A method and system for automatic detection of the frequency of a radio frequency signal

Abstract

The present application relates to a kind of automatic detection method and system of radio frequency signal frequency, input radio frequency signal is divided into radio frequency detection signal and radio frequency main signal by first coupler;Radio frequency detection signal is converted into voltage value by detector, whether signal power is judged by first comparator, and the high-low level for output is used for transceiver control;Radio frequency main signal is divided into transmission and reception path by first switch, in transmission path, it is divided into different frequency band signals by diplexer, whether corresponding frequency band has signal output is judged by second coupler and second comparator to realize frequency control;The signal of diplexer output is amplified, and by third switch, it is divided into corresponding frequency band and is filtered, finally, signal is transmitted to antenna by transceiver control and frequency control.The frequency of the double band-pass filter of diplexer is automatically identified frequency band, and coupling detection is carried out, and the voltage after detection controls the switching of switch filter;The amplitude detection of input radio frequency signal is realized to automatically identify the transmission or reception of signal.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency signal frequency detection technology, and particularly relates to an automatic method and system for detecting radio frequency signal frequency. Background Technology

[0002] In modern communications, radar, electronic warfare, and other fields, radio frequency (RF) signals serve as the core carrier for information transmission and processing. The accurate detection of their frequency parameters directly impacts the stability of signal reception, the reliability of communication links, and the synergy of equipment operation. With the rapid development of communication technology, the application frequency bands of RF signals are constantly expanding, and scenarios involving multiple frequency bands are becoming increasingly common. Equipment must be able to determine the frequency band attributes of the input RF signal in real time and automatically switch to the corresponding path for signal processing to avoid problems such as signal attenuation and increased interference caused by frequency band mismatch.

[0003] Traditional radio frequency (RF) signal frequency detection methods often rely on manually preset frequency bands or single hardware filtering circuits, which have significant limitations. Firstly, manual preset methods cannot adapt to dynamically changing signal environments. When the signal frequency band switches, equipment parameters must be manually adjusted, resulting in slow response times and susceptibility to operational errors. Secondly, a single filtering circuit can only process fixed frequency bands. To cover multiple frequency bands, multiple independent paths often need to be designed and switched externally, increasing equipment size and cost, and potentially leading to signal loss due to switching delays. Furthermore, some existing detection solutions lack real-time signal power monitoring mechanisms, making it difficult to determine whether the signal is being transmitted effectively. In weak or no-signal scenarios, misjudgments are prone to occur, further affecting the equipment's operational stability.

[0004] In current communication equipment, the transmission and reception of communication devices require external control signals. Simultaneously, frequency band switching of radio frequency signals also requires control signals. This is typically achieved through external TTL levels, FPGAs, SPI communication, etc., to control the operation of internal devices. This reliance on external control signals for device operation can easily lead to problems such as signal interference, complex control components, and poor module independence.

[0005] To address these issues, the industry has gradually explored hardware-based automatic detection technologies. These technologies utilize the collaborative work of devices such as couplers, duplexers, and comparators to automatically identify the power and frequency band of radio frequency signals. However, existing technologies still have room for improvement in terms of the accuracy of frequency band allocation, the simplicity of detection logic, and the efficiency of path switching. For example, some solutions have ambiguous frequency band boundaries, which can easily lead to misjudgments in frequency band transition areas; some solutions have lengthy detection links, resulting in increased signal loss and reduced response speed.

[0006] Therefore, how to improve the existing technical problems and realize the detection method and system for automatic path switching has become an urgent technical problem to be solved in the current radio frequency technology field. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic detection method and system for radio frequency signals. In intelligent radio frequency signal and frequency detection technology, a coupler is added to the input section to realize the detection of the presence or absence of radio frequency signals; a duplexer is added before signal amplification to perform frequency segmentation to realize automatic frequency identification and detection.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] In a first aspect, an automatic method for detecting the frequency of a radio frequency signal is provided, comprising the following steps:

[0010] The radio frequency (RF) signal is input to a coupler, which splits the RF signal into two signals through electromagnetic induction. One signal is a radio frequency (RF) detection signal, and the specific processing procedure for the RF detection signal is as follows:

[0011] The detection signal is converted into a voltage value reflecting the power of the radio frequency signal by a detector;

[0012] The detected voltage value is used by the first comparator to determine whether the input RF signal power is present or not. The high and low levels output by the first comparator are used for transmit and receive control.

