JP6818055B2 - Error rate measuring device and error rate measuring method - Google Patents

Description

The present invention relates to an error rate measuring device and an error rate measuring method for measuring an error rate of a multi-valued PAM signal by a pulse-amplitude modulation method in which the amplitude is divided into four or more levels for each symbol.

As the number of users increases and multimedia communication becomes widespread, various digital communication devices are required to have a larger capacity transmission capacity.

For this reason, in recent years, with the spread of mobile terminals and cloud computing, the amount of data communication has been steadily increasing, and the transmission speed has also been remarkably increased. The international standard for high-speed data transmission is quadruple pulse amplitude modulation (PAM4), which is modulated to four amplitude levels for each symbol, instead of NRZ transmission using conventional NRZ signals (binary) for both electrical and optical interfaces. It is changing to PAM4 transmission by signal.

One of the indexes for quality evaluation of digital signals in a device under test (DUT: Device Under Test) that performs PAM4 transmission is defined as a comparison between the number of received data in which a code error has occurred and the total number of received data. The Bit Error Rate (BER) is known. As a conventional device for measuring the bit error rate, a test signal of a known pattern is input to the DUT, a PAM4 signal transmitted from the DUT accompanying the input of the test signal is received as input data, and the input data of the input data is received. It is known that a BER is measured by comparison with an input test signal (see, for example, Patent Document 1).

The error rate measuring device described in Patent Document 1 has settings necessary for measuring the total BER of the PAM4 signal and measurement results (threshold voltage Vth1, Vth2, Vth3, BER for each voltage range E1, E2, E3, PAM4. It has a function of displaying the signal total BER) on the same display screen (see, for example, paragraph 0073).

JP-A-2017-220756

The NRZ signal from the DUT that performs NRZ transmission has, for example, an eye pattern as shown in FIG. Since the NRZ signal is binary (one eye), there are only two patterns of error transitions: transition from L level to H level (Insertion) and transition from H level to L level (Omission). do not do. Therefore, in the error rate measuring device for the NRZ signal, the screen for displaying the measurement result is, for example, as shown in FIG. 12, for each of the two patterns, Insertion (INS) and Omission (OMI). It was sufficient to have the display items of the error rate (ER) and the error count (EC) and the total value (Total) of each of the ER and EC.

On the other hand, the eye pattern of the PAM4 signal has, for example, three eyes as shown in FIG. Since the PAM4 signal having three eyes is divided into four amplitude levels of 0, 1, 2, and 3, the error transitions are as follows from each level of 0, 1, 2, and 3, respectively. There are a total of 12 transition patterns that transition to the level.

In Patent Document 1, which handles PAM4 signals, BER is measured every time the threshold voltage range is changed, but since the measurement timing is serial, the transition as a symbol should be confirmed during measurement. I couldn't. Moreover, in the one described in Patent Document 1, only the total BER is displayed as the measurement result of the PAM4 signal, and the above-mentioned 12 kinds of error transition patterns are not considered to be displayed in a graspable manner.

Therefore, with this type of conventional error rate measuring device, it is difficult for the user to visually grasp the 12 error transitions when measuring the PAM4 signal, and a function of displaying the error transition pattern in an easy-to-understand manner is desired. Was there.

The present invention has been made to solve such a conventional problem, and it is possible to easily grasp an error transition pattern from each amplitude level of a PAM signal having an amplitude level of 4 or more to another amplitude level. An object of the present invention is to provide an error rate measuring device and an error rate measuring method.

In order to solve the above problems, the error rate measuring device according to claim 1 of the present invention is generated by using a known pulse pattern, and the pulse amplitude modulation (PAM) is divided into levels of 4 or more for each symbol. The PAM decoding means (3a) for decoding the measured signal into a binary signal by inputting the PAM signal according to the method) as the measured signal and detecting the level of the measured signal for each symbol, and the known PAM decoding means. By holding the pulse pattern as a reference signal and comparing the decoded binary signal with the reference signal for each symbol, it is determined that a bit error in which the level of the signal to be measured differs from the level of the reference signal. Then, for the bit error measuring means (3d ) that calculates the error rate (BER) based on the determination result and the symbol for which the bit error is determined , the signal to be measured has a level of 4 or more. With the error transition pattern detecting means (3e) for detecting which of the plurality of error transition patterns, which indicates the transition from the level corresponding to the reference signal to the other level, is used for the transition. The configuration includes a display control means (7d) for displaying the number of times (EC) of bit errors of each error transition pattern measured by the display means (6) in a tabular format.

With this configuration, the error rate measuring apparatus according to claim 1 of the present invention displays a plurality of types of error transition patterns of PAM signals having an amplitude of 4 or more levels for each symbol in a tabular format, thereby causing error transitions. All of the error transition patterns can be intuitively expressed even for PAM signals having 12 or more patterns, and the error transition patterns can be grasped at a glance.

The error rate measuring device according to claim 2 of the present invention includes error transition management means (5b, 7b) for managing error transition management information including the number of times of bit error measurement of each error transition pattern, and the error transition management information. Based on the above, worksheet data (table data) having a registration cell for registering the number of bit error occurrences corresponding to each transition source and each transition destination with each level of the above 4 or higher levels as a transition source and other levels as transition destinations. ) Is further included, and the display control means is configured to display the number of times of measurement of the bit error of each error transition pattern based on the worksheet data.

With this configuration, in the error rate measuring device according to claim 2 of the present invention, for example, using spreadsheet software, bit errors of the error transition pattern can be obtained for the registered cells corresponding to each transition source and each transition destination. It is possible to create worksheet data in which the number of measurements is registered, and easily display 12 or more error transition patterns using the worksheet data.

The error rate measuring device according to claim 3 of the present invention generates a receiving means (4) that accepts the setting of a measurement pattern and the pulse pattern corresponding to the set measurement pattern, and a test signal based on the pulse pattern. The PAM decoding means inputs the PAM signal transmitted from the device under test that has received the test signal as the signal to be measured, and has a pattern generating unit (2) that generates the PAM signal. It has a configuration for performing decoding processing.

With this configuration, in the error rate measuring device according to claim 3 of the present invention, the user can easily test the device under test with a test signal having a pulse pattern corresponding to the measurement pattern by setting a desired measurement pattern. Can be executed.

In the error rate measuring apparatus according to claim 4 of the present invention, the PAM signal is a PAM4 signal having four levels that can be represented by a most significant bit string signal (MSB) and a least significant bit string signal (LSB) for each symbol. The PAM decoding means decodes the measured signal into the most significant bit string signal and the least significant bit string signal for each symbol, and the error transition pattern detecting means obtains the most significant bit string signal for each symbol. Twelve error transition patterns that transition from each level of levels 0, 1, 2, and 3 corresponding to the 2-bit signals 00, 01, 10, and 11 that can be represented by the least significant bit string signal to the other three levels It has a configuration to detect.

