A high-precision interferometer

Abstract

The present invention discloses a high-precision interferometer, which includes an antenna array, a radio frequency channel, and a baseband processing module. The antenna array is connected to the radio frequency channel, which is connected to the baseband processing module. The antenna array includes six antennas, four of which form two mutually perpendicular long baselines, and the other two antennas are combined with two of the four antennas to form two mutually perpendicular short baselines. There are three radio frequency channels, each of which is connected to a corresponding antenna via a switching switch. The baseband processing module calculates the incident angle for real-time measurement of the incident angle of the incident wave. The present invention improves the angle measurement accuracy at a low cost by adding an antenna array. By adding a baseline perpendicular to the original baseline, it is ensured that when the incident wave is incident from any direction, there is always a baseline whose perpendicular line has an angle less than or equal to 45 degrees with the incident wave. By switching the channel switch, only antennas are added without adding radio frequency channels, thus controlling costs.

Description

Technical Field

[0001] The invention belongs to the technical field of radio direction finding and relates to a high-precision interferometer. Background Art

[0002] Interferometer direction finding technology uses the different phase responses and the phase relationship between them generated when the same phase wavefront of the electromagnetic wave of the radiation source in the propagation direction reaches the spatially separated sensors (usually a multi-element antenna array) to measure the direction. Interferometers are divided into dual-channel interferometers and multi-channel interferometers according to the number of channels, and are divided into single-baseline interferometers, dual-baseline interferometers and multi-baseline interferometers according to the number of baselines. In order to improve the lateral accuracy, a three-channel long-short baseline interferometer is generally used. The short baseline is used to resolve ambiguity, and the long baseline is used to improve the direction finding accuracy. Figure 1 and Figure 2 shown.

[0003] When designing an interferometer, it is usually hoped to improve the angle measurement accuracy as much as possible under the condition of low cost.

[0004] The cost of an interferometer is limited by the number of antennas and RF channels. Typically, one antenna corresponds to one RF channel, and the cost of the RF channel is much greater than the cost of the antenna.

[0005] According to the principle of interferometer, there are two factors that limit the accuracy of angle measurement: one is the baseline length. The longer the baseline, the higher the accuracy; the other is the direction of the incoming wave. When the baseline length remains unchanged and the incoming wave direction is perpendicular to the baseline, the accuracy is highest. When it is parallel to the baseline (that is, the incident angle is around 90 degrees), the accuracy is the worst.

[0006] In order to solve the problem of poor angle measurement accuracy when the incoming wave direction is nearly parallel to the baseline, a servo system is usually installed under the interferometer to adjust the direction of the incident wave in real time. However, the servo system is large in size and expensive.

[0007] In order to maximize the angle measurement accuracy at a lower cost, this patent innovatively proposes a low-cost and high-precision interferometer design. Summary of the Invention

[0008] (1) Purpose of the invention

[0009] The purpose of the present invention is to provide a low-cost high-precision interferometer to improve the angle measurement accuracy at a lower cost, in view of the poor angle measurement accuracy when the incoming wave direction is nearly parallel to the baseline. Installing a servo system to improve the accuracy also increases the cost.

[0010] (2) Technical solution

[0011] In order to solve the above technical problems, the present invention provides a high-precision interferometer including an antenna array, a radio frequency channel and a baseband processing module; the antenna array is connected to the radio frequency channel, and the radio frequency channel is connected to the baseband processing module. The antenna array includes six antennas, four of which form two long baselines perpendicular to each other, and the other two antennas are combined with two of the four antennas to form two short baselines perpendicular to each other; there are three radio frequency channels, which are connected to the corresponding antennas through switching switches, and the incident angle is calculated by the baseband processing module for real-time measurement of the incident angle of the incident wave.

[0012] (3) Beneficial effects

[0013] The low-cost, high-precision interferometer provided by the above technical solution improves the angle measurement accuracy at a low cost by adding an antenna array. By adding a baseline perpendicular to the original baseline, it is ensured that no matter from which direction the incident wave is incident, there is always a vertical line of the baseline and the angle between the incident wave is less than or equal to 45 degrees. By switching the channel switch, only the antenna is added, and the RF channel is not added, thus controlling the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of angle measurement using long-short baseline interferometer.

[0015] Figure 2 Schematic diagram of the connection between the long-short baseline interferometer antenna and the RF channel.

[0016] Figure 3 Schematic diagram of low-cost, high-precision interferometer angle measurement.

[0017] Figure 4 Schematic diagram of the connection between the low-cost, high-precision interferometer antenna and the RF channel. DETAILED DESCRIPTION

[0018] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0019] Reference Figure 3 As shown, the high-precision interferometer of this embodiment includes an antenna array, a radio frequency channel and a baseband processing module; the antenna array is connected to the radio frequency channel, and the radio frequency channel is connected to the baseband processing module. The antenna array includes six antennas, four of which form two long baselines perpendicular to each other, and the other two antennas are combined with two of the four antennas to form two short baselines perpendicular to each other; there are three radio frequency channels, which are connected to the corresponding antennas through switching switches, and the incident angle is calculated by the baseband processing module for real-time measurement of the incident angle of the incident wave.

