Jitter tolerance measuring device and jitter tolerance measuring method

Abstract

This invention provides a jitter tolerance measuring device and method that automatically calculates the reliability level of the output signal of the object under test when jitter tolerance is obtained, allowing for quick and easy confirmation of the reliability of jitter tolerance after a jitter tolerance test. [Solution] The jitter tolerance measuring device 1 includes an error measurement unit 14 that measures the error measurement value of the output signal of the DUT200, which receives a pattern signal synchronized with a jitter clock phase-modulated by a jitter modulation signal, over a predetermined measurement time; a jitter tolerance measuring unit 16 that changes the jitter amplitude and jitter frequency of the jitter modulation signal and estimates the maximum jitter amplitude at which the error measurement value measured by the error measurement unit 14 is less than or equal to a predetermined tolerance value as the jitter tolerance of the DUT200 for each jitter frequency; a reliability level calculation unit 20 that calculates the reliability level related to the tolerance value of the error rate of the output signal of the DUT200; and a display unit 32 that displays a result display screen showing the jitter tolerance and reliability level.

Description

[Technical Field]

[0001] The present invention relates to a jitter tolerance measuring device and a jitter tolerance measuring method for measuring the jitter tolerance of an object under test. [Background technology]

[0002] For example, in communication standards such as USB® (Universal Serial Bus) and PCIe® (Peripheral Component Interconnect Express), jitter tolerance tests are conducted to determine whether the receiving section of the device under test (DUT) has the desired jitter tolerance (see, for example, Patent Documents 1 and 2).

[0003] Figure 6 shows the configuration of a conventional jitter tolerance measuring device 70 for performing jitter tolerance testing. This jitter tolerance measuring device 70 consists of a jitter generator 71 that outputs a jitter clock phase-modulated with a jitter modulation signal whose jitter amplitude and jitter frequency are variable, a pattern signal generator 72 that outputs a pattern signal synchronized with the jitter clock output from the jitter generator 71 to the DUT 75, and an error measuring device 73 that measures the error of the output signal of the DUT 75 relative to the pattern signal.

[0004] The jitter tolerance measuring device 70 configured in this way changes the jitter amplitude of the jitter modulated signal and measures the maximum jitter amplitude at which the number of errors or error rate measured by the error measuring device 73 is less than or equal to a predetermined tolerance value, as the jitter tolerance of the DUT 75.

[0005] Here, the lower limit of the jitter tolerance required for DUT75 is given as a jitter mask as shown in Figure 7.

[0006] Here, the confidence level (CL) for the error rate of the output signal when jitter tolerance is achieved is defined by the following equation (1). The confidence level CL represents the probability that the true error rate of the output signal of DUT75 will be less than the predefined target BER (Bit Error Rate).

[0007]

number

[0008] In equation (1), N: Bitrate [bit / s] × Measurement time [s] (Number of bits measured) BER S :Target BER E: Target number of errors That is the case. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 08-050156 [Patent Document 2] Patent No. 4376064 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, conventional measuring devices, such as those disclosed in Patent Documents 1 and 2, could not automatically evaluate the reliability level CL of the output signal of the DUT75 when the jitter tolerance was obtained.

[0011] Therefore, conventionally, when conducting jitter tolerance tests, there was a problem in that users themselves had to perform cumbersome tasks such as opening websites and performing calculations based on the test results in order to obtain the reliability level CL of the test results.

[0012] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a jitter tolerance measuring device and a jitter tolerance measuring method that can automatically calculate the reliability level of the output signal of the object under test when the jitter tolerance is obtained, and that can quickly and easily confirm the reliability of the jitter tolerance after the jitter tolerance test. [Means for solving the problem]

