A front-end dual-path radio frequency device for receiving eLoran signals

Abstract

The application belongs to the technical field of communication. The application provides a front double-path radio frequency device for receiving an eLoran signal. The receiving antenna of the disclosed embodiment receives an eLoran signal from space; a tuning and matching module filters and impedance matches the eLoran signal and then outputs a low-frequency analog signal; a filtering module performs secondary filtering on the low-frequency analog signal; a difference module performs single-ended to differential processing on the low-frequency analog signal after secondary filtering; and an AGC module automatically adjusts the gain of the low-frequency analog signal after single-ended to differential processing, so that the low-frequency analog signal is stabilized at-5~+5V output. The device can solve the problems of poor indoor reception and waveform distortion caused by a large decrease in transmission power of the eLoran signal at a long distance, and provide an input with an adjustable gain of about 9~45dB for subsequent digital signal processing.

Description

Technical Field

[0001] This disclosure relates to the field of communication technology, and in particular to a front-end dual-channel radio frequency device for receiving eLoran signals. Background Technology

[0002] The eLoran system, as an internationally standardized ground-based radio system, provides PNT (Place-to-Network) services with strong anti-jamming capabilities and wide coverage. Its robust stability and excellent performance make it a promising and important supplement and backup system to GNSS systems. In recent years, many countries and regions around the world have initiated or restarted the development of the eLoran system.

[0003] Since the eLoran signal is an amplitude-modulated signal on a 100kHz carrier, it primarily propagates as a ground wave in the 100kHz frequency band. Under ideal conditions, the eLoran signal can cover a range of hundreds of kilometers using ground wave propagation. Ground wave propagation is more stable than sky wave propagation and less affected by external factors, but signal loss is still influenced by ground conductivity, industrial equipment interference, and atmospheric interference. Furthermore, the 100kHz signal gradually attenuates with increasing propagation distance. Therefore, the selection of reception methods and the optimization of filtering and amplification techniques for the 100kHz signal are crucial.

[0004] In terms of filtering technology, accurate extraction and processing of low-frequency signals requires highly selective narrowband filters, and the parasitic parameters of filter components have a significant impact on filter performance. Furthermore, the center frequency and bandwidth of filter components drift under different temperature conditions. Therefore, it is necessary to adjust the component parameters appropriately to meet operational requirements.

[0005] Because 100kHz signals are inherently weak and susceptible to interference, low-noise amplifier modules need to carefully consider gain stability, bandwidth, and linearity balance to prevent signal distortion and harmonic interference. Addressing this requirement focuses on the selection of amplifier chips and the design of the circuit topology, while also considering component noise figures and matching.

[0006] Therefore, it is necessary to improve one or more of the problems existing in the above-mentioned related technical solutions.

[0007] It should be noted that this section is intended to provide background or context for the technical solutions of this disclosure as set forth in the claims. The description herein does not constitute an admission that it is prior art simply because it is included in this section. Utility Model Content

[0008] The purpose of this disclosure is to provide a front-end dual-channel radio frequency device for receiving eLoran signals, thereby overcoming, at least to some extent, one or more problems caused by limitations and defects in related technologies.

[0009] According to embodiments of this disclosure, a front-end dual-channel radio frequency device for receiving eLoran signals is provided, comprising: The system comprises an antenna module and a radio frequency (RF) module. The antenna module includes a receiving antenna and a tuning and matching module. The RF module includes a filtering module, a differential module, and an AGC module. The receiving antenna, tuning and matching module, filtering module, differential module, and AGC module are connected in series. A receiving antenna for receiving eLoran signals from space; The tuning and matching module is used to filter and impedance match the eLoran signal before outputting a low-frequency analog signal. The filtering module is used to perform secondary filtering on low-frequency analog signals. The differential module is used to perform single-ended to differential conversion on the low-frequency analog signal after secondary filtering; The AGC module is used to automatically adjust the gain of the low-frequency analog signal after single-ended to differential conversion, so that it is stabilized at -5~+5V output.

[0010] Furthermore, the receiving antenna includes multiple multi-turn loop antennas connected in parallel, with the first ends of all the multi-turn loop antennas connected by a first wire and the second ends of all the multi-turn loop antennas connected by a second wire.

