Testing method and testing device

Abstract

A testing device (10) generates noise so as to cause the noise to be superimposed on a communication signal, and detects the state of noise that causes a communication error in an ECU (20). A communication IC (30) of the ECU (20) operates in such a manner as to adjust a noise reduction function in accordance with the noise superimposed on the communication signal. A testing method according to the present disclosure involves, at least at a timing at which a testing condition is changed, setting the state to either a state in which the adjustment operation of the noise reduction function by the communication IC (30) is stopped or a state in which the adjustment of the noise reduction function is initialized. As a result, it is possible to test the ECU (20) in a state where the adjustment of the noise reduction function is stopped or in a state where the adjustment of the noise reduction function is insufficient. Accordingly, it becomes possible to correctly evaluate the limit of communication quality and noise resistance of the ECU (20) through testing.

Description

Test method and test equipment CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2024-70738 filed in Japan on April 24, 2024, the contents of which are incorporated by reference in their entirety.

[0002] The present disclosure relates to a test method and test device for testing a communication device that communicates via a communication line.

[0003] For example, Patent Document 1 describes a method for evaluating electronic products. According to this evaluation method, common mode noise is injected into a transmission line while sweeping its frequency. Frequency characteristics indicating the noise level at each frequency of the common mode noise injected into the electronic product via the transmission line are measured. Durability characteristics indicating the noise level at each noise frequency at which the electronic product malfunctions are obtained. Then, from the frequency characteristics and durability characteristics, the frequency band of the common mode noise that causes the electronic product to malfunction is identified.

[0004] Patent No. 7075121

[0005] A communication device that communicates via a communication line is generally provided with a filter that blocks noise propagating through the communication line and passes communication signals. In some cases, such a filter is capable of adjusting its noise reduction function, including adjusting its cutoff frequency, according to the noise propagating through the communication line.

[0006] When testing the noise immunity and communication quality of a communication device equipped with a filter with adjustable noise reduction function as described above, if the noise reduction function of the filter is adjusted in response to noise, normal communication may occur even when noise that would cause a communication error occurs if the noise reduction function is not adjusted or is not adjusted sufficiently. This makes it difficult to correctly evaluate the limits of the noise immunity and communication quality of the communication device through testing.

[0007] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a test method and test device that can correctly evaluate the noise resistance and communication quality limits of a communication device.

[0008] In order to achieve the above object, the testing method disclosed herein is a testing method for testing a communication device that communicates via a communication line, wherein the communication device operates to adjust a noise reduction function in accordance with noise superimposed on a communication signal, and includes: generating noise by the testing device so that the noise is superimposed on the communication signal; detecting by the testing device a noise state that causes a communication error in the communication device; and stopping the adjustment operation of the noise reduction function by the communication device or initializing the adjustment of the noise reduction function at least at the timing when the test conditions are changed.

[0009] In addition, the test apparatus according to the present disclosure is a test apparatus for testing a communication device that communicates via a communication line, the communication device operates to adjust a noise reduction function in accordance with noise superimposed on a communication signal, and includes: a noise generating unit that generates noise so that the noise is superimposed on the communication signal; a noise state detecting unit that detects a noise state that causes a communication error in the communication device; and a control unit that controls the communication device so that, at least at the timing when the test conditions are changed, the communication device stops adjusting the noise reduction function or initializes the adjustment of the noise reduction function.

[0010] As described above, the test method and test apparatus disclosed herein test a communication device by generating noise so that the noise is superimposed on a communication signal and detecting a noise state that causes a communication error in the communication device.

[0011] A communication device operates to adjust its noise reduction function in response to noise superimposed on a communication signal. However, according to the test method and test device disclosed herein, the adjustment operation of the noise reduction function by the communication device is stopped or the adjustment of the noise reduction function is initialized at least when the test conditions are changed. As a result, it is possible to test the communication device with the noise reduction function adjustment stopped or insufficiently adjusted. Therefore, the test makes it possible to correctly evaluate the noise tolerance and communication quality limits of the communication device.

[0012] The reference numbers in parentheses in the claims merely indicate an example of a correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0013] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings.

