A device and method for online monitoring insulation characteristics of telephone cables

Abstract

The present application discloses an online monitoring device and method for the insulation characteristics of telephone cables. The device is used to monitor the insulation characteristics of telephone cables. The telephone cables include line A and line B. The device includes: a first sampling module, a second sampling module, a first voltage acquisition module, a second voltage acquisition module, and a processing module; the first sampling module is connected in series with line A; the second sampling module is connected in series with line B; the first voltage acquisition module is connected with the first sampling module; the second voltage acquisition module is connected with the second sampling module; the first voltage acquisition module and the second voltage acquisition module are connected with the processing module. The present application can be widely used in the field of equipment communication technology.

Description

Technical Field

[0001] The present application relates to the technical field of equipment communication, and in particular to an online monitoring device and method for insulation characteristics of telephone cables. Background Art

[0002] With the development of information technology, modern communication methods are diverse. Among them, the commonly used communications include Internet communication, mobile communication, satellite communication, optical fiber communication and radio communication. Modern communication has the characteristics of fast transmission speed, large capacity and strong anti-interference ability, but it also has the risk of information leakage and hacker attack. Therefore, in some special applications with high requirements for information security, such as internal communication of large enterprises, internal communication of government agencies, and internal communication of the military, traditional automatic telephones are still the main means of communication. Telephone cables, like other products, have a certain lifespan. When the lifespan expires, new wire and cable products must be replaced. After a period of time, many telephone cables have aging problems, which in turn affects the normal use of the business.

[0003] Traditionally, cable aging is usually determined by testing the insulation characteristics of the cable, which usually uses a multimeter or resistance tester to measure the insulation resistance of the cable. The problem with this method is that the detection process requires maintenance personnel to operate and it is impossible to monitor the cable status in real time, resulting in inaccurate measurements. Therefore, there are still technical problems that need to be solved in the relevant technology. Summary of the invention

[0004] The purpose of this application is to solve one of the technical problems existing in the prior art to at least a certain extent.

[0005] To this end, an object of an embodiment of the present application is to provide an online monitoring device and method for the insulation characteristics of a telephone cable, which can reduce manual participation and improve the real-time performance of detection, thereby improving the accuracy of device detection.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the embodiment of the present application includes: an online monitoring device for insulation characteristics of a telephone cable, which is used to monitor the insulation characteristics of a telephone cable, wherein the telephone cable includes an A line and a B line, and the device includes:

[0007] A first sampling module, a second sampling module, a first voltage acquisition module, a second voltage acquisition module and a processing module;

[0008] The first sampling module is connected in series with the A line; the second sampling module is connected in series with the B line; the first voltage acquisition module is connected with the first sampling module; the second voltage acquisition module is connected with the second sampling module;

[0009] The first voltage acquisition module and the second voltage acquisition module are connected to the processing module.

[0010] In addition, the online monitoring device for insulation characteristics of telephone cables according to the above embodiment of the present invention may also have the following additional technical features:

[0011] Furthermore, in the embodiment of the present application, the first voltage acquisition module and the second voltage acquisition module have the same structure.

[0012] Further, in an embodiment of the present application, the first voltage acquisition module includes: a first voltage acquisition unit, a first resistor and a second resistor; one end of the first voltage acquisition unit is connected to one end of the first resistor; the other end of the first voltage acquisition unit is connected to one end of the second resistor; the other end of the second resistor is connected to one end of the first sampling module; and the other end of the first resistor is connected to the other end of the first sampling module.

[0013] Furthermore, in the embodiment of the present application, the resistance values ​​of the first resistor and the second resistor are the same; the resistance value of the first resistor is greater than or equal to 100KΩ.

[0014] Further, in an embodiment of the present application, the second voltage acquisition module includes: a second voltage acquisition unit, a third resistor and a fourth resistor; one end of the second voltage acquisition unit is connected to one end of the third resistor; the other end of the voltage acquisition unit is connected to one end of the third resistor; the other end of the fourth resistor is connected to one end of the first sampling module; and the other end of the fourth resistor is connected to the other end of the first sampling module.

[0015] Furthermore, in the embodiment of the present application, the first sampling module includes one or more resistive devices.

[0016] Furthermore, in an embodiment of the present application, when the number of the resistive devices is greater than 1, two or more of the resistive devices are connected in series with each other.

[0017] Furthermore, in the embodiment of the present application, the resistance of the first sampling module is less than or equal to 10 ohms.

