Jitter tolerance measuring device and jitter tolerance measuring method

Abstract

The invention provides a jitter tolerance measuring device and a jitter tolerance measuring method, which can automatically calculate the confidence level of an output signal of a measured object when the jitter tolerance is obtained, and can quickly and easily confirm the confidence level of the jitter tolerance after a jitter tolerance test. A jitter tolerance measurement device is provided with: an error code measurement unit that measures, within a predetermined measurement time, an error measurement value of an output signal of a DUT that receives a code pattern signal synchronized with a jitter clock phase-modulated by a jitter modulation signal; a jitter tolerance measuring unit that changes the jitter amplitude and jitter frequency of the jitter modulation signal and estimates, for each jitter frequency, the maximum jitter amplitude at which the error measurement value measured by the error code measuring unit is equal to or less than a prescribed allowable value as the jitter tolerance of the DUT; a confidence level calculation unit that calculates a confidence level relating to an allowable value of the error rate of the output signal of the DUT; and a display unit that displays a result display screen showing the shake tolerance and the confidence level.

Description

Technical Field

[0001] This invention relates to a jitter tolerance measuring device and a jitter tolerance measuring method for measuring the jitter tolerance of a test object. Background Technology

[0002] For example, in communication standards such as USB (Universal Serial Bus) or PCIe (Peripheral Component Interconnect Express), a jitter tolerance test is performed to test whether the receiving part of the device under test (DUT) has the desired jitter tolerance (for example, see Patent Documents 1 and 2).

[0003] Figure 6 The structure of a conventional jitter tolerance measurement device 70 for performing jitter tolerance tests is shown. The jitter tolerance measurement device 70 consists of a jitter generator 71 that outputs a jitter clock that is phase-modulated using a jitter modulation signal with variable jitter amplitude and jitter frequency, a code pattern signal generator 72 that outputs a code pattern signal synchronized with the jitter clock output from the jitter generator 71 to the DUT 75, and a bit error rate meter 73 that performs bit error rate measurement of the output signal of the DUT 75 relative to the code pattern signal.

[0004] The jitter tolerance measuring device 70 configured in this way changes the jitter amplitude of the jitter modulation signal and measures the number of errors or error rate measured by the bit error rate measuring device 73. The maximum jitter amplitude below the specified allowable value is used as the jitter tolerance of the DUT 75.

[0005] Here, the lower limit of the jitter tolerance required in DUT75 is used as... Figure 7 The jitter mask shown is provided.

[0006] Here, the confidence level (CL) associated with 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 actual error rate of the DUT75's output signal is smaller than the predefined target BER (Bit Error Rate).

[0007] [Formula 1]

[0008]

[0009] In addition, in equation (1),

[0010] N: Bit rate [bit / s] × Measurement time [s] (number of bits measured)

[0011] BER S Target BER

[0012] E: Target error count.

[0013] Patent Document 1: Japanese Patent Application Publication No. 08-050156

[0014] Patent Document 2: Japanese Patent No. 4376064

[0015] However, conventional measuring devices, as disclosed in Patent Documents 1 and 2, cannot automatically evaluate the confidence level CL of the output signal of the DUT75 when jitter tolerance is obtained.

[0016] Therefore, the following problem existed in the past: when conducting jitter tolerance tests, in order to obtain the confidence level CL of the test results, the user had to perform complicated tasks such as opening websites to perform calculations based on the test results. Summary of the Invention

[0017] This invention was made to solve this previous problem, and its purpose is to provide a jitter tolerance measuring device and a jitter tolerance measuring method that automatically calculates the confidence level of the output signal of the test object when jitter tolerance is obtained and can quickly and easily confirm the confidence level of jitter tolerance after jitter tolerance test.

[0018] To address the aforementioned issues, the jitter tolerance measurement device of 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 jitter clock that has undergone phase modulation according to the jitter amplitude and the jitter frequency; a code pattern signal generation unit 13 that outputs a code pattern signal synchronized with the jitter clock to the device under test (DUT); a bit error rate measurement unit 14 that measures the number of errors and the error rate of the output signal of the DUT that receives the code pattern signal within a specified measurement time; and a jitter tolerance measurement unit 16 that changes the jitter amplitude and the jitter frequency of the jitter modulation signal output by the jitter modulation signal output unit, and estimates the maximum jitter amplitude below a specified allowable value for each jitter frequency as the jitter tolerance of the DUT. The jitter tolerance measuring device 1 includes a display unit 32 that displays a jitter tolerance result display screen 50 and 60 and a setting screen 40 for setting conditions related to the jitter tolerance measurement. The jitter tolerance measuring device 1 has the following structure: the result display screen displays the jitter tolerance and the confidence level; the setting screen includes a measurement time input unit 43 for inputting the measurement time of the output signal; and target error rate input units 45a and 45b for inputting the allowable value of the error rate of the output signal. The jitter tolerance measuring device includes a confidence level calculation unit 20 for calculating the confidence level related to the allowable value of the error rate of the output signal. The confidence level calculation unit calculates the confidence level based on the data transmission rate of the output signal, the number of errors in the output signal obtained by the jitter tolerance measuring unit at the jitter tolerance, and the measurement time and the allowable value of the error rate input to the setting screen.