[0013] To solve the above problems, the jitter tolerance measuring device according to the present invention includes: a jitter modulation signal output unit (11) that outputs a jitter modulation signal with variable jitter amplitude and jitter frequency; a jitter clock output unit (12) that receives the jitter modulation signal from the jitter modulation signal output unit and outputs a phase-modulated jitter clock according to the jitter amplitude and jitter frequency; a pattern signal generation unit (13) that outputs a pattern signal synchronized with the jitter clock to the object under test; an error measurement unit (14) that measures the number of errors and error rate of the output signal of the object under test that receives the pattern signal over a predetermined measurement time; and the jitter amplitude and jitter frequency of the jitter modulation signal output by the jitter modulation signal output unit, and the maximum jitter amplitude at which the number of errors or error rate measured by the error measurement unit is less than or equal to a predetermined allowable value, for each jitter frequency, to be measured to the object under test. The system includes a jitter tolerance measurement unit (16) that estimates the jitter tolerance of an object, a reliability level calculation unit (20) that calculates a reliability level related to the allowable value of the error rate of the output signal, a result display screen (50, 60) that shows the jitter tolerance and the reliability level, and a display unit (32) that displays a setting screen (40) for setting the measurement conditions for the jitter tolerance. The setting screen includes a measurement time input unit (43) for inputting the measurement time of the output signal and a target error rate input unit (45a, 45b) for inputting the allowable value of the error rate of the output signal. The reliability level calculation unit calculates the reliability level based on the data rate of the output signal, the number of errors in the output signal when the jitter tolerance is obtained by the jitter tolerance measurement unit, and the allowable values ​​of the measurement time and error rate input to the setting screen.

[0014] With this configuration, the jitter tolerance measurement device according to the present invention automatically calculates the reliability level of the output signal of the measured object when the jitter tolerance is obtained, and displays the measurement results of the jitter tolerance and the reliability level on the result display screen. Thereby, the jitter tolerance measurement device according to the present invention enables the user to quickly and easily confirm the reliability of the jitter tolerance after the jitter tolerance test.

[0015] Further, in the jitter tolerance measurement device according to the present invention, the reliability level calculation unit substitutes the product of the data rate and the measurement time into N in the following formula (2), and sets the allowable value of the error rate to ER in the following formula (2). S It may be substituted into E in the following formula (2) for the number of errors, and the reliability level may be calculated. [Number]

[0016] Further, the jitter tolerance measurement device according to the present invention further includes a pass / fail determination unit (17) that determines the pass / fail of the jitter tolerance based on a predetermined jitter mask, and the result display screen displays the jitter tolerance, the determination result of the pass / fail determination unit, and the reliability level for each jitter frequency.

[0017] With this configuration, the jitter tolerance measurement device according to the present invention displays the determination result of the pass / fail determination unit and the reliability level on the result display screen for each jitter frequency. Thereby, the jitter tolerance measurement device according to the present invention facilitates the user to verify the pass or fail determination by the pass / fail determination unit using the reliability level.

[0018] Further, the jitter tolerance measurement device according to the present invention may further include a result output unit (21) that outputs the jitter tolerance, the determination result of the pass / fail determination unit, and the reliability level for each jitter frequency displayed on the result display screen in a predetermined file format.

[0019] With this configuration, the jitter tolerance measuring device according to the present invention outputs the jitter tolerance for each jitter frequency, the pass / fail judgment result from the pass / fail judgment unit, and the reliability level, displayed on the results display screen, in a predetermined file format. This makes it easy for the user to verify the measurement results of the jitter tolerance test using the reliability level, even at a later date after the jitter tolerance test.

[0020] Furthermore, the jitter tolerance measurement method according to the present invention uses a jitter tolerance measuring device (1) comprising: a jitter modulation signal output unit (11) that outputs a jitter modulation signal with variable jitter amplitude and jitter frequency; a jitter clock output unit (12) that receives the jitter modulation signal from the jitter modulation signal output unit and outputs a phase-modulated jitter clock according to the jitter amplitude and jitter frequency; a pattern signal generation unit (13) that outputs a pattern signal synchronized with the jitter clock to the object under test; an error measurement unit (14) that measures the number of errors and error rate of the output signal of the object under test that receives the pattern signal over a predetermined measurement time; and a jitter tolerance measurement unit (16) that changes the jitter amplitude and jitter frequency of the jitter modulation signal output by the jitter modulation signal output unit and estimates the maximum jitter amplitude at which the number of errors or error rate measured by the error measurement unit is less than or equal to a predetermined allowable value as the jitter tolerance of the object under test for each jitter frequency. The system includes a setting screen display step (S1) which displays a setting screen (40) for setting the measurement conditions for the jitter tolerance on a display unit (32), an input step (S2) which inputs the measurement time of the output signal and the allowable value of the error rate of the output signal to the setting screen, a reliability level calculation step (S12) which calculates a reliability level for the allowable value of the error rate based on the data rate of the output signal, the number of errors in the output signal when the jitter tolerance is obtained by the jitter tolerance measurement unit, and the allowable value of the measurement time and the allowable value of the error rate input to the setting screen, and a result display screen display step (S14) which displays a result display screen (50, 60) showing the jitter tolerance and the reliability level on a display unit (32), wherein the setting screen includes a measurement time input unit (43) for inputting the measurement time of the output signal and a target error rate input unit (45a, 45b) for inputting the allowable value of the error rate of the output signal. [Effects of the Invention]