[0013] The other signal is the main radio frequency (RF) signal, and the specific processing procedure for the main RF signal is as follows:

[0014] The main radio frequency (RF) signal is split into a transmitting path and a receiving path by the first switch. In the transmitting path, the main RF signal is split into two RF signals with frequency bands of 108M-174M and 225M-400M by the first duplexer and the second duplexer. In the 108M-174M frequency band path, the main RF signal is split into two RF signals with frequency bands of 108M-174M by the second coupler to extract part of the signal for frequency detection. The frequency control can be realized by determining whether there is a signal output in the 108M-174M frequency band through the second comparator.

[0015] When there is power output in the 108M-174M frequency band, the radio frequency signal is in the 108M-174M frequency band; if there is no power output in the 108M-174M frequency band, the radio frequency signal is in the 225M-400M frequency band.

[0016] After the output of the second duplexer, the signal is amplified by the RF signal amplification section. The amplified RF signal is then divided into two RF signals, 108M-174M and 225M-400M, by the frequency control third switch. The two frequency bands are then filtered by low-band filtering and high-band filtering, respectively.

[0017] The corresponding radio frequency signal is transmitted to the antenna via the second switch of transmit / receive control and frequency control.

[0018] Secondly, an automatic detection system for radio frequency signal frequency is provided, including a signal input terminal, a first coupler, a second coupler, a detector, a first comparator, a second comparator, a first duplexer, a second duplexer, a first switch, a second switch, a third switch, and a signal output terminal;

[0019] The input terminal of the first coupler is connected to the signal input terminal, and the output terminal of the first coupler is connected to the detector and the first switch respectively. The detector is connected to the first comparator.

[0020] The first switch is connected to the input terminal of the first duplexer, the output terminal of the first duplexer is connected to the input terminals of the second coupler and the second duplexer respectively, the output terminal of the second coupler is connected to the input terminal of the second duplexer, the second coupler is connected to the input terminal of the second comparator, and one signal output by the second coupler is input to the second comparator after passing through the detection frequency.

[0021] The second duplexer is connected to the third switch. The signal output by the second duplexer is amplified and then enters the third switch. The signal after passing through the third switch is filtered according to the frequency band, and then transmitted to the antenna through the second switch.

[0022] Preferably, the first or second coupler distributes the signal proportionally, extracts one radio frequency signal through electromagnetic induction to detect the power of the signal, and the other radio frequency signal is split into the transmitting path and the receiving path by the first switch for processing respectively.

[0023] Preferably, the detector is an RMS detector. Part of the radio frequency signal output from the first coupler is converted into DC voltage by the RMS detector to perform real-time power monitoring of the device. The higher the input signal power, the higher the detector output voltage.

[0024] Preferably, the first comparator or the second comparator includes a first resistor to a twelfth resistor, a first comparator chip to a fourth comparator chip, and a first capacitor;

[0025] The first resistor is connected to the non-inverting input of the first comparator chip. The second resistor is connected to the inverting input and output of the first comparator chip. The output of the first comparator chip is connected to the third resistor. The third resistor is connected to the sixth resistor and the non-inverting input of the second comparator chip. The inverting input of the second comparator chip is connected to the fourth and fifth resistors. The output of the second comparator chip is connected to the seventh resistor and the first capacitor. The other end of the seventh resistor is connected to the eighth resistor and the input of the third NOT gate. The output of the third NOT gate is connected to the ninth resistor. The other end of the ninth resistor is connected to the eleventh and tenth resistors. The tenth resistor is connected to the input of the fourth NOT gate. The output of the fourth NOT gate is connected to the twelfth resistor.

[0026] Preferably, the detected voltage output by detector 1 is used to amplify the signal current through the first comparator chip. The first and third resistors serve as port protection resistors for the first and second comparator chips, the second resistor is a feedback resistor, the fourth and fifth resistors are used to adjust the reference voltage, and the sixth and eighth resistors serve as voltage divider resistors. The detected voltage is compared with the reference voltage through the second comparator chip to convert the analog signal of the radio frequency power into a digital pulse signal. The first capacitor is a filter capacitor, the seventh resistor is a current limiting resistor, and the ninth to twelfth resistors are protection resistors used to protect the third and fourth NOT gates. The signal is output as control signal 1 and control signal 2 through the third and fourth NOT gates. The characteristics of the NOT gates are used to control the switching of high and low segments to realize the transmission and reception control or frequency band control of the communication equipment.

