Error rate measurement device and error rate measurement method

Abstract

To provide an error rate measurement device and an error rate measurement method that can display a setting screen for setting measurement conditions for measuring an error rate of an input signal, and display calculation results of the measurement time that is to obtain a desired target reliability level according to the measurement conditions entered on the setting screen.SOLUTION: An error rate measurement device includes a display unit that displays a setting screen 50 for setting measurement conditions for an error rate of an input signal from a DUT, and a processing unit that calculates a measurement time on the basis of the measurement conditions input to the setting screen 50, and the setting screen 50 includes a target reliability level input unit 60 for inputting a target reliability level, transmission speed input units 52, 59 for inputting a transmission speed, target error rate input units 53a, 53b for inputting a target error rate, an expected error number input unit 54 for inputting an expected number of errors during the measurement time, and measurement time display units 58a, 58b for displaying the measurement time.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an error rate measuring device and an error rate measuring method for measuring the error rate of a signal input from a measurement target object.

Background Art

[0002] Previously, error rate measurement has been performed in an error rate measuring device (Bit Error Rate Tester: BERT) (see, for example, Patent Documents 1 to 3). Measurement of the error rate is a very important analysis means when evaluating the performance of various communication devices that are measurement targets.

[0003] Most of the errors occurring in an actual system are due to random noise, and errors occur at random times. Also, in a system using a Decision Feedback Equalizer (DFE), random errors may become burst errors.

[0004] Therefore, the reliability evaluation of the normal bit error rate (BER) is performed under the condition of E≧1 using the confidence level defined by the following formula (1). Here, the confidence level CL in formula (1) indicates the probability that the true BER of the system is smaller than the target BER (target BER).

[0005]

Equation

[0006] In formula (1), N: bit rate [bit / s] × measurement time [s] (number of measured bits) BER S : target BER E: assumed number of errors is.

[0007] For a pre-defined target BER, the measurement time required to achieve a desired reliability level CL varies depending on the desired reliability level CL and the bit rate. For example, when E = 0 during error-free measurement, if BER S and CL are given, it is easy to solve Equation (1) for N. However, when E ≥ 1, it is mathematically very difficult and unrealistic to solve Equation (1) for N.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0009] That is, conventional error rate measuring devices as disclosed in Patent Documents 1 to 3 cannot automatically evaluate how long the measurement time needs to be in order to achieve the required reliability level when the assumed number of errors E is 1 or more.

[0010] In reality, the step of the measurement time set by the user is 1 second or 0.1 second step, and there is no need to obtain the measurement time mathematically strictly. For example, when the bit rate = 32 Gbit / s, BER S = 1E-10, and E = 2, the reliability level CL with respect to the measurement time is as shown in the graph of FIG. 9. For example, when CL = 95%, the measurement time is approximately 1.967 seconds, but in reality, an accuracy of 2 seconds (CL = 95.36%) is sufficient.

[0011] However, conventionally, the user had to search for the measurement time that could obtain the desired reliability level CL by changing the measurement time substituted into Equation (1) little by little, or set the measurement time longer, resulting in a problem of reduced work efficiency.

[0012] Also, currently, error measurements by error rate measurement devices cover a wide variety, and not only the BER of the conventional NRZ (Non Return to Zero) signal (hereinafter also simply referred to as "NRZ signal"), but also the symbol error rate (SER) of signals of the PAM4 (Pulse Amplitude Modulation 4) system (hereinafter also simply referred to as "PAM4 signal") and the like are added to the evaluation indices. Furthermore, in standards premised on forward error correction (FEC) such as 400 GbE (Gigabit Ethernet) and PCIe (registered trademark) (Peripheral Component Interconnect Express) Gen (Generation) 6, not only evaluations such as BER and SER are important, but also indices such as "Uncorrectable Codeword Rate" and "Flit Error Rate", which indicate whether error correction by FEC can be performed, are important.

[0013] The present invention has been made to solve such conventional problems, and an object thereof is to provide an error rate measurement device and an error rate measurement method capable of displaying a setting screen for setting measurement conditions related to error rate measurement of an input signal and displaying a calculation result of a measurement time that can obtain a desired target reliability level according to the measurement conditions input to the setting screen.

Means for Solving the Problems

[0014] In order to solve the above problems, an error rate measurement device according to the present invention is an error rate measurement device (1) that measures the error rate of an input signal from a measurement object (200), and includes a display unit (42) that displays a setting screen (50) for setting measurement conditions related to the measurement of the error rate, and a processing unit (30) that calculates the measurement time of the input signal. The setting screen includes a target reliability level input unit (60) for inputting a target reliability level, a transmission speed input unit (52, 59) for inputting the transmission speed of the input signal, a target error rate input unit (53a, 53b) for inputting the target error rate of the input signal, an assumed error number input unit (54) for inputting the assumed number of errors during the measurement time of the input signal, and a measurement time display unit (58a, 58b) for displaying the measurement time of the input signal. The processing unit is configured to calculate the measurement time that gives the target reliability level based on the target reliability level, the transmission speed, the target error rate, and the assumed number of errors input on the setting screen.