[0021] The present invention provides a jitter tolerance measuring device and a jitter tolerance measuring method that automatically calculate the reliability level of the output signal of the object under test when jitter tolerance is obtained, and that allow for quick and easy confirmation of the reliability of jitter tolerance after a jitter tolerance test. [Brief explanation of the drawing]

[0022] [Figure 1] This is a block diagram showing the configuration of a jitter tolerance measuring device according to an embodiment of the present invention. [Figure 2] This is an example of a settings screen for a jitter tolerance measuring device according to an embodiment of the present invention. [Figure 3] This is an example of a result display screen for a jitter tolerance measuring device according to an embodiment of the present invention. [Figure 4] This is an example of a detailed results display screen for a jitter tolerance measuring device according to an embodiment of the present invention. [Figure 5] This flowchart shows the process of a jitter tolerance measurement method using a jitter tolerance measuring device according to an embodiment of the present invention. [Figure 6] This is a block diagram showing the configuration of a conventional jitter tolerance measuring device. [Figure 7] This is a diagram illustrating an example of a jitter mask. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the jitter tolerance measuring device and jitter tolerance measuring method according to the present invention will be described with reference to the drawings.

[0024] As shown in Figure 1, the jitter tolerance measuring device 1 according to an embodiment of the present invention performs a jitter tolerance test to measure the jitter tolerance of the DUT200, and comprises a jitter generation unit 10, a pattern signal generation unit 13, an error measurement unit 14, a control unit 15, a data storage unit 30, an operation unit 31, and a display unit 32.

[0025] Examples of standards supported by the DUT200 include PCIe Gen1-6, USB® (Universal Serial Bus) 3.0-4, CEI (Common Electrical Interface), IEEE 802.3, InfiniBand HDR, and Fibre Channel.

[0026] The jitter generation unit 10 includes a jitter modulation signal output unit 11 and a jitter clock output unit 12.

[0027] The jitter modulation signal output unit 11 outputs a jitter modulation signal with variable jitter amplitude and jitter frequency. The jitter modulation signal is, for example, a periodic jitter such as sinusoidal jitter.

[0028] The jitter clock output unit 12 receives a jitter modulated signal from the jitter modulated signal output unit 11 and outputs a phase-modulated jitter clock according to the jitter amplitude and jitter frequency of the jitter modulated signal.

[0029] The data storage unit 30 is composed of memory such as RAM (Random Access Memory). The data storage unit 30 stores known pattern signal data that is input to the DUT200 from the pattern signal generation unit 13, which will be described later. For example, it stores bit sequence data (data consisting of a sequence of bits consisting of 0s or 1s) of NRZ (Non Return to Zero) type signals (hereinafter also simply referred to as "NRZ signals") and symbol sequence data (data consisting of a sequence of symbols consisting of 0s, 1s, 2s, or 3s) of PAM4 (Pulse Amplitude Modulation 4) type signals (hereinafter also simply referred to as "PAM4 signals").

[0030] Furthermore, the data storage unit 30 may also store the bit sequence data of the MSB (Most Significant Bit) and LSB (Least Significant Bit) of the PAM4 signal input to the DUT200. The symbol sequence data of the PAM4 signal, the bit sequence data of the MSB and LSB, and the bit sequence data of the NRZ signal stored in the data storage unit 30 also serve as reference data for comparison by the error measurement unit 14, which will be described later, with the output signal of the DUT200.

[0031] The pattern signal generation unit 13 generates a pattern signal consisting of data of known patterns input from the data storage unit 30, synchronized with the jitter clock from the jitter clock output unit 12.

[0032] The pattern signal generation unit 13 then outputs the generated pattern signal to the DUT 200 as a test signal. At this time, the DUT 200 folds back the pattern signal output from the pattern signal generation unit 13 and uses it as the output signal to the error measurement unit 14.

[0033] The error measurement unit 14 measures the number of errors and the error rate of the output signal of the DUT200, which receives a pattern signal from the pattern signal generation unit 13, for each combination of jitter amplitude and jitter frequency of the jitter modulated signal over a predetermined measurement time.

[0034] The error measurement unit 14 calculates the error rate of the output signal of the DUT200 by sequentially comparing the bit sequence data or symbol sequence data contained in the output signal of the DUT200 with reference data stored in the data storage unit 30.

