A wired transmission signal monitoring device and a monitoring method

Abstract

The application discloses a kind of wired transmission signal monitoring device and monitoring method, belong to security technology field, including wired probe, communication cable, monitoring receiver and coaxial cable;The wired probe is connected with monitoring receiver by communication cable, coaxial cable, realizes data transmission, control and signal transmission;By the wired probe, the electrical signal transmitted in telephone line, cable television coaxial cable or power grid is acquired;By monitoring receiver, the received electrical signal is analyzed and judged, and suspicious electrical signal is judged.The active probe in the device is separated from the receiver, modular design is adopted, is convenient to carry, the receiver can still be used as independent equipment, improves the utilization of equipment, reduces use cost;Cover the commonly used wired signal transmission mode, can effectively detect wired electrical signal transmission;Highly integrated probe cooperates with the graphical control software of receiver, reduces the learning, use difficulty of wired signal monitoring.

Description

Technical Field

[0001] This invention relates to the field of security technology, specifically to a wired signal transmission monitoring device and monitoring method. Background Technology

[0002] Security checks and measures, such as eavesdropping prevention and electromagnetic signal detection, are conducted in confidential offices, important locations, or before important meetings to prevent information leaks. Existing detection methods include: 1. Nonlinear node detectors, which locate working semiconductor devices to detect eavesdropping equipment. However, they have high requirements for the detection environment; the environment must not contain signals in the device's operating frequency band, otherwise false detections will occur. 2. Radio receivers, which monitor radio signals in the environment, analyze and compare their characteristics to identify illegal radio signals. They have even higher requirements for the working environment, requiring an electromagnetically shielded environment to obtain accurate results. 3. Red and black power supplies, which isolate the power grid from working equipment, preventing the transmission of useful electrical signals. 4. VoIP monitoring equipment, which can only analyze signals conforming to its communication format. 5. Physical isolation, achieved by not using network or landline telephone equipment.

[0003] Of the methods mentioned above, methods 3 and 4 can isolate the electrical signals transmitted via wired connections, but they cannot transmit useful electrical signals; furthermore, physical isolation is difficult to implement in the workplace. Wired transmission is currently the most common communication method in offices, therefore a device is needed to compensate for the shortcomings of the aforementioned methods. To this end, a wired transmission signal monitoring device is proposed. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to solve the loopholes in existing security and surveillance methods, and to provide a wired signal transmission monitoring device.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution: The present invention includes a wired probe, a communication cable, a monitoring receiver, and a coaxial cable; the wired probe is connected to the monitoring receiver through the communication cable and the coaxial cable to realize data transmission, control, and signal transmission; the wired probe acquires electrical signals transmitted in telephone lines, cable TV coaxial cables, or power grids; the monitoring receiver analyzes and judges the received electrical signals to identify suspicious electrical signals.

[0006] Furthermore, the active probe includes a telephone line signal input circuit, a power grid signal input circuit, a cable TV signal input line, a high-voltage matrix switch, an audio decoding circuit, an A / D sampling circuit, an embedded system, a serial communication circuit, a digital meter circuit, and a radio frequency switch;

[0007] The telephone line signal input circuit and the power grid signal input circuit are respectively connected to the high-voltage matrix switch. The high-voltage matrix switch is respectively connected to the audio decoding circuit and the digital meter circuit, and the high-voltage matrix switch is directly connected to the A / D sampling circuit. The audio decoding circuit is connected to the embedded system through the A / D sampling circuit. The digital meter circuit is directly connected to the embedded system. The embedded system is connected to the serial communication circuit. The serial communication circuit is connected to the monitoring receiver through a communication cable. The power grid signal input circuit and the cable TV signal input line are respectively connected to the radio frequency switch. The radio frequency switch is connected to the monitoring receiver through a coaxial cable.

[0008] Furthermore, the telephone line signal introduction circuit includes an input connector and an output connector, which are respectively connected to a high-voltage switch matrix.

