the antenna switch control unit 7 (FIG. 3) includes a “NOT” block 76, a first “AND-NOT” block 77, a second “AND-NOT” block 78, a third AND-NOT block 79, and a fourth 80 "block AND-NOT ”, fifth AND-NOT block 81, shift register 82. Moreover, the input of AND-NOT block 76, which is the first input of the antenna switch control unit 7, is connected to the second input of the second AND-NOT block 78 ", The first input of which, which is the second input of the antenna switch control unit 7, is connected to the first input of the first AND-NOT block 77, the output of which is connected respectively to the first inputs third 79, fourth 80, fifth 81 “NAND” blocks, the outputs of which are respectively the first, second, third outputs of the antenna switch control unit 7, all of the third inputs of which are connected to each other and the output of the second “AND-NOT” block 78, and the second inputs, respectively, with the first, second, third outputs of the shift register 82, the first input of which is connected to the output of the “NOT” block and the second input of the first AND-NOT block 77, and the second input of the shift register 82 is the fifth output of the synchronizer 14 (FIG. .4), the signal 83 is connected to the second input of the trigger 28 flag radiation.

Correlation meter height and components of the vector of ground speed works as follows.

After supplying power to the meter, the computing device 15 carries out with the signal 40 the initial setting of the trigger 28 of the radiation flag of the synchronizer 14, with the signal 83 the initial setting of the shift register 82 of the AP control unit 7, the signals 65 and 64 record the zero gain and attenuation values in the gain control blocks 17 and 18 and attenuation (Nc = 0, Nrel = 0), writes the code value 44 to signals 44 of the RAM RAM address 13 by signals 52 and 53 on the data bus 55 to the counter (thereby setting a low logic level of the signal 39 — end of the radiation mode and accumulation Ia), the exchange conducts polling controller 16 with external systems, which translates to caliper delay measurement signal reflected by the underlying surface mode, sets the signals 63 and 67 of the microwave carrier frequency - the generator 1 to the middle working range.

After that, the computing device 15 starts the subroutine setting the parameters of the transceiver module (MRP) and the start of radiation and accumulation. The algorithm of the subroutine is shown in figure 5. The subroutine sets the carrier frequency Fnes on a discretely controlled microwave generator 1, writes the gain and attenuation values to the gain and attenuation control units 17 and 18, writes the zero value of the code to the counter 44 of the RAM address of the RAM, starts the timer for the time tp.ppm - parameter setting time in PPM (discretely controlled microwave generator 1, directional coupler 2, pulse modulator 3, phase shifter 4, controlled attenuator 5, low-noise UHF 9, phase detector 10, video amplifier 11), after which the radiation mode is started of accumulation and analysis, analysis of the radiation flag 42.

Figure 6 shows the timing diagrams of the operation of the unit 7 for controlling the antenna switch in the radiation and accumulation modes. The antenna switch 6 connects to the reception alternately the first, second, third antennas (Fig.7). Each antenna is turned on to receive radio pulses for a time equal to the duration of two periods of radiation (periods with phases 0 and π / 2). After a time equal to the duration of six periods of radiation of the probe pulses, the reception cycle (for three receiving antennas) of radio pulses reflected from the underlying surface is repeated.

Through the circulator 8, the transceiver antenna (input / output 2) of the antenna system 8, radiation of radio pulses is provided in the direction of the underlying surface.

The radio pulses 95 (via the second microwave key 74), the radio pulses 94 (through the third microwave key 75), the radio pulses 96 through the circulator 8, and the first microwave key 73 are received at the input of the low-noise UHF 9 (signal 93) received from the underlying surface by the antenna system 8. At the end of the subroutine, the computing device 15 reads the data BOSU 13, and then carries out data processing, scanning the range of delays, determining the time delay of the digital signals from the underlying surface.

The radiation and timing of the ADC 12 and the recording in the BOSU 13 begin at time t0 (Fig. 8) [3]. Radio pulses are emitted at ticks with numbers 0, km + 1, 2km + 3, ..., nk (m + 1), ... (figa, 8b), where m is the nonius parameter, k is the time range extender for the signal, and n is radiation number, Teesl - period of clock pulses.

The conversion of the received signal (pigv) in the ADC 12 and recording in the BOSU 13 is carried out for each clock cycle with a period of Tozu (pigg, 8d). If the condition for the coincidence of the fronts of the clock pulses of radiation and the timing of the ADC 12 and BOSU 13:

Condition (1) can be written as:

where Fizl = 1 / Tizl - frequency of radiation clock pulses; Fozu = 1. / Tozu - the clock frequency of the ADC 12 and BOSU 13.