[0019] According to this structure, the jitter tolerance measurement device of the present invention automatically calculates the confidence level of the output signal of the test object under jitter tolerance and displays the measurement results of jitter tolerance and confidence level on the result display screen. Therefore, the jitter tolerance measurement device of the present invention enables users to quickly and easily confirm the confidence level of jitter tolerance after a jitter tolerance test.

[0020] Furthermore, the jitter tolerance measurement device involved in this invention can have the following structure: the confidence level calculation unit substitutes the product of the data transmission rate and the measurement time into N in the following equation (2), and substitutes the allowable value of the error rate into ER in the following equation (2). S The confidence level is calculated by substituting the number of errors into E in the following equation (2).

[0021] [Formula 2]

[0022]

[0023] Furthermore, the jitter tolerance measurement device involved in the present invention may have the following structure, namely, it further includes a pass / fail determination unit 17 that determines whether the jitter tolerance is qualified or not based on a preset jitter mask, and the result display screen displays the jitter tolerance, the determination result of the pass / fail determination unit and the confidence level for each jitter frequency.

[0024] According to this structure, the jitter tolerance measurement device of the present invention displays the judgment result and confidence level of the pass / fail determination unit on the result display screen according to each jitter frequency. Therefore, the jitter tolerance measurement device of the present invention makes it easy for users to perform verification based on the pass / fail determination unit using the confidence level.

[0025] Furthermore, the jitter tolerance measurement device according to the present invention may have the following structure, namely, it further includes a jitter tolerance for each jitter frequency, the determination result of the pass / fail determination unit, and the result output unit of the confidence level, which outputs the result in a predetermined file format and displays it on the result display screen.

[0026] According to this structure, the jitter tolerance measurement device of the present invention outputs the jitter tolerance, the judgment result of the pass / fail determination section, and the confidence level for each jitter frequency displayed on the result display screen in a specified file format. Therefore, even after a jitter tolerance test, the jitter tolerance measurement device of the present invention makes it easy for the user to verify the measurement results of the jitter tolerance test using the confidence level.

[0027] Furthermore, the jitter tolerance measurement method of the present invention uses a jitter tolerance measurement device 1, which 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 jitter clock that has undergone phase modulation according to the jitter amplitude and the jitter frequency; a code pattern signal generation unit 13 that outputs a code pattern signal synchronized with the jitter clock to the device under test; and a bit error rate measurement unit 14. The measurement unit 16 measures the number of errors and the error rate of the output signal of the device under test (DUT) receiving the code signal within a specified measurement time. The jitter tolerance measurement unit 16 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 below a specified allowable value for each jitter frequency, using this maximum jitter amplitude as the jitter tolerance of the DUT. The display unit 32 displays a result screen showing the jitter tolerance. 50, 60, and setting screen 40, the jitter tolerance measurement method has the following structure, namely: a setting screen display step S1, displaying a setting screen on the display unit for setting conditions related to the jitter tolerance measurement; an input step S2, inputting the measurement time of the output signal and the allowable value of the error rate of the output signal into the setting screen; a confidence level calculation step S12, calculating a confidence level related to the allowable value of the error rate based on the data transmission rate of the output signal, the number of errors of the output signal when the jitter tolerance is obtained by the jitter tolerance measurement unit, and the measurement time and the allowable value of the error rate input into the setting screen; and a result display screen display step S14, displaying a result display screen showing the jitter tolerance and the confidence level on the display unit. The setting screen includes: a measurement time input unit 43 for inputting the measurement time of the output signal; and target error rate input units 45a and 45b for inputting the allowable value of the error rate of the output signal.

[0028] Furthermore, the jitter tolerance measurement method involved in this invention can be structured as follows: in the confidence level calculation step, the product of the data transmission rate and the measurement time is substituted into N in the following equation (2), and the allowable value of the error rate is substituted into ER in the following equation (2). S The confidence level is calculated by substituting the number of errors into E in the following equation (2).

