JP2017138153A - Jitter tolerance measurement device and jitter tolerance measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To predict the jitter tolerance point of a desired bit error rate.SOLUTION: An operation unit 3a selects one of upward, downward, and binary as a search method, sets a reference bit error rate in accordance with the search method so as to satisfy the relationship of bit error rate 1E-6 > upward reference bit error rate ER1 > binary reference bit error rate ER2 > downward reference bit error rate ER3, and sets a bit error rate to be predicted. A control unit 3b narrows down the value of sine jitter amplitude toward a reference error rate that corresponds to the search method selected by the operation unit 3a, finds a virtual linear line using a least square method on the basis of a measurement result in a preset calculation range of measurement results thereby, and predicts the intersection of this linear line with the bit error rate set by the operation unit 3a as a jitter tolerance point.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a jitter tolerance measuring apparatus and a jitter tolerance measuring method for measuring a jitter tolerance of a desired bit error rate of a measurement target such as a data transmission device.

  The jitter tolerance characteristic represents a limit for each jitter frequency with respect to the amount of jitter that is gradually added to the measurement target, to what extent the jitter can be tolerated without generating an error. This jitter tolerance characteristic is known as a typical characteristic defined in international standards such as ITU-T and Telcordia, regarding the jitter characteristic of a device connected to a network such as SDH, SONET, and OTN. The jitter tolerance characteristic can be determined by comparing the characteristic JT obtained by the measurement with the standard characteristic R to determine whether the jitter tolerance of the measurement object is good or bad.

  Conventionally, as a jitter tolerance measuring apparatus for automatically measuring the jitter tolerance described above, for example, the one disclosed in Patent Document 1 below is known.

  The jitter tolerance measuring device disclosed in Patent Document 1 includes a jitter generation unit, an error measuring device, a jitter tolerance detector, a specific error determination unit, and an error measurement regulation unit. More specifically, the jitter generation unit in the jitter tolerance measuring apparatus generates a data signal to which jitter is added and inputs the data signal to the measurement target. The error measuring device measures the error rate of the data signal output from the measurement object in accordance with the input of the data signal to which jitter is added. The jitter tolerance detector varies the amount of jitter added to the data signal by the jitter generator in accordance with the preset change width and the measurement result of the error rate measuring device, and the maximum error rate falls within a predetermined value. Is determined as the jitter tolerance value of the measurement target. The specific error determination unit determines whether or not the measurement target is in the specific error state every time the jitter tolerance detector changes the jitter amount. The error measurement restricting means stops the measurement operation by the error measuring device while the measurement target is in the specific error state. As a result, even when the measurement object enters a specific error state due to the variable amount of jitter, it is possible to accurately measure the jitter tolerance characteristic.

Japanese Patent Laying-Open No. 2005-030868

  By the way, when measuring the jitter tolerance of the measurement object by the jitter tolerance measurement apparatus, an upward which increases the jitter amount by a predetermined step toward the jitter tolerance point of the desired bit error rate, the jitter tolerance point of the desired bit error rate Either a downward search that reduces the jitter amount by a predetermined step toward the target, or a binary (binary search) search that changes the jitter amount while halving the search interval toward the jitter tolerance point of the desired bit error rate The method is used to drive the jitter tolerance point.

However, when the jitter tolerance is measured using the jitter tolerance measuring apparatus disclosed in Patent Document 1, it is possible to cope with the short-time measurement of the jitter tolerance point at a high rate. However, as shown in FIG. There is a problem that it takes a lot of time to actually measure a low-rate jitter tolerance point of −12 (= 10 ⁻¹² ) or less.

  Therefore, the present invention has been made in view of the above problems, and a jitter tolerance measuring apparatus and jitter tolerance capable of predicting a jitter tolerance point of a desired bit error rate in a jitter tolerance characteristic of a measurement target in a short time. The purpose is to provide a measurement method.

To achieve the above object, a jitter tolerance measuring apparatus according to claim 1 of the present invention is a jitter tolerance measuring apparatus 1 for measuring a jitter tolerance point at a predetermined bit error rate.
Select one of the search methods from among the up search that increases the jitter amount by a predetermined step width, the down word that decreases the jitter amount by a predetermined step width, and the binary that changes the jitter amount while dividing the search interval in half. Bit error rate 1E-6> Upward reference bit error rate ER1> Binary reference bit error rate ER2> Downward reference bit error rate ER3 in accordance with the selected search method An operation unit 3a for setting a reference bit error rate and setting a bit error rate to be predicted;
The value of the sine jitter amplitude is driven toward the reference error rate corresponding to the search method selected by the operation unit, and the minimum two values are obtained based on the measurement result in the preset calculation range of the measurement result obtained by this tracking. And a control unit 3b that obtains a virtual straight line using multiplication and predicts an intersection between the virtual straight line and the bit error rate set by the operation unit as a jitter tolerance point.