[0020] Among them, the six antennas of the antenna array are respectively recorded as antenna A1, antenna A2, antenna A3, antenna B1, antenna B2, and antenna B3. Antenna A1 and antenna A3 form a long baseline, antenna B1 and antenna B3 form a second long baseline, and the two long baselines are perpendicular to each other; antenna A1 and antenna A2 form a short baseline, antenna B1 and antenna B2 form a second short baseline, and the two short baselines are perpendicular to each other.

[0021] Antenna A2 is arranged between antenna A1 and antenna A3, and antenna B2 is arranged between antenna B1 and antenna B3.

[0022] The lengths of the two long baselines can be equal or different, but the lengths are set as long as possible to improve the angle measurement accuracy. The specific length is limited by the size of the interferometer installation platform. The length of each long baseline only needs to be no less than the length of the installation platform corresponding to the installation position of the long baseline. For example, if the interferometer is installed on a vehicle, antenna A1 and antenna A3 are arranged along the length direction of the vehicle body, then the length of the long baseline only needs to be no less than the length of the vehicle.

[0023] The lengths of the two short baselines can be equal or different. The length of the short baseline is limited by the wavelength of the incoming wave and can be less than half of the wavelength of the incoming wave.

[0024] Reference Figure 4 As shown, based on the above-mentioned high-precision interferometer, the real-time measurement process of the incident wave incident angle is as follows:

[0025] The first step is to control the switch so that antenna A1 is connected to RF channel 1, antenna A2 is connected to RF channel 2, and antenna A3 is connected to RF channel 3. Calculate the incident angle of the incident wave.

[0026] The second step is to determine the incident angle of the incident wave Is it greater than 45 degrees? If not, this angle is used as the actual measurement angle of the incident wave. If it is greater than 45 degrees, control the switch to connect antenna B1 to RF channel 1, antenna B2 to RF channel 2, and antenna B3 to RF channel 3, and calculate the incident wave incident angle β.

[0027] The third step is to determine whether the incident wave incident angle β is greater than 45 degrees. If it is not greater than 45 degrees, this angle is used as the actual measurement angle of the incident wave; if it is greater than 45 degrees, control the switch to connect antenna A1 to RF channel 1, antenna A2 to RF channel 2, antenna A3 to RF channel 3, and the incident wave incident angle

[0028] In the fourth step, the second and third steps are repeated to perform real-time measurement of the incident angle of the incident wave.

[0029] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for real-time measurement of incident wave angle of incidence, characterized in that: The measurement is performed based on a high-precision interferometer, which includes an antenna array, a radio frequency channel, and a baseband processing module. The antenna array is connected to the radio frequency channel, which is in turn connected to the baseband processing module. The antenna array includes six antennas, four of which form two mutually perpendicular long baselines, and the other two antennas are combined with two of the four antennas to form two mutually perpendicular short baselines. There are three radio frequency channels, each connected to a corresponding antenna via a switch. The baseband processing module calculates the incident angle for real-time measurement of the incident wave's angle of incidence. The six antennas of the antenna array are respectively denoted as antenna A1, antenna A2, antenna A3, antenna B1, antenna B2, and antenna B3. Antenna A1 and antenna A3 form a long baseline, antenna B1 and antenna B3 form a second long baseline, and the two long baselines are perpendicular to each other; antenna A1 and antenna A2 form a short baseline, antenna B1 and antenna B2 form a second short baseline, and the two short baselines are perpendicular to each other; antenna A2 is arranged between antenna A1 and antenna A3; antenna B2 is arranged between antenna B1 and antenna B3; the lengths of the two long baselines are equal or unequal; the lengths of the two long baselines are limited by the size of the interferometer installation platform, and the length of each long baseline is not less than the length of the installation platform corresponding to the installation position of the long baseline; the lengths of the two short baselines are equal or unequal; the lengths of the two short baselines are limited by the wavelength of the incoming wave, and both are less than half the wavelength of the incoming wave; The measurement process is as follows: The first step is to control the switch so that antenna A1 is connected to RF channel 1, antenna A2 is connected to RF channel 2, and antenna A3 is connected to RF channel 3. Calculate the incident wave angle The second step is to determine the incident angle of the incident wave Is it greater than 45 degrees? If not, this angle is used as the actual measurement angle of the incident wave. If it is greater than 45 degrees, control the switch to connect antenna B1 to RF channel 1, antenna B2 to RF channel 2, and antenna B3 to RF channel 3, and calculate the incident wave incident angle β. The third step is to determine whether the incident wave incident angle β is greater than 45 degrees. If it is not greater than 45 degrees, this angle is used as the actual measurement angle of the incident wave; if it is greater than 45 degrees, control the switch to connect antenna A1 to RF channel 1, antenna A2 to RF channel 2, antenna A3 to RF channel 3, and the incident wave incident angle In the fourth step, the second and third steps are repeated to perform real-time measurement of the incident angle of the incident wave.

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