A method for testing amplitude and phase consistency of a quadrature vector synthesis intermediate frequency receiver

Abstract

The application discloses a method for testing amplitude and phase consistency of a quadrature vector synthesis channel intermediate frequency receiver, which comprises the following steps: S1, according to the input signal of the quadrature vector synthesis channel intermediate frequency receiver, deducing the intermediate frequency receiver output intermediate frequency signal formula, and establishing a signal model; S2, normalizing and demodulating the signal after channel merging in the intermediate frequency receiver, and outputting two direct current voltage signals carrying target spatial position information; S3, defining the direct current signal output after the two normalized direct current voltage signals are detected and amplified as two angle channel output voltages; testing the two angle channel output voltages by using an angle channel output voltage testing method; and S4, on the basis of completing the amplitude and phase consistency adjustment of the three signals of the intermediate frequency receiver, testing the azimuth characteristics of the two angle channels by using an azimuth characteristic testing method. The application can effectively test the amplitude and phase consistency of the quadrature vector synthesis channel intermediate frequency receiver.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of avionics, and particularly relates to a phase and amplitude consistency test method for an AK intermediate frequency receiver. BACKGROUND

[0002] With the rapid development of modern high-tech equipment, higher requirements are put forward for missile guidance technology. The seeker is the core component of precision guided weapons, and is used to complete the predetermination, automatic search, identification and tracking of targets. The AK intermediate frequency receiver loaded by the seeker adopts a phase and difference monopulse angle measurement system, and obtains the azimuth and elevation angles of a target in space through sum and difference operations on four sub-beams of an antenna. In this two-dimensional angle measurement system, the sum channel signal, the elevation signal and the azimuth signal generated by the sum and difference operations are amplified and filtered in respective channels, and after the sum and difference channel signals are normalized and the sum and difference phase is compared, two-dimensional angle measurement can be realized. The overall design scheme of the AK intermediate frequency receiver adopts typical superheterodyne technology, and after twice down-conversion of an input first intermediate frequency signal, the indirect frequency modulation technology (channel merging scheme of AK) is used to merge and normalize the ∑, △1 and △2 three-way signals into two-way △1 / ∑ and △2 / ∑ signals. For a radar receiver using the channel merging technology, the phase imbalance and amplitude imbalance of the sum and difference channels before channel merging have a great influence on the output signal, and are also a difficult problem for accurate testing. Research shows that the amplitude and relative phase difference existing in the sum and difference channels will inevitably lead to angle measurement error; therefore, the amplitude and phase consistency test before channel merging is very important.

[0003] In the prior art, the amplitude and phase test adopts a gain phase meter or a vector network analyzer. A paper titled "A Method for Testing Amplitude and Phase Characteristics of Receiver Using Vector Network Analyzer" published in March 2009 in the 34th volume, 3rd issue of Electronic Measurement Technology discloses a detection method. The method is to use a vector network analyzer to imitate the frequency conversion times of the measured receiver, select relevant mixers and filters, build an external reference receiver and a calibration receiver, complete calibration in the working frequency of the measured receiver, and then use the same calibration data to complete the test of the amplitude and phase parameters of different receiving channels. The disadvantage of the method is that the test is complex, the test steps are extremely tedious, the calibration reference receiver and the calibration receiver need to be built before each measurement, the test time is long, the test instrument is expensive, and the test cost is high. SUMMARY

[0004] To solve the above problems, the purpose of the present application is to provide a phase and amplitude consistency test method for an AK intermediate frequency receiver.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] A method for testing amplitude and phase consistency of a quadrature vector synthesis channel intermediate frequency receiver, comprising the following steps:

[0007] S1. Deriving an intermediate frequency receiver output intermediate frequency signal formula according to an input signal of the quadrature vector synthesis channel intermediate frequency receiver, and establishing a signal model;

[0008] The specific process of establishing the signal model is that the received signals of two sub-beams of the phase comparison single pulse antenna are respectively:

[0009]

[0010] In the formula, K represents a fixed coefficient and an amplitude coefficient of a return signal; θ represents an included angle between a target return signal direction and an equal strength signal axial direction; f0 represents a radio frequency signal frequency; d represents a sub-beam interval; λ represents a radio frequency signal wavelength; and θ0 represents a target-to-antenna axial angle;

[0011] Supposing that an amplitude imbalance coefficient of the microwave channel is g and a relative phase difference is φ, then sum channel signals s Σ(t,θ) and difference channel signals s Δ(t,θ) input to the quadrature vector synthesis channel intermediate frequency receiver are:

[0012]

[0013]

[0014] In the formula, φ represents a phase difference of the received antenna signal caused by a path difference;

[0015] Under the premise of ignoring amplitude and phase inconsistency of the input signals of the intermediate frequency receiver, the sum channel signals s Σ(t,θ) and the difference channel signals s Δ(t,θ) in formula (3) are respectively:

[0016]

[0017] The signals output by the phase comparator are:

[0018]

[0019] In the formula, K P represents an amplitude imbalance coefficient of the receiver sum and difference channels; K Δ represents a sum channel amplitude coefficient; and K Σ represents a difference channel amplitude coefficient.

