A medium-long wave communication receiving device

Abstract

The utility model discloses a kind of middle-long wave communication receiving device, it relates to wireless communication technical field.The device includes the protection circuit, first filter circuit, limiting amplifier circuit, low-noise amplifier circuit and power division circuit connected in turn.Signal is divided into one wideband channel and three narrowband channels by power division circuit;Each channel includes the frequency conversion circuit, second filter circuit and gain adjustment circuit connected in turn, and finally access multi-channel acquisition circuit;The frequency conversion circuit of narrowband channel is also connected with local oscillator circuit;Control circuit is connected with last stage monitoring, and control gain adjustment circuit and local oscillator circuit.The utility model realizes spectrum environment monitoring and multi-target receiving by wideband channel, realizes high reliability communication under strong interference by narrowband channel, and supports multi-channel parallel operation and silence management, significantly improves the anti-interference ability, communication rate and flexibility of middle-long wave communication.

Description

Technical Field

[0001] This utility model relates to a medium- and long-wave communication receiving device in the field of communications, which is applicable to medium- and long-wave receiving communication systems in the field of wireless communication. Background Technology

[0002] Long-wave communication plays a vital role in daily life, military defense, and national security, especially in submarine and strategic communications. Mid- and long-wave frequencies are susceptible to various noises and interferences, including industrial interference, electrical spark interference, and other radio signal interference, which can cause communication interruptions. Currently, most mid- and long-wave communications use a single channel to convert the received signal to a fixed intermediate frequency (IF), perform narrowband filtering, and then send it to a demodulator. Therefore, real-time monitoring of the spectrum environment and selection of frequency points with clean spectrum are crucial for mid- and long-wave communication; a strong anti-interference capability in the receiving system is also an important way to improve reliability. Utility Model Content

[0003] This invention discloses a medium-to-long-wave communication receiving device. It features a wideband receiving channel, suitable for direct wideband, multi-target reception, and also for real-time monitoring of the spectrum environment across the entire operating frequency band, selecting frequencies with clean electromagnetic environments for communication. Simultaneously, when significant interference exists within the wideband receiving channel, this invention employs three narrowband receiving channels to filter out interference within the operating frequency band through mixing and narrowband filtering before receiving and demodulating. These three narrowband receiving channels can simultaneously communicate with three stations at the other end, enabling real-time interaction and tripling efficiency and communication speed.

[0004] The technical solution adopted in this utility model is as follows: A medium- and long-wave communication receiving device includes a protection circuit 1, a first filter circuit 2, a limiting circuit 3, a low-noise amplifier circuit 4, a power divider circuit 5, and a multi-channel acquisition circuit 9, and also includes a control circuit 11 and a local oscillator circuit 12. The circuit includes a protection circuit 1, a first filter circuit 2, a limiting circuit 3, a low-noise amplifier circuit 4, and a power divider circuit 5 connected in sequence. The three output terminals of the power divider circuit 5 correspond to three narrowband channels, and the other output terminal corresponds to a wideband channel. In both the narrowband and wideband channels, there are frequency converter circuits 6, second filter circuits 7, and gain adjustment circuits 8 connected in sequence. The other input terminal of the frequency converter circuit 6 is connected to the local oscillator source of the local oscillator circuit 12. The input terminal of the control circuit is connected to the previous level monitoring, and the output terminal is connected to the gain adjustment circuit and the local oscillator circuit.

[0005] Furthermore, the low-noise amplifier circuit 4 includes a first switch 13, an attenuator 14, a second switch 15, a low-noise amplifier 16, and a third filter circuit 17; the common port of the first switch 13 is connected to the output terminal of the limiting circuit 3, and the two switching ports of the first switch 13 are respectively connected to the low-noise amplifier 16 and the attenuator 14. The low-noise amplifier 16 and attenuator 14 are respectively connected to the two switching ports of the second switch 5; the common port of the second switch 5 is connected to the third filter circuit 17, and the other end of the third filter circuit 17 is connected to the power divider circuit 5.