[0009] Furthermore, the power grid signal input circuit includes a power grid input interface, capacitors C1 and C2, current-limiting resistors R1 and R2, operating mode selection switches KM1 and KM2. The power grid signal is input through the power grid input interface and AC coupled through capacitors C1 and C2, current-limiting resistors R1 and R2. Then, it is connected to the operating mode selection switches KM1 and KM2 respectively. The common terminal of the operating mode selection switches KM1 and KM2 is connected to the primary coil of transformer T1 for input and output isolation. The first measured signal is coupled out from the secondary coil of transformer T1 and sent to the input terminal of the RF switch through the output interface TP1.

[0010] Furthermore, the cable TV signal input line is a coupler, which is provided with an input terminal, an output terminal, a coupling output port, and a ground terminal; the coupling output port is connected to a radio frequency switch, and the second test signal is coupled out through the coupler and connected to the radio frequency switch along with the first test signal, and the output signal is selected by switching the operating mode.

[0011] Furthermore, the high-voltage switch matrix includes row switches KS1-KSn, access column switches KI1-KIn, output column switches KO1-KOn, common terminal switch KC, measurement terminal switch KV, measurement terminal interface JV, common terminal interface JC, measurement circuit selection switch SW1, and measurement circuit selection switch SW2. Row switches KS1-KSn are connected in series between the input connector and the output connector; access column switches KI1-KIn are connected in series between the input connector and the common terminal switch KC; output column switches KO1-KOn are connected in series between the output connector and the measurement terminal switch KV; the live wire, neutral wire, and protective ground wire of the power grid input interface are respectively connected to the measurement circuit selection switch SW1 and the measurement circuit selection switch SW2. The common terminal of SW1 is connected to the measurement terminal switch KV, the common terminal of SW2 is connected to the common terminal switch KC, the common terminal switch KC is connected to the common terminal interface JC, and the measurement terminal switch KV is connected to the measurement terminal interface JV.

[0012] Furthermore, the digital meter circuit is connected to the measurement terminal interface JV and the common terminal interface JC, and the audio decoding circuit 105 is connected to the measurement terminal interface JV and the common terminal interface JC.

[0013] Furthermore, the A / D sampling circuit has two input signals. One input is connected to the measurement terminal interface JV and the common terminal interface JC of the high-voltage switch matrix to sample the electrical signal on the telephone line. The other input is connected to the output of the audio decoding circuit to sample the analog audio signal. The sampled data is sent to the embedded system. After the embedded system encodes the sampled analog audio data, it performs signal format conversion through the serial communication circuit and then sends the data to the monitoring receiver through the communication cable.

[0014] Furthermore, the serial communication circuit is a full-duplex communication mode, using differential signals for signal transmission.

[0015] The present invention also provides a method for monitoring wired transmission signals, which uses the above-mentioned monitoring device to monitor wired transmission signals, including the following steps:

[0016] S1: Select the monitoring mode according to the line being monitored, and connect the monitoring device to the line being monitored;

[0017] S2: According to the monitoring mode, switch the measurement terminal switch KV and the common terminal switch KC in the RF switch and high voltage switch matrix. The line under test is connected to the digital meter circuit or coupled to the monitoring receiver. The monitoring receiver analyzes and judges the received electrical signal to identify suspicious electrical signals.

[0018] Furthermore, in step S2, when the monitoring mode is telephone line test, the following sub-steps are specifically included:

[0019] S201: By closing the row switch, the combination of input column switch and output column switch is switched in sequence to measure the DC voltage between different lines. The measurement data is transmitted to the monitoring receiver, which compares it with the pre-stored telephone line voltage values ​​and determines which lines are working lines.

[0020] S202: Close the line column switch on the working line and open the row switch to measure the DC current on the working line. Monitor the receiver to compare and analyze the obtained voltage and current to determine the working status of the line; or collect the electrical signal of the working line through the sampling circuit, draw the time domain waveform diagram on the monitoring receiver, analyze the time domain waveform diagram, and determine the working status of the line.

[0021] Furthermore, in step S2, when the monitoring mode is power line testing, the following sub-steps are specifically included:

[0022] S211: By switching the measurement terminal switch, the common terminal switch, and the measurement circuit selection switch, the combination mode is switched in sequence to measure the AC voltage and DC voltage between different lines of the power line. The measurement data is transmitted to the monitoring receiver, which compares it with the pre-stored power line voltage values ​​and determines whether the line is working normally.