[0014] 1 is a configuration diagram showing a test device according to an embodiment and two electronic control units (ECUs) having communication functions that are to be tested by the test device. FIG. 1 is a configuration diagram showing the details of the configuration of the test device and the ECU. FIG. 2 is a diagram showing an example of a communication signal on which high-frequency noise is superimposed, and an example of a communication signal from which high-frequency noise has been removed by an LPF. FIG. 2 is a flowchart showing an example of each process included in a program executed by at least one processor of the test device to test an ECU. FIG. 3 is a diagram for explaining an example of changing the noise mode. FIG. 4 is a graph showing the differential voltage when a communication error occurs when the magnitude of differential noise applied at the same frequency is increased stepwise. FIG. 5 is a diagram for explaining another example of changing the noise mode.

[0015] Hereinafter, embodiments of a test method and test device according to the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments, and various modifications described below are also included within the technical scope of the present disclosure. Furthermore, in addition to the following, various modifications can be implemented without departing from the gist of the present disclosure. The embodiments and various modifications can be implemented in appropriate combinations as long as no technical contradictions arise. In the following description, identical or similar components may be assigned the same reference numbers across multiple drawings, and their description may be omitted. Furthermore, when only a portion of a component is mentioned, the description given elsewhere may apply to the other components.

[0016] 1 is a configuration diagram showing a test device 10 according to this embodiment and two electronic control units (ECUs) 20 and 40 having a communication function that are to be tested by the test device 10. In other words, the two ECUs 20 and 40 correspond to the communication devices in this disclosure.

[0017] The two ECUs 20 and 40 are mounted on a vehicle and communicate with each other via a communication line 11 for cooperative control or to acquire sensor information, for example. Therefore, the two ECUs 20 and 40 each include a communication IC. The configuration of the communication IC will be described in detail later. Communication between the two ECUs 20 and 40 can use various communication standards and methods that can be used for in-vehicle LANs, such as a Controller Area Network (CAN, registered trademark), Ethernet (registered trademark), a Local Interconnect Network (LIN), Low-Voltage Differential Signaling (LVDS), or a Serializer / Deserializer (SER-DES). That is, communication between the two ECUs 20 and 40 can be differential signal transmission such as CAN, Ethernet, or LVDS, or single-ended signal transmission such as LIN. In the case of differential signal transmission, the communication line 11 can be half-duplex or full-duplex.

[0018] The test device 10 is used to test, for example, the immunity performance and communication quality of the ECU 20 when the ECU 20 performs communication. The test device 10 may be configured by a computer including at least one processor such as a CPU or a DSP, and a memory for storing programs executed by the processor. FIG. 1 shows a configuration in which the test device 10 is provided for the ECU 20. However, a test device similar to the test device 10 may also be provided for the ECU 40.

[0019] The configurations of the test device 10 and the ECU 20 will be described in detail below with reference to Figures 1 and 2. Figure 2 shows a configuration in which the ECU 20 performs differential signal transmission over a half-duplex communication line 11. Figure 2 also shows, in block diagram form, functions that the test device 10 performs as a result of a program executed by a processor.

[0020] The ECU 20 is connected to two communication lines 11 via a connector 21. Capacitors 22 and 23 for removing DC components are connected to the two internal wires of the ECU 20 that are connected to the connector 21. That is, the capacitors 22 and 23 are used for AC coupling within the ECU 20. The two internal wires downstream of the capacitors 22 and 23 are grounded via electrostatic discharge (ESD) protection elements 24 and 25, such as Zener diodes and varistors, respectively.

[0021] Furthermore, termination resistors 26 and 27 for suppressing signal reflection are connected to the two internal wirings downstream of the ESD protection elements 24 and 25. The two internal wirings downstream of the termination resistors 26 and 27 are connected to a common mode choke coil (CMC) 28 for removing common mode noise. The two internal wirings downstream of the CMC 28 are connected to a communication IC 30.

[0022] The communication IC 30 includes a low-pass filter (LPF) 31, a controller 33, and a transceiver 34. The LPF 31 is used to remove high-frequency noise superimposed on the communication signal. For example, when high-frequency noise is superimposed on the communication signal as shown in Fig. 3(a), the high-frequency noise is removed by the LPF 31, resulting in a communication signal as shown in Fig. 3(b).

