An active omnidirectional magnetic antenna differential receiver for long-wave positioning, navigation, and timing, and its design method.

Abstract

This invention discloses an active omnidirectional magnetic antenna differential receiver and its design method for long-wave positioning, navigation, and timing. The device includes a long magnetic core and two short magnetic cores, with the two short cores located on either side of the long core. The three cores are arranged in a cross shape. A set of receiving coils is wound around each end of the long core, and a set of receiving coils is wound around each of the two short cores. The leads of all four sets of receiving coils are connected to the common ground of the circuit board. Furthermore, the four sets of receiving coils are electrically connected to an amplifier circuit. The receiver disclosed in this invention achieves omnidirectionality and miniaturization of the magnetic antenna, improving anti-interference capability. It also has strong generalization ability, utilizing the tuning function of the amplifier circuit to be applicable to the reception and amplification of long-wave signals of different frequencies.

Description

Technical Field

[0001] This invention belongs to the field of positioning, navigation and timing devices, and specifically relates to an active omnidirectional magnetic antenna differential receiver for long-wave positioning, navigation and timing and its design method, used for differential reception of long-wave positioning, navigation and timing signals and implementation of positioning, navigation and timing (PNT) functions. Background Technology

[0002] Positioning, navigation, and timing (PNT) systems are spatiotemporal systems composed of positioning, navigation, and timing. They are key technologies enabling humans to accurately describe time and space amidst a sea of ​​information. Common PNT systems include the US GPS, the EU's Galileo, Russia's GLONASS, and China's BeiDou. All four of these systems are satellite-based, primarily utilizing navigation satellites for timing and ranging. Satellite navigation systems offer advantages such as high positioning accuracy, short observation times, and the ability to provide three-dimensional coordinates, making them the mainstream PNT system. However, their anti-jamming capabilities are severely lacking, making them highly vulnerable to enemy destruction of satellites or interference with communication links in modern warfare.

[0003] To compensate for the inherent limitations of satellite positioning and navigation systems, mainstream technologies employ very low frequency (VLF) long-wave radio positioning and navigation systems as a backup. The main principle of long-wave radio positioning and navigation systems is to determine the azimuth and distance of a moving vehicle relative to the navigation station by measuring parameters such as the time, phase, amplitude, and frequency of signals transmitted by ground-based radio navigation stations, thereby achieving positioning, navigation, and timing for the moving vehicle. Currently, the mainstream long-wave radio positioning, navigation, and timing system is the Loran-C system, another major system in the PNT (Positioning, Navigation, and Timing) architecture.

[0004] The key technology of long-wave positioning, navigation, and timing systems lies in the receiver's ability to receive and process very low frequency (VLF) long-wave (100kHz) radio positioning and navigation signals. Electric dipole antennas or magnetic dipole antennas are typically used to receive long-wave radio signals. However, while ordinary long-wave electric and magnetic dipole antennas achieve omnidirectional coverage, they are large in size, lack sufficient anti-interference capabilities, and do not have the ability to distinguish signals from multiple directions. Even with signal processing algorithms, accurate positioning, navigation, and timing functions cannot be achieved. Summary of the Invention

[0005] To address the problems of large size and insufficient anti-interference capability of conventional long-wave receiving antennas, this invention provides a miniaturized active omnidirectional magnetic antenna differential receiving device for long-wave positioning, navigation, and timing, and its design method.

[0006] The present invention adopts the following technical solution:

[0007] An active omnidirectional magnetic antenna differential receiver for long-wave positioning, navigation, and timing is improved in that it includes a long magnetic core and two short magnetic cores, with the two short magnetic cores located on both sides of the long magnetic core. The three magnetic cores are arranged in a cross shape. A set of receiving coils is wound at each end of the long magnetic core, and a set of receiving coils is wound on each of the two short magnetic cores. The lead terminals of the four sets of receiving coils are all connected to the common ground of the circuit board. In addition, the four sets of receiving coils are also electrically connected to the amplifier circuit.

[0008] Furthermore, both the long and short magnetic cores are made of ferrite with an initial permeability of Ui=2000, and the ferrite core is rectangular in shape.

[0009] Furthermore, the long magnetic core has a length of 127mm, a width of 20mm, and a height of 4mm, while the two short magnetic cores each have a length of 53.5mm, a width of 20mm, and a height of 4mm.

[0010] Furthermore, two short magnetic cores are glued and fixed to both sides of the long magnetic core.

[0011] Furthermore, the receiving coil uses enameled wire with a diameter of Ф=0.12mm, with 200 turns. The winding direction is as follows: the enameled wire is wound clockwise to the right in a single-layer structure for 50 turns, and then wound back to the starting point in a clockwise direction, so that the right side forms a double layer with a total of 100 turns. Then, the enameled wire is pulled to the left by a certain distance and wound clockwise to the left in a single-layer structure for 50 turns, and then wound back in a clockwise direction, so that the left side forms a double layer with a total of 100 turns.

[0012] Furthermore, the amplifier circuit includes a pre-amplifier circuit and a post-amplifier circuit.