[0011] Furthermore, each multi-turn loop antenna consists of 6 multi-turn loop coils, and the average inductance of a single-turn loop coil is... .

[0012] Furthermore, the tuning and matching module includes: A series-connected LC tuning circuit and impedance matching circuit; wherein, The LC tuning circuit includes inductor L2, capacitor C5, and capacitor C6; the first end of the receiving antenna, the first end of capacitor C5, and the first end of capacitor C6 are electrically connected; the second end of the receiving antenna, the second end of capacitor C5, the second end of capacitor C6, and the first end of inductor L2 are electrically connected; and the second end of inductor L2 is electrically connected to the impedance matching circuit.

[0013] Furthermore, the filtering module includes: The first operational amplifier active filter circuit and the second operational amplifier active filter circuit are connected in series; wherein, The first operational amplifier active filter circuit includes: Resistors R1, R2, R3, R4, R5, capacitors C1 and C2, and the first operational amplifier; The first end of resistor R1 is electrically connected to the impedance matching circuit. The second end of resistor R1 is electrically connected to the first end of resistor R2, the first end of capacitor C1, and the first end of capacitor C2, respectively. The second end of capacitor C1 and the first end of resistor R3 are electrically connected to the inverting input of the first operational amplifier. The first ends of resistor R4 and resistor R5 are electrically connected to the non-inverting input of the first operational amplifier. The second ends of capacitor C2, resistor R3, and resistor R4 are electrically connected to the output terminal of the first operational amplifier. The second operational amplifier active filter circuit includes: Resistors R6, R7, R8, R9, R10, capacitor C3, capacitor C4, and the second operational amplifier; The first end of resistor R6 is electrically connected to the output terminal of the first operational amplifier. The second end of resistor R6 is electrically connected to the first end of resistor R7, the first end of capacitor C3, and the first end of capacitor C4, respectively. The second end of capacitor C3 and the first end of resistor R8 are electrically connected to the inverting input of the second operational amplifier. The first ends of resistor R10 and resistor R9 are electrically connected to the non-inverting input of the second operational amplifier. The second ends of capacitor C4, resistor R8, and resistor R10 are electrically connected to the output terminal of the second operational amplifier.

[0014] Furthermore, the differential module includes: Resistors R11, R12, R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, and the third operational amplifier; among which, The first terminal of resistor R14 is electrically connected to the output terminal of the second operational amplifier. The second terminal of resistor R14 is electrically connected to the first terminal of resistor R13. The second terminal of resistor R13 and the first terminal of resistor R16 are electrically connected to the non-inverting input of the third operational amplifier. The first terminal of resistor R11 is electrically connected to the first terminal of resistor R12. The second terminal of resistor R11 and the first terminal of resistor R15 are electrically connected to the inverting input of the third operational amplifier. The second terminal of resistor R16 and the first terminal of resistor R19 are electrically connected to the first output terminal of the third operational amplifier. The second terminal of resistor R19, the first terminal of resistor R21 and the first terminal of resistor R17 are electrically connected. The second terminal of resistor R17 is connected to the first Output -. The second terminal of resistor R15 and the first terminal of resistor R20 are electrically connected to the second output terminal of the third operational amplifier. The second terminal of resistor R20 and the first terminal of resistor R22 are electrically connected to the first terminal of resistor R18. The second terminals of resistor R21 and R22 are grounded. The second terminal of resistor R18 is connected to the first Output +.