[0006] Furthermore, the local oscillator circuit has three local oscillator sources; each local oscillator source includes a reference phase-locked loop circuit 18, a frequency source circuit 19, a frequency divider circuit 20, an amplifier circuit 21, and a fourth filter circuit 22 connected in sequence.

[0007] Furthermore, the control circuit includes a serially connected MCU and a 485 conversion chip. The MCU sends a binary bit stream to the frequency source circuit 19 of the local oscillator circuit 12 via the SPI bus to generate the required frequency. The MCU communicates with the upper-level monitoring via the RS485 bus to change the frequency, power or report the module status. The MCU controls the link gain change of the gain adjustment circuit 8 via the GPIO port.

[0008] Furthermore, it also includes a power supply circuit 10, which includes a switching power supply 23 and a linear power supply. The switching power supply 23 is used to efficiently convert the external power supply voltage into the required low voltage input. The linear power supply is used to power the local oscillator circuit and different channel circuits. At the same time, depending on the actual use scenario, each receiving channel and different local oscillator circuits can be powered off and enter a silent state through control.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. This utility model is designed with one broadband receiving channel, which can be directly used for broadband, multi-target reception, or for real-time monitoring of the spectrum environment of the entire operating frequency band, selecting a frequency point with a clean electromagnetic environment for communication; simultaneously, when there is significant interference within the broadband receiving channel, 2. This utility model has three narrowband receiving channels, which can communicate with three stations on the other end at the same time during actual operation, enabling real-time interaction and increasing efficiency and communication speed by three times.

[0010] 3. Each channel of this utility model has a silent function. In actual operation, broadband communication, narrowband single-channel communication, narrowband dual-channel communication, and narrowband triple-channel communication can be selected according to the application scenario. Non-working channels can be turned off or silenced through the control module.

[0011] 4. This utility model only illustrates three narrowband receiving channels. In actual applications, the number of narrowband channels can be increased, or each narrowband receiving channel can be replaced with a dual-channel bandwidth receiving channel, which has scalability.

[0012] 5. In this application, the reference signal is not directly used to supply the phase-locked source, but is further subjected to ultra-low phase noise phase-locking, which further improves the phase noise of the reference source, resulting in an increase of about 10dB in the phase noise of the final source output, which greatly improves the receiving reciprocal mixing performance. Attached Figure Description

[0013] Figure 1 This is a block diagram illustrating the principle of an embodiment of this utility model.

[0014] Figure 2 This is a block diagram illustrating the principle of a low-noise amplifier circuit according to an embodiment of the present invention.

[0015] Figure 3 This is a schematic block diagram of the local oscillator circuit in an embodiment of the present invention.

[0016] Figure 4 This is a schematic block diagram of the control circuit in an embodiment of the present invention. Detailed Implementation

[0017] The specific embodiments of this utility model will be described in complete detail below with reference to the accompanying drawings. This section will fully elaborate on the structure, function, collaborative working relationship of each component, and detailed process for implementing various working modes, to support those skilled in the art in understanding and implementing this utility model.

[0018] I. Overall Structure and Signal Flow of the Device Reference Figure 1 The block diagram of the medium- and long-wave communication receiving device of this utility model shows that its hardware entity is composed of a series of functional circuit modules. The medium- and long-wave signals received by the antenna flow sequentially through protection circuit 1, first filter circuit 2, limiting circuit 3, and low-noise amplifier circuit 4 to form a common receiving front end. Subsequently, the signal is split into four paths by power divider circuit 5, which enter three narrowband receiving paths 1, 2, and 3 and one wideband receiving path 4, respectively.

[0019] In the narrowband path, the signal sequentially passes through the frequency conversion circuit 6, the second filter circuit 7 (acting as a narrowband filter), and the gain adjustment circuit 8, and is finally digitized by the multi-channel acquisition circuit 9. The local oscillator circuit 12 provides a high-spectral-purity local oscillator signal for all the frequency conversion circuits 6 in the narrowband path.