[0015] With this configuration, the error rate measurement device according to the present invention can display a setting screen for setting measurement conditions related to the measurement of the error rate of an input signal, and can display the calculation result of the measurement time that can obtain a desired target reliability level without making the user aware that the calculation process of the measurement time is performed according to the measurement conditions input on the setting screen.

[0016] Further, the error rate measurement device according to the present invention may further include an error rate calculation unit (25) that calculates the error rate of the input signal over the measurement time calculated by the processing unit.

[0017] With this configuration, the error rate measurement device according to the present invention can calculate the error rate of the input signal over the measurement time that can obtain a desired target reliability level.

[0018] In addition, the error rate measuring apparatus according to the present invention may include a measurement unit input unit (52) for the transmission speed input unit to input a measurement unit of the error rate, and a baud rate input unit (59) for inputting the baud rate of the input signal, and the processing unit may include a transmission speed conversion unit (37) that converts the baud rate into the transmission speed corresponding to the measurement unit.

[0019] With this configuration, the error rate measuring apparatus according to the present invention can calculate a measurement time according to the transmission speed in various measurement units of the input signal.

[0020] In addition, the measurement unit of the error rate measuring apparatus according to the present invention may be any one of bits, symbols, flits, or codewords.

[0021] In addition, the error rate measurement method according to the present invention measures the error rate of an input signal from a measurement object (200). In the error rate measurement device An error rate measurement method includes a setting screen display step (S11) of displaying a setting screen (50) for setting the measurement conditions of the error rate on a display unit (42), a target reliability level, the transmission speed of the input signal, the target error rate of the input signal, and the assumed number of errors during the measurement time of the input signal. of The setting screen to Input accept An input step (S12), a processing step (S14) of calculating the measurement time for giving the target reliability level based on the target reliability level, the transmission speed, the target error rate, and the assumed number of errors input to the setting screen, and a measurement time display step (S15) of displaying the measurement time calculated by the processing step. The setting screen includes a target reliability level input unit (60) for inputting the target reliability level, a transmission speed input unit (52, 59) for inputting the transmission speed, a target error rate input unit (53a, 53b) for inputting the target error rate, an assumed number of errors input unit (54) for inputting the assumed number of errors, and a measurement time display unit (58a, 58b) for displaying the measurement time.

[0022] Further, the error rate measurement method according to the present invention may further include an error rate calculation step (S17) of calculating the error rate of the input signal over the measurement time displayed in the measurement time display step.

[0023] Further, the error rate measurement method according to the present invention includes a measurement unit input unit (52) for the transmission speed input unit to input the measurement unit of the error rate, and a baud rate input unit (59) for inputting the baud rate of the input signal. The processing step may include a transmission speed conversion step (S13) of converting the baud rate into the transmission speed according to the measurement unit.

Advantages of the Invention

[0024] The present invention provides an error rate measurement device and an error rate measurement method capable of displaying a setting screen for setting measurement conditions for measuring the error rate of an input signal, and displaying a calculation result of a measurement time for obtaining a desired target reliability level according to the measurement conditions input to the setting screen.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0026] Hereinafter, embodiments of an error rate measurement device and an error rate measurement method according to the present invention will be described with reference to the drawings.

[0027] As shown in FIG. 1, an error rate measurement device 1 according to an embodiment of the present invention measures the error rate of an input signal output from a device under test (DUT) 200, and includes a signal output unit 10, a signal input unit 20, a data storage unit 40, an operation unit 41, a display unit 42, and a control unit 43.

[0028] Examples of the standards corresponding to the DUT 200 include PCIe Gen1 to 6, USB (registered trademark) (Universal Serial Bus) 3.1 to 4, CEI (Common Electrical Interface), IEEE802.3, InfiniBand HDR, Fibre Channel, and the like.

[0029] The data storage unit 40 is composed of a memory such as a RAM (Random Access Memory). The data storage unit 40 stores, as signal data of a known pattern input from the signal output unit 10 to the DUT 200 described later, for example, bit string data of an NRZ signal (data of a bit string consisting of 0 or 1) or symbol string data of a PAM4 signal (data of a symbol string consisting of 0, 1, 2, or 3).

[0030] Further, the data storage unit 40 may store bit string data of the MSB (Most Significant Bit) and LSB (Least Significant Bit) of the PAM4 signal input to the DUT 200. The symbol string data of the PAM4 signal, the bit string data of the MSB and LSB, and the bit string data of the NRZ signal stored in the data storage unit 40 also serve as reference data for the error rate calculation unit 25 described later to compare with the input signal from the DUT 200.

[0031] The signal output unit 10 generates a test signal composed of data of a known pattern input from the data storage unit 40. Then, the signal output unit 10 outputs the generated test signal to the DUT 200. At this time, the DUT 200 folds back the test signal output from the signal output unit 10 and uses it as an input signal to the signal input unit 20.