With this configuration, the error rate measuring device according to claim 4 of the present invention can sensuously express 12 error transition patterns of a PAM4 signal having four levels of amplitude for each symbol, and at first glance It is possible to grasp these 12 kinds of error transition patterns.

Further, in order to solve the above problems, the error rate measuring method according to claim 5 of the present invention is generated by using a known pulse pattern, and the pulse amplitude modulation is divided into levels of 4 or more for each symbol. The known step (S2) of inputting a PAM signal according to the (PAM) method as a signal to be measured and detecting the level of the signal to be measured for each symbol to decode the signal to be measured into a binary signal. By holding the pulse pattern as a reference signal and comparing the decoded binary signal with the reference signal for each symbol, it is determined that a bit error in which the level of the signal to be measured differs from the level of the reference signal. Then, in the error rate measuring method including the step (S3) of calculating the error rate (BER) based on the determination result, the measured signal is the target of the symbol for which the bit error is determined. , An error transition for detecting which of a plurality of error transition patterns indicating which level of the four or more levels match the reference signal has transitioned to, which of the error transition patterns has been used. It includes a pattern detection step (S15) and a display control step (S16 to S19) for displaying the number of times (EC) of bit errors of each error transition pattern are measured in a tabular format on the display means (6).

With this configuration, in the error rate measuring method according to claim 5 of the present invention, error transitions are displayed by displaying a plurality of types of error transition patterns of PAM signals having an amplitude of 4 or more levels for each symbol in a tabular format. Even for PAM signals with 12 or more patterns, all the error transition patterns can be sensuously expressed, and it is possible to grasp them at a glance.

In the method for measuring the error rate according to claim 6 of the present invention, the PAM signal is a PAM4 signal having the four levels that can be represented by the most significant bit string signal (MSB) and the least significant bit string signal (LSB) for each symbol. In the decoding step, the measured signal is decoded into the most significant bit string signal and the least significant bit string signal for each symbol, and in the error transition pattern detection step, the most significant bit string signal is used for each symbol. Twelve error transition patterns that transition from each level of levels 0, 1, 2, and 3 corresponding to the 2-bit signals 00, 01, 10, and 11 that can be represented by the least significant bit string signal to the other three levels It is to detect.

With this configuration, in the error rate measurement method according to claim 6 of the present invention, 12 error transition patterns of a PAM4 signal having four levels of amplitude for each symbol can be sensuously expressed, and at first glance It is possible to grasp these 12 kinds of error transition patterns.

The present invention can provide an error rate measuring device and an error rate measuring method capable of easily grasping an error transition pattern from each amplitude level of a PAM signal having an amplitude level of 4 or more to another amplitude level.

It is a block diagram which shows the whole structure of the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the PAM decoder of the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the functional structure of the control part of the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a schematic diagram which shows an example of the eye pattern of the PAM4 signal of the error transition pattern measurement target in the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a schematic diagram which shows the relationship between the PAM4 signal generated by the pattern generation part of the error rate measuring apparatus which concerns on one Embodiment of this invention, and the threshold voltage at the time of BER measurement. It is a schematic diagram which shows the signal form in the decoding process of the PAM4 signal in the pattern receiving part of the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a table diagram which shows an example of the error transition management table in the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a figure which shows the display example of the error transition confirmation screen in the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the bit error measurement processing operation in the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the error transition management processing operation in the error rate measuring apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the eye pattern of the NRZ signal. It is a figure which shows the display example of the measurement result of the NRZ signal. It is a figure which shows an example of the eye pattern of a PAM4 signal.

Hereinafter, embodiments of the error rate measuring device and the error rate measuring method according to the present invention will be described in detail with reference to the accompanying drawings.

The present invention sends a test signal (PAM signal) of a known pattern to the device W to be tested, receives the PAM signal transmitted by the device W to be tested to which the test signal is input, as a signal to be measured, and receives the test signal. It is assumed that the bit error rate (BER) of the measurement signal is measured by bit comparison with the test signal input to the device W to be tested, and in particular, the amplitude of the test signal of the symbol in which the bit error of the signal to be measured is measured. It has a processing function of specifying the transition pattern of the amplitude level with respect to the level as an error transition pattern and displaying the count value (error count: EC) of the error transition pattern in a tabular format.

As a transmission method for handling a PAM signal, for example, a PAM4 method for transmitting a PAM4 signal, a PAM8 method for transmitting a PAM8 signal, and the like are known. Of these, the PAM4 method uses a pulse amplitude modulation (PAM) signal in which the amplitude of an information signal is encoded by a sequence of pulse signals, and a bit string composed of logic "0" and "1" is provided at four voltage levels or light. This is a method of modulating and transmitting as a power pulse signal.

The PAM4 signal is divided into four types of amplitude for each symbol, for example, as shown in FIGS. 4 and 13, it has four different amplitude levels L0, L1, L2, L3, and is based on the entire amplitude voltage range. Upper signal (high level signal), which is divided into low voltage range H1, medium voltage range H2, and high voltage range H3 from the line (L0: 0 level) and has a different magnitude of amplitude level with respect to the baseline (L0: 0 level). The three eye pattern openings (Upper Eye, Middle Eye, Lower Eye) by the Middle signal (medium level signal) and the Lower signal (low level signal) consist of a signal having a continuous amplitude range.

Hereinafter, in the present embodiment, a case where a PAM4 signal is generated and BER measurement is performed will be described as an example.

In a PAM4 signal having an eye pattern as shown in FIG. 4, there are 12 patterns of bit errors for each symbol due to a transition from any one of the four amplitude levels to any of the other three amplitude levels. An error can occur due to the transition pattern of. Therefore, in the present embodiment, the measurement result of the PAM4 signal is displayed so that the above 12 types of error transition patterns can be grasped together with the number of bit errors thereof.

Next, the configuration of the error rate measuring device 1 will be described. As shown in FIG. 1, the error rate measuring device 1 according to the present embodiment includes a pattern generating unit 2 as a PPG (Pulse Pattern Generator) module, a pattern receiving unit 3 as an ED (Error Detector) module, and an operating unit 4. It is configured to include a storage unit 5, a display unit 6, and a control unit 7.

The pattern generation unit 2 transmits a PAM4 signal as a test signal to the device W to be tested, and as shown in FIG. 1, the pattern generation unit 21, the second pattern generation unit 22, and the pattern synthesis output unit 23 Consists of including.

The first pattern generation unit 21 and the second pattern generation unit 22 generate a pattern signal for generating a PAM4 signal based on a measurement pattern set by the user. Specific pattern signals generated by the pattern generating units 21 and 22 include, for example, PRBS7 (pattern length: 2 ⁷ -1), PRBS ⁹ (pattern length: 2 ⁹ -1), and PRBS ¹⁰ (pattern length: 2 ¹⁰ -1). , PRBS11 (pattern length: 2 ¹¹ -1), PRBS15 (pattern length: 2 ¹⁵ -1), PRBS20 (pattern length: 2 ²⁰ -1), and other pseudo-random patterns, and PAM such as PRBS13Q, PRQS10, and SSPR. There is an evaluation pattern for evaluation.