[0027] Preferably, the first duplexer and the second duplexer are connected by a second capacitor, a third capacitor, and a fourth capacitor. A second coupler is connected between the second capacitor and the third capacitor. The first duplexer and the second duplexer determine the frequency range of the radio frequency signal and divide the radio frequency signal into two radio frequency signals with frequency bands of 108M-174M and 225M-400M. The second capacitor, the third capacitor, and the fourth capacitor are DC blocking capacitors. A portion of the radio frequency signal is extracted through the second coupler. The presence or absence of power in the 108M-174M radio frequency signal is detected by the detector 2 to determine the frequency band of the communication device signal and realize the frequency detection of the device.

[0028] The beneficial effects of this invention include:

[0029] The automatic frequency detection method and system for radio frequency signals provided by this invention divides the input radio frequency signal into a radio frequency detection signal and a main radio frequency signal through a first coupler. The radio frequency detection signal is converted into a voltage value by a detector, and a first comparator determines whether the signal power is present. The high and low levels of the output are used for transmit / receive control. The main radio frequency signal is split into transmit and receive paths by a first switch. In the transmit path, it is split into different frequency band signals by a duplexer. A second coupler and a second comparator determine whether there is a signal output in the corresponding frequency band to achieve frequency control. The duplexer output signal is amplified and then split into the corresponding frequency band by a third switch for filtering. Finally, the signal is transmitted to the antenna through transmit / receive control and frequency control. The frequency band is automatically identified by the dual bandpass filter of the duplexer and coupled for detection. The detected voltage controls the switching of the filter. Automatic identification of signal transmission or reception is achieved by detecting the amplitude of the input radio frequency signal.

[0030] First, it achieves full automation of RF signal frequency detection and path switching. Without manual intervention to preset frequency bands or adjust parameters, the signal splitting process via the first coupler, along with the coordinated action of devices such as duplexers and comparators, enables rapid determination of signal power presence and frequency band identification. For example, by using the second comparator to assess the output of signals in the 108MHz-174MHz band, the signal's frequency band can be directly determined, significantly shortening detection and response time and effectively improving overall processing efficiency.

[0031] Secondly, regarding detection accuracy, multi-level processing and precise judgment mechanisms ensure the reliability of the results. After the RF detection signal is converted into a voltage value by the detector, the first comparator determines the presence or absence of power, providing an accurate basis for transmit / receive control. For the main RF signals, the division of specific frequency bands by the first and second duplexers, combined with the detection by the second coupler and the second comparator, accurately distinguishes between 108MHz-174MHz and 225MHz-400MHz frequency bands, reducing the possibility of frequency band misjudgment. Simultaneously, the real-time monitoring of signal power by the RMS detector and the processing of analog signals into digital signals by various comparators further improve detection accuracy.

[0032] Finally, regarding system stability and signal transmission quality, the main RF signal undergoes power amplification in the signal amplification section during processing, compensating for signal loss during transmission. Furthermore, low-band and high-band filtering for different frequency bands effectively removes noise interference, ensuring the purity of the output signal. In addition, the coordinated use of transmit / receive control and frequency control switches ensures accurate transmission of the corresponding frequency band RF signal to the antenna, avoiding signal attenuation issues caused by frequency band mismatch and guaranteeing signal transmission stability. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the automatic detection system for radio frequency signals according to the present invention.

[0034] Figure 2 The waveform of the input signal and output voltage value of the waveguide of the present invention.

[0035] Figure 3 The comparator control principle block diagram of the present invention.

[0036] Figure 4 The 108MHz-174MHz bandpass spectrum analysis diagram of the instrument of the present invention.

[0037] Figure 5 The 225MHz-400MHz bandpass spectrum analysis diagram of the duplexer of the present invention.

[0038] Figure 6 The principle block diagram of the duplexer for identifying signal frequency of the present invention. Detailed Implementation

[0039] The following is in conjunction with the appendix Figures 1-6 The present invention will be further described in detail below:

[0040] Example 1

[0041] See Figure 1 An automatic method for detecting the frequency of a radio frequency signal includes the following steps:

[0042] The radio frequency (RF) signal is input to the coupler, which splits the RF signal into two signals through electromagnetic induction. One signal is used as the RF detection signal. The coupler distributes the signal proportionally and extracts a portion of the RF signal through electromagnetic induction to detect the signal power. A suitable coupler is selected based on actual engineering needs, taking into account factors such as the coupler's frequency range, coupling degree, insertion loss, and directivity. The coupling degree represents the strength of the coupled signal.