[0023] In this embodiment, the LPF 31 may be configured, for example, by a digital filter. The LPF 31 is configured to be able to adjust its filter characteristics, including the cutoff frequency, according to a setting value written to the register 32 of the LPF 31. Adjustment of the filter characteristics of the LPF 31 is not limited to the above example and can be achieved by other methods. For example, it is possible to adjust the filter characteristics of the LPF 31 by preparing multiple sub-LPFs each having a different cutoff frequency and switching which sub-LPF to use. In this case, the multiple sub-LPFs may be configured by digital filters or analog filters. Alternatively, it is possible to adjust the filter characteristics of the LPF 31 by dividing the frequency band into multiple sections (especially the gain of multiple sections belonging to the high frequency band) like an equalizer. In this way, the LPF 31 of the communication IC 30 of this embodiment is configured to be able to adjust its filter characteristics.

[0024] The controller 33 adjusts the filter characteristics of the LPF 31 based on the result of high-frequency noise removal by the LPF 31. This adjusts the noise reduction function of the communication IC 30 (i.e., the ECU 20). For example, if the controller 33 determines, based on the result of high-frequency noise removal by the LPF 31, that the LPF 31 has sufficiently removed high-frequency noise, the controller 33 adjusts the filter characteristics so as to lower the cutoff frequency. Conversely, if the controller 33 determines, based on the result of high-frequency noise removal by the LPF 31, that the LPF 31 has excessively removed high-frequency noise, the controller 33 adjusts the filter characteristics so as to raise the cutoff frequency. By repeating this adjustment of the filter characteristics, the controller 33 can adjust the filter characteristics of the LPF 31 to filter characteristics suitable for removing high-frequency noise superimposed on the communication signal.

[0025] The adjustment of the filter characteristics by the controller 33 can be performed by changing the setting values ​​written to the registers described above, by selecting a sub-LPF having a desired cutoff frequency from among a plurality of sub-LPFs, or by changing the gain of each frequency band. Furthermore, the initial values ​​of the filter characteristics of the LPF 31 before the adjustment of the filter characteristics of the LPF 31 by the controller 33 are determined in advance. Therefore, the adjustment of the filter characteristics of the LPF 31 starts from the initial values ​​set in advance.

[0026] The transceiver 34 generates a communication signal to be transmitted to a communication partner and performs a transmission process, and also performs a reception process to receive a communication signal transmitted from the communication partner. The transceiver 34 also detects communication errors during the transmission or reception process. For example, in the case of CAN communication, the transceiver 34 detects bit errors, format errors, ACK errors, CRC errors, and stop errors as communication errors. The method for detecting communication errors may vary depending on the communication standard and communication method. When the transceiver 34 detects a communication error, it notifies the test apparatus 10.

[0027] As shown in FIG. 2, the test apparatus 10 includes a noise generating section 14, a filter control section 16, and a noise state detecting section 18.

[0028] The noise generating unit 14 generates noise so as to superimpose the noise on the communication signals while the ECU 20 and the ECU 40 transmit and receive the communication signals to and from each other via the communication lines 11. For example, as shown in FIG. 1 , the test apparatus 10 may include a probe 12 that can directly apply or inject noise into the communication lines 11. In this case, the noise generating unit 14 can inject differential noise into the two communication lines 11 via the probe 12. However, instead of directly injecting noise into the communication lines 11 via the probe 12, the noise generating unit 14 may superimpose noise on the communication signals by, for example, irradiating the communication lines 11 with electromagnetic noise.

[0029] The noise generating unit 14 is configured to be able to change at least one of the frequency of the generated noise, whether or not modulation is performed, the noise pattern, and the noise magnitude. For example, the noise generating unit 14 may be configured to be able to change the noise frequency within a range from 1 MHz to 400 MHz. Furthermore, the noise generating unit 14 can generate sinusoidal carrier noise of any frequency without modulation, or it can generate noise in which a sinusoidal carrier of any frequency is amplitude-modulated using, for example, a 1 kHz modulated wave. That is, the noise generating unit 14 may be configured to be able to change whether or not modulation is performed when generating noise. Switching between modulation and non-modulation changes the pattern of the generated noise. Therefore, it can also be said that the noise generating unit 14 is able to change the noise pattern of the generated noise. However, the noise generating unit 14 may be configured to change the noise pattern not only by whether or not modulation is performed, but also by changing the shape of the noise itself, for example, between sinusoidal noise and pulse-like noise. Furthermore, the noise generating unit 14 may be configured to generate noise of different magnitudes without changing the frequency, i.e., at the same frequency.