The pattern synthesis output unit 23 synthesizes the pattern signal generated by the first pattern generation unit 21 and the pattern signal generated by the second pattern generation unit 22, and uses the operation unit 4 as a test signal to be transmitted to the device under test W. The PAM4 signal based on the measurement pattern set by the user operation in is output. For example, the first pattern generating unit 21 generates a pattern signal corresponding to PPG1 in FIG. 5A, and the second pattern generating unit 22 generates a pattern signal corresponding to PPG2 in FIG. 5A. Then, the pattern synthesis output unit 23 synthesizes these two pattern signals and outputs a PAM4 signal based on the measurement pattern.

The pattern receiving unit 3 receives the PAM4 signal transmitted by the device under test input W to which the test signal from the pattern generating unit 2 is input as the signal to be measured and performs BER measurement. The PAM decoder 3a and the bit error measurement The unit 3d and the error transition pattern detection unit 3e are included.

The PAM decoder 3a inputs the PAM4 signal as a signal to be measured, detects the level of the signal to be measured for each symbol, and decodes the signal to be measured into a binary signal. The PAM decoder 3a is composed of, for example, a 0/1 determination circuit 3b and a decoding circuit 3c, as shown in FIG. The 0/1 determination circuit 3b has, for example, three 0/1 discriminators 3ba, 3bb, and 3bc connected in parallel to a transmission line through which a PAM4 signal is transmitted. The decoding circuit 3c is composed of a logic circuit. For example, as shown in FIG. 2, the first AND (logical product) circuit 3ca, the second AND (logical product) circuit 3cc, and the third AND (third AND (logical product) circuit 3c) A logical product) circuit 3cc and an OR (logical sum) circuit 3cd are provided. As will be described later (see FIG. 6), the PAM decoder 3a takes in the PAM4 signal, which is the signal to be measured, and from the PAM4 signal, the most significant bit string signal (Most Significant Bit: MSB) and the least significant bit string signal (Least Significant). Decode processing to restore Bit: LSB) is performed. The PAM decoder 3a constitutes the PAM decoding means of the present invention.

The bit error measuring unit 3d holds a known pulse pattern as a reference signal, and compares the binary signal decoded by the PAM decoder 3a with the reference signal for each symbol, so that the level of the signal to be measured is the reference signal. It measures bit errors that differ from the level. The bit error measuring unit 3d constitutes the bit error measuring means of the present invention.

The error transition pattern detection unit 3e transitions the measured signal from the level corresponding to the reference signal among the four levels related to the amplitude to any other level for the symbol in which the bit error of the measured signal is measured. It detects which of the plurality of error transition patterns indicating whether or not the error has occurred. The error transition pattern detection unit 3e constitutes the error transition pattern detection means of the present invention.

The operation unit 4 is composed of, for example, an operation knob, various keys, switches, buttons, soft keys on the display screen of the display unit 6, and the like. The operation unit 4 is operated by the user when making various settings related to the BER measurement of the PAM4 signal, such as designating the pattern receiving unit 3, selecting the measurement pattern, setting the measurement time, and instructing the start / end of the BER measurement.

Since the storage unit 5 generates the PAM4 signal of the measurement pattern set by the operation unit 4, the pattern file of the pattern signal generated by the first pattern generation unit 21 and the pattern signal generated by the second pattern generation unit 22 Each pattern file is stored in association with the measurement pattern. Specifically, for example, a first pattern is generated in association with a measurement pattern such as a pseudo-random pattern such as PRBS7, PRBS9, PRBS10, PRBS11, PRBS15, PRBS20, or a pattern for evaluating PAM such as PRBS13Q, PRQS10, SSPR. The pattern file of the pattern signal generated by the unit 21 and the pattern file of the pattern signal generated by the second pattern generating unit 22 are stored.

Further, the storage unit 5 stores the threshold voltage Vth1 in the high voltage range H3, the threshold voltage Vth2 in the medium voltage range H2, and the threshold voltage Vth3 in the low voltage range H1. The storage unit 5 also stores a processing program for executing each process of BER measurement and error transition pattern detection, various setting values related to BER measurement, measurement results, and the like. Further, in the present embodiment, the bit error management table 5a for storing information on the bit error of the signal to be measured and the error transition management table 5b for managing the occurrence status of the error transition pattern are also stored in the storage unit 5.

The display unit 6 is composed of, for example, a liquid crystal display or the like, and displays a setting screen and a measurement result related to BER measurement. As an example of the measurement result, for example, the error transition confirmation screen 6a shown in FIG. 8 is displayed. The display unit 6 constitutes the display means of the present invention.

The control unit 7 collectively controls the pattern generation unit 2, the pattern reception unit 3, the operation unit 4, the storage unit 5, and the display unit 6. For example, as shown in FIG. 3, the bit error management unit 7a and the error It has a transition management unit 7b, a table data creation unit 7c, and a display control unit 7d.

The bit error management unit 7a takes in the three BER measurement results of the high voltage range H3, the medium voltage range H2, and the low voltage range H1 output by the bit error measurement unit 3d, and calculates and measures the total BER of the PAM4 signal. I do. The bit error management unit 7a stores and manages the BER and the total BER of each symbol of the measured PAM4 signal by using, for example, the bit error management table 5a prepared in advance in the storage unit 5.

The error transition management unit 7b manages error transition management information including the number of times of bit error measurement of 12 error transition patterns detected by the error transition pattern detection unit 3e and the total number thereof. Specifically, the error transition management unit 7b sequentially counts the error transition patterns for each of the four amplitude levels of the PAM4 signal, and stores and manages the aggregated result of the counted values using the error transition management table 5b. The error transition management unit 7b, together with the error transition management table 5b, constitutes the error transition management means of the present invention.

FIG. 7 shows an example of the error transition management table 5b managed by the error transition management unit 7b. As shown in FIG. 7, the error transition management table 5b has each management item such as a number, an error transition pattern, and a bit error count value. In particular, the error transition management table 5b illustrated in FIG. 7 manages the bit error count values and the total number of the 12 error transition patterns from No. 1 to No. 12 as error transition management information.

Of the 12 error transition patterns shown in FIG. 7, the numbers 1 to 3 are among the four levels 0, 1, 2, and 3 of the PAM4 signal which is the input data (measured signal) for the pattern receiving unit 3. It shows a pattern of transition from level 0 to the other three levels 1, 2, and 3. Numbers 4 to 6 indicate a pattern of transition from level 1 to the other three levels 0, 2, and 3. Numbers 7 to 9 indicate a pattern of transition from level 2 to the other three levels 0, 1, and 3. Numbers 10 to 12 indicate a pattern of transition from level 3 to the other three levels 0, 1, and 2.