[0043] The specific processing procedure for radio frequency detection signals is as follows:

[0044] The detection signal is converted into a voltage value reflecting the power of the radio frequency signal by a detector. The detected voltage value is used by a first comparator to determine whether the input radio frequency signal power is present. The high and low levels output by the first comparator are used for transmit and receive control.

[0045] The other signal is the main radio frequency (RF) signal, and the specific processing procedure for the main RF signal is as follows:

[0046] The main radio frequency (RF) signal is split into a transmitting path and a receiving path via a first switch. In the transmitting path, the RF signal is divided into two RF signals, one in the 108MHz-174MHz band and the other in the 225MHz-400MHz band, by a first duplexer and a second duplexer. In the 108MHz-174MHz band, a portion of the RF signal is extracted by a second coupler for frequency detection. Frequency control is achieved by determining whether there is a signal output in the 108MHz-174MHz band using a second comparator. When there is power output in the 108MHz-174MHz band, the RF signal is in the 108MHz-174MHz band; if there is no power output in the 108MHz-174MHz band, the RF signal is in the 225MHz-400MHz band. After the second duplexer outputs, the signal is amplified by the RF signal amplification section. The amplified RF signal is then split into two RF signals, one in the 108M-174M band and the other in the 225M-400M band, by the third frequency control switch. The two bands are then filtered for low-band and high-band respectively. The corresponding RF signals are transmitted to the antenna via the transmit / receive control and the second frequency control switch.

[0047] Example 2

[0048] Based on Example 1, see Figure 1 An automatic frequency detection system for radio frequency signals includes a signal input terminal, a first coupler, a second coupler, a detector, a first comparator, a second comparator, a first duplexer, a second duplexer, a first switch, a second switch, a third switch, and a signal output terminal. The input terminal of the first coupler is connected to the signal input terminal, and the output terminal of the first coupler is connected to both the detector and the first switch. The detector is connected to the first comparator. The first switch is connected to the input terminal of the first duplexer, and the output terminal of the first duplexer is connected to the input terminals of both the second coupler and the second duplexer. The output terminal of the second coupler is connected to the input terminal of the second duplexer, and the second coupler is connected to the input terminal of the second comparator. One signal output from the second coupler is detected and then input to the second comparator.

[0049] The second duplexer is connected to the third switch. The signal output from the second duplexer is amplified and then enters the third switch. The signal passing through the third switch is filtered according to the frequency band, with low-band filtering and high-band filtering performed separately, before being transmitted to the antenna through the second switch. The first or second coupler distributes the signal proportionally, extracting one radio frequency signal through electromagnetic induction to detect the signal power. The other radio frequency signal is split by the first switch into the transmit path and the receive path for processing respectively.

[0050] The detector is an RMS detector. A portion of the RF signal output from the first coupler is converted into DC voltage by the RMS detector, enabling real-time power monitoring of the equipment. The higher the input signal power, the higher the detector's output voltage. The RMS detector features wide dynamic range detection, true RMS power detection, and arbitrary waveform detection. The detection signal involves converting a portion of the RF signal output from the coupler into DC voltage via the RMS detector for real-time power monitoring of the equipment. See also... Figure 2 As shown, the higher the input signal power, the higher the detector output voltage.

[0051] Example 3

[0052] Based on Embodiment 1 or Embodiment 2, the first comparator or the second comparator includes a first resistor to a twelfth resistor, a first comparator chip to a fourth comparator chip, and a first capacitor;

[0053] The first resistor is connected to the non-inverting input of the first comparator chip. The second resistor is connected to the inverting input and output of the first comparator chip. The output of the first comparator chip is connected to the third resistor. The third resistor is connected to the sixth resistor and the non-inverting input of the second comparator chip. The inverting input of the second comparator chip is connected to the fourth and fifth resistors. The output of the second comparator chip is connected to the seventh resistor and the first capacitor. The other end of the seventh resistor is connected to the eighth resistor and the input of the third NOT gate. The output of the third NOT gate is connected to the ninth resistor. The other end of the ninth resistor is connected to the eleventh and tenth resistors. The tenth resistor is connected to the input of the fourth NOT gate. The output of the fourth NOT gate is connected to the twelfth resistor.