[0032] The signal input unit 20 inputs the input signal output from the DUT 200 and includes an equalizer 21 and an error rate measurement unit 22.

[0033] The input signal from the DUT 200 is, for example, a test signal such as a PAM4 signal output from the signal output unit 10 folded back from the DUT 200.

[0034] The equalizer 21 is configured to adjust the frequency characteristics of the input signal from the DUT 200. The equalizer 21 is composed of, for example, a CTLE (Continuous Time Linear Equalizer), an LFE (Low Frequency Equalizer), a DFE, etc.

[0035] The error rate measurement unit 22 includes a clock recovery unit 23, a data extraction unit 24, an error rate calculation unit 25, and a processing unit 30, and is configured to measure the error rate of the input signal from the DUT 200.

[0036] The clock reproduction unit 23 is configured to generate a reproduction clock signal from the input signal from the DUT 200 adjusted by the equalizer 21.

[0037] The data extraction unit 24 is configured to extract bit string data or symbol string data of the input signal from the DUT 200 adjusted by the equalizer 21.

[0038] The data extraction unit 24 extracts the bit string data or symbol string data of the input signal output from the DUT 200 by punching out the input signal adjusted by the equalizer 21 at the timing of the rising edge or falling edge of the clock signal. Here, the clock signal used by the data extraction unit 24 may be the reproduction clock signal output from the clock reproduction unit 23 or an external clock signal corresponding to the baud rate of the input signal. In this specification, the reproduction clock signal and the external clock signal are collectively referred to simply as the "clock signal".

[0039] For example, the data extraction unit 24 has a plurality of 0 / 1 discriminators, and by inputting a clock signal to each 0 / 1 discriminator, it is possible to determine the level of the input signal output from the DUT 200 at the timing of the clock signal. Note that the reproduction clock signal output from the clock reproduction unit 23 may be used as an operation clock not only in the data extraction unit 24 but also in each part constituting the error rate measurement device 1.

[0040] The error rate calculation unit 25 calculates the error rate of the input signal from the DUT 200 extracted by the data extraction unit 24 by sequentially comparing the bit string data or symbol string data extracted by the data extraction unit 24 with the reference data stored in the data storage unit 40. In this specification, BER, SER, Uncorrectable Codeword Rate, and Flit Error Rate are collectively referred to simply as the "error rate".

[0041] The error rate calculation unit 25 counts the number of errors in the input signal from the DUT 200 over the measurement time set by a setting screen 50 described later, or over the measurement time calculated by a measurement time calculation unit 38 described later. Further, the error rate calculation unit 25 calculates, as the error rate of the input signal from the DUT 200, a value obtained by dividing the counted number of errors by the number of measurement data of the input signal over the above measurement time.

[0042] The processing unit 30 is based on the target reliability level CL S , the data rate of the input signal, the target error rate ER S of the input signal, and measurement conditions such as the assumed number of errors E during the measurement time of the input signal, and calculates the measurement time of the input signal that gives the target reliability level CL S . The target reliability level CL S represents the probability that the true error rate of the input signal from the DUT 200 is smaller than the target error rate ER S .

[0043] As shown in FIG. 2, the processing unit 30 includes an average value calculation unit 31, a provisional reliability level calculation unit 32, an upper and lower limit value update unit 33, a convergence determination unit 36, a transmission speed conversion unit 37, and a measurement time calculation unit 38.

[0044] The average value calculation unit 31 is configured to calculate a sum x of a value obtained by dividing a variable min_x by 2 and a value obtained by dividing a variable max_x by 2.

[0045] Note that the provisional reliability level CLx obtained when the initial value of the variable min_x is substituted into x in Equation (2) described later needs to be smaller than the target reliability level CL S . Similarly, the provisional reliability level CLx obtained when the initial value of the variable max_x is substituted into x in Equation (2) described later needs to be larger than the target reliability level CL S .

[0046] Therefore, for example, the initial value of the variable min_x should be 0, and the initial value of the variable max_x should be the maximum valid value of the numerical type used in the calculation.

[0047] The average value calculation unit 31 performs a rounding process of truncating the numerical values of the lower digits of each value so that each of the values of min_x / 2, max_x / 2, and x fits within the maximum number of significant digits of the numerical type being used. That is, min_x / 2, max_x / 2, and x calculated by the average value calculation unit 31 all contain a rounding error. Note that the above rounding process is not limited to truncation and may be any arbitrary rounding process such as rounding up.

[0048] The numerical types of the variables min_x, max_x, and the sum x are, for example, any of single-precision floating-point numbers (float type), double-precision floating-point numbers (double type), or fixed-point numbers. Among these, the double type is 64-bit data consisting of a 1-bit sign part, a 52-bit mantissa part, and an 11-bit exponent part. The maximum valid value of the double type is 1.79769313486232E+308 in decimal conversion.