The table data creation unit 7c can display the error transition confirmation screen 6a (see FIG. 8) based on the error transition management information including the aggregation result of the error transition pattern stored in the error transition management table 5b. Create data. As shown in FIG. 8, the error transition confirmation screen 6a has 12 EC value input fields corresponding to 12 error transition patterns of the signal to be measured, and four levels related to the amplitude of the signal to be measured. It has a total EC value input field corresponding to each of the above, an ER value input field and a total ER value input field for each of the four levels, and the count values of the corresponding measurement items are input to each of the above input fields. It is a configuration.

The table data creation unit 7c is realized by, for example, spreadsheet software, and creates worksheet data in a worksheet format for displaying the error transition confirmation screen 6a having the above configuration. In short, the table data creation unit 7c sets each level of the four levels as the transition source and the other level as the transition destination based on the error transition management information such as the aggregation result of the error transition pattern, and sets each transition source and each transition destination, respectively. Create worksheet data (table data) having a registration cell (input field) for registering the corresponding number of bit error occurrences (bit error count value). The table data creation unit 7c constitutes the sheet creation means in the present invention.

The display control unit 7d performs display control for displaying various information on the display unit 6. In the present embodiment, the display control unit 7d displays the total result of the error transition pattern stored in the error transition management table 5b based on the table data created by the table data creation unit 7c on the error transition confirmation screen 6a (FIG. 8). Refer to) to control the display on the display unit 6. The display control unit 7d constitutes the display control means in the present invention.

Next, the operation of the error rate measuring device 1 will be described. First, the BER measurement operation will be described. Here, a test signal (PAM4 signal) having a known pattern is input from the pattern generation unit 2 to the device W to be tested, and the PAM4 signal transmitted by the device W to be tested in response to the input of the test signal is transmitted by the pattern reception unit 3. A case where the BER measurement is performed by receiving the signal to be measured will be described.

When performing BER measurement, the user sets various parameters such as the ED module to be used, the measurement pattern to be measured, and the measurement time. This setting is performed, for example, by displaying a setting display screen (not shown) on the display unit 6 and selecting a setting content on the setting display screen or inputting necessary items by operating the operation unit 4. be able to.

In the present embodiment, the pattern receiving unit 3 is set as the ED module. When a plurality of ED modules exist, a desired ED module can be selected and set from the ED modules. The measurement pattern is set, for example, by displaying a preset known measurement pattern (for example, PRBS7, PRBS9, PRBS10, PRBS11, PRBS15, PRBS20, etc.) and selecting a desired measurement pattern. The measurement time does not necessarily have to be set, and in that case, the measurement time set in the error rate measuring device 1 is adopted as the default value.

In order to start the BER measurement after setting the various parameters described above, when the user performs the measurement start operation on the setting display screen, the control unit 7 is associated with the measurement pattern set by the user. The pattern file is read from the storage unit 5 and the pattern generation instruction is output to the pattern generation unit 2.

When the pattern generation instruction is input from the control unit 7, the pattern generation unit 2 generates a pattern signal for generating a PAM signal based on the measurement pattern. At that time, for example, as shown in FIG. 5A, in the pattern generation unit 2, the first pattern generation unit 21 generates a pulse pattern (PPG1) corresponding to the MSB, and the second pattern generation unit 22 generates the LSB. A pulse pattern (PPG2) corresponding to is generated. PPG1 and PPG2 correspond to the known pulse patterns in the present invention.

In FIG. 5A, in particular, an example in which a pulse pattern corresponding to the MSB having a value of 00222020 ... Is generated as PPG1 and a pulse pattern corresponding to the LSB having a value of 01010011 ... Is generated as PPG2 is given. ing.

In the pattern generation unit 2, the pattern synthesis output unit 23 synthesizes the MSB generated from the first pattern generation unit 21 and the LSB generated from the second pattern generation unit 22 to generate a PAM4 signal. In the example of FIG. 5A, the MSB and the LSB are combined to generate a PAM4 signal having a value of 01232031 ... One by one in the time series direction. Here, the division of each number in the time series direction corresponds to the symbol in the present embodiment. The pattern generation unit 2 outputs the PAM4 signal generated by the pattern synthesis output unit 23 as a test signal.

The PAM4 signal in FIG. 5 (a) has a waveform as shown by a thick solid line in FIG. 5 (b). That is, this PAM4 signal has an eye pattern having three eyes, an upper eye, a middle eye, and a lower eye. Further, this PAM4 signal has various parameters (voltage range (H3 to H1), threshold voltage (Vth1 to Vth3), level (L3 to L0), etc.) related to BER measurement of the PAM4 signal according to the present embodiment shown in FIG. As can be seen from the comparison with the setting status (see FIG. 4), the amplitude level for each symbol is divided into four levels of L0, L1, L2, and L3, respectively.

As shown in FIG. 5 (b), in the PAM4 signal, PPG1 (see FIG. 5 (a)) used for its synthesis appears as an MSB pattern only in the middle eye region (shaded region with a downward-sloping diagonal line). There is. Since the middle eye is an eye generated when the MSB becomes "H", the middle eye is called the MSB. On the other hand, the other PPG2 (see FIG. 5 (a)) used for synthesizing the PAM4 signal was divided into both the upper eye and lower eye regions (shaded regions with upward-sloping diagonal lines), and each of them was divided into regions. It appears as LSB pattern for "2" and "3" levels and LSB pattern for "0" and "1" levels. Since the lower eye and the upper eye are eyes generated when the MSB becomes "H", both of them are collectively called LSB.

According to the appearance of the MSB and the LSB described above, it can be seen that the MSB can be restored from the middle eye region in the decoding of the PAM4 signal shown in FIG. 5 (b). Similarly, from this PAM4 signal, it can be seen that the LSB can be restored from both the upper eye and lower eye regions. Specifically, it can be understood that the LSB corresponding to level 2 or 3 can be restored from the upper eye region of the PAM4 signal, and the LSB corresponding to level 0 or 1 can be restored from the lower eye region. .. The levels 0, 1, 2, and 3 referred to here correspond to the levels L0, L1, L2, and L3 in FIG. 4, respectively.

Further, according to the PAM4 signal generation process described with reference to FIG. 5, when the pattern signals of PPG1 and PPG2 are known patterns, the known pattern is transmitted to the pattern receiving unit 3 that decodes the PAM4 signal. For example, by setting (holding) it as a reference signal, it is possible to perform BER measurement of the PAM4 signal. In this case, the pattern receiving unit 3 first inputs a PAM4 signal (see FIG. 5) as a signal to be measured, detects the level of the signal to be measured for each symbol, and decodes the PAM4 signal into binary MSB and LSB, respectively. To do. Next, the pattern receiver 3 compares the decoded 2-bit signals (MSB and LSB) with the reference signal held in advance for each symbol, so that the level of the signal to be measured differs from the level of the reference signal. It is possible to recognize that an error has occurred (bit error) for the bits to be processed.