[0015] Furthermore, the AGC module includes: Differential operational amplifier U1, capacitors C7, C8, C9, C10, resistors R23, R24, R25, R26, R27, R28, and R29; among which, The first terminal of capacitor C9 is electrically connected to the first Output+, the first terminal of capacitor C9 is electrically connected to the first terminal of resistor R23, and the second terminal of resistor R23 is electrically connected to pin 3 of differential operational amplifier U1. The first terminal of capacitor C10 is electrically connected to the second output terminal, and the first terminal of capacitor C10 is electrically connected to the first terminal of resistor R24. The second terminal of resistor R24 ​​is electrically connected to pin 2 of differential operational amplifier U1. The first end of resistor R27 is electrically connected to pin 16 of differential operational amplifier U1. The second end of resistor R27, the first end of capacitor C7, and the first end of resistor R28 are electrically connected. The second end of resistor R28, the first end of resistor R29, and the first end of capacitor C8 are all electrically connected to pins 7, 8, and 13 of differential operational amplifier U1. The second end of resistor R29 and the second end of capacitor C7 are grounded. The first end of resistor R25 is electrically connected to pin 9 of differential operational amplifier U1. The second end of resistor R25 is electrically connected to pin 10 of differential operational amplifier U1 and is connected to the second Output+. The first end of resistor R26 is electrically connected to pin 12 of differential operational amplifier U1. The second end of resistor R26 is electrically connected to pin 11 of differential operational amplifier U1 and is connected to the second Output-.

[0016] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects: In the embodiments of this disclosure, the aforementioned device, on the one hand, receives eLoran signals from space; the tuning and matching module filters and impedance-matches the eLoran signal before outputting a low-frequency analog signal; the filtering module performs secondary filtering on the low-frequency analog signal; the differential module performs single-ended to differential conversion on the secondary filtered low-frequency analog signal; and the AGC module automatically adjusts the gain of the low-frequency analog signal after single-ended to differential conversion to stabilize it at -5 to +5V. On the other hand, this device can solve the problems of poor indoor reception and waveform distortion caused by the significant reduction in power during long-distance transmission of eLoran signals, providing an input with an adjustable gain of approximately 9 to 45 dB for subsequent digital signal processing. Furthermore, the multi-turn loop antenna structure is simple and inexpensive, and the center frequency drift of the received signal is still controlled within 2% after passing through two stages of active filtering circuits, meeting the requirements for precise positioning and timing of the eLoran system. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] Figure 1 This diagram illustrates the structure of a front-end dual-channel radio frequency device for receiving eLoran signals according to an exemplary embodiment of this disclosure. Figure 2 This diagram illustrates the structure of the receiving antenna in an exemplary embodiment of this disclosure. Figure 3 A circuit diagram of an LC tuning circuit in an exemplary embodiment of this disclosure is shown; Figure 4 A circuit diagram of the filtering module in an exemplary embodiment of this disclosure is shown; Figure 5 This diagram shows a simulation test diagram of the center frequency drift of the filtering module in an exemplary embodiment of this disclosure; Figure 6 A circuit diagram of the differential module in an exemplary embodiment of this disclosure is shown; Figure 7 A circuit diagram of the AGC module in an exemplary embodiment of this disclosure is shown. Detailed Implementation

[0019] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0020] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0021] This example implementation first provides a dual-channel preamplifier radio frequency device for receiving eLoran signals. (See reference...) Figure 1 As shown, the front-end dual-channel radio frequency device for receiving eLoran signals may include: The system comprises an antenna module and a radio frequency (RF) module. The antenna module includes a receiving antenna and a tuning and matching module. The RF module includes a filtering module, a differential module, and an AGC module. The receiving antenna, tuning and matching module, filtering module, differential module, and AGC module are connected in series. A receiving antenna for receiving eLoran signals from space; The tuning and matching module is used to filter and impedance match the eLoran signal before outputting a low-frequency analog signal. The filtering module is used to perform secondary filtering on low-frequency analog signals; The differential module is used to perform single-ended to differential conversion on the low-frequency analog signal after secondary filtering; The AGC module is used to automatically adjust the gain of the low-frequency analog signal after single-ended to differential conversion, so that it is stabilized at -5~+5V output.

[0022] Through the aforementioned device, on the one hand, the receiving antenna receives eLoran signals from space; the tuning and matching module filters and impedance-matches the eLoran signal before outputting a low-frequency analog signal; the filtering module performs secondary filtering on the low-frequency analog signal; the differential module performs single-ended to differential conversion on the secondary filtered low-frequency analog signal; and the AGC module automatically adjusts the gain of the low-frequency analog signal after single-ended to differential conversion, stabilizing it at an output voltage of -5 to +5V. On the other hand, this device can solve the problems of poor indoor reception and waveform distortion caused by the significant reduction in power during long-distance transmission of eLoran signals, providing an input with an adjustable gain of approximately 9 to 45 dB for subsequent digital signal processing. Furthermore, the multi-turn loop antenna structure is simple and inexpensive, and the center frequency drift of the received signal is still controlled within 2% after passing through two stages of active filtering circuits, meeting the precise positioning and timing requirements of the eLoran system.