If the second and subsequent radiation to give out in moments

n * (km + 1) * Teesl, then the next cycle of the ADC 12 and BOSU 13 will come at the moment

n * (k (m-1) +1) * Tozy with a delay dtn, then from the equation:

n * (km + 1) * Tizzle + dtn = n * (k (m-1) +1) * Tosu

it can be shown that the nth radiation begins earlier than n * (k (m-1) +1) of the ADC 12 and BOSU 13 clock pulses by:

dtn = n * Tozu / m.

From this we obtain that in order to restore the received signal with a step of Tozu / m, Nizl = m is necessary, and the volume of the BOSU 13 Lozu is determined from the equation:

m * (km + 1) * Tizl = Lozu * Tozu, then the volume of BOSU 13 needed to restore the received signal is equal to Lozu = (km + 1) (m-1).

The above reasoning allows us to obtain that to restore the value of the received signal at the delay i * dt in digital form, we can derive the expression:

Ui = RAM {(i mod M) * m + [i / M]},

where the brackets {...} mean the contents of the RAM cell with the given number, the expression (i mod M) is the remainder of dividing i by M, and the bracket [...] is the integer part of the number, M = k (m-1) +1.

On fig.8e shows an example of the restored signal for k = 1, m = 8.

When reflected from the underlying surface, the change in the attenuation of the reflected signals at the input of the low-noise UHF 9 can be of the order of 30 dB, which leads to amplitude fluctuations and a change in the steepness of the reflected signal front and, as a result, to an additional error in measuring the delay of the reflected signal and the flight altitude of the aircraft.

To maintain a stable slope of the front of the reconstructed signal at a delay of i * dt, the computing device 15 starts after each radiation cycle and accumulation, a subroutine for automatically adjusting the gain of the video amplifier 11 and the power of the emitted radio pulses by the gain control unit 17, the gain control unit 18, and the UN current source 19, respectively ( Fig.9). The level of the reconstructed reflected signal is estimated. If the signal level exceeds the threshold, then the radiated power and the gain of the video amplifier 11 are reduced, if it does not exceed the threshold, then an increase.

After stabilization of the steepness of the front of the reflected signal (approximately 5-6 emitted packets of radio pulses), the computing device 15 provides the result of the measured flight altitude to the exchange controller 16 and puts the meter in the mode of measuring the longitudinal and transverse components of the ground speed vector.

The algorithm of the subroutine for calculating the longitudinal and lateral components Vx and Vz is turned on (Fig. 10).

One of the factors affecting the accuracy of measuring the components of the velocity vector is the position of the signal strobe (cross-section) on the signal reflected from the underlying surface. At the maximum of the pulse, the maximum fluctuation power of the signal is provided, therefore, the cross section on the envelope of the signal reflected from the underlying surface is set in the region of its maximum. Then, at this section, the values of the signal slice are sampled, storing them in BOSU 13.

Since the attenuation of signals in the microwave paths of each of the receiving antennas can be somewhat different, then to ensure the accuracy of the measurement of the components of the ground speed vector, before constructing the FCF in the computing device 15, the signal power is normalized for each of the three antennas:

,

,

, k=0…N-1,

,

,

, k = 0 ... N-1,

,

,

- значения исходных ненормированных сигналов, принятых на 1-ю, 2-ю и 3-ю антенны в моменты времени t_k; если отсчитывать время от начала пакета, тоWhere

,

,

- the values of the initial unnormalized signals received at the 1st, 2nd and 3rd antennas at time t _k ; if you count the time from the start of the packet, then

t ₀ = 0, t ₁ = Δt, ..., t _N-1 = (N-1) · Δt,

where Δt = time step of digitizing the signal,

N is the number of time samples;

,

,

- нормированные сигналы, принятые на 1-ю, 2-ю и 3-ю антенны в те же моменты времени t_k;

,

,

- normalized signals received at the 1st, 2nd and 3rd antennas at the same time t _k ;

,

,

- средние значения исходных сигналов на промежутке времени от t₀ до t_N-1;

,

,

- average values of the source signals over a period of time from t ₀ to t _N-1 ;

U ₀ is a constant that sets the average level of normalized signals. The instantaneous values of the cross-correlation functions between the signals received by the 1st and 2nd and 2nd and 3rd antennas are calculated.