[0030] The filter control unit 16 instructs the controller 33 of the communication IC 30 to stop adjusting the noise reduction function in the communication IC 30 or to initialize the adjustment of the noise reduction function at least when the test conditions are changed. Hereinafter, this instruction will be referred to as a reset instruction. For example, changing at least one of the frequency of the noise generated by the noise generating unit 14, whether or not to use modulation, the noise pattern, and the noise magnitude corresponds to changing the test conditions.

[0031] Upon receiving the reset instruction, the controller 33 of the communication IC 30 can stop the adjustment operation of the noise reduction function of the communication IC 30, for example, by fixing the setting value written to the register 32 to an initial value, fixing a sub-LPF selected from the multiple sub-LPFs to an initially set sub-LPF, or fixing the gain of each frequency band to an initial value. Here, when the controller 33 of the communication IC 30 stops the adjustment operation of the noise reduction function of the communication IC 30 in response to the reset instruction, the test apparatus 10 may simply send the reset instruction immediately after the start of the test. In this case, the adjustment operation of the noise reduction function of the communication IC 30 can be maintained in a stopped state during the test unless the test apparatus 10 instructs the controller 33 to cancel the reset instruction. Therefore, by simply sending the reset instruction immediately after the start of the test, the test apparatus 10 can stop the adjustment operation of the noise reduction function of the communication IC 30 at least at the timing when the test conditions are changed.

[0032] Alternatively, upon receiving a reset instruction, the controller 33 may perform the above-described filter characteristic adjustment while, for example, initializing the setting value written to the register 32, determining which sub-LPF is selected from the plurality of sub-LPFs as the initially set sub-LPF, or setting the gain of each frequency band to an initial value. This allows the adjustment of the noise reduction function in the communication IC 30 to be initialized at least when the test conditions are changed. Therefore, the test apparatus 10 can test the immunity performance (noise resistance) and communication quality of the ECU 20 with the noise reduction function in the communication IC 30 in an insufficiently adjusted state each time the test conditions are changed.

[0033] Alternatively, if the communication IC 30 is configured to initialize the adjustment of the noise reduction function when the power is turned off, the controller 33 may, upon receiving the reset instruction, temporarily turn off the power to the communication IC 30 (or the ECU 20) and then turn the power on. Also, if the communication IC 30 is configured to initialize the adjustment of the noise reduction function when communication with the communication partner is cut off, the controller 33 may, upon receiving the reset instruction, temporarily terminate communication with the transceiver 34 and then instruct it to resume communication with the communication partner.

[0034] The noise condition detector 18 detects the noise condition (for example, the noise frequency, noise magnitude, presence or absence of modulation, noise pattern, etc.) when a communication error is detected in the transceiver 34 .

[0035] As described above, in this embodiment, when a reset command is received from the filter control unit 16 of the test apparatus 10, the controller 33 of the communication IC 30 stops adjusting the noise reduction function of the communication IC 30 or initializes the adjustment of the noise reduction function. As a result, the test apparatus 10 can test the ECU 20 with the adjustment of the noise reduction function stopped or with the noise reduction function adjusted insufficiently. Therefore, the test apparatus 10 can correctly evaluate the noise resistance and communication quality limits of the ECU 20 through testing.

[0036] Next, an example of each process included in a program executed by at least one processor of the test apparatus 10 to test the ECU 20 in this embodiment will be described with reference to the flowchart of Figure 4. Note that the flowchart of Figure 4 illustrates an example in which the test apparatus 10 initializes the adjustment of the noise reduction function in the communication IC 30 in response to a change in the test conditions, such as a change in the type of noise generated (at least one of the noise frequency, presence or absence of modulation, noise pattern, and noise magnitude). The execution of each process illustrated in the flowchart of Figure 4 by at least one processor of the test apparatus 10 corresponds to the implementation of a test method by the test apparatus 10.

[0037] In the first step S100, the processor of the test apparatus 10 instructs the controller 33 of the communication IC 30 to initialize the filter adjustment function of the communication IC 30. This instruction corresponds to the reset instruction described above. In response to this instruction, the controller 33 performs, for example, initializing the setting value written to the register 32, determining which sub-LPF to select from the multiple sub-LPFs as the initially set sub-LPF, or initializing the gain of each frequency band. Additionally or alternatively, the processor of the test apparatus 10 may instruct the communication IC 30 (or the ECU 20) to power off and then power on. The processor of the test apparatus 10 may also instruct the transceiver 34 to temporarily terminate communication and then resume communication. After the noise reduction function of the communication IC 30 is initialized in this manner, the controller 33 adjusts the filter characteristics of the LPF 31 during testing by the test apparatus 10.