[0049] The provisional reliability level calculation unit 32 is configured to calculate the provisional reliability level CLx by substituting the sum x calculated by the average value calculation unit 31 into the following formula (2). As can be seen from formula (2), the provisional reliability level CLx is monotonically increasing with respect to the sum x.

[0050]

Equation

[0051] In formula (2), x: N × ER S N: data rate [data / s] × measurement time [s] ER S : target error rate (Error Rate: ER) E: assumed number of errors That is, formula (2) is N × BER of formula (1) Sto N × ER S (=x) is replaced.

[0052] The data rate is a parameter indicating the number of measurement units included in the input signal from the DUT200 per second. The measurement unit is, for example, any one of 1 bit, 1 PAM4 symbol, 1 flit, or 1 codeword. Therefore, N is a parameter indicating the number of measurement units included in the input signal from the DUT200 over the measurement time, that is, the number of measurement data. The target error rate ER S is, for example, any one of BER, SER, Uncorrectable Codeword Rate, or Flit Error Rate, and is the upper limit value allowable as the error rate of the input signal.

[0053] The upper and lower limit value update unit 33 substitutes the latest sum x into the variable min_x when the provisional reliability level CLx calculated by the provisional reliability level calculation unit 32 is less than or equal to the target reliability level CL S in the following cases. On the other hand, the upper and lower limit value update unit 33 substitutes the latest sum x into the variable max_x when the provisional reliability level CLx calculated by the provisional reliability level calculation unit 32 is greater than the target reliability level CL S When it is larger.

[0054] Since the provisional reliability level CLx increases monotonically with respect to the sum x, by repeating the processing by the average value calculation unit 31, the provisional reliability level calculation unit 32, and the upper and lower limit value update unit 33, the range of the value of the sum x can be narrowed down to obtain an approximate value of the sum x. FIG. 3 is a diagram for explaining the narrowing process of the sum x by the average value calculation unit 31, the provisional reliability level calculation unit 32, and the upper and lower limit value update unit 33.

[0055] First, the average value calculation unit 31 calculates the sum x using the initial value of the variable min_x and the initial value of the variable max_x (step S1).

[0056] Next, the provisional reliability level calculation unit 32 calculates the provisional reliability level CLx by substituting the sum x calculated in step S1 into Equation (2). When the provisional reliability level CLx calculated by the provisional reliability level calculation unit 32 is greater than the target reliability level CL S , the latest sum x is substituted into the variable max_x. The average value calculation unit 31 calculates the sum x again using the initial value of the variable min_x and the updated variable max_x (step S2).

[0057] Next, the provisional reliability level calculation unit 32 calculates the provisional reliability level CLx by substituting the sum x calculated in step S2 into Equation (2). When the provisional reliability level CLx calculated by the provisional reliability level calculation unit 32 is less than or equal to the target reliability level CL S , the latest sum x is substituted into the variable min_x. The average value calculation unit 31 calculates the sum x again using the updated variable min_x and the variable max_x (step S3).

[0058] Next, the provisional reliability level calculation unit 32 calculates the provisional reliability level CLx by substituting the sum x calculated in step S3 into Equation (2). When the provisional reliability level CLx calculated by the provisional reliability level calculation unit 32 is greater than the target reliability level CL S , the latest sum x is substituted into the variable max_x. The average value calculation unit 31 calculates the sum x again using the variable min_x and the updated variable max_x (step S4).

[0059] That is, the average value calculation unit 31 calculates the latest sum x using the latest variable min_x and the latest variable max_x. Further, the provisional reliability level calculation unit 32 calculates the provisional reliability level CLx by substituting the latest sum x into Equation (2). Then, the upper and lower limit value update unit 33 substitutes the latest sum x into the variable min_x or the variable max_x according to the latest provisional reliability level CLx. In this way, the processing unit 30 repeats the narrowing-down process of the sum x by the average value calculation unit 31, the provisional reliability level calculation unit 32, and the upper and lower limit value update unit 33 using the latest variable min_x and the latest variable max_x.

[0060] The convergence determination unit 36 is configured to determine whether or not the change in the value of the sum x calculated by the average value calculation unit 31 converges within a predetermined range. As an example, the convergence determination unit 36 may determine whether or not the significant digits of the sum x calculated by the average value calculation unit 31 converge to a constant value. When the variable min_x, the variable max_x, and the numerical type of the sum x are of the double type, the significant digits of the variable min_x, the variable max_x, and the sum x are the mantissa parts of the double type.

[0061] For example, when the latest sum x is equal to the previous sum x, the convergence determination unit 36 determines that the significant digits of the sum x have converged to a constant value. Alternatively, the convergence determination unit 36 may determine that the significant digits of the sum x have converged to a constant value when the sum x calculated by the average value calculation unit 31 is equal for any number of times continuously three or more times.