[0018] On the other hand, the embodiment of the present application further provides a method for online monitoring of insulation characteristics of telephone cables, characterized in that the method is implemented by the online monitoring device for insulation characteristics of telephone cables as described in any of the above items, and the method includes:

[0019] The first voltage acquisition module acquires the first voltage at both ends of the first sampling module and sends it to the processing module;

[0020] The second voltage acquisition module acquires the second voltage at both ends of the second sampling module and sends it to the processing module;

[0021] The processing module converts the first voltage into a first current and converts the second voltage into a second current;

[0022] The processing module determines a target insulation characteristic result based on a phone state, the first current, and the second current.

[0023] Further, in the embodiment of the present application, the processing module determines the target insulation characteristic result based on the telephone state, the first current and the second current, including:

[0024] The processing module calculates a target current difference between the first current and the second current;

[0025] When the telephone is in an on-hook state, determining the magnitude relationship between the target current difference, the first preset threshold value, and the second preset threshold value, and if the target current difference is less than the first preset threshold value, the processing module generates a first target insulation characteristic result;

[0026] When the telephone is in an on-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the second preset threshold, the processing module generates a second target insulation characteristic result;

[0027] When the telephone is in an on-hook state, if the target current difference is greater than the second preset threshold, the processing module generates a third target insulation characteristic result;

[0028] When the telephone is in an off-hook state, determining the magnitude relationship between the target current difference, the first preset threshold and the third preset threshold, and if the target current difference is less than the first preset threshold, the processing module generates the first target insulation characteristic result;

[0029] When the telephone is in an off-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the third preset threshold, the processing module generates the second target insulation characteristic result;

[0030] When the telephone is in an off-hook state, if the target current difference is greater than or equal to the third preset threshold, the processing module generates the third target insulation characteristic result;

[0031] Among them, the first target insulation characteristic result is used to characterize that the cable has good insulation; the second target insulation characteristic result is used to characterize that the cable has slightly poor insulation and does not affect telephone service; the third target insulation characteristic result is used to characterize that the cable has severely poor insulation and affects telephone service.

[0032] The advantages and benefits of the present application will be partially given in the following description, and partially become apparent from the following description, or be understood through the practice of the present application:

[0033] The present application can detect the insulation of the A line and the B line of the telephone cable in real time through the online monitoring device for the insulation characteristics of the telephone cable composed of the first sampling module, the second sampling module, the first voltage acquisition module, the second voltage acquisition module and the processing module, and finally obtain the detection result. The present application can improve the accuracy and timeliness of the detection by allowing manual participation in the detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a module schematic diagram of an online monitoring device for insulation characteristics of telephone cables in a specific embodiment of the present invention;

[0035] Figure 2 A schematic diagram of a module of a monitoring system in a specific embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the connection of two cables of a telephone in the prior art;

[0037] Figure 4 A schematic diagram of connecting two cables of another telephone set in the prior art;

[0038] Figure 5 It is a module schematic diagram of a monitoring system in another specific embodiment of the present invention;

[0039] Figure 6 It is a circuit structure diagram of an on-line monitoring device for insulation characteristics of telephone cables in another specific embodiment of the present invention;

[0040] Figure 7 The figure is a schematic diagram of the installation and deployment of the monitoring equipment in the present invention. DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below with reference to the accompanying drawings to explain the principle and process of the on-line monitoring device and method for insulation characteristics of telephone cables in the embodiments of the present invention.

[0042] Reference Figure 1The present application provides an online monitoring device for the insulation characteristics of telephone cables. The device can be used to monitor the insulation characteristics of telephone cables. The monitored telephone cables may include line A and line B. The monitoring device may include: a first sampling module 1, a second sampling module 2, a first voltage acquisition module 3, a second voltage acquisition module 4 and a processing module 5. The first sampling module 1 is connected in series with line A. The second sampling module 2 is connected in series with line B. The first voltage acquisition module 3 is connected to the first sampling module 1. The second voltage acquisition module 4 is connected to the second sampling module 2. The first voltage acquisition module 3 and the second voltage acquisition module 4 are connected to the processing module 5.

[0043] Furthermore, in some feasible embodiments of the present application, the first voltage acquisition module and the second voltage acquisition module have the same structure.

[0044] Further, in some feasible embodiments of the present application, the first voltage acquisition module includes: a first voltage acquisition unit, a first resistor and a second resistor. One end of the first voltage acquisition unit is connected to one end of the first resistor. The other end of the first voltage acquisition unit is connected to one end of the second resistor. The other end of the second resistor is connected to one end of the first sampling module. The other end of the first resistor is connected to the other end of the first sampling module.