[0023] S212: After the AC and DC voltage measurements between power lines are completed, disconnect the measurement terminal switch and the common terminal switch;

[0024] S213: By switching the working mode selection switch, the combination mode is switched in sequence, and the signal coupling between different lines of the power line is carried out through the transformer, and the coupled output signal is sent to the radio frequency switch.

[0025] S214: Switch the RF switch to select the signal output by the power line coupling, transmit the signal to the monitoring receiver, analyze the spectrum of the signal, compare it with the preset spectrum lines, and determine the suspicious electrical signal.

[0026] Furthermore, in step S2, when the monitoring mode is cable television line test, the following sub-steps are specifically included:

[0027] S221: By switching the radio frequency switch, the coupler couples the signal transmitted in the cable TV to the output and transmits the coupled output signal to the monitoring receiver;

[0028] S222: The monitoring receiver analyzes the spectrum of the signal and compares it with the preset spectrum lines to determine suspicious electrical signals.

[0029] Compared with the prior art, the present invention has the following advantages: the active probe and receiver of the wired transmission signal monitoring device are separated, and the modular design makes it easy to carry. The receiver can still be used as an independent device, which improves the utilization rate of the device and reduces the cost of use. It covers common wired signal transmission methods and can effectively detect wired signal transmission. The highly integrated probe, together with the receiver's graphical control software, reduces the learning and usage difficulty of wired signal monitoring. Attached Figure Description

[0030] Figure 1 This is a schematic block diagram of the wired transmission signal monitoring device in an embodiment of the present invention;

[0031] Figure 2 This is a block diagram of the power grid signal introduction circuit in an embodiment of the present invention;

[0032] Figure 3 This is a block diagram of the high-voltage switch matrix in an embodiment of the present invention;

[0033] Figure 4 This is a block diagram of the cable TV signal introduction circuit in an embodiment of the present invention;

[0034] Figure 5(a) is a flowchart of a telephone line monitoring method in an embodiment of the present invention;

[0035] Figure 5(b) is a flowchart of telephone line monitoring method two in an embodiment of the present invention;

[0036] Figure 5(c) is a flowchart of the power line monitoring method in an embodiment of the present invention. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] See Figure 1 This embodiment provides a technical solution: a wired signal transmission monitoring device, including a wired probe 1, a communication cable 2, a monitoring receiver 3, and a coaxial cable 4; the wired probe 1 is connected to the monitoring receiver 3 through the communication cable 2 and the coaxial cable 4 to realize data transmission, control, and signal transmission; the wired probe 1 acquires electrical signals transmitted in telephone lines, cable TV coaxial cables, or power grids; the monitoring receiver 3 analyzes and judges the received electrical signals to identify suspicious electrical signals.

[0039] In this embodiment, the active probe 1 includes a telephone line signal input circuit 101, a power grid signal input circuit 102, a cable TV signal input line 103, a high-voltage matrix switch 104, an audio decoding circuit 105, an A / D sampling circuit 106, an embedded system 107, a serial communication circuit 108, a digital meter circuit 109, and an RF switch 110.

[0040] The telephone line signal input circuit 101 and the power grid signal input circuit 102 are respectively connected to the high-voltage matrix switch 104. The high-voltage matrix switch 104 is respectively connected to the audio decoding circuit 105 and the digital meter circuit 109. The high-voltage matrix switch 104 is directly connected to the A / D sampling circuit 106. The audio decoding circuit 105 is connected to the embedded system 107 through the A / D sampling circuit 106. The digital meter circuit 109 is directly connected to the embedded system 107. The embedded system 107 is connected to the serial communication circuit 108. The serial communication circuit 108 is connected to the monitoring receiver 3 through the communication cable 2. The power grid signal input circuit 102 and the cable TV signal input line 103 are respectively connected to the radio frequency switch 110. The radio frequency switch 110 is connected to the monitoring receiver 3 through the coaxial cable 4.