The jitter tolerance measuring method according to claim 2 is a jitter tolerance measuring method for measuring a jitter tolerance point at a predetermined bit error rate.
The search method is selected from among an upward that increases the jitter amount by a predetermined step width, a downward that decreases the jitter amount by a predetermined step width, and a binary that changes the jitter amount while dividing the search interval in half. Steps,
Bit error rate 1E-6> Reference bit error rate ER1 of the above> Reference bit error rate ER2 of the binary> Reference bit error rate ER3 of the down word is satisfied according to the selected search method. Setting a reference bit error rate;
Setting the bit error rate you want to predict;
The value of the sine jitter amplitude is driven toward the reference error rate corresponding to the selected search method, and the least square method is used based on the measurement result of the preset calculation range of the measurement result obtained by this tracking. Obtaining a virtual straight line and predicting an intersection between the virtual straight line and the set bit error rate as a jitter tolerance point.

  According to the present invention, it is possible to predict a jitter tolerance point of a desired bit error rate in a jitter tolerance characteristic to be measured in a short time. And even if it is a low rate jitter tolerance point which requires a long time in normal measurement, it can be predicted in the same time as the conventional jitter tolerance measurement.

1 is a block diagram of a jitter tolerance measuring apparatus according to the present invention. It is a figure which shows the relationship between a sine jitter amplitude and a bit error rate. It is a figure which shows an example of the relationship between a sine jitter amplitude and a bit error rate when an upward is selected and set as a search method in the jitter tolerance measuring apparatus which concerns on this invention. It is a figure which shows an example of the relationship between a sine jitter amplitude and a bit error rate when a down word is selected and set as a search method in the jitter tolerance measuring apparatus based on this invention. It is a figure which shows an example of the relationship between a sine jitter amplitude and a bit error rate when binary is selected and set as a search method in the jitter tolerance measuring apparatus according to the present invention. It is a figure which shows the relationship between a bit error rate and measurement time.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, the jitter tolerance measuring apparatus 1 is roughly configured to include a jitter generating unit 2 and a jitter measuring unit 3, and a measurement target 4 such as a data transmission device is a data signal or the like at a desired bit error rate. Jitter tolerance is measured to show how much the phase fluctuation (jitter) can be tolerated, and has a function of predicting a jitter tolerance point of an arbitrary bit error rate in the jitter tolerance characteristics.

  The jitter generator 2 generates a data signal to which a jitter amount proportional to the amplitude of the modulation signal (sine jitter amplitude: SJ amplitude) is given. As shown in FIG. 1, the modulation signal generator 2a and the jitter signal are generated. The generator 2b is configured.

  The modulation signal generator 2a generates a modulation signal having a measurement modulation frequency and a sine jitter amplitude according to a search method selected by an operation of an operation unit 3a described later. The jitter signal generator 2b generates a data signal synchronized with the clock signal phase-modulated by the modulation signal.

  The jitter measuring unit 3 measures the jitter tolerance by receiving the data signal output from the measurement object 4 that has received the data signal generated by the jitter generating unit 2, and as shown in FIG. The unit 3b includes a storage unit 3c and a display unit 3d.

  The operation unit 3a includes, for example, various keys, switches, buttons provided on the apparatus main body, soft keys on the display screen of the display unit 3d, and the like, and is operated by the user when performing various settings and instructions related to jitter tolerance measurement. The

  Specifically, in addition to the instruction to start and end the jitter tolerance measurement of the measurement target 4, on the setting screen displayed on the display unit 3d, the setting of the measurement modulation frequency of the measurement target 4 and the sign jitter applied to the measurement target 4 Amplitude range (for example, a range of 0 UI (lower limit value) to 1 UI (upper limit value) at 100 MHz) and a search method (upward: Upward, downward: Downward, binary: Binary) as a selection setting and search method The setting of the step width of the sine jitter amplitude and the setting of the predicted bit error rate when the upward or downward is selected and set are performed by operating the operation unit 3a, and instructions and setting information based on the operation of these operation units 3a Input to the controller 3b.

  Note that the upward, downward, and binary in this example are search methods defined as follows. The upward is a search method in which the amount of jitter is increased by a predetermined step toward a jitter tolerance point of a reference bit error rate described later. Downward is a search method that reduces the amount of jitter by a predetermined step toward a jitter tolerance point of a reference bit error rate described later. Binary is a search method based on a binary search in which the amount of jitter is changed while a search interval toward a jitter tolerance point of a reference bit error rate described later is divided in half.

  The control unit 3b performs overall control of the entire apparatus. Based on an instruction or setting information from the operation unit 3a, control of start and end of jitter tolerance measurement, measurement modulation frequency and sign input to the modulation signal generator 2a. Control of jitter amplitude (SJ amplitude), prediction of jitter tolerance point of desired bit error rate, setting information and measurement result of each measurement point, storage control of prediction result to storage unit 3c, measurement result to display unit 3d, Control the display of prediction results.

  Further, as shown in FIG. 1, the control unit 3b is configured to include an error rate prediction unit 3ba and a jitter amplitude control unit 3bb.