[0013] A design method for designing the above-mentioned receiving device, the improvement of which includes the following steps:

[0014] Step 1: Select a suitable ferrite core as the core shaft of the receiving coil based on the characteristics of very low frequency long wave electromagnetic waves.

[0015] Step 2: Select an enameled wire of appropriate diameter and wind it around the ferrite core a certain number of turns to form a ferrite receiving coil.

[0016] Step 3: Arrange a certain number of ferrite receiving coils into a specific shape;

[0017] Step 4: Design the differential amplifier circuit after the receiving coil.

[0018] The beneficial effects of this invention are:

[0019] The receiving device disclosed in this invention uses a cross-shaped ferrite receiving coil for differential reception of long-wave positioning, navigation, and timing signals. While effectively receiving long-wave positioning, navigation, and timing signals, it combines the far-field propagation characteristics of electromagnetic waves and digital signal processing algorithms to determine the direction of multiple incoming waves (navigation stations) based on the phase characteristics of the output signal. This provides the ability to distinguish incoming waves from multiple directions, solving the problem that conventional antennas cannot achieve positioning and navigation. It enables more accurate long-wave positioning, navigation, and timing functions and is a miniaturized active omnidirectional magnetic antenna suitable for long-wave positioning, navigation, and timing. Experimental verification shows that it meets practical requirements and is easy to operate and maintain, with reliable quality.

[0020] The receiving device disclosed in this invention achieves omnidirectionality and miniaturization of the magnetic antenna, thus improving its anti-interference capability. It also exhibits strong generalization ability, utilizing the tuning function of the amplifier circuit to be applicable to the reception and amplification of long-wave signals of different frequencies.

[0021] The design method disclosed in this invention has a clear concept and is highly operable. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the arrangement of the receiving coil in the receiving device disclosed in this invention;

[0023] Figure 2 This is a schematic diagram of the structural dimensions of a cuboid magnetic core;

[0024] Figure 3 This is a schematic diagram showing the length and width dimensions of the long and short magnetic cores;

[0025] Figure 4 This is a schematic diagram of the winding direction of the receiving coil;

[0026] Figure 5 This is a schematic diagram of the phase difference of waves arriving from different angles;

[0027] Figure 6 This is a schematic diagram of the pre-amplifier circuit;

[0028] Figure 7 This is a schematic diagram of the post-amplifier circuit;

[0029] Figure 8(a) is the amplitude and phase characteristic curve of the active omnidirectional magnetic antenna disclosed in this invention in the direction of incoming wave at 45°.

[0030] Figure 8(b) is the amplitude and phase characteristic curve of the active omnidirectional magnetic antenna disclosed in this invention in the direction of incoming wave at 315°.

[0031] Figure 9 This is a flowchart illustrating the design method disclosed in this invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0033] Example 1 discloses an active omnidirectional magnetic antenna differential receiver for long-wave positioning, navigation, and timing, such as... Figure 1 As shown, the circuit includes a long magnetic core 1 and two short magnetic cores 2. The two short magnetic cores are respectively glued and fixed to both sides of the long magnetic core. The three magnetic cores are arranged in a cross shape. A set of receiving coils (labeled B1B2 and D1D2) is wound at each end of the long magnetic core, and a set of receiving coils (labeled A1A2 and C1C2) is wound on each of the two short magnetic cores. The lead terminals of the four sets of receiving coils, labeled A2, B2, C2, and D2, are all connected to the common ground of the circuit board. In this way, the lead terminals labeled A1 and C1 form a differential output signal, and the lead terminals labeled B1 and D1 form a differential output signal, which has a certain anti-interference capability. In addition, the four sets of receiving coils are also electrically connected to the amplifier circuit.

[0034] Once the polarization direction of the transmitted signal is determined, the phase of the signals induced on the four sets of receiving coils by long-wave positioning, navigation, and timing signals from different incoming wave directions will be different, such as... Figure 5 As shown.

[0035] Figure 5 The vertical dark dashed circle represents the radiation pattern of the receiving antenna group consisting of receiving coils A and C, while the horizontal light dashed circle represents the radiation pattern of the receiving antenna group consisting of receiving coils B and D.

[0036] Taking incoming wave directions of 45°, 135°, 225°, and 315° as examples, the four solid arrows correspond to the magnetic field directions of the incoming waves at these directions. The magnetic field directions of the incoming waves differ depending on their orientation, resulting in different voltage amplitudes and phases induced in the receiving coil. Using this receiving device and a specific signal processing algorithm, different phase information can be obtained, representing different incoming wave azimuths. Combined with the position and time information carried by the signal itself, more accurate positioning, navigation, and timing functions can be achieved.

[0037] In selecting a ferrite core (receiving coil core), two main aspects are considered: the initial permeability of the ferrite core and its shape. For applications involving very low frequency long waves (generally below 300kHz) electromagnetic waves, both long and short cores utilize MXD-2000 ferrite cores with an initial permeability Ui=2000. For example... Figure 2 As shown, to facilitate the installation and fixation of the receiving coil, the ferrite core is rectangular in shape. Figure 2The length of the ferrite core is L=53.5mm, the width is S=20mm, and the height is H=4mm.