[0029] [Formula 1]

[0030]

[0031] Furthermore, the jitter tolerance measurement method involved in this invention can be structured as follows: using a pre-set jitter mask as a reference, a judgment is made on whether the jitter tolerance is qualified or not; the result display screen displays the jitter tolerance, the judgment result after the qualification or failure judgment, and the confidence level for each jitter frequency.

[0032] Furthermore, the jitter tolerance measurement method involved in this invention can be structured as follows: outputting the jitter tolerance, the pass / fail determination result, and the confidence level result for each jitter frequency displayed on the result display screen in a specified file format.

[0033] Invention Effects

[0034] This invention provides a jitter tolerance measurement device and method that automatically calculates the confidence level of the output signal of the test object when jitter tolerance is obtained and can quickly and easily confirm the confidence level of jitter tolerance after jitter tolerance test. Attached Figure Description

[0035] Figure 1 This is a block diagram illustrating the structure of the jitter tolerance measurement device according to an embodiment of the present invention.

[0036] Figure 2 This is an example of the setting screen of the jitter tolerance measurement device according to an embodiment of the present invention.

[0037] Figure 3 This is an example of a result display screen of a jitter tolerance measurement device according to an embodiment of the present invention.

[0038] Figure 4 This is an example of a detailed result display screen of the jitter tolerance measurement device according to an embodiment of the present invention.

[0039] Figure 5 This is a flowchart illustrating the process of a jitter tolerance measurement method using the jitter tolerance measurement device according to an embodiment of the present invention.

[0040] Figure 6 This is a block diagram showing the structure of a conventional jitter tolerance measurement device.

[0041] Figure 7 This is a diagram used to illustrate an example of a dithering mask. Detailed Implementation

[0042] Hereinafter, embodiments of the jitter tolerance measurement device and jitter tolerance measurement method according to the present invention will be described with reference to the accompanying drawings.

[0043] like Figure 1As shown, the jitter tolerance measuring device 1 according to the embodiment of the present invention performs a jitter tolerance test to measure the jitter tolerance of DUT200, and includes a jitter generation unit 10, a code pattern signal generation unit 13, a bit error measurement unit 14, a control unit 15, a data storage unit 30, an operation unit 31, and a display unit 32.

[0044] Examples of standards corresponding to DUT200 include PCIe Gen1-6, USB (registered trademark) (Universal Serial Bus) 3.0-4, CEI (Common Electrical Interface), IEEE 802.3, InfiniBand HDR, and Fibre Channel.

[0045] The jitter generator 10 has a jitter modulation signal output unit 11 and a jitter clock output unit 12.

[0046] 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.

[0047] The jitter clock output unit 12 receives the jitter modulation signal from the jitter modulation signal output unit 11 and outputs a jitter clock whose phase is modulated according to the jitter amplitude and jitter frequency of the jitter modulation signal.

[0048] The data storage unit 30 is composed of a memory such as RAM (Random Access Memory). The data storage unit 30 stores, for example, bit string data (data consisting of bit strings of 0 or 1) of NRZ (Non Return to Zero) signals (hereinafter also referred to as "NRZ signals") or symbol string data (data consisting of symbol strings of 0, 1, 2 or 3) of PAM4 (Pulse Amplitude Modulation 4) signals (hereinafter also referred to as "PAM4 signals") as known code pattern signal data input to the DUT200 from the code pattern signal generation unit 13 described later.

[0049] Furthermore, the data storage unit 30 can store the bit string data of the MSB (Most Significant Bit) and LSB (Least Significant Bit) of the PAM4 signal input to the DUT200. 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 30 also serve as reference data for the bit error rate measurement unit 14, described later, to compare with the output signal of the DUT200.

[0050] The pattern signal generation unit 13 generates a pattern signal composed of data with known patterns input from the data storage unit 30 and synchronizes it with the jitter clock from the jitter clock output unit 12.

[0051] Furthermore, the pattern signal generator 13 outputs the generated pattern signal to the DUT 200 as a test signal. At this time, the DUT 200 feeds back the pattern signal output from the pattern signal generator 13 and sets it as the output signal to the bit error measurement unit 14.

[0052] The bit error measurement unit 14 measures the number of errors and the error rate of the output signal of the DUT200 received from the code pattern signal generation unit 13 according to each combination of jitter amplitude and jitter frequency of the jitter modulation signal within a specified measurement time.

[0053] The bit error measurement unit 14 calculates the error rate of the output signal of the DUT200 by sequentially comparing the bit string data or symbol string data contained in the output signal of the DUT200 with the reference data stored in the data storage unit 30.