[0062] FIG. 4 is a table showing the changes in the values when the numerical types of the variable min_x, the variable max_x, and the sum x are of the double type. FIG. 5 is a graph showing data in the vicinity where the sum x converges in the changes of the variable min_x, the variable max_x, and the sum x shown in FIG. 4. Here, it is assumed that the input signal from the DUT 200 is an NRZ signal, the data rate is 2.4 Gbps, the target error rate ER S which is the standard of the reliability level is 1E-14, the assumed number of errors E which is the standard of the reliability level is 3, and the target reliability level CL S is 0.98.

[0063] In the example of FIG. 4, it can be seen that in the 1071st and 1072nd calculation results, although the value of min_x has changed, the value of x has not changed. This indicates that the value of x has converged due to rounding errors.

[0064] Note that in the calculation results from the 1069th to the 1072nd, CL S and CLx are the same, but depending on the input values to the formula (2), CL SBefore x converges, it may converge before it matches CLx. Therefore, CL S It is not desirable to use whether it matches CLx as the end determination condition for the narrowing process of x.

[0065] When using, for example, the double type for the variable min_x, the variable max_x, and the numerical type of sum x, a result with about 14 significant digits in decimal conversion can be obtained. The number of repetitions of the narrowing process of sum x is about 1000 times, and the time required for 1000 repetitions is about several tens of ms. Therefore, it is considered that the narrowing process of sum x will not impair the convenience of the user.

[0066] Also, in this narrowing process, the convergence of sum x due to rounding error rather than the number of repetitions of the process is used as the end determination condition. For this reason, the user does not need to consider the range that can be considered as the value of sum x and the number of repetitions of the process every time various measurement conditions are changed on the setting screen 50.

[0067] Alternatively, the convergence determination unit 36 may not wait for the convergence of sum x due to rounding error, but may determine whether the change in the value of sum x calculated by the average value calculation unit 31 is less than or equal to a predetermined value with fewer digits than the maximum significant digits of the numerical type being used. In this case, although the number of significant digits decreases, it is possible to further speed up the narrowing process.

[0068] The transmission speed conversion unit 37 is configured to convert the baud rate input to the setting screen 50 described later into a transmission speed (data rate) corresponding to the measurement unit.

[0069] The measurement time calculation unit 38 calculates, as shown in the following formula (3), the sum x calculated by the average value calculation unit 31 and determined to have converged by the convergence determination unit 36, divided by the product of the data rate converted by the transmission speed conversion unit 37 and the target error rate ER S and calculates the result as the measurement time.

[0070] Measurement time [s] = x / (data rate [data / s] × ER S ) ···(3)

[0071] The operation unit 41 is for receiving operation inputs by the user, and is composed of a user interface such as, for example, an operation knob, various keys, switches, buttons, and soft keys on the display screen of the display unit 42, which is provided in the error rate measurement device 1 shown in FIG. 1. Further, the operation unit 41 performs various settings related to the error rate measurement of the error rate measurement device 1 and various measurement condition settings on the setting screen 50.

[0072] The display unit 42 is composed of a display device such as, for example, an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), which is provided in the error rate measurement device 1 shown in FIG. 1, and displays the setting screen 50, measurement results, etc. based on a display control signal from the control unit 43. Note that the display unit 42 may have an operation function of the operation unit 41 such as soft keys on the display screen.

[0073] The control unit 43 performs overall control over the signal output unit 10, the signal input unit 20, the data storage unit 40, the operation unit 41, and the display unit 42. Further, the control unit 43 is composed of a control device such as a computer including, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), a ROM (Read Only Memory), a RAM, and an HDD (Hard Disk Drive). Also, the control unit 43 can also be configured to be at least partially software-based for the error rate measurement unit 22 by executing a predetermined program by the CPU or the GPU.

[0074] As shown in FIG. 6, the display unit 42 is configured to display a setting screen 50 for setting the measurement conditions of the error rate of the input signal from the DUT 200.

[0075] The setting screen 50 includes, in the display area 51 ("Gating" in the figure), a pull-down menu 52 for "Target", text boxes 53a and 53b for "ER", a text box 54 for "EC", text 55 indicating the unit of the assumed error number E, a pull-down menu 56 for "Cycle", a pull-down menu 57 for "Unit", text boxes 58a and 58b for the measurement time, a text box 59 for "Baud Rate", and a text box 60 for "Confidence Level".

[0076] The pull-down menu 52 for "Target" constitutes a measurement unit input section for inputting the measurement unit of the error rate. The pull-down menu 52 for "Target" can select any measurement unit such as "Bit", "PAM4 Symbol", "Flit", or "Codeword", for example. The measurement unit input section and the baud rate input section described later constitute a transmission speed input section for inputting the transmission speed of the input signal from the DUT 200.

[0077] Figure 7 is a table showing the measurement units selectable in the pull-down menu 52 for "Target" and the data rates of the respective measurement units converted by the transmission speed conversion unit 37.