[0035] Furthermore, the jitter tolerance of the error measurement unit 14 itself is sufficiently higher than the jitter tolerance measurement range of the DUT200.

[0036] The error measurement unit 14 counts the number of errors in the output signal of the DUT200 over a measurement period set by the setting screen 40, which will be described later. Furthermore, the error measurement unit 14 calculates the error rate of the output signal of the DUT200 by dividing the counted number of errors by the number of measurement data points of the output signal over the above measurement period.

[0037] The control unit 15 is composed of a control device such as a computer, which includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), ROM (Read Only Memory), RAM, and an HDD (Hard Disk Drive).

[0038] The control unit 15 provides overall control over the jitter generation unit 10, the pattern signal generation unit 13, the error measurement unit 14, the data storage unit 30, the operation unit 31, and the display unit 32. Furthermore, for example, the control unit 15 configures the jitter tolerance measurement unit 16, the pass / fail determination unit 17, the transmission speed conversion unit 18, the reliability level calculation unit 20, and the result output unit 21 through software by executing a predetermined program using the CPU or GPU.

[0039] The operation unit 31 is for receiving user input and consists of a user interface such as an operation knob, various keys, switches, buttons, and soft keys on the display screen of the display unit 32, which are provided by the jitter tolerance measuring device 1 shown in Figure 1. The operation unit 31 also performs various settings related to jitter tolerance measurement of the jitter tolerance measuring device 1 and sets various measurement conditions on the setting screen 40, which will be described later.

[0040] The display unit 32 is comprised of a display device such as an LCD (Liquid Crystal Display) or CRT (Cathode Ray Tube), which is part of the jitter tolerance measuring device 1 shown in Figure 1. Based on display control signals from the control unit 15, it displays the setting screen 40, the result display screen 50, and the detailed result display screen 60, etc. The display unit 32 may also have operating functions for the operation unit 31, such as soft keys on the display screen.

[0041] The jitter tolerance measurement unit 16 changes the jitter amplitude and jitter frequency of the jitter modulated signal output by the jitter modulated signal output unit 11, and estimates the maximum jitter amplitude at which the number of errors or error rate (hereinafter also referred to as "error measurement value") measured by the error measurement unit 14 is less than or equal to a predetermined tolerance value Th, as the jitter tolerance of the DUT200 for each jitter frequency.

[0042] For example, the jitter tolerance measurement unit 16 gradually increases the jitter amplitude from a predetermined lower limit LL until the error measurement value exceeds the allowable value Th. If the error measurement value exceeds the allowable value Th while reaching a predetermined upper limit UL, the jitter tolerance is set to the maximum jitter amplitude before the error measurement value exceeded the allowable value Th. If the error measurement value does not exceed the allowable value Th even when the jitter amplitude is equal to or greater than the upper limit UL, the jitter tolerance measurement unit 16 sets the upper limit UL as the jitter tolerance. If the error measurement value already exceeds the allowable value Th when the jitter amplitude is at the lower limit LL, the jitter tolerance measurement unit 16 sets the lower limit LL as the jitter tolerance.

[0043] The pass / fail determination unit 17 determines whether the jitter tolerance estimated by the jitter tolerance measurement unit 16 is pass or fail, based on a predetermined jitter mask.

[0044] As shown in Figure 2, the display unit 32 displays a setting screen 40 for setting the measurement conditions for the jitter tolerance of the output signal of the DUT200.

[0045] The settings screen 40 includes the "Unit" pull-down menus 41a and 41b, the "Gating" radio button 42a, the "Target Confidence Level" radio button 42b, the "Gating" spin box 43, the "Target Confidence Level" spin box 44, the "Target ER" spin boxes 45a and 45b, the "Target EC" spin box 46, and the "Close" soft key 47.

[0046] The "Unit" pull-down menu 41a allows the user to select whether the error measurement unit 14 measures the number of errors or the error rate of the output signal of the DUT200. The "Unit" pull-down menu 41b allows the user to select the measurement unit for the number of errors or the error rate set in the "Unit" pull-down menu 41a from options such as Bit, PAM4 Symbol, Flit, or Codeword.

[0047] The "Gating" radio button 42a and the "Target Confidence Level" radio button 42b either set the measurement time in the "Gating" spin box 43, or set the acceptable confidence level CL in the "Target Confidence Level" spin box 44. S You can choose whether to set it or not.