[0054] In addition, the jitter tolerance of the bit error measurement unit 14 itself is significantly higher than the jitter tolerance measurement range of the DUT200.

[0055] The bit error rate measurement unit 14 counts the number of errors in the output signal of the DUT200 within the measurement time set by the setting screen 40 (described later). Furthermore, the bit error rate measurement unit 14 calculates the error rate of the output signal by dividing the counted number of errors by the number of measured data points of the output signal within the aforementioned measurement time.

[0056] The control unit 15 may be composed of a computer or other control device, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (Field Programmable Gate Array), ROM (Read Only Memory), RAM, HDD (Hard Disk Drive).

[0057] The control unit 15 centrally controls the jitter generation unit 10, the code pattern signal generation unit 13, the bit 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 software-configures the jitter tolerance measurement unit 16, the pass / fail determination unit 17, the transmission speed conversion unit 18, the confidence level calculation unit 20, and the result output unit 21 by executing a predetermined program via a CPU or GPU.

[0058] The operation unit 31 is used to accept user operation input, by Figure 1 The jitter tolerance measuring device 1 shown has a user interface consisting of, for example, an operation knob, various keys, switches, buttons, or soft keys on the display screen of the display unit 32. Furthermore, the operation unit 31 performs various settings related to the jitter tolerance measurement of the jitter tolerance measuring device 1, or sets various measurement conditions on the setting screen 40 described later.

[0059] Display unit 32 consists of Figure 1 The jitter tolerance measuring device 1 shown is equipped with a display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays a setting screen 40, a result display screen 50, and a detailed result display screen 60 based on the display control signal from the control unit 15. Furthermore, the display unit 32 may have the operation functions of the operation unit 31, such as soft keys on the display screen.

[0060] The jitter tolerance measurement unit 16 changes the jitter amplitude and jitter frequency of the jitter modulation signal output by the jitter modulation signal output unit 11, and estimates the number of errors or error rate (hereinafter also referred to as "error measurement value") measured by the bit error measurement unit 14 at each jitter frequency. The maximum jitter amplitude below the specified allowable value Th is used as the jitter tolerance of the DUT200.

[0061] For example, the jitter tolerance measurement unit 16 gradually increases the jitter amplitude from a predetermined lower limit value LL until the erroneous measurement value exceeds the allowable value Th. If the erroneous measurement value exceeds the allowable value Th while reaching the predetermined upper limit value UL, the maximum jitter amplitude before the erroneous measurement value exceeds the allowable value Th is taken as the jitter tolerance. If the erroneous measurement value does not exceed the allowable value Th even if the jitter amplitude reaches or exceeds the upper limit value UL, the jitter tolerance measurement unit 16 sets the upper limit value UL as the jitter tolerance. If the erroneous measurement value has exceeded the allowable value Th when the jitter amplitude is at the lower limit value LL, the jitter tolerance measurement unit 16 takes the lower limit value LL as the jitter tolerance.

[0062] The pass / fail determination unit 17 determines whether the jitter tolerance estimated by the jitter tolerance measurement unit 16 is pass / fail based on a preset jitter mask.

[0063] like Figure 2 As shown, the display unit 32 displays a setting screen 40 for setting the measurement conditions related to the jitter tolerance of the output signal of the DUT200.

[0064] The settings screen 40 includes drop-down menus 41a and 41b for "Unit", radio buttons 42a for "Gating", radio buttons 42b for "Target Confidence Level", a rotary box 43 for "Gating", a rotary box 44 for "Target Confidence Level", rotary boxes 45a and 45b for "Target ER", a rotary box 46 for "Target EC", and a soft key 47 for "Close".

[0065] The "Unit" drop-down menu 41a allows selection of either the number of errors or the error rate of the output signal of the DUT200 measured by the bit error measurement unit 14. The "Unit" drop-down menu 41b allows selection of the measurement unit for the number of errors or the error rate set by the "Unit" drop-down menu 41a, for example, from Bit, PAM4 Symbol, Flit, or Codeword.

[0066] The radio buttons 42a for “Gating” and 42b for “Target Confidence Level” allow users to choose whether to set the measurement time using the “Gating” rotary dial 43 or to set the allowable value of the confidence level, i.e., the target confidence level CL, using the “Target Confidence Level” rotary dial 44. S .

[0067] When the radio button 42a for "Gating" is selected, the "Gating" rotary box 43 allows the measurement time to be input in 1-second units within a range of 1 to 86,400 seconds. That is, the "Gating" rotary box 43 constitutes a measurement time input section for inputting the measurement time of the output signal of the DUT200.