[0045] Further, in some feasible embodiments of the present application, the resistance values ​​of the first resistor and the second resistor are the same. The resistance value of the first resistor is greater than or equal to 100KΩ. Similarly, the resistance value of the second resistor is greater than or equal to 100KΩ. Since the second voltage acquisition module and the second voltage acquisition module have the same structure, the resistance values ​​of the third resistor and the fourth resistor are also greater than or equal to 100KΩ. In this embodiment, according to the call loop impedance of the telephone network of 600Ω, the impedance of the line changes to 598.2Ω after the 100kΩ resistor is incorporated, and the impedance change rate is only 0.25%, which can be ignored for the impedance characteristics of the entire user interface, so the voltage at both ends of the sampling module can be accurately read.

[0046] Further, in some feasible embodiments of the present application, the second voltage acquisition module includes: a second voltage acquisition unit, a third resistor and a fourth resistor. One end of the second voltage acquisition unit is connected to one end of the third resistor. The other end of the voltage acquisition unit is connected to one end of the third resistor. The other end of the fourth resistor is connected to one end of the first sampling module. The other end of the fourth resistor is connected to the other end of the first sampling module.

[0047] Furthermore, in some feasible embodiments of the present application, the first sampling module includes one or more resistive devices.

[0048] Furthermore, in some feasible embodiments of the present application, when the number of resistive devices is greater than 1, two or more resistive devices are connected in series with each other.

[0049] Further, in some feasible embodiments of the present application, the resistance of the first sampling module is less than or equal to 10 ohms. In this embodiment, the line model is constructed according to the measured single-line resistance of 130Ω for a user line of 1km. When a 10Ω resistor is inserted in series into the two lines respectively, the line resistance change rate is 7.7%, which is equivalent to the extension of the telephone line by 77m. According to the attenuation constant of 1.9dB / km of the double-line, the effect of the inserted resistor on the attenuation of the voice signal is very small, not more than 0.15dB.

[0050] In addition, the present application also provides a method for online monitoring of insulation characteristics of telephone cables. The method can be implemented by any of the above-mentioned online monitoring devices for insulation characteristics of telephone cables. The monitoring method may include steps S101 to S104.

[0051] S101: A first voltage acquisition module acquires a first voltage at two ends of a first sampling module and sends the first voltage to a processing module.

[0052] S102: The second voltage acquisition module acquires a second voltage at two ends of the second sampling module and sends the second voltage to the processing module.

[0053] S103, the processing module converts the first voltage into a first current and converts the second voltage into a second current.

[0054] S104: Based on the phone state, the first current, and the second current, the processing module determines a target insulation characteristic result.

[0055] Further, in some feasible embodiments of the present application, based on the state of the phone, the first current and the second current, the step of the processing module determining the target insulation characteristic result may include:

[0056] S201: A processing module calculates a target current difference between a first current and a second current.

[0057] S202: When the telephone is in an on-hook state, determine the magnitude relationship among the target current difference, the first preset threshold value, and the second preset threshold value.

[0058] S203: If the target current difference is less than a first preset threshold, the processing module generates a first target insulation characteristic result.

[0059] S204: When the telephone is in an on-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the second preset threshold, the processing module generates a second target insulation characteristic result.

[0060] S205: When the telephone is in an on-hook state, if the target current difference is greater than a second preset threshold, the processing module generates a third target insulation characteristic result.

[0061] S206: When the telephone is in an off-hook state, determine the magnitude relationship among the target current difference, the first preset threshold value, and the third preset threshold value.

[0062] S207: If the target current difference is less than the first preset threshold, the processing module generates a first target insulation characteristic result.

[0063] S208, when the telephone is in the off-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the third preset threshold, the processing module generates a second target insulation characteristic result.

[0064] S209: When the telephone is in an off-hook state, if the target current difference is greater than or equal to a third preset threshold, the processing module generates a third target insulation characteristic result.

[0065] The first target insulation characteristic result is used to indicate that the cable has good insulation. The second target insulation characteristic result is used to indicate that the cable has slightly poor insulation and does not affect telephone service. The third target insulation characteristic result is used to indicate that the cable has severely poor insulation and affects telephone service.

[0066] The specific implementation principle of this application is described below with reference to the accompanying drawings:

[0067] In this embodiment, the monitoring device of the present application is also a monitoring circuit. The first sampling module and the second sampling module are both 10 ohm resistors. The first resistor, the second resistor, the third resistor, and the fourth resistor are all 100 kΩ resistors.