[0020] The entire device is powered by the power supply circuit 10 and intelligently managed and controlled by the control circuit 11 to achieve frequency configuration, gain adjustment, mode switching and channel muting.

[0021] For narrowband receiving paths: This system primarily targets a known frequency point for medium- and long-wave reception. The medium- and long-wave signal received by the antenna enters protection circuit 1 for protection against large external pulses and voltages. It then passes through first filter circuit 2 to filter out out-of-band interference, followed by limiting circuit 3 to further limit the output amplitude of the external signal to protect subsequent low-noise amplifier and other small-signal circuits. After passing through low-noise amplifier circuit 4, the received small signal is amplified with low noise. Then, power divider circuit 5 sends the signal to narrowband channels 1, 2, or 3. First, it enters frequency conversion circuit 6, which adjusts the output frequency of external local oscillator circuit 12 according to the received frequency. This signal then enters the frequency conversion circuit and mixes with the main received signal to output a fixed intermediate frequency (IF) signal. After passing through second filter circuit 7 and gain adjustment circuit 8, the signal enters multi-channel acquisition circuit 9, where it is converted into a digital bitstream and then demodulated and restored.

[0022] For broadband receiving channels: This system primarily targets the entire medium- and long-wave receiving frequency band. The medium- and long-wave signals received by the antenna enter protection circuit 1 for protection against large external pulses and voltages. They then pass through the first filter circuit 2 to filter out out-of-band interference, followed by a limiting circuit 3 to further limit the output amplitude of the external signal, protecting subsequent low-noise amplifier and other small-signal circuits. After passing through the low-noise amplifier circuit 4, the received small signal is amplified with low noise. Then, after the power divider circuit 5, the signal enters the broadband receiving path channel 4. Following the second filter circuit 7 and the gain adjustment circuit 8 for signal amplitude adjustment, the signal enters the multi-channel acquisition circuit 9, which simultaneously acquires multiple signals from the medium- and long-wave frequency band and sends them to the demodulator.

[0023] The intermediate protection circuit 1 is used to prevent external instantaneous high voltage, such as surges or lightning strikes, from damaging the receiving link. The first filter circuit 2 is used to filter out interference outside the medium and long wave operating frequency band to prevent link blockage, affecting the dynamics of the receiving link, or even affecting the reception of useful signals. The limiting circuit 3 is mainly used to prevent large signals within the band from entering the receiving channel and burning out the small signal components in the subsequent stages.

[0024] The low-noise amplifier circuit 4 also includes a first switch 13 and a second switch 15 for switching the gain when receiving large signals, a low-noise amplifier 16 for amplifying small signals received by the antenna while minimizing the degradation of signal quality and carrier-to-noise ratio, an attenuator 14 for attenuating signals when receiving large and small signals to ensure unsaturated compression of the subsequent channel link, and a third-stage filter circuit 17 after the switches for further filtering out out-of-band interference, image frequency interference, and image frequency noise.

[0025] See the detailed flowchart. Figure 2 Block diagram of low-noise amplifier circuit.

[0026] The power divider circuit 5 is used to split the received signal and then send it to different channels in the subsequent stage for different processing.

[0027] The frequency conversion circuit 6 is used to convert the received signal with a known frequency into a fixed intermediate frequency (IF) output through the local oscillator circuit 12.

[0028] The second filter circuit 7 is used to filter out the intermediate frequency signal after mixing, and at the same time filter out the local oscillator signal and out-of-band spurious signals.

[0029] Gain adjustment circuit 8 is used to adjust the power level of the AD acquisition circuit, similar to the function of AGC, to ensure that the same level is output to the ADC under different input levels for demodulation.

[0030] The multi-channel acquisition circuit 9 is used to simultaneously amplify and convert the intermediate frequency signals of multiple channels into ADC signals, converting analog signals into digital signals and sending them to the demodulator.