[0068] Furthermore, when the radio button 42b for “Target Confidence Level” is selected, the “Gating” rotation box 43 becomes uninputable, for example, displaying the measurement time calculated by a mechanism not shown in 1 second in the range of 1 to 172,800 seconds.

[0069] When the radio button 42b for “Target Confidence Level” is selected, the “Target Confidence Level” rotary box 44 allows the target confidence level CL to be entered in 0.1% units within a range of 0.0% to 99.9%. S .

[0070] Furthermore, when the radio button 42a for “Gating” is selected, the swivel box 44 for “Target Confidence Level” becomes unreadable.

[0071] The rotating frames 45a and 45b of “Target ER” constitute the target error rate ER for inputting the output signal of DUT200. s The target error rate input section. Target error rate ER s It is the allowable value for the error rate of the output signal of DUT200 in the bit error measurement based on the bit error measurement unit 14.

[0072] Rotating frames 45a and 45b can input the target error rate ER using exponential markings. s Enter the significant digit in rotation box 45a and the exponent digit in rotation box 45b. For example, values ​​in the range of 1E-15 to 9E-3 can be entered in rotation boxes 45a and 45b.

[0073] When the radio button 42b for “Target Confidence Level” is selected, the rotary box 46 for “Target EC” can be used to input the target error number E in the measurement time of the output signal of the DUT200.

[0074] For example, a value in the range of 0 to 10 can be entered in the rotation box 46. The unit of the target error number E entered in the rotation box 46 changes according to the measurement unit selected via the "Unit" drop-down menu 41b.

[0075] Furthermore, when the radio button 42a for “Gating” is selected, the swivel box 46 for “Target EC” becomes unenterable.

[0076] If the user presses the "Close" soft key 47, the control unit 15 sets the measurement time of the rotating frame 43 currently displayed on "Gating" to the error measurement unit 14 and ends the display of the setting screen 40.

[0077] The transmission speed conversion unit 18 converts the known baud rate of the DUT200's output signal into a transmission speed (data transfer rate) corresponding to the measurement unit of the DUT200's output signal. The baud rate of the DUT200's output signal can be set on a setting screen (not shown).

[0078] Data transfer rate is a parameter representing the number of measurement units contained in one second of the DUT200's output signal. The measurement unit can be, for example, any of the following: bit, symbol (PAM4 symbol), flow control unit (Flit), or codeword.

[0079] Target Error Rate (ER) S For example, it can be any of BER, SER (Symbol Error Rate), Uncorrectable Codeword Rate, or Flit Error Rate, which is the upper limit that the bit error rate of the output signal can be allowed.

[0080] "Bit" is the measurement unit when measuring the BER of the DUT200's output signal. When the measurement unit is "Bit" and the DUT200's output signal is an NRZ signal, the transmission speed conversion unit 18 directly outputs the baud rate of the DUT200's output signal as the data transmission rate. When the measurement unit is "Bit" and the DUT200's output signal is a PAM4 signal, the transmission speed conversion unit 18 outputs the rate obtained by multiplying the DUT200's output signal's baud rate by 2 as the data transmission rate.

[0081] “PAM4 Symbol” is the measurement unit when measuring the SER of the output signal of DUT200. When the measurement unit is “PAM4 Symbol” and the output signal of DUT200 is a PAM4 signal, the transmission speed conversion unit 18 directly outputs the baud rate of the output signal of DUT200 as the data transmission rate.

[0082] "Flit" is the unit of measurement for the Flit Error Rate of the DUT200's output signal. When the unit of measurement is "Flit," the data transmission rate is obtained by multiplying the baud rate of the DUT200's output signal output by the transmission speed conversion unit 18 by 2 and dividing by the Flit length. Here, the Flit length is 2048 bits.

[0083] "Codeword" is the unit of measurement for the Uncorrectable Codeword Rate of the DUT200's output signal. When the unit of measurement is "Codeword," the data transmission rate is obtained by multiplying the baud rate of the DUT200's output signal output by the transmission speed conversion unit 18 by 2 and dividing by the CW (Codeword) length. Here, in the case of RS-FEC (Reed-Solomon Forward Error Correction) (544, 514) as specified in IEEE 802.3, the CW length is 5440 bits.

[0084] The confidence level calculation unit 20 uses the number of errors measured by the bit error measurement unit 14 when the jitter tolerance is obtained by the jitter tolerance measurement unit 16 to calculate the target error rate ER. s The relevant confidence level. The confidence level represents the correlation with the target error rate ER. S The probability that the true error rate of the output signal of DUT200 is reduced compared to that of DUT200.