[0020] Supposing that the microwave channel is amplitude and phase balanced, i.e. g = 1 and φ = 0, the signals output by the phase comparator are:

[0021]

[0022] When φ Δ = φ Σ and θ0 is very small, sin θ0 ≈ θ0,

[0023]

[0024] This formula is the same as the analysis result of the monopulse ratio angle measurement system.

[0025] If the amplitude and phase inconsistency of the intermediate frequency receiver is considered, formula (6) is transformed into:

[0026]

[0027] In the formula, p represents the amplitude imbalance coefficient of the intermediate frequency receiver and difference channel; φ Δ represents the phase shift of the intermediate frequency receiver difference channel; φ Σ represents the phase shift of the intermediate frequency receiver and channel;

[0028] When the channel amplitudes are consistent, i.e. g = 1, p = 1, formula (8) is transformed into:

[0029]

[0030] Using the first order Taylor series approximation, we get:

[0031]

[0032] According to formula (10), the phase inconsistency adjusts the gain of the error angle voltage output; the phase shift voltage compensation of the seeker computer adjusts the relative phase difference between the sum channel and difference channel; when the relative phase difference between the sum channel and difference channel is zero, the test angle output signal changes with the amplitudes of the sum signal and difference signal.

[0033] S2, the signals after the sum of the channels in the intermediate frequency receiver are normalized and demodulated, and two direct current voltage signals carrying the spatial position information of the target are output, which are △1 / ∑ and △2 / ∑, respectively. The amplitude of the signal is proportional to the ratio of the amplitude value before the sum of the channels, and reflects the size of the angle of the target deviating from the axis of the seeker antenna. The polarity of the direct current voltage signal △1 / ∑ and the direct current voltage signal △2 / ∑ reflects the phase of the normalized signal compared with the phase of the reference signal, which indicates the direction of the target deviating from the axis of the seeker antenna.

[0034] ​S3, the direct current signals outputted after the normalized two-way direct current voltage signals △1 / ∑ and direct current voltage signals △2 / ∑ are detected and amplified are defined as △1, △2 angle channel output voltage; the angle channel output voltage test method is used to test the △1, △2 angle channel output voltage, and the method is as follows: the same frequency and amplitude sinusoidal signals outputted by the same signal source are used as the input signal and the difference input signal, the attenuation amounts of the sum channel and the difference channel attenuators are both set as 0dB, the seeker amplitude control voltage is set as 0V, the seeker computer phase shift control voltage is adjusted, and the △1, △2 angle output direct current voltage is detected;

[0035] S4, on the basis of completing the amplitude and phase consistency adjustment of the three-way signals ∑, △1 and △2 of the intermediate frequency receiver, the azimuth characteristic test method is used to test the azimuth characteristics of the △1, △2 angle channels, and the method is as follows: the amplitudes of the three-way input signals of the intermediate frequency receiver are consistent, and the amplitude imbalance degree of the sum signal and the difference signal is ensured to be within ±0.5dB; after the amplitude and phase consistency adjustment is completed, the amplitude of the ∑-way signal is kept unchanged, the power of the input signals of the △1, △2 angle channels is changed at a certain step, and the change of the output voltage of the △1, △2 angle channels with the input signal is detected.

[0036] An amplitude and phase consistency test system of a quadrature vector synthesis channel intermediate frequency receiver, comprising:

[0037] A signal source for generating a reference signal;

[0038] A three-way power divider connected with the output end of the signal source, taking the reference signal of the signal source as the input, and dividing the reference signal into two-way same signals and outputting the two-way same signals;

[0039] A first attenuator and a second attenuator connected with the output end of the three-way power divider, respectively receiving the two-way signals outputted by the three-way power divider, adjusting the power of the signals and then outputting the signals;

[0040] An intermediate frequency receiver for receiving the signals outputted by the three-way power divider, the first attenuator and the second attenuator, normalizing and demodulating the signals, and outputting two direct current voltage signals carrying target spatial position information; for receiving two-way continuous adjustable direct current phase shift control voltage and amplitude control voltage outputted by a seeker computer;

[0041] A second local oscillator and a third local oscillator for inputting second local oscillator signals and third local oscillator signals to the intermediate frequency receiver;

[0042] The intermediate frequency receiver is connected with a digital multimeter.