[0038] In step S110, the processor of the test apparatus 10 generates noise for a predetermined time period in a constant noise form. In other words, the noise form (frequency, presence or absence of modulation, noise pattern, and noise magnitude) is not changed during this predetermined period of noise generation. However, the noise form to be generated is changed according to predetermined rules and sequences each time the process of step S110 is repeated in response to a determination in step S140 (described later) that a change in the noise form is necessary. The process of step S110 corresponds to the noise generating unit 14 of the present disclosure.

[0039] In step S120, the processor of the test apparatus 10 determines whether a communication error has occurred in the ECU 20. That is, the processor of the test apparatus 10 determines whether a notification of the occurrence of a communication error has been received from the transceiver 34 of the communication IC 30. If it is determined that a communication error has occurred, the processor of the test apparatus 10 proceeds to the processing of step S130. On the other hand, if it is determined that a communication error has not occurred, the processor of the test apparatus 10 proceeds to the processing of step S140.

[0040] In step S130, the processor of the test device 10 detects and records the noise state when a communication error occurs. The processing of step S130 corresponds to the noise state detection unit 18 of the present disclosure. As described above, the noise frequency, presence or absence of modulation, noise pattern, noise magnitude, etc. are changed according to predetermined rules and sequences, and the noise reduction function adjustment of the communication IC 30 is initialized in response to the changes, and the noise state in which the communication error occurred is detected and recorded. This makes it possible to correctly evaluate the immunity performance and communication quality limits related to communication of the ECU 20.

[0041] In step S140, the processor of the test apparatus 10 determines whether or not a change in the noise mode is necessary. As described above, the noise mode is changed according to predetermined rules and sequences. That is, in step S140, the processor of the test apparatus 10 determines whether or not all of the planned noise generation in various modes has been completed. If it is determined that a change in the noise mode is necessary, the processor of the test apparatus 10 returns to the processing of step S100. If it is determined that a change in the noise mode is not necessary, that is, that all of the planned noise generation in various modes has been completed, the test apparatus 10 ends the processing shown in the flowchart of FIG. 4, that is, ends the test.

[0042] Here, some examples of noise modification will be described.

[0043] Fig. 5 is a graph with frequency on the horizontal axis and noise amplitude on the vertical axis. The noise mode can be changed, for example, by gradually increasing the noise amplitude at the same frequency while gradually changing the frequency in the range of 1 MHz to 400 MHz. The graph in Fig. 5 shows an example in which, when the noise amplitude is increased in stages from 120, 140, 160, and 180 mA at a frequency of 30 MHz, a communication error occurs before the target noise amplitude of 200 mA is reached.

[0044] Here, suppose that when noise of different magnitudes at the same frequency is applied, the noise reduction function of the communication IC 30 is continuously adjusted. In this case, by repeatedly adjusting the noise reduction function from when the noise magnitude is small, it becomes more likely that the noise reduction function will be properly adjusted when the noise magnitude increases. As a result, there is a possibility that the noise magnitude will reach the target value of 200 (mA) without causing a communication error.

[0045] In contrast, in this embodiment, for example, in the case of a communication error in Fig. 5 , each time the noise level increases stepwise, it is determined that the noise type has changed, and adjustment of the noise reduction function in the communication IC 30 is initialized. Therefore, each time the noise level changes, adjustment of the noise reduction function in the communication IC 30 becomes insufficient. This makes it possible to correctly evaluate the limit of immunity performance related to communication of the ECU 20, regardless of the noise reduction function in the communication IC 30.

[0046] The graph in Figure 6 shows the differential voltage (peak-to-peak voltage) when a communication error occurs when the magnitude of the applied differential noise is increased stepwise at the same frequency. The left side of Figure 6 shows the differential voltage when a communication error occurs when the adjustment of the noise reduction function in the communication IC 30 is initialized each time the magnitude of the differential noise is changed. On the other hand, the right side of Figure 6 shows the differential voltage when a communication error occurs when the adjustment of the noise reduction function in the communication IC 30 is continued regardless of the change in the magnitude of the differential noise. The results shown in Figure 6 also show that the noise reduction function of the communication IC 30 increases the apparent differential noise tolerance.