[0031] The local oscillator circuit 12 in this invention includes three local oscillator sources, which respectively provide the source required for frequency conversion to channels 1, 2, and 3. Each local oscillator source includes a reference phase-locked loop circuit 18, a frequency source circuit 19, a frequency divider circuit 20, an amplifier circuit 21, and a fourth filter circuit 22. The reference phase-locked loop circuit 18 is used to lock the reference signal at a high frequency, further improving the phase noise of the reference source. The frequency source circuit 19 includes a phase detector, a voltage-controlled oscillator, and a loop filter, used to generate a high-quality single-frequency signal. After passing through the frequency divider circuit 20, it generates the local oscillator frequency required for receiving the frequency conversion. After passing through the amplifier circuit 21 and the fourth filter circuit 22, it is sent to the frequency conversion circuit 6. See the schematic diagram for details. Figure 3 Local oscillator circuit block diagram.

[0032] The control circuit 11 in this invention includes an MCU and a RS485 converter chip. The MCU sends a binary bit stream to the frequency source circuit 19 of the local oscillator circuit 12 via the SPI bus to generate the required frequency. The MCU communicates with the upper-level monitoring unit via the RS485 bus to change the frequency, power, or report the module status. Simultaneously, it controls the link gain of the gain adjustment circuit 8 and the power supply switch of the receiving channel via the GPIO port. See the schematic diagram for details. Figure 4 The control circuit principle block diagram.

[0033] The power supply circuit 10 in this utility model includes a switching power supply 23, a linear power supply 24, 25, 26, and 27. The switching power supply 23 is used to efficiently convert the external power supply voltage into the required low voltage input, thereby reducing the power consumption of the components. The linear power supply is used to power the local oscillator circuit 12 and different channel circuits. At the same time, depending on the actual usage scenario, each receiving channel and different local oscillator circuits can be powered off and enter a silent state through control.

[0034] The working principle of this utility model is as follows: A medium-to-long-wave communication receiver is placed at each end of the communication, and the transmitting device uses existing, standardized equipment. In actual use, the transmitting and receiving ends operate in a fixed TDD mode, transmitting and receiving according to the agreed time slots. The receiving device uses a broadband channel for receiving, and at the same time, the control circuit 11 powers off and silences the three narrowband receiving channels and the local oscillator circuit 12.

[0035] The receiving devices at both ends receive signals through a broadband channel. The signals pass through the device's protection circuit 1, first filter circuit 2, limiting circuit 3, low-noise amplifier circuit 4, power divider circuit 5, etc., and then through the second filter circuit 7 and gain adjustment circuit 8 of channel 4 into the multi-channel acquisition circuit 9. If the transmit and receive frequency levels and signal-to-noise ratio are sufficient, demodulation and communication can be performed directly. When there are multiple targets, the received signals from different targets at various frequencies f1, f2, etc., are all sent to the multi-channel acquisition circuit 9 through multiple channels. After digital filtering, different target signals are filtered out and demodulated separately.

[0036] If, after receiving signals, the broadband receiving channel detects interference on the currently used frequency or a very poor signal-to-noise ratio, it notifies the other end to change the transmitting frequency via the transmitting channel. The local end then re-receives the new frequency.

[0037] If the broadband receiving channel detects significant interference within the entire operating frequency band after receiving signals, it notifies the other end to change the frequency point f0 and then activates the narrowband receiving mode. Based on the target number of the system, it activates the corresponding number of channels. The corresponding channel is activated through the control circuit 11, and then the corresponding channel's local oscillator circuit 12 is configured with a bit stream of the corresponding frequency via the SPI bus to output the required local oscillator frequency. At this time, narrowband channel communication is used. After passing through circuits 1 to 5, the signal enters the narrowband channel, is converted to intermediate frequency (IF) by the frequency conversion circuit 6, and then passes through the narrowband second filter circuit 7 to filter out significant interference within the operating frequency band. After passing through the gain adjustment circuit 8, the signal enters the multi-channel acquisition circuit 9 and is converted into a digital bit stream before entering the demodulator for demodulation.