[0043] Due to the adoption of the technical scheme, the present application has the following advantages:

[0044] The amplitude-phase consistency test method of the quadrature vector synthesis channel intermediate frequency receiver is simple in operation, low in cost, rapid in detection, suitable for the production line mode, and can effectively detect the amplitude-phase consistency of the quadrature vector synthesis channel intermediate frequency receiver by establishing a receiver signal model, deriving the law of the output signal of the receiver with amplitude inconsistency and phase inconsistency, and applying an indirect test method without increasing the hardware cost of equipment and improving the test efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is the angle channel output voltage and azimuth characteristic test principle block diagram in the application. DETAILED DESCRIPTION

[0046] The technical solutions of the application will be further described in detail below with reference to the drawings and embodiments.

[0047] As Figure 1 shown, an amplitude-phase consistency test system of a quadrature vector synthesis channel intermediate frequency receiver includes:

[0048] A signal source is configured to generate a reference signal.

[0049] A one-to-three power divider is connected to the output end of the signal source and takes the reference signal of the signal source as input, and divides the reference signal into two equal signals.

[0050] A first attenuator and a second attenuator are connected to the output end of the one-to-three power divider and receive the two signals output by the one-to-three power divider, respectively, to adjust the power of the signals and then output.

[0051] An intermediate frequency receiver is configured to receive the signals output by the one-to-three power divider, the first attenuator, and the second attenuator, normalize and demodulate the signals, and output two direct current voltage signals carrying target spatial position information, and receive two continuously adjustable direct current phase shift control voltages and amplitude control voltages output by a signal processor of a seeker.

[0052] A second local oscillator source and a third local oscillator source are configured to input a second local oscillator signal and a third local oscillator signal to the intermediate frequency receiver.

[0053] The output end of the intermediate frequency receiver is connected to a digital multimeter.

[0054] An amplitude-phase consistency test method of a quadrature vector synthesis channel intermediate frequency receiver includes the following specific steps:

[0055] S1, power supply for the intermediate frequency receiver, and input of a second local oscillator signal and a third local oscillator signal to the intermediate frequency receiver through a second local oscillator and a third local oscillator.

[0056] S2, input the signal source signal to the power divider to divide into three same amplitude and frequency signals, input to the intermediate frequency receiver Σ, Δ1, Δ2;

[0057] S3, input two continuously adjustable DC phase shift control voltage and amplitude control voltage to the intermediate frequency receiver, and set to 0V;

[0058] S4, adjust the two computer phase shift control voltages until the DC voltage of the angle output of the intermediate frequency receiver is the maximum value, at this time it indicates that the three signals Σ, Δ1, Δ2 of the intermediate frequency receiver are same frequency, same amplitude and same phase;

[0059] S5, adjust the attenuation amount of the attenuation unit of the Δ1, Δ2 channel, attenuate 6dB each time, and detect the output voltage of the Δ1, Δ2 angle channel after each attenuation; because the angle output voltage is the DC voltage after synchronous detection of Δ1 / Σ and Δ2 / Σ when the attenuation unit attenuates the Δ1, Δ2 signal by 6dB, the angle output voltage is reduced by half each time, since the antenna adjustment system Δ1 / Σ and Δ2 / Σ of the front end of the intermediate frequency receiver is a%, which represents that the equal strength signal of the signal deviates 1 degree from the normal direction of the antenna, and since the -3dB directional diagram width of the antenna is b°, the center of the antenna polarization normal direction has a directional diagram width of b / 2° to the left and right, b / 2° is selected to inversely deduce the maximum adjustment system of the difference channel Δ1 / Σ and Δ2 / Σ as a%×b / 2°=50%, in order to comprehensively evaluate the amplitude and phase consistency of the intermediate frequency receiver within the antenna directional diagram, the "difference" signal is selected to be attenuated by 0dB, 12dB, 18dB, 24dB, 30dB, that is, the adjustment system is 100%, 50%, 25%, 12.5%, 6.25% respectively, and the angle channel output voltage should be V1, V2, V3, V4, V5 respectively, and the angle channel output voltage is calculated according to formula (11), that is, the azimuth characteristic slope is obtained;

[0060] K=10×Vi×VΣ÷VΔi (11)

[0061] In the formula: K represents the azimuth characteristic slope, unit mV / %; Vi represents the output voltage of the angle channel, unit V; VΣ represents the voltage of XS1 input signal, unit μV; VΔi represents the voltage of XS2 (or XS3) input signal corresponding to the i-th attenuation, unit μV;

[0062] The azimuth characteristic slope calculated according to formula (11) is kmV / %, and the detected angle channel output voltage is within the range of (k±10) mV / %, which indicates that the amplitude and phase consistency of the intermediate frequency receiver is qualified.