[0047] Furthermore, as an example of changing the noise form, it is possible to switch between a state in which sinusoidal carrier noise is generated without modulation as shown in Fig. 7(a) and a state in which noise is generated by amplitude-modulating a sinusoidal carrier wave with, for example, a 1 kHz modulation wave as shown in Fig. 7(b). Alternatively, the shape of the noise itself may be changed, such as between sinusoidal noise and pulse noise.

[0048] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be modified as follows.

[0049] For example, in the above-described embodiment, the test conditions are primarily changed to test the immunity performance of the communication IC 30 (ECU 20). The test apparatus 10 and test method according to the present disclosure can also be applied to testing communication quality when the communication environment with the communication partner changes, in addition to or instead of testing the immunity performance described above. For example, the communication environment with the communication partner changes when at least one of the length of the communication line 11, the type of the communication line 11, and the number of relay devices interposed in the communication line 11 is changed. Such a change in the communication environment with the communication partner can be considered a change in test conditions, and the noise reduction function of the communication IC 30 may be stopped from adjusting or initialized. This allows the test apparatus 10 and test method according to the present disclosure to test whether communication quality can be ensured in the communication between the ECU 20 and the ECU 40 in the changed communication environment.

[0050] In the above-described embodiment, the noise generating unit 14 applies and injects differential noise into the two communication lines 11 that perform differential signal transmission. However, the noise generating unit 14 may also apply and inject in-phase noise into the two communication lines 11.

[0051] Furthermore, in the above-described embodiment, when the controller 33 of the communication IC 30 receives a reset instruction from the test device 10, it may stop the adjustment operation of the noise reduction function in the communication IC 30, or may perform any combination of multiple measures to initialize the adjustment of the noise reduction function.

[0052] The flowcharts shown in the present disclosure are merely examples, and the number of steps constituting the flowchart and the execution order of the processes can be changed as appropriate. Furthermore, the apparatus and method described in the present disclosure may be implemented by a dedicated computer comprising a processor programmed to execute one or more functions embodied in a computer program. The apparatus and method described in the present disclosure may be implemented using dedicated hardware logic circuits. The apparatus and method described in the present disclosure may be implemented by one or more dedicated computers configured by combining a processor that executes a computer program with one or more hardware logic circuits. For example, some or all of the functions of the test apparatus 10 may be implemented as hardware. Implementations of certain functions as hardware include implementations using one or more integrated circuits (ICs). The processor may be a CPU, an MPU, a GPU, a data flow processor (DFP), or the like. Some or all of the functions of the test apparatus 10 may be implemented using any of a system-on-chip (SoC), an integrated circuit (IC), and a field-programmable gate array (FPGA). The concept of IC also includes ASIC (Application Specific Integrated Circuit). Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. Examples of storage media for the program include hard-disk drives (HDDs), solid-state drives (SSDs), and flash memory. The scope of the present disclosure also includes programs for causing a computer to function as the test device 10, and non-transitory tangible storage media, such as semiconductor memory, on which the programs are stored.

[0053] Finally, this specification discloses the following technical concepts and combinations thereof. The combinations of the following technical concepts apply not only to the test method but also to the test apparatus.

[0054] (Technical Idea 1) A test method for testing a communication device (20) that communicates via a communication line (11), wherein the communication device operates to adjust a noise reduction function in response to noise superimposed on a communication signal, the test method comprising: generating noise by a test device (10) so that the noise is superimposed on the communication signal; detecting by the test device a noise state that causes a communication error in the communication device; and stopping the adjustment operation of the noise reduction function by the communication device or initializing the adjustment of the noise reduction function at least at the timing when test conditions are changed.

[0055] (Technical Idea 2) The test method is for testing the immunity performance of the communication device, and the test device is capable of changing at least one of the frequency of the generated noise, whether or not it is modulated, the noise pattern, and the noise magnitude, and changing at least one of the frequency of the generated noise, whether or not it is modulated, the noise pattern, and the noise magnitude by the test device corresponds to changing the test conditions. This is the test method described in Technical Idea 1.

[0056] (Technical Idea 3) The test method is for testing the communication quality of the communication device, and the test method described in Technical Idea 1 or 2, in which changing at least one of the length of the communication line, the line type of the communication line, and the number of relay devices interposed in the communication line corresponds to changing the test conditions.

[0057] (Technical Idea 4) A test method described in any one of Technical Ideas 1 to 3, in which the adjustment of the noise reduction function of the communication device is performed by changing the characteristics of a filter provided in the communication device, and by fixing the characteristics of the filter, the adjustment operation of the noise reduction function of the communication device is stopped.