[0054] See Figure 3 As shown, the detected voltage is amplified by the first comparator to increase the signal current. The first and third resistors serve as port protection resistors for the first and second comparators, respectively. The second resistor is a feedback resistor. The fourth and fifth resistors are used to adjust the reference voltage. The sixth and eighth resistors serve as voltage divider resistors. The second comparator compares the detected voltage with the reference voltage to convert the analog signal of the radio frequency power into a digital pulse signal. The first capacitor is a filter capacitor. The seventh resistor is a current-limiting resistor. The ninth to twelfth resistors are protection resistors used to protect the third and fourth NOT gates. The signal outputs control signal 1 and control signal 2 through the third and fourth NOT gates. The characteristics of the NOT gates are used to control the switching of high and low segments to realize the transmission and reception control or frequency band control of the communication equipment.

[0055] The detected voltage output from detector 1 is amplified by the current of the first comparator chip. The first and third resistors serve as port protection resistors for the first and second comparator chips. The second resistor is a feedback resistor. The fourth and fifth resistors are used to adjust the reference voltage. The sixth and eighth resistors serve as voltage divider resistors. The second comparator chip compares the detected voltage with the reference voltage, converting the analog signal of the radio frequency power into a digital pulse signal. The first capacitor is a filter capacitor. The seventh resistor is a current-limiting resistor. The ninth to twelfth resistors are protection resistors used to protect the third and fourth NOT gates. The signal outputs control signal 1 and control signal 2 through the third and fourth NOT gates. The characteristics of the NOT gates are used to control the switching of high and low segments, realizing the transmission and reception control or frequency band control of the communication equipment.

[0056] The first duplexer and the second duplexer are connected by a second capacitor, a third capacitor, and a fourth capacitor. A second coupler is connected between the second capacitor and the third capacitor. The first duplexer and the second duplexer determine the frequency range of the radio frequency signal and divide the radio frequency signal into two radio frequency signals with frequency bands of 108M-174M and 225M-400M. The second capacitor, the third capacitor, and the fourth capacitor are DC blocking capacitors. A portion of the radio frequency signal is extracted through the second coupler. The presence or absence of power in the 108M-174M radio frequency signal is detected by detector 2 to determine the frequency band of the communication device signal and realize the frequency detection of the device.

[0057] See Figure 4 and Figure 5 Both the first and second duplexers employ frequency division duplexers (FDDs), internally using two sets of bandpass filters at different frequencies. Spectral analysis of the two bandpass filters within the duplexer reveals that insertion loss is approximately 1 dB when signals pass through a specific frequency band, while insertion loss is significant for signals outside that band, and signals within the specific band pass through with almost no attenuation. When an RF signal enters the duplexer, the bandpass filters filter the frequency range of the RF signal and transmit it to the corresponding frequency band output port, thus identifying the frequency range of the RF signal.

[0058] Specifically Figure 4 and Figure 5 The horizontal axis represents frequency (MHz); the red vertical axis (left) represents insertion loss (dB); and the blue vertical axis (right) represents return loss (RL) (dB).

[0059] Depend on Figure 4As can be seen, the red curve represents the insertion loss of RF signals at different frequencies passing through the duplexer. When the frequency range is 108MHz-174MHz, the insertion loss of the RF signal is within 1dB, which is very small. However, when RF signals of other frequencies pass through, the insertion loss of the duplexer is very large, which can effectively suppress the passage of RF signals of other frequencies. The blue curve represents the return loss of RF signals at different frequencies passing through the duplexer. When the frequency range is 108MHz-174MHz, the return loss is above 20dB, indicating that the reflected power ratio is within 1%, ensuring efficient power transmission and equipment safety of the system.

[0060] Depend on Figure 4 As can be seen, the red curve represents the insertion loss of RF signals at different frequencies passing through the duplexer. When the frequency range is 225M-400M, the insertion loss of the RF signal is within 1dB, which is very small. However, when RF signals of other frequencies pass through, the insertion loss of the duplexer is very large, which can suppress the passage of RF signals of other frequencies. The blue curve represents the return loss of RF signals at different frequencies passing through the duplexer. When the frequency range is 225M-400M, the return loss is above 20dB, indicating that the reflected power ratio is within 1%, ensuring efficient power transmission and equipment safety of the system.