[0063] The above merely describes preferred embodiments of the present application, but not intended to limit the present application. Any equivalent changes and modifications made without departing from the spirit and scope of the present application shall fall within the scope of the patent protection of the present application.

Claims

1. A method for testing the amplitude and phase consistency of an orthogonal vector synthesis channel intermediate frequency receiver, characterized in that: It includes the following steps: S1. Based on the input signal of the intermediate frequency receiver in the orthogonal vector synthesis channel, derive the formula for the output intermediate frequency signal of the intermediate frequency receiver and establish the signal model; The specific process of establishing the signal model is as follows: The received signals of the two sub-beams of the phase-monolithic antenna are as follows: In the formula: K represents a fixed coefficient, the amplitude coefficient of the echo signal; θ represents the angle between the direction of the target echo signal and the axis of the equal-intensity signal; f0 represents the frequency of the radio frequency signal; d represents the sub-beam spacing; λ represents the wavelength of the radio frequency signal; θ0 represents the deflection angle of the target relative to the antenna axis; Let the amplitude imbalance coefficient of the microwave channel be g and the relative phase difference be φ, then the sum channel signal s input to the intermediate frequency receiver of the orthogonal vector synthesis channel is... ∑(t,θ) Differential channel signal s Δ(t,θ) for: In the formula: This indicates the phase difference in the received antenna signal caused by the path difference; Assuming that the amplitude and phase inconsistencies in the input signal of the intermediate frequency receiver are ignored, the sum channel signal s in formula (3) ∑(t,θ) Differential channel signal s Δ(t,θ) After normalization, they are as follows: The signal output by the phase comparator is: Where: K P K represents the amplitude imbalance coefficient of the receiver's sum and difference channels; Δ Represents the channel amplitude coefficient; K ∑ Indicates the difference channel amplitude coefficient; Assuming the microwave channel is in phase-amplitude balance, i.e., g = 1 and φ = 0, the signal output by the phase comparator is: When φ Δ =φ ∑ And when θ0 is very small, sinθ0≈θ0. This formula yields the same results as the analysis of the single-pulse phase ratio angle measurement system. If the amplitude-phase inconsistency of the intermediate frequency receiver is also taken into account, then formula (6) becomes: In the formula: p represents the amplitude imbalance coefficient of the intermediate frequency receiver's sum and difference channels; φ Δ This indicates the differential channel phase shift in the intermediate frequency receiver; φ Σ This indicates the phase shift of the intermediate frequency receiver and the channel; When the channel amplitudes are consistent, i.e., g=1 and p=1, formula (8) transforms into: Will Approximating with a first-order Taylor series, we obtain: According to formula (10), the phase inconsistency is adjusted by controlling the gain of the error angle voltage output; the relative phase difference between the sum and difference channels is compensated by adjusting the phase shift voltage of the seeker computer; when the relative phase difference between the sum and difference channels is zero, the variation law of the angle output signal with the amplitude of the sum and difference signals is examined. S2. The intermediate frequency receiver normalizes and demodulates the channel-merged signal, outputting two DC voltage signals carrying target spatial position information, Δ1 / ∑ and Δ2 / ∑. The amplitude of the signal is proportional to the amplitude value before channel merging, reflecting the magnitude of the target's deviation from the seeker antenna axis. The polarity of the DC voltage signals Δ1 / ∑ and Δ2 / ∑ reflects the phase of the normalized signal compared to the phase of the reference signal, indicating the direction of the target's deviation from the seeker antenna axis. S3. Define the normalized two-channel DC voltage signals △1 / ∑ and △2 / ∑ as the DC signals after detection and amplification, and define them as the △1 and △2 angle channel output voltages. Test the △1 and △2 angle channel output voltages using the angle channel output voltage test method. The method is as follows: use the same frequency and amplitude sine wave signals from the same signal source as the input signal and the difference input signal. Set the attenuation of the attenuators of the input channel and the difference channel to 0dB. Set the seeker amplitude control voltage to 0V. Adjust the seeker computer phase shift control voltage and detect the △1 and △2 angle output DC voltages. S4. After completing the amplitude and phase consistency adjustment of the three signals ∑, △1, and △2 of the intermediate frequency receiver, the azimuth characteristics of the △1 and △2 angle channels are tested using the azimuth characteristic test method. The method is as follows: make the amplitudes of the three input signals of the intermediate frequency receiver consistent, and ensure that the amplitude imbalance between the sum and difference signals is within ±0.5dB; after completing the amplitude and phase consistency adjustment, keep the amplitude of the ∑ signal constant, change the power of the △1 and △2 input signals in a certain step, and detect the change of the output voltage of the △1 and △2 angle channels with the input signals.

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