[0085] Specifically, the confidence level calculation unit 20 substitutes the product of the data transmission rate [data / s] output from the transmission speed conversion unit 18 and the measurement time [s] of the rotating frame 43 of "Gating" input on the setting screen 40 into N in the following formula (2), and calculates the target error rate ER of the rotating frames 45a and 45b of "Target ER" input on the setting screen 40. s Substituting ER into equation (2) below S The confidence level CL is calculated by substituting the number of errors measured by the error measurement unit 14 into E in the following formula (2).

[0086] [Formula 3]

[0087]

[0088] N is a parameter representing the number of measurement units, i.e., the number of measurement data, contained in the output signal of DUT200 during the measurement time. The measurement unit can be set through the "Unit" drop-down menu 41b on the setting screen 40.

[0089] Figure 3The result display screen 50 shown by the display unit 32 is illustrated. The result display screen 50 includes a measurement result table 51 and a soft key 52 for "Detail".

[0090] The “Meas.[UI]” column in the measurement results table 51 shows the jitter tolerance estimated by the jitter tolerance measurement unit 16 for each jitter frequency.

[0091] The "Meas.Judge" column in Measurement Results Table 51 displays the judgment result based on the pass / fail determination unit 17 for each jitter frequency. "PASS" indicates that the jitter tolerance estimated by the jitter tolerance measurement unit 16 is above the preset jitter mask. "FAIL" indicates that the jitter tolerance estimated by the jitter tolerance measurement unit 16 is below the preset jitter mask.

[0092] The “CL” column in the measurement results table 51 represents the confidence level CL[%] calculated by the confidence level calculation unit 20 for each jitter frequency.

[0093] If the user presses the "Detail" soft key 52, the control unit 15 will... Figure 4 The detailed results display screen 60 is displayed on the display unit 32. 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 confidence level CL calculated by the confidence level calculation unit 20 are also displayed for each jitter frequency.

[0094] exist Figure 3 and Figure 4 In the example shown, the confidence level CL in the "CL" column is 0.0% when the result of the pass / fail determination unit 17 is "FAIL". However, based on the allowable value Th of the number of errors or error rate in the jitter tolerance measurement unit 16 and the value of the jitter mask, it can take a value greater than 0.0%.

[0095] The results output unit 21 outputs various measurement results, including jitter tolerance, judgment result, and confidence level CL, displayed in the measurement results table 51 or detailed measurement results table 61 in a specified file format. Here, the specified file format is, for example, HTML (HyperText Markup Language) or CSV (Comma Separated Values).

[0096] The file output from the output unit 21 can be stored in the data storage unit 30, or it can be stored in an external storage device or a computer-readable recording medium.

[0097] The following describes the jitter tolerance measurement method using the jitter tolerance measurement device 1 of this embodiment, with reference to... Figure 5The flowchart illustrates one example of its processing. Additionally, descriptions that overlap with the description of the structure of the jitter tolerance measuring device 1 described above are omitted where appropriate.

[0098] First, the control unit 15 displays a setting screen 40 on the display unit 32 for setting the measurement conditions related to the jitter tolerance of the output signal of the DUT200 (setting screen display step S1).

[0099] Next, the user, via the operation unit 31, inputs the measurement time of the DUT200's output signal, 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. s Input the measurement conditions on the setting screen 40 (input step S2).

[0100] Next, the transmission speed conversion unit 18 converts the baud rate of the output signal of the DUT200 into a transmission speed (data transmission rate) corresponding to the measurement unit input in the setting screen 40 in the input step S2 (step S3).

[0101] Next, by having the user press the "Close" soft key 47 on the setting screen 40, the control unit 15 sets the measurement time of the rotating frame 43 of "Gating" currently displayed on the setting screen 40 to the error measurement unit 14 (step S4).

[0102] Next, the jitter tolerance measurement unit 16 sets the specified jitter frequency to the jitter modulation signal output unit 11 (step S5).

[0103] Next, the jitter tolerance measurement unit 16 sets the specified jitter amplitude to the jitter modulation signal output unit 11 (step S6).

[0104] Next, the code signal generation unit 13 outputs the code signal, which has been phase-modulated according to the jitter frequency and jitter amplitude set in steps S5 and S6, to the DUT200 (step S7).

[0105] Next, the error measurement unit 14 counts the number of errors in the output signal of the DUT200 within the measurement time set by the control unit 15 in step S4, and calculates the error rate of the output signal of the DUT200 (step S8).