[0068] The system of this embodiment mainly includes a hardware platform, a software platform and a WEB interface. The hardware platform mainly includes an interface circuit, a monitoring circuit, a control circuit and a power supply circuit; the software platform mainly includes data acquisition, business management, alarm management and network management; the WEB interface includes device management and human-computer interaction. Figure 2 shown.

[0069] As we all know, telephone cables generally have two wire cores, which we call A wire and B wire. Figure 3 When the telephone line is normal, line A and line B form a loop, and the current on line A is I A The current I on line B B Save the consistency, that is, I A =I B .

[0070] Reference Figure 4 When the line has poor insulation, such as poor insulation of line B, leakage current IC At this time, there will be a certain current difference between line A and line B, that is, I C =I A -I B We can use the leakage current I C The size of the insulation is used to identify the insulation characteristics of the telephone cable.

[0071] Reference Figure 5 The hardware platform mainly includes interface circuit, monitoring circuit, control circuit and power supply circuit. The hardware interface includes internal line interface, external line interface, power supply interface, debugging serial port and network management interface. The monitoring circuit monitors the loop current of the line by combining low-resistance series connection and high-resistance jumper connection. The control circuit mainly controls the data acquisition of the online monitoring unit through the CPU, as well as the control circuits of reset, button, fan and buzzer. The power supply circuit mainly converts the AC 220V voltage into 12V voltage to power the board, and the 12V voltage is then converted by the power management chip into 5V and 3.3V voltages used by various circuit modules.

[0072] The monitoring circuit adopts the connection mode of resistor series connection and high impedance jumper connection. The monitoring process will not affect the business in use. The device connection is as follows: Figure 6 As shown. The first acquisition module is a 10Ω resistor, and the first voltage acquisition module acquires the voltage V at both ends of the 10Ω resistor. a1 and V a2 , and then calculate the current I of the telephone line A cable A =(V a1 -V a2 ) / 10. Similarly, the second voltage acquisition module obtains the current I of cable B B =(V b1 -V b2 ) / 10.

[0073] Through the above analysis of the insulation characteristics monitoring principle, it can be known that the insulation characteristics of the cable can be identified by the size of the leakage current IC. Through the fault simulation test, the following data is obtained:

[0074]

[0075]

[0076] Table 1 Through the data in Table 1, we can get the insulation characteristic judgment conditions in the on-hook state as shown in Table 2:

[0077] Serial number Judgment conditions Verdict Remark 1 IC<1mA Cable insulation is good and business is normal 2 <h2 style=";text-align:left;direction:ltr">1m≤IC<6mA<h2 style=";text-align:left;direction:ltr"> Slight insulation failure, no impact on business 3 IC≥6mA Severe insulation failure affects business 4 IC rises more than 0.5mA Indicates cable degradation

[0078] Table 2

[0079]

[0080]

[0081] Table 3 Through the data in Table 3, we can get the insulation characteristic judgment conditions in the off-hook state as shown in Table 4:

[0082] Serial number Judgment conditions Verdict Remark 1 IC<1mA Cable insulation is good and business is normal 2 1m≤IC<5mA Slight insulation failure, no impact on business 3 IC≥5mA Severe insulation failure affects business 4 IC rises more than 0.5mA Indicates cable degradation

[0083] Table 4

[0084] Through the insulation poor judgment condition table 2 in the on-hook state and the insulation poor judgment condition table 4 in the off-hook state, we can realize the real-time monitoring of the insulation characteristics of the telephone cable, and when the cable deteriorates, a warning of cable degradation can be given.

[0085] Reference Figure 7 The monitoring device of this embodiment is connected in series between the program-controlled switch and the telephone. Its installation, deployment and wiring are convenient and quick. Equipment abnormalities, power outages, or software upgrades will not affect the current services. It can realize real-time monitoring of the insulation characteristics of telephone cables and the aging status of cables.

[0086] In some optional embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the application is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Optional embodiments are expected, wherein the order of various operations is changed and the sub-operation described as a part of a larger operation is performed independently.

[0087] In addition, although the present application is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features can be integrated into a single physical device and / or software module, or one or more functions and / or features can be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present application. More specifically, in view of the properties, functions, and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional techniques of the engineer. Therefore, those skilled in the art can implement the present application set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present application, which is determined by the full scope of the attached claims and their equivalents.

[0088] The logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable programs for implementing the logical functions, and may be embodied in any computer-readable medium for use by a program execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch and execute a program from a program execution system, device or apparatus), or in conjunction with such program execution systems, devices or apparatuses. For purposes of this specification, a "computer-readable medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by a program execution system, device or apparatus, or in conjunction with such program execution systems, devices or apparatuses.