[0038] In its implementation, this invention features a single broadband receiving channel for real-time monitoring of the spectrum environment across the entire operating frequency band, allowing for the selection of frequencies with clean electromagnetic environments for communication. Simultaneously, it has three narrowband receiving channels, enabling simultaneous communication with three remote stations in real-time, resulting in a three-fold increase in efficiency and communication speed. Each channel has a mute function, allowing for selection of broadband, narrowband single-channel, narrowband dual-channel, or narrowband triple-channel communication depending on the application scenario. Inactive channels can be shut down or muted via a control module. This invention only illustrates three narrowband receiving channels; in practical applications, the number of narrowband channels can be increased, or each narrowband receiving channel can be replaced with a dual-channel bandwidth receiving channel, providing scalability. Furthermore, the reference signal is not directly used to supply the phase-locked source but is further subjected to ultra-low phase-noise phase-locking, further improving the phase noise of the reference source. This results in an approximately 10dB increase in the final output phase noise of the source, significantly enhancing the reciprocal mixing performance.

Claims

1. A medium-to-long-wave communication receiving device, comprising a protection circuit (1), a first filter circuit (2), a limiting circuit (3), a low-noise amplifier circuit (4), a power divider circuit (5), and a multi-channel acquisition circuit (9), characterized in that, It also includes a control circuit (11) and a local oscillator circuit (12); The circuit includes a protection circuit (1), a first filter circuit (2), a limiting circuit (3), a low-noise amplifier circuit (4), and a power divider circuit (5) connected in sequence. The three output terminals of the power divider circuit (5) correspond to three narrowband channels, and the other output terminal corresponds to a wideband channel. In both the narrowband and wideband channels, there are frequency converter circuits (6), second filter circuits (7), and gain adjustment circuits (8) connected in sequence. The other input terminal of the frequency converter circuit (6) is connected to the local oscillator source of the local oscillator circuit (12). The input terminal of the control circuit is connected to the previous level monitoring, and the output terminal is connected to the gain adjustment circuit and the local oscillator circuit.

2. The medium-long wave communication receiving device according to claim 1, characterized in that, The low-noise amplifier circuit (4) includes a first switch (13), an attenuator (14), a second switch (15), a low-noise amplifier (16), and a third filter circuit (17); the common port of the first switch (13) is connected to the output terminal of the limiting circuit (3), and the two switching ports of the first switch (13) are respectively connected to the low-noise amplifier (16) and the attenuator (14). The low-noise amplifier (16) and attenuator (14) are respectively connected to the two switching ports of the second switch (15); the common port of the second switch (15) is connected to the third filter circuit (17), and the other end of the third filter circuit (17) is connected to the power divider circuit (5).

3. The medium-to-long-wave communication receiving device according to claim 1, characterized in that, The local oscillator circuit has three local oscillator sources; each local oscillator source includes a reference phase-locked loop circuit (18), a frequency source circuit (19), a frequency divider circuit (20), an amplifier circuit (21), and a fourth filter circuit (22) connected in sequence.

4. The medium-long wave communication receiving device according to claim 1, characterized in that, The control circuit includes a serial-connected MCU and a 485 conversion chip. The MCU sends a binary bit stream to the frequency source circuit (19) of the local oscillator circuit (12) via the SPI bus to generate the required frequency. The MCU communicates with the upper-level monitoring via the RS485 bus to change the frequency, power or report the module status. The MCU controls the link gain change of the gain adjustment circuit (8) via the GPIO port.

5. A medium-to-long-wave communication receiving device according to claim 1, characterized in that, It also includes a power supply circuit (10), which includes a switching power supply (23) and a linear power supply. The switching power supply (23) is used to efficiently convert the external power supply voltage into the required low voltage input. The linear power supply is used to power the local oscillator circuit and different channel circuits. At the same time, depending on the actual usage scenario, each receiving channel and different local oscillator circuits can be powered off by control and enter a silent state.

Images