[0048] The "Gating" spin box 43 allows input of the measurement time in 1-second increments, for example, within a range of 1 second to 86,400 seconds, when the "Gating" radio button 42a is selected. In other words, the "Gating" spin box 43 constitutes a measurement time input section for inputting the measurement time of the output signal of the DUT200.

[0049] Furthermore, when the "Target Confidence Level" radio button 42b is selected, the "Gating" spin box 43 becomes uninputtable, and displays the measurement time calculated by a means not shown, for example, in increments of one second within a range of 1 to 172800 seconds.

[0050] The spin box 44 for "Target Confidence Level" is set to target confidence level CL when the radio button 42b for "Target Confidence Level" is selected. S For example, you can input a value in 0.1% increments within a range of 0.0 to 99.9%.

[0051] Additionally, the spin box 44 for "Target Confidence Level" becomes unusable when the radio button 42a for "Gating" is selected.

[0052] The "Target ER" spin boxes 45a and 45b target the error rate ER of the output signal of the DUT200. s This section contains a target error rate input unit for inputting the target error rate ER. s This is the allowable error rate of the output signal of the DUT200 in the error measurement performed by the error measurement unit 14.

[0053] Spin boxes 45a and 45b have a target error rate ER sThe system allows input in exponential notation, with the mantissa being entered in spin box 45a and the exponent in spin box 45b. For example, spin boxes 45a and 45b can accept values ​​in the range of 1E-15 to 9E-3.

[0054] The "Target EC" spin box 46 allows you to input the target number of errors E during the measurement time of the DUT200's output signal when the "Target Confidence Level" radio button 42b is selected. For example, the spin box 46 can accept values ​​in the range of 0 to 10. The unit of the target number of errors E entered into the spin box 46 changes depending on the measurement unit selected in the "Unit" pull-down menu 41b.

[0055] Additionally, when the "Gating" radio button 42a is selected, the spin box 46 for "Target EC" will be in a state where no value can be entered.

[0056] When the user presses the "Close" soft key 47, the control unit 15 sets the measurement time currently displayed in the "Gating" spin box 43 to the incorrect measurement unit 14 and ends the display of the setting screen 40.

[0057] The transmission speed conversion unit 18 converts the known baud rate of the output signal of the DUT200 to a transmission speed (data rate) corresponding to the measurement unit of the output signal of the DUT200. The baud rate of the output signal of the DUT200 may be set via a setting screen (not shown).

[0058] The data rate is a parameter that indicates the number of measurement units contained per second in the output signal of the DUT200. The measurement units can be, for example, bits, symbols (PAM4 Symbol), frits, or codewords.

[0059] Target Error Rate (ER)S This can be, for example, BER, SER (Symbol Error Rate), Uncorrectable Codeword Rate, or Flit Error Rate, and represents the upper limit of the error rate that can be tolerated for the output signal.

[0060] "Bit" is the unit of measurement used when measuring the BER of the output signal of the DUT200. When the unit of measurement is "Bit" and the output signal of the DUT200 is an NRZ signal, the transmission speed conversion unit 18 outputs the baud rate of the output signal of the DUT200 as the data rate. When the unit of measurement is "Bit" and the output signal of the DUT200 is a PAM4 signal, the transmission speed conversion unit 18 outputs a rate obtained by doubling the baud rate of the output signal of the DUT200 as the data rate.

[0061] "PAM4 Symbol" is the unit of measurement used when measuring the SER of the output signal of the DUT200. When the unit of measurement is "PAM4 Symbol" and the output signal of the DUT200 is a PAM4 signal, the transmission speed conversion unit 18 outputs the baud rate of the output signal of the DUT200 as the data rate.

[0062] "Flit" is the unit of measurement used when measuring the Flit Error Rate of the output signal of the DUT200. When the unit of measurement is "Flit", the transmission speed conversion unit 18 outputs a data rate obtained by doubling the baud rate of the output signal of the DUT200 and dividing it by the Flit length. Here, the Flit length is 2048 bits.

[0063] "Codeword" is the measurement unit when measuring the Uncorrectable Codeword Rate of the output signal of DUT200. When the measurement unit is "Codeword", the transmission rate conversion unit 18 outputs the rate obtained by doubling the baud rate of the output signal of DUT200 and dividing it by the CW (Codeword) length as the data rate. Here, the CW length is 5440 bits in the case of RS-FEC (Reed-Solomon Forward Error Correction) (544,514) defined in IEEE802.3.