When the PAM4 signal (see FIG. 5) generated by the pattern generation unit 2 is received by the device W to be tested, the device W to be tested sends a PAM4 signal to be a signal to be measured. In the error rate measuring device 1, the pattern receiving unit 3 receives the PAM4 signal from the device W to be measured as a signal to be measured, decodes the signal to be measured into MSB and LSB, and executes BER measurement.

As described above, in the error rate measuring device 1 (see FIG. 1) according to the present embodiment, the operation unit 4 constitutes a receiving means for receiving the setting of the measurement pattern. The pattern generation unit 2 generates a pulse pattern corresponding to the set measurement pattern, and generates a PAM4 signal as a test signal based on the pulse pattern. On the other hand, in the pattern receiving unit 3, the PAM decoder 3a performs a process of inputting a PAM4 signal transmitted from the device under test receiving the test signal as a signal to be measured and decoding it.

The BER measurement process performed after the PAM4 signal decoding process will be described with reference to the flowchart shown in FIG. When the BER measurement process is started, the PAM4 signal received by the pattern receiving unit 3 becomes, for example, three 0/1s in the 0/1 determination circuit 3b of the PAM decoder 3a as the signal to be measured, as shown in FIG. It is input to the discriminators 3ba, 3bb, and 3bc, respectively (step S1).

The PAM decoder 3a performs a process of decoding the input PAM4 signal into MSB and LSB for each symbol (step S2). In this decoding process, first, the 0/1 discriminator 3ba of the 0/1 determination circuit 3b determines whether the Upper signal (signal in the upper eye region) of the PAM4 signal to be measured is 0 or 1. It is determined by comparison with the voltage Vth1. Here, the 0/1 discriminator 3ba outputs DU = "1" as a discrimination signal if the Upper signal is the threshold voltage Vth1 or more, and determines DU = "0" if the Upper signal is not the threshold voltage Vth1 or more. Output as.

The 0/1 discriminator 3bb determines whether the Middle signal (signal in the middle eye region) of the PAM4 signal is 0 or 1, by comparison with the threshold voltage Vth2. Here, the 0/1 discriminator 3bb outputs DM = "1" as a discrimination signal if the Middle signal is the threshold voltage Vth2 or more, and determines DM = "0" if the Middle signal is not the threshold voltage Vth2 or more. Output as.

The 0/1 discriminator 3bc determines whether the Lower signal (signal in the lower eye region) of the PAM4 signal is 0 or 1 by comparison with the threshold voltage Vth3. Here, the 0/1 discriminator 3bc outputs DL = "1" as a discrimination signal if the Lower signal is the threshold voltage Vth3 or higher, and determines DL = "0" if the Lower signal is not the threshold voltage Vth3 or higher. Output as.

Each of the DH, DM, and DL discrimination signals output from the 0/1 discriminator 3ba is input to the decoding circuit 3c. In the decoding circuit 3c, the first AND circuit 3ca receives the discrimination signal (DU) from the first 0/1 discriminator 3ba and the discrimination signal (DL) from the third 0/1 discriminator 3bc as inputs. Performs a logical product operation.

The second AND circuit 3bc performs a logical product operation by inputting a discrimination signal (DU) from the first 0/1 discriminator 3ba and a discrimination signal (DM) from the second 0/1 discriminator 3bb. ..

The third AND circuit 3cc is logically input by inputting a signal obtained by inverting the discrimination signal (DM) from the second 0/1 discriminator 3bb and a discrimination signal (DL) from the third 0/1 discriminator 3bc. Perform a product operation.

The OR circuit 3cd performs a logical sum operation by inputting signals from the first AND circuit 3ca, the second AND circuit 3cc, and the third AND circuit 3cc.

Through the above processing, the decoding circuit 3c outputs the discrimination signal (DM) from the second 0/1 discriminator 3bb as it is as an MSB, and outputs the output from the OR circuit 3cd as an LSB. As a result, the PAM decoder 3a performs a process of decoding the PAM4 signal into the MSB and the LSB.

In the above decoding process, for example, when the PAM4 signal (see FIG. 5) generated by the encoding process in the pattern generation unit 2 is received and decoded by the PAM decoder 3a including the 0/1 determination circuit 3b and the decoding circuit 3c, The waveform of the received PAM4 signal shown in FIG. 6A is separated into a waveform into MSB and LSB (MSB / LSB) as shown in FIG. 6B.

At this time, the MSB pattern has a one-to-one correspondence with the waveform of the middle eye. On the other hand, the LSB pattern is a waveform obtained by synthesizing the waveforms of the upper eye and the lower eye, and does not have a one-to-one correspondence with the waveforms of the upper eye and the lower eye. Therefore, in the pattern receiving unit 3, the decoding circuit 3c uses a mask for separating the pattern for the upper eye and a mask for separating the pattern for the lower eye, and the pattern for the upper eye is changed from the LSB pattern. The pattern for the lower eye is separated and output. As a result, the PAM decoder 3a can separately output the MSB pattern, the LSB pattern for the upper eye, and the LSB pattern for the lower eye from the PAM4 signal.

The output (demodulation data) of the PAM decoder 3a in FIG. 6B is input to the bit error measuring unit 3d and the error transition pattern detecting unit 3e in the configuration of FIG. On the other hand, in the bit error measuring unit 3d and the error transition pattern detecting unit 3e, the pattern data (PPG1 (MSB), PPG2 (LSB)) used for generating the PAM4 signal in the pattern generating unit 2 is used in the control unit 7. It is set (held) in advance as a reference signal by the control of.

As a result, the bit error measurement unit 3d takes in the decoding result (demodulation data) after the decoding process of the PAM4 signal in step S2, compares it with the reference signal for each symbol, and executes the BER measurement process (step S3). ). Here, the bit error measuring unit 3d compares the MSB / LSB value separated by the decoding process with the PAM decoder 3a and the MSB / LSB value of the reference signal for each symbol, and if they do not match, a bit error occurs. judge. Further, the bit error measuring unit 3d calculates the ratio of the total number of bits of the PAM 4 related to the series of bit error measurements output from the pattern generating unit 2 to the number of bits determined to be the above-mentioned bit error as BER.

While executing the above-mentioned BER measurement, for example, the bit error management unit 7a determines whether or not it is set to execute the measurement of the error transition pattern (step S4). Here, when it is set to execute the measurement of the error transition pattern (YES in step S4), the error transition management unit 7b performs the error transition based on the detection result of the error transition pattern in the error transition pattern detection unit 3e. The pattern management process is executed (step S5). After that, the process proceeds to step S6 while executing the error transition pattern management process in step S5.

On the other hand, when it is not set to execute the measurement of the error transition pattern (NO in step S4), the bit error management unit 7a immediately proceeds to step S6.