[0041] In this embodiment, see Figure 3 The telephone line signal introduction circuit 101 includes an input connector 101-1 and an output connector 101-2, which are respectively connected to the high-voltage switch matrix 104.

[0042] In this embodiment, the power grid signal input circuit 102 includes a power grid input interface 102-1, capacitors C1 and C2, current-limiting resistors R1 and R2, a working mode selection switch KM1, and a working mode selection switch KM2. The power grid signal is input through the power grid input interface 102-1 and AC coupled through capacitors C1 and C2, current-limiting resistors R1 and R2. Then, it is connected to the working mode selection switches KM1 and KM2 respectively. The common terminal of the working mode selection switches KM1 and KM2 is connected to the primary coil of transformer T1 for input and output isolation. The measured signal is coupled out from the secondary coil of transformer T1 and sent to the input terminal of the RF switch 110 through the output interface TP1.

[0043] Among them, capacitors C1 and C2 are safety capacitors.

[0044] In this embodiment, see Figure 4 The cable television signal input line 103 is a coupler 103-3, which is provided with an input terminal 103-1, an output terminal 103-2, a coupling output port 103-5, and a ground terminal 103-4.

[0045] In this embodiment, see Figure 3 The high-voltage switch matrix 104 includes row switches (KS1~KSn), input column switches (KI1~KIn), output column switches (KO1~KOn), common terminal switch KC, measurement terminal switch KV, measurement terminal interface JV, common terminal interface JC, measurement circuit selection switch SW1, and measurement circuit selection switch SW2. The row switches (KS1~KSn) in the high-voltage switch matrix 104 are connected in series between the input connector 101-1 and the output connector 101-2; the input column switches (KI1~KIn) are connected in series... Between input connector 101-1 and common terminal switch KC; output column switches (KO1~KOn) are connected in series between output connector 101-2 and measurement terminal switch KV; the live wire, neutral wire and protective ground wire of the power grid input interface 102-1 are connected to measurement circuit selection switch SW1 and measurement circuit selection switch SW2 respectively. The common terminal of SW1 is connected to measurement terminal switch KV, the common terminal of SW2 is connected to common terminal switch KC, common terminal switch KC is connected to common terminal interface JC, and measurement terminal switch KV is connected to measurement terminal interface JV.

[0046] In this embodiment, the digital meter circuit is connected to the measurement terminal interface JV and the common terminal interface JC, which can realize the testing of parameters such as DC voltage, DC current, AC voltage, AC current, and circuit impedance; and can directly measure the voltage of the mains power grid.

[0047] In this embodiment, the audio decoding circuit 105 is connected to the measurement terminal interface JV and the common terminal interface JC to decode the signal on the telephone line and restore it to an analog audio signal.

[0048] In this embodiment, the A / D sampling circuit 106 has two input signals. One input is connected to the measurement terminal interface JV and the common terminal interface JC of the high-voltage switch matrix 104 to sample the electrical signal on the telephone line. The other input is connected to the output of the audio decoding circuit 105 to sample the analog audio signal. The sampled data is sent to the embedded system 107. After the embedded system 107 encodes the sampled analog audio data, it performs signal format conversion through the serial communication circuit 108, and then sends the data to the monitoring receiver 3 through the communication cable 2.

[0049] In this embodiment, the serial communication circuit 108 is a full-duplex communication mode, using differential signals for signal transmission.

[0050] In this embodiment, the cable TV signal input circuit 103 uses a coupler to couple the output of the signal under test. The electrical signal coupled to the power grid is connected to the radio frequency switch 110, and the output signal is selected by switching the operating mode.

[0051] In this embodiment, the monitoring receiver 3 receives signals that have three working modes (monitoring modes): power line test, telephone line test, and cable TV line test.

[0052] In this embodiment, the monitoring receiver 3 controls the working mode of the active probe through the communication cable 2; receives audio encoded data, stores it or plays it; receives telephone line sampling data, plots a time-domain waveform, and realizes real-time monitoring of the telephone line.

[0053] In this embodiment, the monitoring receiver 3 receives the radio frequency electrical signal coupled out by the active probe through the coaxial cable 4, plots the spectrum, and compares and analyzes it to realize the monitoring and identification of suspicious transmission signals.