[0064] The reliability level calculation unit 20 calculates the reliability level regarding the target error rate ER using the number of errors measured by the error measurement unit 14 when the jitter tolerance is obtained by the jitter tolerance measurement unit 16. s The reliability level represents the probability that the true error rate of the output signal of DUT200 is smaller than the target error rate ER. S

[0065] Specifically, the reliability level calculation unit 20 substitutes the product of the data rate [data / s] output from the transmission rate conversion unit 18 and the measurement time [s] input to the spin box 43 of "Gating" on the setting screen 40 into N in the following formula (2), and substitutes the target error rate ER input to the spin boxes 45a, 45b of "Target ER" on the setting screen 40 into ER in the following formula (2), and substitutes the number of errors measured by the error measurement unit 14 into E in the following formula (2) to calculate the reliability level CL. s S

[0066]

Equation

[0067] N is a parameter indicating the number of measurement units included in the output signal of DUT200 over the measurement time, that is, the number of measurement data. The measurement unit can be set in the pull-down menu 41b of "Unit" on the setting screen 40.

[0068] Figure 3 shows the results display screen 50 displayed by the display unit 32. The results display screen 50 includes a measurement results table 51 and a "Detail" soft key 52.

[0069] In the measurement results table 51, the "Meas. [UI]" column shows the jitter tolerance estimated by the jitter tolerance measurement unit 16 for each jitter frequency.

[0070] The "Meas.Judge" column in the measurement results table 51 shows the pass / fail judgment result by the pass / fail judgment unit 17 for each jitter frequency. "PASS" indicates that the jitter tolerance estimated by the jitter tolerance measurement unit 16 is equal to or greater than a predetermined jitter mask. "FAIL" indicates that the jitter tolerance estimated by the jitter tolerance measurement unit 16 is less than a predetermined jitter mask.

[0071] The "CL" column in the measurement results table 51 shows the reliability level CL[%] calculated by the reliability level calculation unit 20 for each jitter frequency.

[0072] When the user presses the "Detail" soft key 52, the control unit 15 displays a detailed results display screen 60 on the display unit 32, as shown in Figure 4. In the detailed measurement results table 61 of the detailed results display screen 60, the jitter tolerance estimated by the jitter tolerance measurement unit 16 and the reliability level CL calculated by the reliability level calculation unit 20 are shown for each jitter frequency.

[0073] In the examples shown in Figures 3 and 4, the reliability level CL value in the "CL" column is always 0.0% when the pass / fail judgment result of the pass / fail judgment unit 17 is "FAIL". However, depending on the allowable value Th of the number of errors or error rate and the jitter mask value in the jitter tolerance measurement unit 16, it may take a value greater than 0.0%.

[0074] The result output unit 21 outputs various measurement results, including jitter tolerance, judgment result, and reliability level CL, displayed in the measurement result table 51 or detailed measurement result table 61, in a predetermined file format. Here, the predetermined file format is, for example, HTML (HyperText Markup Language) or CSV (Comma Separated Values).

[0075] The file output from the result output unit 21 may be stored in the data storage unit 30, or it may be stored in an external storage device or a computer-readable recording medium.

[0076] Below, an example of a jitter tolerance measurement method using the jitter tolerance measuring device 1 of this embodiment will be described with reference to the flowchart in Figure 5. Note that explanations that overlap with the above-described explanation of the configuration of the jitter tolerance measuring device 1 will be omitted as appropriate.

[0077] First, the control unit 15 displays a setting screen 40 on the display unit 32 for setting the measurement conditions for the jitter tolerance of the output signal of the DUT200 (setting screen display step S1).

[0078] Next, the user can control the measurement time of the output signal of the DUT200, the measurement unit of the number of errors or error rate of the output signal, and the target error rate ER of the output signal via the control unit 31. s Enter the measurement conditions, such as those listed above, into the settings screen 40 (input step S2).

[0079] Next, the transmission speed conversion unit 18 converts the baud rate of the output signal of the DUT200 to a transmission speed (data rate) corresponding to the measurement unit entered in the setting screen 40 in input step S2 (step S3).

[0080] Next, when the user presses the "Close" soft key 47 on the settings screen 40, the control unit 15 sets the measurement time currently displayed in the "Gating" spin box 43 on the settings screen 40 to the measurement unit 14 (step S4).

[0081] Next, the jitter tolerance measurement unit 16 sets a predetermined jitter frequency to the jitter modulation signal output unit 11 (step S5).

[0082] Next, the jitter tolerance measurement unit 16 sets a predetermined jitter amplitude to the jitter modulation signal output unit 11 (step S6).