[0023] Below, we will refer to Figures 1 to 7 The various parts of the front-end dual-channel radio frequency device for receiving eLoran signals described in this example embodiment will be explained in more detail.

[0024] In one embodiment, the front-end dual-channel radio frequency device for receiving eLoran signals includes: a receiving antenna, a tuning and matching module, a filtering module, a differential module, and an AGC module connected in sequence. These modules work together to achieve effective reception and processing of eLoran signals, as detailed below: A receiving antenna is used to receive eLoran signals covering a 1MHz bandwidth from space. The receiving antenna, along with the LC tuning circuit and impedance matching circuit, constitutes an antenna system. The total inductance of the receiving antenna in the antenna system satisfies the following condition: (in The number of coil turns. (where is the average inductance of a single-turn coil) to maximize the total inductance with a limited wire length.

[0025] The tuning and matching module consists of an LC tuning circuit and an impedance matching circuit. In the LC tuning circuit, the receiving antenna acts as an inductor with an inductance of approximately 1200μH, and the matching capacitor value meets the following requirements: (in The eLoran signal carrier frequency is 100kHz, and the LC tuning circuit uses a parallel resonance method, where the input impedance is mapped to a parallel resistance at the resonant point. (in For quality factors, (This refers to the series resistor of the coil). The impedance matching circuit uses an L-type matching circuit, with a capacitor connected in parallel at the high-resistivity source end. and series inductor Connect to the load to achieve matching with the approximately 5kΩ input impedance of the subsequent RF circuitry.

[0026] The filtering module consists of two cascaded operational amplifier active filter circuits with similar structures. It is used to perform secondary filtering on the low-frequency analog signal output by the tuning and matching module, so that the center frequency drift of the filtered eLoran signal is controlled within 2%.

[0027] The differential module is used to convert the low-frequency analog signal output by the filter module from single-ended to differential, while also achieving impedance matching and signal conditioning to ensure that the op-amp operates in the linear region and improve the common-mode rejection ratio.

[0028] The AGC module is used to automatically adjust the gain of the low-frequency analog signal output by the differential module, providing an adjustable gain of 9~45dB, and ultimately stabilizing the output signal at -5~+5V, providing a suitable input signal for subsequent digital signal processing.

[0029] In one embodiment, the receiving antenna has a multi-turn ring structure, specifically, the single-turn coils are concentrated within the same approximate radius and divided into 6 multi-turn ring coils. The average inductance of a single-turn coil of the receiving antenna is... Furthermore, the radius difference between the coils is small to ensure high mutual inductance across the coils.

[0030] In one embodiment, in the tuning and matching module, the capacitance value of the LC tuning circuit is approximately 2.1nF, and the input impedance of the parallel resonance at the resonant point is mapped to the parallel resistance. ≈1.75MΩ; In an L-type matching circuit, the capacitor connected in parallel to the high-impedance source terminal. Series inductors .

[0031] In one embodiment, the two-stage operational amplifier active filter circuit of the filtering module operates on the same principle. In each stage of the circuit: the signal passes through a resistor... Input, resistance Pull-down resistors provide a stable low-potential reference for the node when there is no input signal; capacitors , With resistance A filter network is constructed to filter out high-frequency noise and interference signals in specific frequency bands from the input signal; the operational amplifier is configured as an inverting amplifier or filter, and the inverting input receives the signal after filtering. The processed signal has its non-inverting input grounded; resistor and A feedback network is formed to set the gain or filtering characteristics of this stage of the circuit, and the amplification factor of this stage of the circuit for the input signal is based on the gain formula of the inverting amplifier. Calculate (where for The equivalent value, for (Equivalent value of the front-end resistor).