[0061] See Figure 6 As shown, the frequency range of the radio frequency signal is determined by the first duplexer and the second duplexer, and the radio frequency signal is divided into two radio frequency signals with frequency bands of 108M-174M and 225M-400M. C1, C2 and C3 are DC blocking capacitors. A portion of the radio frequency signal is extracted by the second coupler. The presence or absence of power in the 108M-174M radio frequency signal is detected by the detector, which can determine the frequency band of the communication equipment signal and realize the frequency detection of the equipment.

[0062] In summary, the automatic radio frequency (RF) signal frequency detection method and system provided by this invention divides the input RF signal into an RF detection signal and a main RF signal using a first coupler. The RF detection signal is converted into a voltage value by a detector, and a first comparator determines whether signal power is present. The high and low levels of the output are used for transmit / receive control. The main RF signal is split into transmit and receive paths by a first switch. In the transmit path, it is split into different frequency bands by a duplexer. A second coupler and a second comparator determine whether there is a signal output in the corresponding frequency band to achieve frequency control. The duplexer output signal is amplified and then split into the corresponding frequency band by a third switch for filtering. Finally, the signal is transmitted to the antenna through transmit / receive control and frequency control. The frequency band is automatically identified by the dual bandpass filter of the duplexer and coupled for detection. The detected voltage controls the switching of the filter. Automatic identification of signal transmission or reception is achieved by detecting the amplitude of the input RF signal. This achieves full automation of RF signal frequency detection and path switching. Without requiring manual intervention to preset frequency bands or adjust parameters, the signal can be split and processed by the first coupler, and the synergistic effect of devices such as duplexers and comparators can quickly determine the presence or absence of signal power and identify the frequency band. For example, by using the second comparator to determine the output of signals in the 108M-174M frequency band, the frequency band to which the signal belongs can be directly determined, significantly shortening the detection and response time and effectively improving the overall processing efficiency.

[0063] The reliability of the results is ensured through multi-stage processing and precise judgment mechanisms. After the RF detection signal is converted into a voltage value by the detector, the first comparator determines the presence or absence of power, providing an accurate basis for transmit / receive control. For the main RF signal, the division of specific frequency bands by the first and second duplexers, combined with the detection by the second coupler and second comparator, accurately distinguishes between 108MHz-174MHz and 225MHz-400MHz frequency bands, reducing the possibility of frequency band misjudgment. Simultaneously, the real-time monitoring of signal power by the RMS detector and the conversion of analog signals to digital signals by various comparators further improve detection accuracy. Regarding system stability and signal transmission quality, the main RF signal undergoes power amplification in the signal amplification section during processing, compensating for signal loss during transmission. Furthermore, low-band and high-band filtering for different frequency bands effectively removes noise interference, ensuring the purity of the output signal. In addition, by coordinating the transmit / receive control and frequency control switches, the radio frequency signal of the corresponding frequency band is accurately transmitted to the antenna, avoiding problems such as signal attenuation caused by frequency band mismatch and ensuring the stability of signal transmission.

Claims

1. An automatic method for detecting the frequency of a radio frequency signal, characterized in that, Includes the following steps: The radio frequency (RF) signal is input to a coupler, which splits the RF signal into two signals through electromagnetic induction. One signal is the RF detection signal, and the specific processing procedure for the RF detection signal is as follows: The detection signal is converted into a voltage value reflecting the power of the radio frequency signal by a detector; The detected voltage value is used by the first comparator to determine whether the input RF signal power is present or not. The high and low levels output by the first comparator are used for transmit and receive control. The other signal is the main radio frequency (RF) signal, and the specific processing procedure for the main RF signal is as follows: The main radio frequency (RF) signal is split into a transmitting path and a receiving path by the first switch. In the transmitting path, the main RF signal is divided into two RF signals in the frequency bands 108M-174M and 225M-400M by the first duplexer and the second duplexer. In the 108M-174M frequency band path, the main RF signal is extracted by the second coupler to detect the frequency. The second comparator determines whether there is a signal output in the 108M-174M frequency band to achieve frequency control. When there is power output in the 108M-174M frequency band, the radio frequency signal is in the 108M-174M frequency band; when there is no power output in the 108M-174M frequency band, the radio frequency signal is in the 225M-400M frequency band. After the output of the second duplexer, the signal is amplified by the RF signal amplification section. The amplified RF signal is then divided into two RF signals, 108M-174M and 225M-400M, by the frequency control third switch. The two frequency bands are then filtered by low-band filtering and high-band filtering, respectively. The corresponding radio frequency signal is transmitted to the antenna via the second switch of transmit / receive control and frequency control.