[0083] Next, the pattern signal generation unit 13 outputs a phase-modulated pattern signal to the DUT 200 according to the jitter frequency and jitter amplitude set in steps S5 and S6 (step S7).

[0084] Next, the error measurement unit 14 counts the number of errors in the output signal of the DUT200 and calculates the error rate of the output signal of the DUT200 over the measurement time set by the control unit 15 in step S4 (step S8).

[0085] Next, the jitter tolerance measurement unit 16 determines whether the error measurement value obtained in step S8 is less than or equal to a predetermined allowable value Th (step S9).

[0086] If the error measurement value obtained in step S8 is less than or equal to a predetermined tolerance value Th (step S9: YES), in step S6, the jitter tolerance measurement unit 16 sets an even larger jitter amplitude to the jitter modulation signal output unit 11. In this flowchart, the process in step S6 is to gradually increase the jitter amplitude from a predetermined lower limit value LL for each jitter frequency.

[0087] If the error measurement value obtained in step S8 is greater than a predetermined tolerance value Th (step S9: NO), in step S10 the jitter tolerance measurement unit 16 estimates the maximum jitter amplitude at which the error measurement value obtained in step S8 is less than or equal to the predetermined tolerance value Th as the jitter tolerance at the currently set jitter frequency (step S10).

[0088] Next, the pass / fail determination unit 17 determines whether the jitter tolerance estimated in step S10 is pass or fail based on a predetermined jitter mask (step S11).

[0089] Next, the reliability level calculation unit 20 calculates the data rate converted in step S3, the number of errors in the output signal of the DUT200 when the jitter tolerance was obtained in step S10, and the measurement time and target error rate ER entered into the setting screen 40 in input step S2. S Based on this, the reliability level CL is calculated (reliability level calculation step S12).

[0090] If the jitter tolerance estimation process in step S10 has not been completed for all predetermined jitter frequencies (step S13: NO), in step S5, the jitter tolerance measurement unit 16 sets a new jitter frequency in the jitter modulation signal output unit 11.

[0091] When the jitter tolerance estimation process in step S10 is completed for all predetermined jitter frequencies (step S13: YES), the control unit 15 displays a result display screen 50 on the display unit 32 showing the jitter tolerance estimated in step S10, the pass / fail judgment result of the jitter tolerance determined in step S11, and the reliability level CL calculated in reliability level calculation step S12. Furthermore, if the user presses the "Detail" soft key 52 on the result display screen 50, the control unit 15 displays a detailed result display screen 60 on the display unit 32 (result display screen display step S14).

[0092] As described above, the jitter tolerance measuring device 1 according to this embodiment automatically calculates the reliability level CL of the output signal of the DUT200 when jitter tolerance is obtained, and displays the measurement results of jitter tolerance and reliability level CL on the result display screen 50. This allows the jitter tolerance measuring device 1 according to this embodiment to quickly and easily confirm the reliability of the jitter tolerance after the jitter tolerance test.

[0093] Furthermore, the jitter tolerance measuring device 1 according to this embodiment displays the judgment result of the pass / fail judgment unit 17 and the reliability level CL on the result display screen 50 for each jitter frequency. This makes it easy for the user to verify the Pass (pass) or Fail (fail) judgment by the pass / fail judgment unit 17 using the reliability level CL.

[0094] Furthermore, the jitter tolerance measuring device 1 according to this embodiment outputs the jitter tolerance for each jitter frequency, the pass / fail judgment result of the pass / fail judgment unit 17, and the reliability level CL, which are displayed on the result display screen 50, in a predetermined file format. This makes it easy for the user to verify the measurement results of the jitter tolerance test using the reliability level CL, even at a later date after the jitter tolerance test. [Explanation of Symbols]

[0095] 1. Jitter tolerance measuring device 10 Jitter generation section 11. Jitter Modulation Signal Output Section 12. Jitter Clock Output Section 13 Pattern signal generation unit 14 Error Measurement Unit 15 Control Unit 16. Jitter tolerance measurement section 17. Pass / Fail Judgment Department 18 Transmission speed conversion unit 20 Reliability Level Calculation Unit 21 Result Output Section 30 Data storage unit 31 Operation section 32 Display section 40 Settings screen 41a, 41b Pull-down menu 42a, 42b Radio buttons 43, 44, 45a, 45b, 46 Spin Box 50 Results display screen 51 Measurement Results Table 60 Detailed result display screen (result display screen) 61 Detailed Measurement Results Table I HAVE 200