[0106] Next, the jitter tolerance measurement unit 16 determines whether the erroneous measurement value obtained in step S8 is below the specified allowable value Th (step S9).

[0107] If the error measurement value obtained in step S8 is below the specified allowable value Th (step S9: Yes), in step S6, the jitter tolerance measurement unit 16 sets a larger jitter amplitude to the jitter modulation signal output unit 11. Furthermore, it is assumed that in the processing of step S6 in this flowchart, the jitter amplitude is increased stepwise from the preset lower limit value LL for each jitter frequency.

[0108] If the error measurement value obtained in step S8 is greater than the specified allowable value Th (step S9: no), in step S10, the jitter tolerance measurement unit 16 estimates the maximum jitter amplitude below the specified allowable value Th when the error measurement value obtained in step S8 is obtained, and uses it as the jitter tolerance at the currently set jitter frequency (step S10).

[0109] Next, the pass / fail determination unit 17 determines whether the jitter tolerance estimated in step S10 is pass / fail based on the preset jitter mask (step S11).

[0110] Next, the confidence level calculation unit 20 calculates the data transmission rate converted in step S3, the number of errors in the output signal of the DUT200 when jitter tolerance is obtained in step S10, and the measurement time and target error rate ER input in the setting screen 40 in the input step S2. S Calculate the confidence level CL (confidence level calculation step S12).

[0111] If the jitter tolerance estimation process in step S10 has not yet been completed for all preset jitter frequencies (step S13: No), in step S5, the jitter tolerance measurement unit 16 sets a new jitter frequency to the jitter modulation signal output unit 11.

[0112] When the jitter tolerance estimation process in step S10 is completed for all preset jitter frequencies (step S13: Yes), the control unit 15 displays a display screen 50 on the display unit 32 showing the jitter tolerance estimated in step S10, the result of whether the jitter tolerance determined in step S11 is qualified or not, and the confidence level CL calculated in the confidence 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).

[0113] As explained above, the jitter tolerance measurement device 1 of this embodiment automatically calculates the confidence level CL of the output signal of the DUT200 under jitter tolerance conditions and displays the measurement results of jitter tolerance and confidence level CL on the result display screen 50. Therefore, the jitter tolerance measurement device 1 of this embodiment enables users to quickly and easily confirm the confidence level of the jitter tolerance after a jitter tolerance test.

[0114] Furthermore, the jitter tolerance measuring device 1 according to this embodiment displays the judgment result of the pass / fail determination unit 17 and the confidence level CL on the result display screen 50 according to each jitter frequency. As a result, the jitter tolerance measuring device 1 according to this embodiment makes it easy for users to perform verification based on the pass / fail determination unit 17 using the confidence level CL.

[0115] Furthermore, the jitter tolerance measuring device 1 according to this embodiment outputs the jitter tolerance for each jitter frequency, the judgment result of the pass / fail determination unit 17, and the confidence level CL for each jitter frequency displayed on the result display screen 50 in a prescribed file format. Therefore, even after a jitter tolerance test, the jitter tolerance measuring device 1 according to this embodiment makes it easy for the user to verify the measurement results of the jitter tolerance test using the confidence level CL.

[0116] Symbol Explanation

[0117] 1-Jitter tolerance measurement device, 10-Jitter generator, 11-Jitter modulation signal output unit, 12-Jitter clock output unit, 13-Code pattern signal generator, 14-Bit error measurement unit, 15-Control unit, 16-Jitter tolerance measurement unit, 17-Pass / fail judgment unit, 18-Transmission speed conversion unit, 20-Confidence level calculation unit, 21-Result output unit, 30-Data storage unit, 31-Operation unit, 32-Display unit, 40-Setting screen, 41a, 41b-Drop-down menu, 42a, 42b-Radio buttons, 43, 44, 45a, 45b, 46-Rotating frame, 50-Result display screen, 51-Measurement result table, 60-Detailed result display screen (Result Display Screen), 61-Detailed measurement result table, 200-DUT.