In step S6, the bit error management unit 7a checks whether or not the bit error measurement is completed (step S6). If it is determined that the bit error measurement has not been completed (NO in step S6), the bit error management unit 7a continues the processing after step S3, and if it is determined that the bit error measurement has been completed (step). YES) in S6 ends a series of BER measurement processes.

In the series of BER measurement processes shown in FIG. 9, the bit error management unit 7a stores and manages the BER measurement result by the bit error measurement unit 3d in, for example, the bit error management table 5a. The display control unit 7d has a display control function for displaying the BER measurement result stored in the bit error management table 5a in a preset display form based on a display instruction input by the user, for example, from the operation unit 4. ..

Next, the error transition management processing operation in the error rate measuring device 1 according to the present embodiment will be described with reference to the flowchart shown in FIG. In this error transition management process, for example, during BER measurement by the bit error measurement unit 3d shown in FIG. 9, in step S5, under the control of the error transition management unit 7b, the error transition pattern detection unit 3e, the table creation unit 7c, and the display It is realized by the cooperation of the control unit 7d. In the BER measurement process shown in FIG. 9, an example of executing the error transition management process only when the error transition pattern is set to be measured has been described, but the error transition management process is always performed according to the BER measurement. It may be configured to be performed.

When the error transition management process is started, the error transition management unit 7b first instructs the table data creation unit 7c to create the table data. Based on this instruction, the table data creation unit 7c creates table data capable of displaying the error transition confirmation screen 6a (see FIG. 8) based on the error transition management information stored in the error transition management table 5b (step). S11). The table data created here is, for example, sheet format data (worksheet data) that can be created by spreadsheet software, and has each of the above-mentioned management items and input fields (registration cells) such as EC value input fields. However, each of these input fields is empty (count value is "0: zero").

Subsequently, the error transition management unit 7b instructs the display control unit 7d to display the table data. Upon receiving the display instruction, the display control unit 7d causes the display unit 6 to display the error transition confirmation screen 6a of the mode shown in FIG. 8 based on the table data (worksheet data) generated in step S11 (step). S12). In the error transition confirmation screen 6a displayed here, the value of the input field corresponding to each management item is empty.

Next, the error transition management unit 7b increments the number of symbols n to be monitored by +1 (step S13). The initial value of the number of symbols n is, for example, "0", and the upper limit is a value corresponding to the pattern length (number of bits) of a preset measurement pattern (PRBS 7, 9 to 11, 15, 20, etc.). ..

Subsequently, the error transition management unit 7b takes in the bit error measurement result in the bit error measurement unit 3d for the symbol corresponding to the number of symbols n after the increment, and determines whether or not the bit error of the measured signal is detected ( Step S14).

Here, if it is determined that no bit error has been detected (NO in step S14), the error transition management unit 7b returns to step S11, increments the number of symbols n by +1 and continues the processing after step S13. ..

On the other hand, when it is determined that a bit error has been detected (YES in step S13), the error transition pattern detection unit 3e then, under the control of the error transition management unit 7b, MSB / LSB of the measured signal of the symbol. And the MSB / LSB of the reference signal are compared with each other to identify which of the 12 patterns described above is the error transition pattern (step S15).

Here, the measured signal (PAM4 signal) for which the error transition pattern is detected can have MSB / LSB values of 00, 01, 10, and 11, and these values are levels 0, 1, and 2, respectively. It corresponds to the four amplitude levels of 3. The fact that the correct level (reference signal level) of the symbol of the signal to be measured is any one of levels 0, 1, 2, and 3 means that when the error bit is measured, it is other than the above one. It means that you are transitioning to one of the levels.

Therefore, when the MSB / LSB of the reference signal of the symbol is, for example, level 0, the error transition pattern detection unit 3e has levels 0 to 1 as shown in numbers 1 to 3 in the error transition management table 5b shown in FIG. , Any of the transition patterns from level 0 to 2 and level 0 to 3 can be specified.

Similarly, when the reference data of the symbol is, for example, level 1, as shown in numbers 4 to 6 in the error transition management table 5b, the transition patterns from level 1 to 0, level 1 to 2, and level 1 to 3 Either can be specified.

Further, when the reference data of the symbol is, for example, level 2, any of the transition patterns from level 2 to 0, level 2 to 1, and level 2 to 3 as shown in numbers 7 to 9 in the error transition management table 5b. Can be specified.

Further, when the reference data of the symbol is, for example, level 3, any of the transition patterns from level 3 to 0, level 3 to 1, and level 3 to 2 as shown in numbers 10 to 12 in the error transition management table 5b. Can be specified.

After the error transition pattern specifying process in step S15, the error transition management unit 7b increments the count value (EC) of the error transition pattern specified in step S15 by +1 (step S16), and adds the error transition management table 5b to the error transition management table 5b. The stored error transition management information is updated to the data content reflecting the EC value after the increment (step S17).

After that, the error transition management unit 7b sequentially counts the number of occurrences of bit errors of the above-mentioned 12 types of transition patterns specified by the error transition pattern detection unit 3e until the error transition management process in FIG. 10 is completed, and each of them is counted. The count value (error count: EC) of the number of times of bit error occurrence for each transition pattern is stored and managed in the corresponding registration cell of the error transition management table 5b.

Subsequently, the error transition management unit 7b transmits a table data update instruction to the table data creation unit 7c. When the table data creation unit 7c receives the table data update instruction, it updates the table data based on the error transition management information after the update process in step S17 (step S18).

Further, the error transition management unit 7b transmits a display update instruction to the display control unit 7d. The display control unit 7d updates the display content of the error transition confirmation screen 6a displayed on the display unit 6 based on the table data created (updated) by the table data creation unit 7c based on the display update instruction (step). S19). According to the screen configuration shown in FIG. 8, on the error transition confirmation screen 6a, the EC value of each of the 12 error transition patterns targeting the symbols whose bit errors have been measured up to that stage is the value of another measurement item. Is displayed with. Other measurement items include, for example, the total number of EC values (Total) of three error transition patterns for each of level 0, level 1, level 2, and level 3 to other levels, and the bits corresponding to the total number of EC values. The total number of error occurrence symbols (Symbol) is displayed. Furthermore, the error rate (ER) for each level 0, level 1, level 2, and level 3 and the total number of each ER are also displayed. The error rate value can be displayed on the error transition confirmation screen 6a by reading the BER measurement result managed in the bit error management table 5a and creating table data combined with the EC.

Subsequently, the error transition management unit 7b determines whether or not the BER measurement is completed (step S20). The determination here can be performed, for example, by whether or not the number of symbols n has reached a value corresponding to the number of bits in the measurement target range of the preset measurement pattern. Here, when it is determined that the BER measurement has not been completed (NO in step S20), the error transition management unit 7b controls to continue the processing after step S13.