[0054] The objectives of this invention require further technical measures to be adopted.

[0055] The present invention also provides a method for monitoring wired transmission signals, wherein the telephone line test has two discrimination methods, as shown in Figure 5(a), and the first implementation method is as follows:

[0056] 1) Connect the telephone line to the input connector 101-1 of the telephone line signal input circuit 101; connect the telephone line to the output connector 101-2, and close all the line switches KS1 to KSn. At this time, the line is in a straight-through state. Switch the measuring terminal switch KV and the common terminal KC to the upper contact.

[0057] 2) Close the input column switch KI1, close the output column switch KO2, and open all other column switches. Then set the digital meter to DC voltage measurement mode, read the DC voltage between the working KI1 and KO2 lines, and record it.

[0058] 3) Disconnect KO2 and close KO3. Read and record the DC voltage between the working KI1 and KO3 lines. Repeat the above steps until the DC voltage measurement and recording between KI1 and KOn is completed. At this time, disconnect KI1 and KOn.

[0059] 4) Then, close KI2, close KO1, and then close and open KO1 to KOn in sequence to measure and record the inter-line voltage. Repeat the above steps, closing and opening KI3 to KIn in sequence, and closing and opening KO1 to KOn in sequence to measure and record the inter-line voltage. By following the above steps, the inter-line voltage of all telephone lines can be measured.

[0060] 5) The recorded data is transmitted to the monitoring receiver 3, which compares it with the pre-stored telephone line voltage values ​​and determines which lines are working lines.

[0061] 6) Close the corresponding column switches (KIn, KOn) of the same line in the working circuit in sequence (for example, if the working circuit is 2 and 3, close KI2 and KO2), change the working mode of the digital meter circuit 109 to DC current measurement mode, and then open the corresponding row switch (KSn). At this time, read the working current and record it. Complete the measurement of the working current in the working circuit in sequence according to the above steps.

[0062] 7) Monitor receiver 3 to integrate the line voltage and operating current data, monitor receiver 3 to determine the working status of the telephone line, and determine whether there is any abnormal operation.

[0063] See Figure 5(b), the second implementation method is as follows:

[0064] 1) The steps for determining the working path are the same as steps 1) to 5) in Method 1.

[0065] 2) Use the A / D sampling circuit 106 to sample the working line and upload the data directly to the monitoring receiver 3.

[0066] 3) The monitoring receiver 3 draws the received data into a time-domain waveform diagram for display.

[0067] 4) Compare the time-domain waveform diagrams to determine the working status of the telephone line and whether there are any abnormalities in the line signal.

[0068] As shown in Figure 5(c), the wired transmission signal monitoring method includes the following power line testing method:

[0069] 1) Connect the power cord to the power grid input interface 102-1, and switch the measuring terminal switch KV and the common terminal KC to the lower contact.

[0070] 2) Switch the working mode of digital meter circuit 109 to AC voltage measurement mode.

[0071] 3) Switch the measurement circuit selection switches SW1 and SW2 to L and N channels respectively; digital meter circuit 109 collects and records the AC voltage.

[0072] 4) Switch the measurement line selection switches SW1 and SW2 sequentially according to the combination of (L, PE) and (N, PE), and collect and record the data using a digital meter.

[0073] 5) Switch the corresponding working mode switching switches KM1 and KM2 to L and N channels respectively; switch the RF switch to the power line measurement port.

[0074] 6) The monitoring receiver 3 collects the signal from the coupled output interface TP1, performs signal analysis, draws a spectrum diagram, analyzes the signal frequency points and signal patterns, and stores the records.

[0075] 7) Switch sequentially according to the combination of (L, PE) and (N, PE) to complete the above steps.

[0076] 8) The monitoring receiver 3 compares and analyzes the data recorded in different time periods to determine whether there are any suspicious signals.

[0077] The cable television line testing method for the aforementioned wired transmission signal monitoring method is as follows:

[0078] 1) Connect the cable TV coaxial cable to the input terminal 103-1 of the cable TV line signal input circuit 103, and connect its output terminal 103-2 to a 75Ω load or video output device; switch the RF switch 110 to the lower contact, and the signal transmitted in the cable TV is output through the coupling output port 103-5 of the coupler 103-3.