,

,

,

,

where B is the number of time samples in the base interval used in the construction of the VKF;

K is the number of counts for constructing the VKF (it is understood that the condition B + K≤N is fulfilled, where N is the number of samples of the time of the digitized signal);

Z is the reference number of the VKF corresponding to the 0th delay between the signals (it is understood that the conditions Z <K and Z + K≤N are satisfied);

- взаимная корреляционная функция между сигналами, принятыми на 1-ю и 2-ю антенну, k принимает значения от 0 до К-1 и соответствует значениям ВКФ при задержках между сигналами τ_k:

- the mutual correlation function between the signals received at the 1st and 2nd antenna, k takes values from 0 to K-1 and corresponds to the values of the TCF at delays between the signals τ _k :

τ ₀ = -Z · Δt, τ ₁ = (- Z + 1) · Δt, ..., τ _Z = 0, τ _{Z + 1} = Δt, ..., τ _K-1 = (KZ-1) · Δt,

where Δt is the discrete of constructing the VCF equal to the time step of digitizing the signal;

- взаимная корреляционная функция между сигналами, принятыми 2-й и 3-й антеннами, k принимает значения от 0 до К-1;

- the mutual correlation function between the signals received by the 2nd and 3rd antennas, k takes values from 0 to K-1;

,

,

- нормированные сигналы, принятые на 1-ю, 2-ю и 3-ю антенны в моменты времени t_j.

,

,

- normalized signals received at the 1st, 2nd and 3rd antennas at time t _j .

Instant VKF are placed in the store, allowing you to store VKF, built on M last radiation packets and averaged by ordinary summation

,

,

,

,

- значения ВКФ из магазина, вычисленной по пакету с номером i, между сигналами, принятыми на 1-ю и 2-ю антенну, k принимает значения от 0 до К-1 и соответствует значениям ВКФ при задержках между сигналами τ_k;Where

- VKF values from the store, calculated by the packet with number i, between the signals received at the 1st and 2nd antenna, k takes values from 0 to K-1 and corresponds to the VKF values with delays between the signals τ _k ;

- значения усредненной по М последним пакетам ВКФ между сигналами, принятыми на 1-ю и 2-ю антенну, k принимает значения от 0 до K-1;

- values averaged over the M last VKF packets between the signals received at the 1st and 2nd antenna, k takes values from 0 to K-1;

- значения ВКФ из магазина, вычисленной по пакету с номером i, между сигналами, принятыми на 2-ю и 3-ю антенну, k принимает значения от 0 до K-1;

- VKF values from the store, calculated by the packet with number i, between the signals received at the 2nd and 3rd antenna, k takes values from 0 to K-1;

- значения усредненной по М последним пакетам ВКФ между сигналами, принятыми на 2-ю и 3-ю антенну, k принимает значения от 0 до K-1.

- the values averaged over the M last VKF packets between the signals received at the 2nd and 3rd antenna, k takes values from 0 to K-1.

The number of averages M is set adaptively to the level of the VKF.

To accurately determine the position of the VKF maxima, the VKF is approximated by a parabola using the least squares method using a triangular weight function.

The parabola equation can be written as

Fp _k = a · k ² + b · k + c.

Parameters a, b and c are determined from the system of equations

where a, b, c are the desired coefficients of the approximating function;

2M + 1 - the number of points at which the approximation is made;

N is the number of the discrete, which accounts for the maximum VKF;

F _{N + j} — values of the averaged FCF for delays between signals τ _{N + j} ;

- треугольная весовая функция.

- triangular weight function.

The use of a triangular weight function during approximation is due to the desire to reduce the influence of distortion in the shape of the side slopes on the accuracy of determining the position of the maximum VKF.

The well-known parameters of the parabola determine the position of its peak and, consequently, the maximum VKF (in relative units)

,

,

where Nt is the position of the maximum VKF (in relative units);

a, b are the found coefficients of the approximating function.

The transition to transport delays in time units is carried out according to the formula

,

,

- транспортная задержка между сигналами;Where

- transport delay between signals;

Nt is the position of the maximum VKF (in relative units);

Δt is the discrete of constructing the VCF equal to the time step of digitizing the signal.

Since the signals received by the 1st, 2nd, and 3rd antennas are not recorded at the same time instants, a methodological error arises when determining the transport delays between the signals. Taking into account the structure of the radiation packet, it amounts to 1/3 of the VKF discrete. Therefore, before calculating the components of the velocity vector, a correction is made

,

,

- найденная транспортная задержка между сигналами;Where

- found transport delay between signals;

τ - transport delay after correction;

Δt is the discrete of constructing the VCF equal to the time step of digitizing the signal.

To reduce the random component of the error, before calculating the projections of the velocity vector, the transport delays between the signals are averaged

,

,

τ is the instantaneous transport delay in the current packet;

- усредненная транспортная задержка, полученная в предыдущем пакете;

- The average transport delay received in the previous packet;

- усредненная транспортная задержка в текущем пакете,

- average transport delay in the current packet,

b is the number of averages of transport delays.