On the other hand, when it is determined that the BER measurement is completed (YES in step S20), the error transition management unit 7b ends the series of transition management processes described above.

According to the series of pattern transition management processes shown in FIG. 10, the error transition confirmation screen 6a is displayed on the display unit 6, and the display content (see FIG. 8) is that of the above-mentioned 12 transition patterns of the PAM4 signal. The count value (EC) at the time point is reflected. Therefore, the user can easily confirm what kind of error transition pattern the bit error is occurring at the same time as the bit error is generated by looking at the error transition confirmation screen 6a.

Specifically, on the error transition confirmation screen 6a, the user confirms the number of error transitions from level 0 to levels 1, 2 and 3 and the number of error transitions from level 1 to level 0, 2 for the PAM4 signal (measured signal) to be measured by BER. It is possible to easily grasp the number of error transitions from level 2 to level 0, 1, and 3, and the number of error transitions from level 3 to levels 0, 1, and 2. The user can also grasp the total number of error transitions for each level 0, 1, 2, and 3 on the error transition confirmation screen 6a, and the total number of error transitions for all levels 0, 1, 2, and 3. Further, the user can easily set the error rate (ER) for each level 0, 1, 2, and 3 and the total number of ERs (Total) for all levels 0, 1, 2, and 3 on the error transition confirmation screen 6a. You will be able to grasp it.

In the present embodiment, the bit error management unit 7a has described a processing mode for specifying the type of the transition pattern only for the symbol in which the bit error is measured by the bit error measurement unit 3d, but all the symbols have been described. On the other hand, the bit error management unit 7a may specify the type of the transition pattern.

Further, in the present embodiment, an example in which the bit error measurement unit 3d and the bit error management unit 7a, and the error transition pattern detection unit 3e and the error transition management unit 7b are separately provided is given, but the present invention is limited to this. Instead, for example, a bit error control unit and an error transition management control unit may be collectively provided in the control unit 7.

Further, in the present embodiment, an example is given in which the error transition confirmation screen 6a is displayed during the bit error measurement and the display value is updated according to the count of the error transition pattern, but the present invention is not limited to this, and the BER measurement is performed. After that, the display request operation may be accepted and the EC values of each transition pattern up to that point may be collectively displayed.

Further, in the above embodiment, the error rate measurement of the PAM4 signal has been mainly described, but the present invention is not limited to this, and can be applied to the error rate measurement of the PAM8 signal and the like. The PAM8 signal is a PAM signal divided into eight levels (2 ³ = 8) in which the amplitude can be represented by 3 bits for each symbol. Therefore, in the error rate measuring device 1 that handles the PAM8 signal, the PAM decoder 3a decodes the PAM8 signal input as the measured signal into a 3-bit (1st bit, 2nd bit, 3rd bit) signal and makes an error. The transition pattern detection unit 3e and the error transition management unit 7b span between eight levels 000, 001, 010, 011, 100, 101, 110, and 111 that can be represented by the first bit, the second bit, and the third bit. As the table data creation unit 7c and the display control unit 7d, those having each function configuration for displaying the above 56 types of error transition patterns in a tabular format on the display unit 6 may be adopted. ..

As described above, the error rate measuring device 1 according to the present embodiment inputs a PAM signal generated by using a known pulse pattern and having an amplitude divided into levels of 4 or more for each symbol as a signal to be measured. The PAM decoder 3a that decodes the measured signal into a binary signal by detecting the level of the measured signal for each symbol, and the decoded binary signal and the reference signal that hold the known pulse pattern as a reference signal. By comparing each symbol, the measured signal is 4 for the bit error measuring unit 3d that measures the bit error in which the level of the measured signal is different from the level of the reference signal, and the symbol for which the bit error is measured. Error transition pattern detection unit 3e that detects which of the plurality of error transition patterns, which indicates the transition from the level matching the reference signal among the above levels to which other level, has transitioned. It also has a display control unit 7d that causes the display unit 6 to display the number of times (EC) of bit errors measured for each error transition pattern in a tabular format.

With this configuration, the error rate measuring device 1 according to the present embodiment displays a plurality of types of error transition patterns of PAM signals having an amplitude of 4 or more levels for each symbol in a tabular format, so that the error transition pattern can be obtained. All of the 12 or more PAM signals can be intuitively expressed, and the error transition patterns can be grasped at a glance.

Further, the error rate measuring device 1 according to the present embodiment has an error transition management unit 7b that manages error transition management information including the number of times of bit error measurement of each error transition pattern, and four or more based on the error transition management information. Create worksheet data (table data) with a registration cell that registers the number of bit error occurrences corresponding to each transition source and each transition destination with each level of the level as the transition source and the other level as the transition destination. A unit 7c and a unit 7c are further provided, and the display control unit 7d is configured to display the number of times of measurement of the bit error of each error transition pattern based on the worksheet data.

With this configuration, in the error rate measuring device 1 according to the present embodiment, for example, the number of times the bit error of the error transition pattern is measured for the registered cells corresponding to each transition source and each transition destination by using spreadsheet software. It is possible to create worksheet data in which is registered and easily display 12 or more error transition patterns using the worksheet data.

Further, the error rate measuring device 1 according to the present embodiment generates an operation unit 4 that accepts the setting of the measurement pattern and a pulse pattern corresponding to the set measurement pattern, and a PAM signal as a test signal based on the pulse pattern. The PAM decoder 3a is configured to input the PAM signal transmitted from the device under test receiving the test signal as the signal to be measured and perform the decoding process. There is.

With this configuration, in the error rate measuring device 1 according to the present embodiment, the user can easily execute the test of the device under test by the test signal having the pulse pattern corresponding to the measurement pattern by setting the desired measurement pattern. be able to.

Further, in the error rate measuring device 1 according to the present embodiment, the PAM signal is a PAM4 signal having four levels that can be represented by a most significant bit string signal (MSB) and a least significant bit string signal (LSB) for each symbol, and is a PAM. The decoder 3a decodes the measured signal into the most significant bit string signal and the least significant bit string signal for each symbol, and the error transition pattern detection unit 3e has two bits that can be represented by the most significant bit string signal and the least significant bit string signal for each symbol. It is configured to detect 12 kinds of error transition patterns that transition from each level 0, 1, 2, 3 corresponding to the signals 00, 01, 10 and 11 of the above to the other three levels.

With this configuration, the error rate measuring device 1 according to the present embodiment can sensuously express 12 error transition patterns of PAM4 signals having four levels of amplitude for each symbol, and these can be sensuously expressed at first glance. It is possible to grasp 12 kinds of error transition patterns.