[0078] "Bit" is the measurement unit to be selected when it is desired to measure the BER of the input signal from the DUT 200. When the input signal from the DUT 200 is an NRZ signal, the transmission speed conversion unit 37 outputs the baud rate input in the text box 59 for "Baud Rate" described later as the data rate as it is. When the input signal from the DUT 200 is a PAM4 signal, the transmission speed conversion unit 37 outputs a rate obtained by doubling the baud rate input in the text box 59 for "Baud Rate" as the data rate.

[0079] "PAM4 Symbol" is a measurement unit selected when it is desired to measure the SER of the input signal from DUT200. When the input signal from DUT200 is a PAM4 signal, the transmission rate conversion unit 37 outputs the baud rate input in the "Baud Rate" text box 59 as the data rate as it is.

[0080] "Flit" is a measurement unit selected when it is desired to measure the Flit Error Rate of the input signal from DUT200. The transmission rate conversion unit 37 outputs the rate obtained by doubling the baud rate input in the "Baud Rate" text box 59 and dividing it by the Flit length as the data rate. Here, the Flit length is 2048 bits.

[0081] "Codeword" is a measurement unit selected when it is desired to measure the Uncorrectable Codeword Rate of the input signal from DUT200. The transmission rate conversion unit 37 outputs the rate obtained by doubling the baud rate input in the "Baud Rate" text box 59 and dividing it by the CW (Codeword) length as the data rate. Here, in the case of RS-FEC (Reed-Solomon Forward Error Correction) (544,514) defined in IEEE802.3, the CW length is 5440 bits.

[0082] The "ER" text boxes 53a, 53b constitute a target error rate input unit for inputting the desired target error rate ER of the input signal from DUT200 s . The text boxes 53a, 53b are capable of inputting the target error rate ER s in exponential notation. The mantissa part is input in the text box 53a, and the exponent part is input in the text box 53b. For example, values in the range of 1E-3 to 1E-15 can be input in the text boxes 53a, 53b.

[0083] The text box 54 for "EC" constitutes an assumed error number input section for inputting the assumed error number E during the measurement time of the input signal from the DUT200. For example, values in the range of 0 to 10 can be input into the text box 54. Also, the display of the text 55 indicating the unit of the assumed error number E input into the text box 54 changes according to the measurement unit selected in the pull-down menu 52 of "Target".

[0084] For example, when "Bit" is selected in the pull-down menu 52 of "Target", the display of the text 55 becomes "Bit". When "PAM4 Symbol" is selected in the pull-down menu 52 of "Target", the display of the text 55 becomes "Symbol". When "Flit" is selected in the pull-down menu 52 of "Target", the display of the text 55 becomes "Flit". When "Codeword" is selected in the pull-down menu 52 of "Target", the display of the text 55 becomes "Codeword".

[0085] The pull-down menu 56 for "Cycle" can, for example, select any of the measurement operations of "Repeat(CL)", "Single(CL)", "Repeat", "Single", or "Untimed".

[0086] "Repeat(CL)" is a measurement operation that repeats the error rate measurement of the measurement time calculated by the measurement time calculation unit 38. "Single(CL)" is a measurement operation that performs the error rate measurement of the measurement time calculated by the measurement time calculation unit 38 once. "Repeat" is a measurement operation that repeats the error rate measurement of the measurement time according to the measurement period selected in the pull-down menu 57 of "Unit" described later. "Single" is a measurement operation that performs the error rate measurement of the measurement time according to the measurement period selected in the pull-down menu 57 of "Unit" once. "Untimed" is a measurement operation that continuously executes the error rate measurement from the measurement start instruction by pressing a measurement start button (not shown) to the measurement end instruction by pressing a measurement stop button (not shown).

[0087] The pull-down menu 57 of "Unit" can be used to select the unit of the measurement period, such as "Time", "Clock Count", or "Error count". When "Repeat(CL)" or "Single(CL)" is selected in the pull-down menu 56 of "Cycle", the pull-down menu 57 of "Unit" is fixed to "Time".

[0088] "Time" is an item for inputting or displaying the measurement time that serves as the unit of the measurement period in the text boxes 58a and 58b for the measurement time. When "Repeat" or "Single" is selected in the pull-down menu 56 of "Cycle", the text boxes 58a and 58b for the measurement time can input the measurement time per measurement cycle in units of 1 second in the range of, for example, 1 second to 99 days 23 hours 59 minutes 59 seconds. In the text box 58a, the number of days in the range of, for example, 0 days to 99 days can be input. Also, in the text box 58b, the time in the range of, for example, 1 second to 23 hours 59 minutes 59.9 seconds can be input.

[0089] When "Repeat(CL)", "Single(CL)", or "Untimed" is selected in the pull-down menu 56 of "Cycle", the values cannot be input into the text boxes 58a and 58b for the measurement time.

[0090] The text boxes 58a and 58b for the measurement time constitute a measurement time display unit that displays the measurement time calculated by the measurement time calculation unit 38 when "Repeat(CL)" or "Single(CL)" is selected in the pull-down menu 56 of "Cycle". The text box 58a can display the number of days in the range of, for example, 0 days to 99 days. Also, the text box 58b can display the time in the range of, for example, 1 second to 23 hours 59 minutes 59.9 seconds.