[0032] In one embodiment, in the differential module: the input signal passes sequentially through two current-limiting resistors to achieve impedance matching with the output impedance of the preceding signal source; resistors and A bias network is constructed to provide a suitable DC bias voltage to the non-inverting input of the operational amplifier; resistors and Forming a feedback network, and According to the in-phase gain formula This differential module amplifies the input signal by 2 times; resistors and A common-mode resistor network is formed to balance the common-mode voltage of the differential output, thereby further improving the common-mode rejection ratio.

[0033] In one embodiment, in the AGC module: the input differential signal undergoes AC coupling, current limiting, and impedance matching processing; the resistor... and This forms a feedback network, connecting the amplifier output and the feedback pin, used to set the amplifier's closed-loop gain to determine the signal amplification factor; resistors , , and Constructing filtering and biasing networks, These are decoupling capacitors, placed close to the power supply pins, used to filter out high-frequency noise on the power lines to ensure stable power supply voltage.

[0034] In one embodiment, after the filtering module performs secondary filtering on the eLoran signal, the signal center frequency drift is ≤2%, in order to meet the requirements of precise positioning and timing of the eLoran system.

[0035] In one specific embodiment, the antenna system consists of a receiving antenna and its associated LC tuning circuit and impedance matching circuit. The antenna operates within a 1MHz bandwidth. The receiving antenna is used to receive radar signals transmitted within the operating frequency range from space. To maximize the total inductance with a limited wire length, the key principle is to wind as many turns as possible, with the coupling between each turn as strong as possible, and the coupling coefficient as close to 1 as possible. This ensures that the total inductance meets the required standards. The compromise method used in this example is as follows: Figure 2 The diagram shows how single-turn coils are concentrated within a roughly equal radius, and then these turns are divided into six multi-turn loop coils. This embodiment results in an antenna with a smaller footprint, smaller radius differences between coils, and simultaneously ensures high mutual inductance across coils and a low average inductance per single-turn coil. .

[0036] Tuning and Matching Module: The tuning and matching module consists of an LC tuning circuit and an impedance matching circuit. For example... Figure 3 The diagram shown is a schematic of the LC resonant circuit. In this embodiment, the antenna itself can be used as an inductor. When using an inductor, a matching capacitor value is required. The capacitor in this embodiment uses a parallel resonance method, where the input impedance at the resonant point is very high. The coil at the resonant point can be mapped as a parallel resistor. Subject to the series resistance of the coil and quality factors The influence of parallel resistance At the resonance point, it satisfies ,like Figure 4 , Figure 6 , Figure 7 The RF circuit shown has an input impedance of approximately 5kΩ. The L-type matching circuit used in this embodiment has a capacitor connected in parallel at the high-impedance source terminal. Then connect an inductor in series. Received load.

[0037] Filtering Module: The filtering module mainly consists of two similar operational amplifier active filter circuits cascaded together. The two circuits operate on similar principles. The signal passes through... Figure 4 As shown enter, A pull-down resistor provides a stable low-potential reference for the node when there is no input signal. , and These components form a filtering network to filter out high-frequency noise or interference signals in a specific frequency band from the input signal. Their R and C parameter values ​​can be calculated from the cutoff frequency. In this embodiment, it is configured as an inverting amplifier or filter, with the inverting input receiving the signal after... After processing, the non-inverting input terminal is grounded. and This forms a feedback network used to set the gain or filtering characteristics of this stage of the circuit. Based on the inverting amplifier gain formula... The feedback resistor here can be considered as The input resistance is The equivalent value of the front-end resistor allows this stage to amplify the input signal by a certain factor while further filtering it.

[0038] After the filtering module performs secondary filtering on the eLoran signal, the center frequency drift of the signal is ≤2%, which meets the requirements of the eLoran system for accurate positioning and timing. Figure 5 This is a simulation test diagram of the center frequency drift of the filter module.