[0079] 2) The monitoring receiver 3 collects the signal output from the coupling output port 103-5, performs spectrum analysis, draws a spectrum diagram, records and stores the data.

[0080] 3) The monitoring receiver 3 compares and analyzes the data recorded in different time periods to determine whether there are any suspicious signals.

[0081] In summary, the wired transmission signal monitoring device described in the above embodiments features a modular design with a separate active probe and receiver, making it easy to carry. The receiver can still be used as an independent device, improving equipment utilization and reducing operating costs. It covers common wired signal transmission methods and can effectively detect wired signal transmission. The highly integrated probe, combined with the receiver's graphical control software, reduces the learning and usage difficulty of wired signal monitoring.

[0082] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A wired signal transmission monitoring device, characterized in that, It includes a wired probe, a communication cable, a monitoring receiver, and a coaxial cable; the wired probe is connected to the monitoring receiver via the communication cable and coaxial cable to realize data transmission, control, and signal transmission; the wired probe acquires electrical signals transmitted in telephone lines, cable TV coaxial cables, or the power grid; the monitoring receiver analyzes and judges the received electrical signals to identify suspicious electrical signals; The wired probe includes a telephone line signal input circuit, a power grid signal input circuit, a cable TV signal input line, a high-voltage matrix switch, an audio decoding circuit, an A / D sampling circuit, an embedded system, a serial communication circuit, a digital meter circuit, and a radio frequency switch; The telephone line signal input circuit and the power grid signal input circuit are respectively connected to the high-voltage matrix switch. The high-voltage matrix switch is respectively connected to the audio decoding circuit and the digital meter circuit, and the high-voltage matrix switch is directly connected to the A / D sampling circuit. The audio decoding circuit is connected to the embedded system through the A / D sampling circuit. The digital meter circuit is directly connected to the embedded system. The embedded system is connected to the serial communication circuit. The serial communication circuit is connected to the monitoring receiver through a communication cable. The power grid signal input circuit and the cable TV signal input line are respectively connected to the radio frequency switch. The radio frequency switch is connected to the monitoring receiver through a coaxial cable.

2. The wired transmission signal monitoring device according to claim 1, characterized in that: The telephone line signal introduction circuit includes an input connector and an output connector, which are respectively connected to a high-voltage switch matrix.

3. The wired transmission signal monitoring device according to claim 2, characterized in that: The power grid signal input circuit includes a power grid input interface, capacitors C1 and C2, current-limiting resistors R1 and R2, operating mode selection switches KM1 and KM2. The power grid signal is input through the power grid input interface and AC coupled through capacitors C1 and C2, current-limiting resistors R1 and R2. Then, it is connected to the operating mode selection switches KM1 and KM2 respectively. The common terminal of the operating mode selection switches KM1 and KM2 is connected to the primary coil of transformer T1 for input and output isolation. The first measured signal is coupled out from the secondary coil of transformer T1 and sent to the input terminal of the RF switch through the output interface TP1.

4. The wired transmission signal monitoring device according to claim 3, characterized in that: The cable TV signal input line is a coupler, which is provided with an input terminal, an output terminal, a coupling output port, and a ground terminal. The coupling output port is connected to a radio frequency switch, and the second test signal is coupled out through the coupler and connected to the radio frequency switch along with the first test signal. The output signal is selected by switching the operating mode.

5. The wired transmission signal monitoring device according to claim 4, characterized in that: The high-voltage switch matrix includes row switches KS1~KSn, input column switches KI1~KIn, output column switches KO1~KOn, common terminal switch KC, measurement terminal switch KV, measurement terminal interface JV, common terminal interface JC, measurement circuit selection switch SW1, and measurement circuit selection switch SW2. The row switches KS1~KSn are connected in series between the input connector and the output connector. The input column switches KI1 to KIn are connected in series between the input connector and the common terminal switch KC; the output column switches KO1 to KOn are connected in series between the output connector and the measurement terminal switch KV. The live wire, neutral wire, and protective ground wire of the power grid input interface are connected to the measurement circuit selection switch SW1 and the measurement circuit selection switch SW2, respectively. The common terminal of SW1 is connected to the measurement terminal switch KV, the common terminal of SW2 is connected to the common terminal switch KC, the common terminal switch KC is connected to the common terminal interface JC, and the measurement terminal switch KV is connected to the measurement terminal interface JV.