[0089] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable program execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0090] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0091] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

[0092] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the described embodiments. Technical personnel familiar with the field may make various equivalent modifications or substitutions without violating the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. An on-line monitoring device for insulation characteristics of telephone cables, characterized in that: Used to monitor the insulation characteristics of a telephone cable, the telephone cable comprising an A line and a B line, the device comprising: A first sampling module, a second sampling module, a first voltage acquisition module, a second voltage acquisition module and a processing module; The first sampling module is connected in series with the A line; the second sampling module is connected in series with the B line; the first voltage acquisition module is connected with the first sampling module; the second voltage acquisition module is connected with the second sampling module; The first voltage acquisition module and the second voltage acquisition module are connected to the processing module.

2. The on-line monitoring device for insulation characteristics of telephone cables according to claim 1, characterized in that: The first voltage acquisition module and the second voltage acquisition module have the same structure.

3. The on-line monitoring device for insulation characteristics of telephone cables according to claim 2, characterized in that: The first voltage acquisition module includes: a first voltage acquisition unit, a first resistor and a second resistor; one end of the first voltage acquisition unit is connected to one end of the first resistor; the other end of the first voltage acquisition unit is connected to one end of the second resistor; the other end of the second resistor is connected to one end of the first sampling module; the other end of the first resistor is connected to the other end of the first sampling module.

4. The on-line monitoring device for insulation characteristics of telephone cables according to claim 3, characterized in that: The first resistor and the second resistor have the same resistance value; the resistance value of the first resistor is greater than or equal to 100KΩ.

5. The on-line monitoring device for insulation characteristics of telephone cables according to claim 2, characterized in that: The second voltage acquisition module includes: a second voltage acquisition unit, a third resistor and a fourth resistor; one end of the second voltage acquisition unit is connected to one end of the third resistor; the other end of the voltage acquisition unit is connected to one end of the third resistor; the other end of the fourth resistor is connected to one end of the first sampling module; the other end of the fourth resistor is connected to the other end of the first sampling module.

6. The on-line monitoring device for insulation characteristics of telephone cables according to any one of claims 1 to 5, characterized in that: The first sampling module includes one or more resistive devices.

7. The on-line monitoring device for insulation characteristics of telephone cables according to claim 6, characterized in that: When the number of the resistive devices is greater than 1, two or more resistive devices are connected in series.

8. The on-line monitoring device for insulation characteristics of telephone cables according to claim 6, characterized in that: The resistance of the first sampling module is less than or equal to 10 ohms.

9. A method for online monitoring of insulation characteristics of telephone cables, characterized in that: The method is implemented by the online monitoring device for insulation characteristics of telephone cables according to any one of claims 1 to 8, and includes: The first voltage acquisition module acquires the first voltage at both ends of the first sampling module and sends it to the processing module; The second voltage acquisition module acquires the second voltage at both ends of the second sampling module and sends it to the processing module; The processing module converts the first voltage into a first current and converts the second voltage into a second current; The processing module determines a target insulation characteristic result based on a phone state, the first current, and the second current.

10. The method for online monitoring of insulation characteristics of telephone cables according to claim 9, characterized in that: The processing module determines a target insulation characteristic result based on the phone state, the first current, and the second current, including: The processing module calculates a target current difference between the first current and the second current; When the telephone is in an on-hook state, determining the magnitude relationship between the target current difference, the first preset threshold value, and the second preset threshold value, and if the target current difference is less than the first preset threshold value, the processing module generates a first target insulation characteristic result; When the telephone is in an on-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the second preset threshold, the processing module generates a second target insulation characteristic result; When the telephone is in an on-hook state, if the target current difference is greater than the second preset threshold, the processing module generates a third target insulation characteristic result; When the telephone is in an off-hook state, determining the magnitude relationship between the target current difference, the first preset threshold and the third preset threshold, and if the target current difference is less than the first preset threshold, the processing module generates the first target insulation characteristic result; When the telephone is in an off-hook state, if the target current difference is greater than or equal to the first preset threshold and less than the third preset threshold, the processing module generates the second target insulation characteristic result; When the telephone is in an off-hook state, if the target current difference is greater than or equal to the third preset threshold, the processing module generates the third target insulation characteristic result; Among them, the first target insulation characteristic result is used to characterize that the cable has good insulation; the second target insulation characteristic result is used to characterize that the cable has slightly poor insulation and does not affect telephone service; the third target insulation characteristic result is used to characterize that the cable has severely poor insulation and affects telephone service.

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