[0039] Differential and AGC Module: This component in this embodiment primarily amplifies and differentially converts the signal, while also providing impedance matching and signal conditioning functions. The input signal passes sequentially through two current-limiting resistors, ensuring that the input impedance matches the output impedance of the preceding signal source, thus reducing signal reflection and attenuation. For example... Figure 6 shown and A bias network is constructed to provide a suitable DC bias voltage to the non-inverting input terminal, ensuring that the op-amp operates in the linear region. and A feedback network is constructed to determine the closed-loop gain of the differential module. This embodiment employs... According to the gain formula of in-phase amplifier It can be calculated that it has a 2x amplification effect on the input signal. and A common-mode resistor network is constructed to balance the common-mode voltage of the differential output, further improving the common-mode rejection ratio and enhancing anti-interference capability. The final output differential signal drives the subsequent differential load. For example... Figure 7 The input differential signals shown are subjected to AC coupling, current limiting, and impedance matching, respectively. and It forms a feedback network, connecting the amplifier's output and feedback pins, and is used to set the amplifier's closed-loop gain, determining the signal amplification factor. , , and Constructing filtering and biasing networks, These are decoupling capacitors, placed close to the power supply pins, used to filter out high-frequency noise on the power lines, ensuring stable power supply voltage and improving the circuit's anti-interference capability.

[0040] The aforementioned dual-channel RF pre-amplifier for receiving eLoran signals serves two purposes. First, the receiving antenna receives eLoran signals from space. The tuning and matching module filters and impedance-matches the eLoran signal before outputting a low-frequency analog signal. The filtering module performs secondary filtering on the low-frequency analog signal. The differential module converts the secondary-filtered low-frequency analog signal from single-ended to differential mode. The AGC module automatically adjusts the gain of the low-frequency analog signal after the single-ended to differential conversion, stabilizing it at -5 to +5V. Second, this device solves the problems of poor indoor reception and waveform distortion caused by the significant reduction in power during long-distance transmission of eLoran signals. It provides an input with an adjustable gain of approximately 9 to 45 dB for subsequent digital signal processing. Furthermore, the multi-turn loop antenna structure is simple and inexpensive. After passing through two stages of active filtering circuits, the center frequency drift of the received signal is still controlled within 2%, meeting the precise positioning and timing requirements of the eLoran system.

[0041] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., in the above description indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this disclosure and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this disclosure.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] In the embodiments of this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0044] In embodiments of this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0046] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the utility models disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A dual-channel preamplifier radio frequency device for receiving eLoran signals, characterized in that, include: The system comprises an antenna module and a radio frequency (RF) module. The antenna module includes a receiving antenna and a tuning and matching module. The RF module includes a filtering module, a differential module, and an AGC module. The receiving antenna, tuning and matching module, filtering module, differential module, and AGC module are connected in series. A receiving antenna for receiving eLoran signals from space; The tuning and matching module is used to filter and impedance match the eLoran signal before outputting a low-frequency analog signal. The filtering module is used to perform secondary filtering on low-frequency analog signals; The differential module is used to perform single-ended to differential conversion on the low-frequency analog signal after secondary filtering; The AGC module is used to automatically adjust the gain of the low-frequency analog signal after single-ended to differential conversion, so that it is stabilized at -5~+5V output.

2. The dual-channel radio frequency device for receiving eLoran signals according to claim 1, characterized in that, The receiving antenna includes multiple multi-turn loop antennas connected in parallel. The first ends of all the multi-turn loop antennas are connected by a first wire, and the second ends of all the multi-turn loop antennas are connected by a second wire.

3. The dual-channel radio frequency device for receiving eLoran signals according to claim 2, characterized in that, Each multi-turn loop antenna consists of 6 multi-turn loop coils, and the average inductance of a single-turn loop coil is... .

4. The dual-channel radio frequency device for receiving eLoran signals according to claim 1, characterized in that, The tuning and matching module includes: A series-connected LC tuning circuit and impedance matching circuit; wherein, The LC tuning circuit includes inductor L2, capacitor C5, and capacitor C6; the first end of the receiving antenna, the first end of capacitor C5, and the first end of capacitor C6 are electrically connected; the second end of the receiving antenna, the second end of capacitor C5, the second end of capacitor C6, and the first end of inductor L2 are electrically connected; and the second end of inductor L2 is electrically connected to the impedance matching circuit.