Claims

1. A jitter tolerance measuring device, comprising: The jitter modulation signal output unit (11) outputs a jitter modulation signal with variable jitter amplitude and jitter frequency; The jitter clock output unit (12) receives the jitter modulation signal from the jitter modulation signal output unit and outputs a jitter clock that has been phase-modulated according to the jitter amplitude and the jitter frequency; The code signal generator (13) outputs a code signal synchronized with the jitter clock to the object under test; The error measurement unit (14) measures the number of errors and the error rate of the output signal of the device under test that receives the code signal within a specified measurement time. The jitter tolerance measurement unit (16) 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 below a predetermined allowable value for the number of errors or error rate measured by the bit error measurement unit at each jitter frequency as the jitter tolerance of the test object. and The display unit (32) displays a result display screen (50, 60) showing the jitter tolerance and a setting screen (40) for setting conditions related to the jitter tolerance measurement. The jitter tolerance measuring device (1) is characterized in that... The results display screen shows the jitter tolerance and confidence level. The settings screen includes: The measurement time input unit (43) is used to input the measurement time of the output signal; and The target error rate input units (45a, 45b) are used to input the allowable value of the error rate of the output signal. The jitter tolerance measurement device includes a confidence level calculation unit (20) that calculates the confidence level related to the allowable value of the error rate of the output signal. The confidence level calculation unit calculates the confidence level based on the data transmission rate of the output signal, the number of errors in the output signal at the jitter tolerance obtained by the jitter tolerance measurement unit, and the allowable values ​​of the measurement time and the error rate input to the setting screen.

2. The jitter tolerance measuring device according to claim 1, characterized in that, The confidence level calculation unit substitutes the product of the data transmission rate and the measurement time into N in the following equation (2), and substitutes the allowable value of the error rate into ER in the following equation (2). S The confidence level is calculated by substituting the number of errors into E in equation (2) below. [Formula 1] 。 3. The jitter tolerance measuring device according to claim 1 or 2, characterized in that, It also has: The pass / fail determination unit (17) determines whether the jitter tolerance is pass / fail based on a preset jitter mask. The results display screen shows the jitter tolerance, the judgment result of the pass / fail determination unit, and the confidence level for each jitter frequency.

4. The jitter tolerance measuring device according to claim 3, characterized in that, It also has: The result output unit (21) outputs the jitter tolerance, the pass / fail determination result and the confidence level of each jitter frequency displayed on the result display screen in a specified file format.

5. A jitter tolerance measurement method, which uses a jitter tolerance measurement device (1), the jitter tolerance measurement device (1) comprising: The jitter modulation signal output unit (11) outputs a jitter modulation signal with variable jitter amplitude and jitter frequency; The jitter clock output unit (12) receives the jitter modulation signal from the jitter modulation signal output unit and outputs a jitter clock that has been phase-modulated according to the jitter amplitude and the jitter frequency; The code signal generator (13) outputs a code signal synchronized with the jitter clock to the object under test; The error measurement unit (14) measures the number of errors and the error rate of the output signal of the device under test that receives the code signal within a specified measurement time. The jitter tolerance measurement unit (16) 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 below a predetermined allowable value for the number of errors or error rate measured by the bit error measurement unit at each jitter frequency as the jitter tolerance of the test object. and The display unit (32) displays a result display screen (50, 60) and a setting screen (40) showing the jitter tolerance result. The jitter tolerance measurement method is characterized by including: In the setting screen display step (S1), the setting screen used to make settings related to the measurement conditions of the jitter tolerance is displayed on the display unit; Input step (S2): Input the measurement time of the output signal and the allowable value of the error rate of the output signal into the setting screen; The confidence level calculation step (S12) calculates a confidence level related to the allowable value of the error rate based on the data transmission rate of the output signal, the number of errors in the output signal at the jitter tolerance time obtained by the jitter tolerance measurement unit, the measurement time input to the setting screen, and the allowable value of the error rate; and In the result display screen step (S14), the result display screen showing the jitter tolerance and the confidence level is displayed on the display unit. The settings screen includes: Measurement time input unit (43) is used to input the measurement time of the output signal; and The target error rate input section (45a, 45b) is used to input the allowable value of the error rate of the output signal.

6. The jitter tolerance measurement method according to claim 5, characterized in that, In the confidence level calculation step, the product of the data transmission rate and the measurement time is substituted into N in the following equation (2), and the allowable value of the error rate is substituted into ER in the following equation (2). S The confidence level is calculated by substituting the number of errors into E in equation (2) below. [Formula 1] 。 7. The jitter tolerance measurement method according to claim 5 or 6, characterized in that, Based on a pre-set jitter mask, a judgment is made as to whether the jitter tolerance is qualified or not. The results display screen shows the jitter tolerance, the judgment result after the pass / fail determination, and the confidence level for each jitter frequency.

8. The jitter tolerance measurement method according to claim 7, characterized in that, The jitter tolerance, the judgment result after the pass / fail determination, and the confidence level result are output and displayed on the result display screen for each jitter frequency in a specified file format.

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