[0038] like Figure 3 As shown, considering the high magnetic resistance of air, the four sets of receiving coils should have the same ferrite composition in the middle. Based on the ferrite core manufacturing process, the long core has a length L2 = 127mm, a width S2 = 20mm, and a height of 4mm, while the two short cores each have a length L1 of 53.5mm, a width S1 of 20mm, and a height of 4mm.

[0039] There are three main aspects to consider when winding a receiving coil: the diameter of the enameled wire, the winding direction, and the number of turns. The receiving coil uses enameled wire with a diameter of Ф=0.12mm and 200 turns.

[0040] like Figure 4 As shown in the diagram, solid arrows indicate the starting position and direction of coil winding, while dashed arrows indicate the ending position and direction. Solid lines indicate winding on the front of the magnetic core, and dashed lines indicate winding on the back. Starting from the solid arrow, the winding direction is to wind the enameled wire clockwise to the right in a single-layer structure for 50 turns, then continue winding clockwise back to the starting point, forming a double layer of 100 turns on the right side. Then, pull the enameled wire to the left a certain distance (e.g., ...). Figure 4 (As shown by the dotted line in the center of the magnetic core) Then wind 50 turns clockwise to the left in a single-layer structure, and then wind back to the dotted arrow in the same clockwise direction, so that a double layer of 100 turns is formed on the left side, and the receiving coil is completed.

[0041] The receiving coil post-amplifier circuit, after pre-amplification in each channel (A1, B1, C1, D1), employs a three-stage operational amplifier structure of an instrumentation amplifier to achieve anti-interference amplification and transmission of differential signals. The amplifier circuit includes... Figure 6 The pre-amplifier circuit shown includes outputs A1 and C1. Figure 7 The post-amplifier circuit with four channels is shown.

[0042] The designed and debugged active omnidirectional magnetic antenna was placed in a magnetically shielded room for testing. The direction of the magnetic field in the magnetically shielded room was adjusted to simulate the signals generated by different navigation stations. Figure 8(a) is the amplitude and phase characteristic curve of the active omnidirectional magnetic antenna in the direction of incoming wave at 45°; Figure 8(b) is the amplitude and phase characteristic curve of the active omnidirectional magnetic antenna in the direction of incoming wave at 315°.

[0043] This embodiment also discloses a design method for designing the above-mentioned receiving device, such as... Figure 9 As shown, it includes the following steps:

[0044] Step 1: Select a suitable ferrite core as the core shaft of the receiving coil based on the characteristics of very low frequency long wave electromagnetic waves.

[0045] Step 2: Select an enameled wire of appropriate diameter and wind it around the ferrite core a certain number of turns to form a ferrite receiving coil.

[0046] Step 3: Arrange a certain number of ferrite receiving coils into a specific shape to achieve omnidirectionality;

[0047] Step 4: Design the differential amplifier circuit after the receiving coil to form an active omnidirectional magnetic antenna receiving device.

Claims

1. A differential receiver device for long-wave positioning, navigation, and timing using an active omnidirectional magnetic antenna, characterized in that: It includes one long magnetic core and two short magnetic cores. The two short magnetic cores are located on both sides of the long magnetic core. The three magnetic cores are arranged in a cross shape. A set of receiving coils is wound on each end of the long magnetic core and a set of receiving coils is wound on each of the two short magnetic cores. The lead terminals of the four sets of receiving coils are all connected to the common ground of the circuit board. In addition, the four sets of receiving coils are also electrically connected to the amplifier circuit. The two short magnetic cores are glued and fixed on both sides of the long magnetic core. The receiving coils are made of enameled wire with a diameter of Ф=0.12mm and 200 turns. The winding direction is as follows: the enameled wire is wound clockwise to the right in a single layer structure for 50 turns, and then wound back to the starting point in a clockwise direction, so that the right side forms a double layer of 100 turns. Then the enameled wire is pulled to the left by a predetermined distance and wound clockwise to the left in a single layer structure for 50 turns, and then wound back in a clockwise direction, so that the left side forms a double layer of 100 turns. Both the long and short magnetic cores use ferrite cores with an initial permeability of Ui=2000, and the shape of the ferrite cores is cuboid. The long magnetic core is 127mm long, 20mm wide, and 4mm high, while the two short magnetic cores are both 53.5mm long, 20mm wide, and 4mm high. An amplifier circuit includes a pre-amplifier circuit and a post-amplifier circuit.

2. A design method for designing the receiving device according to claim 1, characterized in that, Includes the following steps: Step 1: Based on the characteristics of very low frequency long wave electromagnetic waves, select a ferrite core as the core shaft of the receiving coil. Step 2: Select an enameled wire of a predetermined diameter and wind it around the ferrite core a predetermined number of turns to form a ferrite receiving coil. Step 3: Arrange and combine a predetermined number of ferrite receiving coils into a predetermined shape; Step 4: Design the differential amplifier circuit after the receiving coil.

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