2. An automatic detection system for radio frequency signals, characterized in that, It includes a signal input terminal, a first coupler, a second coupler, a detector, a first comparator, a second comparator, a first duplexer, a second duplexer, a first switch, a second switch, a third switch, and a signal output terminal; The input terminal of the first coupler is connected to the signal input terminal, and the output terminal of the first coupler is connected to the detector and the first switch respectively. The detector is connected to the first comparator. The first switch is connected to the input terminal of the first duplexer, the output terminal of the first duplexer is connected to the input terminals of the second coupler and the second duplexer respectively, the output terminal of the second coupler is connected to the input terminal of the second duplexer, the second coupler is connected to the input terminal of the second comparator, and one signal output by the second coupler is input to the second comparator after passing through the detection frequency. The second duplexer is connected to the third switch. The signal output from the second duplexer is amplified and then enters the third switch. The signal after passing through the third switch is filtered according to the frequency band, and then transmitted to the antenna through the second switch. The first or second coupler distributes the signal proportionally, extracts one radio frequency signal through electromagnetic induction to detect the power of the signal, and the other radio frequency signal is split into the transmitting path and the receiving path by the first switch for processing respectively.

3. The automatic detection system for radio frequency signals according to claim 2, characterized in that, The detector is an RMS detector. Part of the radio frequency signal output from the first coupler is converted into DC voltage by the RMS detector to perform real-time power monitoring of the device. The higher the input signal power, the higher the detector output voltage.

4. The automatic detection system for radio frequency signals according to claim 2, characterized in that, The first comparator or the second comparator includes a first resistor to a twelfth resistor, a first comparator chip to a fourth comparator chip, and a first capacitor; The first resistor is connected to the non-inverting input of the first comparator chip. The second resistor is connected to the inverting input and output of the first comparator chip. The output of the first comparator chip is connected to the third resistor. The third resistor is connected to the sixth resistor and the non-inverting input of the second comparator chip. The inverting input of the second comparator chip is connected to the fourth and fifth resistors. The output of the second comparator chip is connected to the seventh resistor and the first capacitor. The other end of the seventh resistor is connected to the eighth resistor and the input of the third NOT gate. The output of the third NOT gate is connected to the ninth resistor. The other end of the ninth resistor is connected to the eleventh and tenth resistors. The tenth resistor is connected to the input of the fourth NOT gate. The output of the fourth NOT gate is connected to the twelfth resistor.

5. The automatic detection system for radio frequency signals according to claim 4, characterized in that, The detected voltage output from detector 1 is amplified by the current of the first comparator chip. The first and third resistors serve as port protection resistors for the first and second comparator chips. The second resistor is a feedback resistor. The fourth and fifth resistors are used to adjust the reference voltage. The sixth and eighth resistors serve as voltage divider resistors. The second comparator chip compares the detected voltage with the reference voltage, converting the analog signal of the radio frequency power into a digital pulse signal. The first capacitor is a filter capacitor. The seventh resistor is a current-limiting resistor. The ninth to twelfth resistors are protection resistors used to protect the third and fourth NOT gates. The signal outputs control signal 1 and control signal 2 through the third and fourth NOT gates. The characteristics of the NOT gates are used to control the switching of high and low segments, realizing the transmission and reception control or frequency band control of the communication equipment.

6. The automatic detection system for radio frequency signals according to claim 2, characterized in that, The first and second duplexers are connected via a second capacitor, a third capacitor, and a fourth capacitor. A second coupler is connected between the second and third capacitors. The first and second duplexers determine the frequency range of the radio frequency signal and divide the radio frequency signal into two channels: a frequency band of 108M-174M and a frequency band of 225M-400M. The second, third, and fourth capacitors are DC blocking capacitors. A portion of the radio frequency signal is extracted through the second coupler. The presence or absence of power in the 108M-174M radio frequency signal is detected by detector 2 to determine the frequency band of the communication device signal, thereby achieving frequency detection of the device.

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