[0058] (Technical Idea 5) A test method described in any one of Technical Ideas 1 to 4, in which the adjustment of the noise reduction function by the communication device is performed by changing the characteristics of a filter provided in the communication device, and the adjustment of the noise reduction function by the communication device is initialized by changing the characteristics of the filter to an initial value at the time the test conditions are changed.

[0059] (Technical Idea 6) A test method described in any one of Technical Ideas 1 to 5, wherein the adjustment of the noise reduction function by the communication device is performed by changing the characteristics of a filter provided in the communication device, and when the power of the communication device is turned off, the adjustment of the noise reduction function is initialized, and the power of the communication device is switched from off to on in accordance with the timing when the test conditions are changed.

[0060] (Technical Idea 7) The adjustment of the noise reduction function by the communication device is performed by changing the characteristics of a filter provided in the communication device, and when communication via the communication line is disconnected, the communication device enters a state in which the adjustment of the noise reduction function is initialized, and communication via the communication line is disconnected in accordance with the timing at which the test conditions are changed, and then communication is resumed, a test method described in any one of Technical Ideas 1 to 6.

Claims

1. A test method for testing a communication device (20) that communicates via a communication line (11), wherein the communication device operates to adjust a noise reduction function in response to noise superimposed on a communication signal, the test method comprising: generating noise by a test device (10) so that the noise is superimposed on the communication signal; detecting by the test device a noise state that causes a communication error in the communication device; and stopping the adjustment operation of the noise reduction function by the communication device or initializing the adjustment of the noise reduction function at least at the timing when test conditions are changed.

2. The test method according to claim 1, wherein the test method is for testing the immunity performance of the communication device, the test device is capable of changing at least one of the frequency of the generated noise, whether or not it is modulated, the noise pattern, and the noise magnitude, and the change of the test conditions by the test device corresponds to the change of the test conditions.

3. The test method according to claim 1, wherein the test method is for testing the communication quality of the communication device, and the change in test conditions corresponds to changing at least one of the length of the communication line, the type of the communication line, and the number of relay devices interposed in the communication line.

4. A test method according to any one of claims 1 to 3, wherein the adjustment of the noise reduction function of the communication device is performed by changing the characteristics of a filter provided in the communication device, and the adjustment operation of the noise reduction function of the communication device is stopped by fixing the characteristics of the filter.

5. A test method according to any one of claims 1 to 3, wherein the adjustment of the noise reduction function of the communication device is performed by changing the characteristics of a filter provided in the communication device, and the adjustment of the noise reduction function of the communication device is initialized by changing the characteristics of the filter to an initial value at the time the test conditions are changed.

6. A test method according to any one of claims 1 to 3, wherein the adjustment of the noise reduction function of the communication device is performed by changing the characteristics of a filter provided in the communication device, and when the power of the communication device is turned off, the adjustment of the noise reduction function is initialized, and the power of the communication device is switched from off to on in accordance with the timing when the test conditions are changed.

7. A test method according to any one of claims 1 to 3, wherein the adjustment of the noise reduction function by the communication device is performed by changing the characteristics of a filter provided in the communication device, and when communication via the communication line is cut off, the communication device is set to a state in which the adjustment of the noise reduction function is initialized, and communication via the communication line is cut off in accordance with the timing at which the test conditions are changed, and then communication is resumed.

8. A test device (10) for testing a communication device (20) that communicates via a communication line (11), the communication device operates to adjust a noise reduction function in response to noise superimposed on a communication signal, the test device comprising: a noise generating unit (14) that generates noise so that the noise is superimposed on the communication signal; a noise state detecting unit (18) that detects a noise state that causes a communication error in the communication device; and a control unit (16) that controls the communication device so that, at least at the timing when test conditions are changed, the communication device stops adjusting the noise reduction function or initializes the adjustment of the noise reduction function.

9. The test equipment according to claim 8, wherein the test equipment is for testing the immunity performance of the communication equipment, the noise generating unit is capable of changing at least one of the frequency of the generated noise, whether or not modulation is performed, the noise pattern, and the noise magnitude, and the control unit controls the communication equipment so that, when the noise generating unit changes at least one of the frequency of the generated noise, whether or not modulation is performed, the noise pattern, and the noise magnitude, the test conditions are changed and the communication equipment is stopped from adjusting the noise reduction function or the adjustment of the noise reduction function is initialized.

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