6. The wired transmission signal monitoring device according to claim 5, characterized in that: The digital meter circuit is connected to the measurement terminal interface JV and the common terminal interface JC, and the audio decoding circuit is connected to the measurement terminal interface JV and the common terminal interface JC.

7. The wired transmission signal monitoring device according to claim 6, characterized in that: The A / D sampling circuit has two input signals. One input is connected to the measurement terminal interface JV and the common terminal interface JC of the high-voltage switch matrix to sample the electrical signal on the telephone line. The other input is connected to the output of the audio decoding circuit to sample the analog audio signal. The sampled data is sent to the embedded system. After the embedded system encodes the sampled analog audio data, it performs signal format conversion through a serial communication circuit and then sends the data to the monitoring receiver through a communication cable.

8. The wired transmission signal monitoring device according to claim 7, characterized in that: The serial communication circuit is a full-duplex communication circuit that uses differential signals for signal transmission.

9. A method for monitoring wired transmission signals, characterized in that, Monitoring wired transmission signals using the monitoring device as described in any one of claims 1 to 8 includes the following steps: S1: Select the monitoring mode according to the line being monitored, and connect the monitoring device to the line being monitored; S2: According to the monitoring mode, switch the measurement terminal switch KV and the common terminal switch KC in the RF switch and high voltage switch matrix. The line under test is connected to the digital meter circuit or coupled to the monitoring receiver. The monitoring receiver analyzes and judges the received electrical signal to identify suspicious electrical signals.

10. A method for monitoring wired transmission signals according to claim 9, characterized in that, In step S2, when the monitoring mode is telephone line test, the following sub-steps are specifically included: S201: By closing the row switch, the combination of the access column switch and the output column switch is switched in sequence to measure the DC voltage between different lines. The measurement data is transmitted to the monitoring receiver, which compares it with the pre-stored telephone line voltage values ​​and determines which lines are working lines. S202: Close the access column switch and output column switch of the working line and open the row switch to measure the DC current on the working line. Monitor the receiver and compare and analyze the obtained voltage and current to determine the working status of the line. S203: The sampling circuit collects the electrical signal of the working line, plots the time-domain waveform on the monitoring receiver, analyzes the time-domain waveform, and judges the suspicious electrical signals of the line; When the monitoring mode is power line testing, the specific steps include the following: S211: Connect the power cord to the mains input interface and switch the measuring terminal switch KV and the common terminal switch KC to the lower contact; switch the digital meter circuit to AC voltage measurement mode; switch the measuring line selection switches SW1 and SW2 to L and N channels; the digital meter circuit acquires and records the AC voltage. The measurement circuit selection switches SW1 and SW2 are switched sequentially according to the combination of (L, PE) and (N, PE), and the data is collected and recorded by a digital multimeter circuit. S212: The corresponding operating mode switching switches KM1 and KM2 are switched to L and N channels, respectively; the RF switch is switched to the power line measurement port. The monitoring receiver acquires the signal from the coupled output interface, performs signal analysis, plots a spectrum, analyzes the signal frequency points and signal patterns, and stores the data; then switches sequentially according to the combination of (L, PE) and (N, PE) to complete the above process again; S213: Switch the radio frequency switch to select the signal output by the power line coupling, and transmit the signal to the monitoring receiver. The monitoring receiver compares and analyzes the data recorded in different time periods to determine whether there is a suspicious electrical signal. When the monitoring mode is cable TV line test, the specific steps include the following: S221: By switching the radio frequency switch, the coupler couples the signal transmitted in the cable TV to the output and transmits the coupled output signal to the monitoring receiver; S222: The monitoring receiver compares and analyzes data recorded at different time periods to determine whether there are any suspicious electrical signals.

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