Further, in the error rate measuring method according to the present embodiment, a PAM signal generated by using a known pulse pattern and having an amplitude divided into levels of 4 or more for each symbol is input as a measured signal, and the measured signal is used. Step S2, which decodes the signal under test into a binary signal by detecting the level for each symbol, holds the known pulse pattern as a reference signal, and compares the decoded binary signal and the reference signal for each symbol. This is an error rate measuring method including step S3 for measuring a bit error in which the level of the signal to be measured is different from the level of the reference signal, and the signal to be measured is targeted at the symbol in which the bit error is measured. Error transition pattern detection that detects which of the multiple error transition patterns that indicates the transition from the level that matches the reference signal among the four or higher levels to any other level. It includes steps S15 and display control steps S16 to S19 for displaying the number of times (EC) of bit errors measured for each error transition pattern on the display unit 6 in a tabular format.

With this configuration, in the error rate measurement method according to the present embodiment, the error transition patterns are 12 by displaying a plurality of types of error transition patterns of PAM signals having an amplitude of 4 or more levels for each symbol in a tabular format. All of these error transition patterns can be sensuously expressed even for PAM signals above the street, and it is possible to grasp them at a glance.

Further, in the error rate measurement method according to the present embodiment, the PAM signal is a PAM4 signal having four levels that can be represented by a most significant bit string signal (MSB) and a least significant bit string signal (LSB) for each symbol, and is decoded. In the step, the measured signal is decoded into the most significant bit string signal and the least significant bit string signal for each symbol, and in the error transition pattern detection step, the two bits that can be represented by the most significant bit string signal and the least significant bit string signal for each symbol are Twelve error transition patterns that transition from each level 0, 1, 2, 3 corresponding to the signals 00, 01, 10 and 11, to the other three levels are detected.

With this configuration, in the error rate measurement method according to the present embodiment, 12 error transition patterns of PAM4 signals having four levels of amplitude for each symbol can be sensuously expressed, and these 12 patterns can be intuitively expressed at first glance. It becomes possible to grasp the street error transition pattern.

Therefore, according to the present embodiment, an error rate measuring device and an error rate measuring method capable of easily grasping an error transition pattern from each amplitude level of a PAM signal having an amplitude level of 4 or more to another amplitude level are provided. be able to.

As described above, the error rate measuring device and the error rate measuring method according to the present invention have the effect that the error transition pattern from each amplitude level of the PAM signal having an amplitude level of 4 or more to another amplitude level can be easily grasped. It is useful for all error rate measuring devices and error rate measuring methods for measuring errors such as PAM4 signal and PAM8 signal.

1 Error rate measuring device 2 Pattern generator 3 Pattern receiver 3a PAM decoder (PAM decoding means)
3d bit error measuring unit (bit error measuring means)
3e Error transition pattern detection unit (error transition pattern detection means)
4 Operation unit (reception means)
5 Storage 5a Bit error management table 5b Error transition management table (error transition management means)
6 Display unit (display means)
6a Error transition confirmation screen 7 Control unit 7a Bit error management unit 7b Error transition management unit (error transition management means)
7c Table data creation unit (sheet creation means)
7d Display control unit (display control means)

Claims (6)

A PAM signal by a pulse amplitude modulation (PAM) method, which is generated using a known pulse pattern and whose amplitude is divided into levels of 4 or more for each symbol, is input as a measured signal, and the level of the measured signal is the symbol. A PAM decoding means (3a) that decodes the signal to be measured into a binary signal by detecting each signal.
By holding the known pulse pattern as a reference signal and comparing the decoded binary signal and the reference signal for each symbol, a bit in which the level of the signal to be measured differs from the level of the reference signal. A bit error measuring means (3d) that determines an error and calculates an error rate (BER) based on the determination result, and
A plurality of error transitions indicating which of the four or more levels the signal under test has transitioned from the level corresponding to the reference signal to any other level for the symbol for which the bit error has been determined. An error transition pattern detecting means (3e) for detecting which of the patterns the error transition pattern was used for the transition, and
A display control means (7d) for displaying the number of bit error measurements (EC) of each error transition pattern on the display means (6) in a tabular format, and
An error rate measuring device characterized by having. Error transition management means (5b, 7b) for managing error transition management information including the number of times of bit error measurement of each error transition pattern, and
Based on the error transition management information, a work having a registration cell for registering the number of bit error occurrences corresponding to each transition source and each transition destination with each level of the four or more levels as a transition source and another level as a transition destination. It further has a sheet creation means (7c) for creating sheet data (table data), and has.
The error rate measuring device according to claim 1, wherein the display control means displays the number of times a bit error is measured for each error transition pattern based on the worksheet data. Reception means (4) that accepts measurement pattern settings and
It has a pattern generation unit (2) that generates the pulse pattern corresponding to the set measurement pattern and generates a PAM signal as a test signal based on the pulse pattern.
The PAM decoding means is characterized in that the PAM signal transmitted from the device under test (W) that has received the test signal is input as the signal to be measured and the decoding process is performed. 2. The error rate measuring device according to 2. The PAM signal is a PAM4 signal having the four levels that can be represented by a most significant bit string signal (MSB) and a least significant bit string signal (LSB) for each symbol.
The PAM decoding means decodes the measured signal into the highest-order bit string signal and the lowest-order bit string signal for each symbol.
The error transition pattern detecting means has levels 0, 1, 2, and 3 corresponding to the 2-bit signals 00, 01, 10, and 11 which can be represented by the highest-order bit string signal and the lowest-order bit string signal for each symbol. The error rate measuring apparatus according to any one of claims 1 to 3, wherein 12 error transition patterns that transition from each level to the other three levels are detected. A PAM signal by a pulse amplitude modulation (PAM) method, which is generated using a known pulse pattern and whose amplitude is divided into levels of 4 or more for each symbol, is input as a measured signal, and the level of the measured signal is the symbol. The step (S2) of decoding the measured signal into a binary signal by detecting each signal, and holding the known pulse pattern as a reference signal, the decoded binary signal and the reference signal are the symbols. A step (S3) of determining a bit error in which the level of the signal to be measured differs from the level of the reference signal by comparing each of them and calculating an error rate (BER) based on the determination result is included. It is an error rate measurement method,
A plurality of error transitions indicating which of the four or more levels the signal under test has transitioned from the level corresponding to the reference signal to any other level for the symbol for which the bit error has been determined. An error transition pattern detection step (S15) for detecting which of the patterns the error transition pattern was used for the transition, and
An error rate measuring method comprising a display control step (S16 to S19) for displaying a bit error measurement number (EC) of each error transition pattern on a display means (6) in a table format. The PAM signal is a PAM4 signal having the four levels that can be represented by a most significant bit string signal (MSB) and a least significant bit string signal (LSB) for each symbol.
In the decoding step, the measured signal is decoded into the highest bit string signal and the lowest bit string signal for each symbol.
In the error transition pattern detection step, the levels 0, 1, 2, and 3 corresponding to the 2-bit signals 00, 01, 10, and 11 that can be represented by the highest-order bit string signal and the lowest-order bit string signal for each symbol, respectively. The error rate measuring method according to claim 5, wherein 12 error transition patterns that transition from each level to the other three levels are detected.

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