[0091] When there is a change in the selection of the pull-down menu 52 of "Target", the input content of the text boxes 53a and 53b of "ER", the input content of the text box 54 of "EC", the input content of the text box 59 of "Baud Rate", or the input content of the text box 60 of "Confidence Level", the display of the calculation result of the measurement time in the text boxes 58a and 58b of the measurement time is also automatically updated.

[0092] Here, for the number of seconds in the measurement time calculated by the measurement time calculation unit 38, the text box 58b displays, for example, a value rounded up at the first or second decimal place. In the example of FIG. 4, the values of the sum x at the 1071st and 1072nd times are 9.08411538241318E+00, and at this time, the measurement time calculated from Equation (3) is 3.78504807600549E+05 [s]. At this time, the number of days "4" is displayed in the text box 58a, and the time of "09:08:24.9" (rounded up at the second decimal place) or "09:08:25" (rounded up at the first decimal place) is displayed in the text box 58b.

[0093] "Clock Count" is an item for enabling the unit of the measurement cycle to be set as the number of clock counts in the text boxes 58a and 58b of the measurement time when "Repeat" or "Single" is selected in the pull-down menu 56 of "Cycle". That is, the error rate measurement ends when a time longer than the number of clock counts set in the text boxes 58a and 58b of the measurement time has elapsed.

[0094] "Error Count" is an item for enabling the unit of the measurement cycle to be set as the number of errors detected by the error rate measurement unit 22 in the text boxes 58a and 58b of the measurement time when "Repeat" or "Single" is selected in the pull-down menu 56 of "Cycle". That is, the error rate measurement ends when the number of errors set in the text boxes 58a and 58b of the measurement time is detected by the error rate measurement unit 22.

[0095] The text box 59 for "Baud Rate" constitutes a baud rate input section for inputting the transmission speed of the input signal from the DUT200 in baud rate. "Baud Rate" is an item for enabling the input of the transmission speed of the input signal from the DUT200, for example, in the range of 2.4 GBaud to 64.2 GBaud in 1 kBaud steps.

[0096] The text box 60 for "Confidence Level" constitutes a target confidence level input section for inputting a desired target confidence level CL when "Repeat(CL)" or "Single(CL)" is selected in the pull-down menu 56 for "Cycle". S Note that the target confidence level CL S becomes 0% when the measurement time is 0 seconds, or when E becomes infinite in Equation (2), which is not realistic in practice. Also, the target confidence level CL S becomes 100% when the measurement time becomes infinite, which is also not realistic in practice. For this reason, the values of 0% and 100% cannot be set in the text box 60.

[0097] For example, when 0% is input into the text box 60, the display unit 42 is configured to automatically switch the input value to the text box 60 to 0.1%. Also, when 100% is input into the text box 60, the display unit 42 is configured to automatically switch the input value to the text box 60 to 99.9%. Alternatively, when 0% or 100% is input into the text box 60, the display unit 42 may display an error dialog to prompt the user to input a target confidence level CL S in the range of 0.1% to 99.9%.

[0098] Further, when "Repeat" or "Single" is selected in the pull-down menu 56 of "Cycle", the text box 60 of "Confidence Level" can display, with rounding to the second decimal place, the confidence level CL calculated by the following formula (4) in the processing unit 30 in the range of 0% to 100% in 0.1% steps. When "Repeat" or "Single" is selected in the pull-down menu 56 of "Cycle", the text box 60 of "Confidence Level" is in a state where a value cannot be input.

[0099]

Number

[0100] In addition, when "Untimed" is selected in the pull-down menu 56 of "Cycle", the display related to "Confidence Level" is erased from the setting screen 50. Also, when a selection other than "Time" is made in the pull-down menu 57 of "Unit", the display related to "Confidence Level" is erased from the setting screen 50.

[0101] Hereinafter, an example of the error rate measurement method using the error rate measurement device 1 of the present embodiment will be described with reference to the flowchart of FIG. 8. Note that descriptions overlapping with the description of the configuration of the above-described error rate measurement device 1 will be omitted as appropriate. Here, the processing when "Repeat(CL)" or "Single(CL)" is selected in the pull-down menu 56 of "Cycle" will be described.

[0102] First, the control unit 43 displays a setting screen 50 for setting the measurement conditions of the error rate of the input signal from the DUT 200 on the display unit 42 (setting screen display step S11).

[0103] Next, the user, via the operation unit 41, sets the target confidence level CL S , the measurement unit of the error rate, the baud rate of the input signal, and the target error rate ER of the input signals and input measurement conditions such as the expected number of errors E during the measurement time of the input signal into the setting screen 50 (input step S12).

[0104] Next, the transmission speed conversion unit 37 converts the baud rate input in the "Baud Rate" text box 59 into a transmission speed (data rate) corresponding to the measurement unit selected by the pull-down menu 52 of "Target" (transmission speed conversion step S13).