5. The dual-channel radio frequency device for receiving eLoran signals according to claim 4, characterized in that, The filtering module includes: The first operational amplifier active filter circuit and the second operational amplifier active filter circuit are connected in series; wherein, The first operational amplifier active filter circuit includes: Resistors R1, R2, R3, R4, R5, capacitors C1 and C2, and the first operational amplifier; The first end of resistor R1 is electrically connected to the impedance matching circuit. The second end of resistor R1 is electrically connected to the first end of resistor R2, the first end of capacitor C1, and the first end of capacitor C2, respectively. The second end of capacitor C1 and the first end of resistor R3 are electrically connected to the inverting input of the first operational amplifier. The first ends of resistor R4 and resistor R5 are electrically connected to the non-inverting input of the first operational amplifier. The second ends of capacitor C2, resistor R3, and resistor R4 are electrically connected to the output terminal of the first operational amplifier. The second operational amplifier active filter circuit includes: Resistors R6, R7, R8, R9, R10, capacitor C3, capacitor C4, and the second operational amplifier; The first end of resistor R6 is electrically connected to the output terminal of the first operational amplifier. The second end of resistor R6 is electrically connected to the first end of resistor R7, the first end of capacitor C3, and the first end of capacitor C4, respectively. The second end of capacitor C3 and the first end of resistor R8 are electrically connected to the inverting input of the second operational amplifier. The first ends of resistor R10 and resistor R9 are electrically connected to the non-inverting input of the second operational amplifier. The second ends of capacitor C4, resistor R8, and resistor R10 are electrically connected to the output terminal of the second operational amplifier.

6. The dual-channel radio frequency device for receiving eLoran signals according to claim 5, characterized in that, The differential module includes: Resistors R11, R12, R13, R14, R15, R16, R17, R18, R19, R20, R21, R22, and the third operational amplifier; among which, The first terminal of resistor R14 is electrically connected to the output terminal of the second operational amplifier. The second terminal of resistor R14 is electrically connected to the first terminal of resistor R13. The second terminal of resistor R13 and the first terminal of resistor R16 are electrically connected to the non-inverting input of the third operational amplifier. The first terminal of resistor R11 is electrically connected to the first terminal of resistor R12. The second terminal of resistor R11 and the first terminal of resistor R15 are electrically connected to the inverting input of the third operational amplifier. The second terminal of resistor R16 and the first terminal of resistor R19 are electrically connected to the first output terminal of the third operational amplifier. The second terminal of resistor R19, the first terminal of resistor R21 and the first terminal of resistor R17 are electrically connected. The second terminal of resistor R17 is connected to the first Output -. The second terminal of resistor R15 and the first terminal of resistor R20 are electrically connected to the second output terminal of the third operational amplifier. The second terminal of resistor R20 and the first terminal of resistor R22 are electrically connected to the first terminal of resistor R18. The second terminals of resistor R21 and R22 are grounded. The second terminal of resistor R18 is connected to the first Output +.

7. The dual-channel radio frequency device for receiving eLoran signals according to claim 6, characterized in that, The AGC module includes: Differential operational amplifier U1, capacitors C7, C8, C9, C10, resistors R23, R24, R25, R26, R27, R28, and R29; among which, The first terminal of capacitor C9 is electrically connected to the first Output+, the first terminal of capacitor C9 is electrically connected to the first terminal of resistor R23, and the second terminal of resistor R23 is electrically connected to pin 3 of differential operational amplifier U1. The first terminal of capacitor C10 is electrically connected to the second output terminal, and the first terminal of capacitor C10 is electrically connected to the first terminal of resistor R24. The second terminal of resistor R24 ​​is electrically connected to pin 2 of differential operational amplifier U1. The first end of resistor R27 is electrically connected to pin 16 of differential operational amplifier U1. The second end of resistor R27, the first end of capacitor C7, and the first end of resistor R28 are electrically connected. The second end of resistor R28, the first end of resistor R29, and the first end of capacitor C8 are all electrically connected to pins 7, 8, and 13 of differential operational amplifier U1. The second end of resistor R29 and the second end of capacitor C7 are grounded. The first end of resistor R25 is electrically connected to pin 9 of differential operational amplifier U1. The second end of resistor R25 is electrically connected to pin 10 of differential operational amplifier U1 and is connected to the second Output+. The first end of resistor R26 is electrically connected to pin 12 of differential operational amplifier U1. The second end of resistor R26 is electrically connected to pin 11 of differential operational amplifier U1 and is connected to the second Output-.

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