Claims

1. A jitter modulation signal output unit (11) outputs a jitter modulation signal with variable jitter amplitude and jitter frequency, A jitter clock output unit (12) receives the jitter modulated signal from the jitter modulated signal output unit and outputs a phase-modulated jitter clock according to the jitter amplitude and the jitter frequency, A pattern signal generation unit (13) outputs a pattern signal synchronized with the jitter clock to the object under measurement, An error measurement unit (14) that measures the number of errors and the error rate of the output signal of the object under test that has received the pattern signal over a predetermined measurement period, A jitter tolerance measuring unit (16) changes the jitter amplitude and jitter frequency of the jitter modulated signal output by the jitter modulated signal output unit, and estimates the maximum jitter amplitude at which the number of errors or error rate measured by the error measurement unit is less than or equal to a predetermined tolerance value, as the jitter tolerance of the object under test for each jitter frequency, A reliability level calculation unit (20) calculates a reliability level relating to the allowable error rate of the output signal, The system includes a display unit (32) that displays a result display screen (50, 60) showing the jitter tolerance and reliability level, and a setting screen (40) for setting the measurement conditions for the jitter tolerance. The aforementioned settings screen is, A measurement time input unit (43) for inputting the measurement time of the output signal, It includes a target error rate input section (45a, 45b) for inputting an acceptable value for the error rate of the output signal, The jitter tolerance measuring device is characterized in that the reliability level calculation unit calculates the reliability level based on the data rate of the output signal, the number of errors in the output signal when the jitter tolerance is obtained by the jitter tolerance measuring unit, and the allowable values ​​of the measurement time and the error rate entered on the setting screen.

2. The reliability level calculation unit substitutes the product of the data rate and the measurement time into N in the following formula (2), and the allowable value of the error rate is calculated as ER in the following formula (2). Ｓ The jitter tolerance measuring device according to claim 1, characterized in that the number of errors is substituted into E in the following formula (2) to calculate the reliability level. [Math 1]

3. The system further includes a pass / fail determination unit (17) that determines whether the jitter tolerance is acceptable or not based on a predetermined jitter mask, The jitter tolerance measuring device according to claim 1 or 2, characterized in that the result display screen displays the jitter tolerance, the judgment result of the pass / fail judgment unit, and the reliability level for each jitter frequency.

4. The jitter tolerance measuring device according to claim 3, further comprising a result output unit (21) that outputs the jitter tolerance for each jitter frequency, the judgment result of the pass / fail judgment unit, and the reliability level displayed on the result display screen in a predetermined file format.

5. A jitter modulation signal output unit (11) outputs a jitter modulation signal with variable jitter amplitude and jitter frequency, A jitter clock output unit (12) receives the jitter modulated signal from the jitter modulated signal output unit and outputs a phase-modulated jitter clock according to the jitter amplitude and the jitter frequency, A pattern signal generation unit (13) outputs a pattern signal synchronized with the jitter clock to the object under measurement, An error measurement unit (14) that measures the number of errors and the error rate of the output signal of the object under test that has received the pattern signal over a predetermined measurement period, A jitter tolerance measurement method using a jitter tolerance measuring device (1) comprising: a jitter tolerance measuring unit (16) that changes the jitter amplitude and jitter frequency of the jitter modulated signal output by the jitter modulated signal output unit, and estimates the maximum jitter amplitude for which the number of errors or error rate measured by the error measurement unit is less than or equal to a predetermined tolerance value, as the jitter tolerance of the object under test for each jitter frequency, wherein the jitter tolerance measuring device (1) is used, A setting screen display step (S1) is performed by displaying a setting screen (40) for setting the measurement conditions for the jitter tolerance on the display unit (32), An input step (S2) is to input the measurement time of the output signal and the allowable error rate of the output signal to the setting screen, A reliability level calculation step (S12) is performed to calculate a reliability level for the allowable error rate based on the data rate of the output signal, the number of errors in the output signal when the jitter tolerance is obtained by the jitter tolerance measuring unit, and the allowable values ​​of the measurement time and the error rate entered in the setting screen. The step includes displaying a result display screen (S14) on a display unit (32) which displays a result display screen (50, 60) showing the jitter tolerance and the reliability level, The aforementioned settings screen is, A measurement time input unit (43) for inputting the measurement time of the output signal, A method for measuring jitter tolerance, characterized by including a target error rate input section (45a, 45b) for inputting an allowable value of the error rate of the output signal.

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