[0105] Next, the measurement time calculation unit 38 uses the data rate converted in the transmission speed conversion step S13 and the target reliability level CL S and the target error rate ER s and the expected number of errors E to calculate the measurement time that gives the target reliability level CL S (processing step S14).

[0106] Next, the display unit 42 displays the measurement time calculated in the processing step S14 in the text boxes 58a and 58b (measurement time display step S15).

[0107] Next, the processing unit 30 sets the information on the measurement time displayed in the measurement time display step S15 in the error rate calculation unit 25 (step S16).

[0108] Next, the error rate calculation unit 25 calculates the error rate of the input signal from the DUT 200 over the measurement time set by the processing unit 30 in step S16 (error rate calculation step S17).

[0109] As described above, the error rate measurement device 1 according to the present embodiment displays the setting screen 50 for setting the measurement conditions for measuring the error rate of the input signal, and according to the measurement conditions input to the setting screen 50, without making the user aware that the calculation process of the measurement time is being performed, it can display the calculation result of the measurement time that can obtain the desired target reliability level CL S .

[0110] In addition, the error rate measurement device 1 according to this embodiment can calculate the error rate of the input signal over a measurement time that can obtain a desired target reliability level CL. S

[0111] Also, the error rate measurement device 1 according to this embodiment can calculate a measurement time according to the data rate of the input signal in various measurement units.

Explanation of Signs

[0112] 1 Error rate measurement device 25 Error rate calculation unit 30 Processing unit 31 Average value calculation unit 32 Provisional reliability level calculation unit 33 Upper and lower limit value update unit 36 Convergence determination unit 37 Transmission speed conversion unit 38 Measurement time calculation unit 41 Operation unit 42 Display unit 43 Control unit 50 Setting screen 52, 56, 57 Pull-down menu 53a, 53b, 54, 58a, 58b, 59, 60 Text box 55 Text 200 DUT

Claims

1. An error rate measuring device (1) for measuring the error rate of an input signal from a measurement object (200), a display unit (42) for displaying a setting screen (50) for setting the measurement conditions of the error rate, and a processing unit (30) for calculating the measurement time of the input signal, The setting screen includes a target reliability level input unit (60) for inputting a target reliability level, a transmission speed input unit (52, 59) for inputting the transmission speed of the input signal, a target error rate input unit (53a, 53b) for inputting the target error rate of the input signal, an assumed error number input unit (54) for inputting the assumed number of errors during the measurement time of the input signal, and a measurement time display unit (58a, 58b) for displaying the measurement time of the input signal, The processing unit calculates the measurement time for giving the target reliability level based on the target reliability level, the transmission speed, the target error rate, and the assumed number of errors input on the setting screen. The error rate measuring device is characterized by this.

2. The error rate measuring device according to claim 1, further comprising an error rate calculation unit (25) for calculating the error rate of the input signal over the measurement time calculated by the processing unit.

3. The transmission speed input unit includes a measurement unit input unit (52) for inputting the measurement unit of the error rate, and a baud rate input unit (59) for inputting the baud rate of the input signal, The processing unit includes a transmission speed conversion unit (37) for converting the baud rate into the transmission speed according to the measurement unit. The error rate measuring device according to claim 1 or claim 2 is characterized by this.

4. The error rate measuring device according to claim 3, wherein the measurement unit is any one of bits, symbols, flits, or codewords.

5. An error rate measurement method in an error rate measuring device for measuring the error rate of an input signal from a measurement object (200), A setting screen display step (S11) of displaying a setting screen (50) for setting the measurement conditions of the error rate on a display unit (42), An input step (S12) of accepting input to the setting screen of a target reliability level, the transmission speed of the input signal, the target error rate of the input signal, and the assumed number of errors during the measurement time of the input signal, A processing step (S14) of calculating the measurement time for giving the target reliability level based on the target reliability level, the transmission speed, the target error rate, and the assumed number of errors input to the setting screen, A measurement time display step (S15) of displaying the measurement time calculated by the processing step, and including, The setting screen is, A target reliability level input unit (60) for inputting the target reliability level, A transmission speed input unit (52, 59) for inputting the transmission speed, A target error rate input unit (53a, 53b) for inputting the target error rate, An assumed number of errors input unit (54) for inputting the assumed number of errors, An error rate measurement method in an error rate measuring device, characterized by including a measurement time display unit (58a, 58b) for displaying the measurement time.

6. The error rate measurement method in the error rate measuring device according to claim 5, further including an error rate calculation step (S17) of calculating the error rate of the input signal over the measurement time displayed by the measurement time display step.

7. The transmission speed input unit is, A measurement unit input unit (52) for inputting the measurement unit of the error rate, a baud rate input unit (59) for inputting the baud rate of the input signal, The error rate measurement method in the error rate measurement device according to claim 5 or claim 6, characterized in that the processing step includes a transmission speed conversion step (S13) of converting the baud rate into the transmission speed according to the measurement unit.

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