The relative position of the emitting and receiving antennas gives formulas for calculating the components of the velocity vector [4, 5]

,

,

,

,

where V _x , V _z are the components of the velocity vector in the projection on the axis of the associated coordinate system;

τ ₁ - transport delay between signals received at the 1st and 2nd antennas;

τ ₂ - transport delay between signals received at the 2nd and 3rd antennas;

X ₀ and Y ₀ are the parameters of the antenna system (Fig.7).

After measuring the flight altitude and components Vx and Vz, the measurement cycle of the above parameters is repeated periodically.

Using the invention allows to expand the functionality of the device, to increase the accuracy of the measurement of the components of the vector of the ground speed of the aircraft.

Literature

1. USSR author's certificate No. 1596934, cl. G01S 13/58. Publ. 04/28/1988

2. Lobach V.T., Uvarov S.N., Bokov G.I. Correlation meter of flight speed and drift angle. USSR copyright certificate No. 1503527, class G01S 13/60. Publ. 07/28/1987

3. RF patent No. 2188399 dated 06/21/1999, class. 7 G01F 23/284. Publ. 06/21/1999

4. USSR author's certificate No. 01689897 of 07/08/1991, class. G01S 13/48 “Receiving antenna system for a correlation meter for drift velocity and drift angle”. Auth. Bannikov V.M., Dyadkov N.A. Publ. November 7, 1991

5. Borkus M.K., Cherny A.E. Correlation meters of ground speed and drift angle of aircraft. M. Sov. radio - 1973

6. Microwave keys. Access mode: http://www.eltech.spb.ru/pdf/270.pdf.

Claims (3)

1. A correlation meter for altitude and components of the ground speed vector, comprising a synchronizer, a computing device, an analog-to-digital converter (ADC), a phase shifter, a pulse modulator, a controlled attenuator, a video amplifier, a buffer memory (BOSU), a gain control unit, an attenuation adjustment unit , voltage-controlled current source, exchange controller, circulator, low-noise high-frequency amplifier (UHF), phase detector, directional coupler, discretely controlled with an ultrahigh-frequency (microwave) generator whose output is connected to the input of a directional coupler, the second output of which is connected to the second input of a phase detector, the first input of which is connected to the output of a low-noise UHF, the first output of the directional coupler is connected to the first input of a pulse modulator, the second input of which is connected to the second synchronizer output, the output of the pulse modulator is connected to the second input of the phase shifter, the first input of which is connected to the first output of the synchronizer, and the output to the first control input a controlled attenuator, the output of which is connected to the first input of the circulator, the second input of the controlled attenuator is connected to the output of a voltage controlled current source, the input of which is connected to the output of the attenuation control unit, all of the first inputs of which are connected via the data bus to all the first inputs of the gain control unit, all six inputs / outputs of the BOZU, all the first inputs / outputs of the exchange controller, all third inputs / outputs of which are the inputs / outputs of the meter, as well as all twelve inputs of the calculator an integral device, the second, third, fourth, fifth outputs of which are connected respectively to the second inputs of the attenuation control unit, gain control unit, exchange controller, BOSU, and the sixth, seventh, thirteenth outputs, respectively, with the third, fourth, seventh inputs of the BOSU, eighth, the ninth outputs, respectively, with the second and third inputs of the synchronizer, the tenth, eleventh outputs, respectively, with the second and first inputs of a discretely controlled microwave generator, the first input with the fourth output of the synchronizer the first input of which is connected to the output of the BOZU, the first input of which is connected to the third output of the synchronizer and the second input of the ADC, all the outputs of which are connected to all fifth inputs of the BOZU, and the first input of the ADC is connected to the output of the video amplifier, the first input of which is connected to the output of the phase detector, the second input - with the output of the gain control unit, the second input - with the output of the gain control unit, characterized in that, in order to expand the functionality of the device, improve the accuracy of measuring the flying vector of the flying speed of the first apparatus, the antenna switch, the antenna switch control unit, the antenna system of the transceiver module are introduced into it, while the second input / output of the circulator is connected to the second input / output of the antenna system, the first and third outputs of which are connected to the fifth and sixth inputs of the antenna switch, the output which is connected to the input of a low-noise UHF, the output of the circulator is connected to the first input of the antenna switch, the second, third, fourth inputs of which are connected to the first, second, third outputs of the control unit an antenna switch, the first, second, third inputs of which are connected respectively to the first, second and fifth outputs of the synchronizer. 2. A correlation meter for height and components of the ground speed vector according to claim 1, characterized in that one of the antennas of the antenna system is made in the form of a transceiver. 3. The correlation meter for the height and components of the ground speed vector according to claim 1, characterized in that the transmit antenna of the antenna system of the transceiver module is made as a separate unit connected to the output of the controlled attenuator, and the first input of the circulator is connected to the matched load.

Images