  The error rate prediction means 3ba obtains the measurement result when the jitter tolerance measurement of the measurement object 4 is performed by the search method selected and set by the operation unit 3a, and based on the measurement result in the preset calculation range. A virtual straight line is obtained using the least square method. The measurement result at this time is a result obtained when the sine jitter amplitude is varied toward the jitter tolerance point of the reference bit error rate described later of the selected search method. For example, when measurement is performed by changing the sine jitter amplitude from 1 UI to 2 UI in 0.1 UI steps, the measurement results are 1, 1.1, 1.2,..., 1.9, 2.0 UI. . In addition, as shown in FIG. 2, a range having linearity (a range surrounded by a dotted line in FIGS. 3 to 5) in the characteristic indicating the relationship between the sine jitter amplitude and the bit error rate is a calculation range. And the intersection of the virtual straight line calculated | required using the least squares method and the bit error rate set in the operation part 3a is estimated as a jitter tolerance point.

  The jitter amplitude control means 3bb variably controls the sine jitter amplitude of the modulation signal output from the modulation signal generator 2a in accordance with the selected search method based on the setting information from the operation unit 3a.

  The storage unit 3c includes setting information set by the operation of the operation unit 3a, a calculation result calculation range (a range surrounded by a dotted line in FIGS. 3 to 5), a measurement result at each measurement point during jitter tolerance measurement, and an error rate prediction. The prediction result predicted by the means 3ba is stored.

  Further, the storage unit 3c stores an upward reference bit error rate ER1, a binary reference bit error rate ER2, and a downward reference bit error rate ER3 as the reference bit error rate ER for each search method.

The reference bit error rates ER1, ER2, and ER3 are within the range in which the measurement time by the tracking to the jitter tolerance point can be performed in the same time as before (the range surrounded by the dotted line in FIGS. 3 to 5)> It is set to satisfy the relationship of ER1>ER2> ER3. In this example, in order to satisfy this condition, for example, an upward reference bit error rate ER1 = 1E-6 (= 10 ⁻⁶ ), a binary reference bit error rate ER2 = 5E-8 (= 5 × 10 ⁻⁸⁾ , Downward reference bit error rate ER3 = 1E-9 (= 10 ⁻⁹ ) is set.

  The display unit 3d is configured by a liquid crystal display, for example, and displays a setting screen, measurement results, prediction results, and the like related to the measurement of the jitter tolerance of the measurement target 4.

  Next, a jitter tolerance measurement method in the case where the jitter tolerance measurement of the measurement object 4 is performed using the jitter tolerance measurement apparatus 1 configured as described above will be described.

  First, various settings necessary for predicting a jitter tolerance point of a desired bit error rate are performed by operating the operation unit 3a. Specifically, the measurement modulation frequency input to the modulation signal generator 2a is set by operating the operation unit 3a. Further, the amplitude range (upper limit value, lower limit value) of the sine jitter amplitude in the jitter tolerance characteristic of the measurement object 4 is set by operating the operation unit 3a. Further, a search method for driving the sine jitter amplitude to the jitter tolerance point of the reference bit error rate (any one of ER1, ER2, ER3) is set by operating the operation unit 3a. In this example, a search method is set by selecting one of an upward, a downward, and a binary by operating the operation unit 3a. Further, the bit error rate for predicting the jitter tolerance point in the jitter tolerance characteristic of the measurement object 4 is set by operating the operation unit 3a.

  When an upward or downward word is selected and set as a search method, the step width of the sine jitter amplitude is set by operating the operation unit 3a.

  When the above setting is completed, the operation unit 3a is operated to instruct the start of jitter tolerance measurement of the measurement target 4. When the jitter tolerance measurement of the measurement object 4 is started by an instruction from the operation unit 3a, the value of the sine jitter amplitude is driven toward the reference error rate corresponding to the search method selected and set by the operation unit 3a. Then, based on the measurement result of the calculation range (calculation range surrounded by a dotted line in FIGS. 3 to 5) obtained from the measurement result by this tracking, a virtual straight line is obtained using the least square method, and this virtual straight line and the operation unit 3a The point of intersection with the bit error rate set in is predicted as the jitter tolerance point, and the prediction result is displayed on the display unit 3d.

  When the setting of the bit error rate is changed by operating the operation unit 3a, the calculation using the least square method is performed again based on the measurement result, and the prediction result is displayed again on the display unit 3d.

  As described above, according to the jitter tolerance measuring apparatus and jitter tolerance measuring method of the present embodiment, the reference bit error rate (upward → ER1, ER1,) for driving the sine jitter amplitude for each search method (upward, downward, binary). Bits in the calculation range (the range enclosed by the dotted lines in FIGS. 3 to 5) set in advance regardless of whether the search method is upward, downword, or binary. An equivalent measurement result is obtained at the jitter tolerance point of the error rate (around 1E-6 to 1E-9), and the jitter tolerance point of the desired bit error rate is set for a short time using the least square method based on this measurement result. Can be predicted.

  In the jitter tolerance measurement, the sine jitter amplitude is driven in the same time as the conventional jitter tolerance measurement with respect to the jitter tolerance point of the reference error rate (either ER1, ER2, ER3) of the selected search method. Since the measurement is performed, it takes a long time in the normal measurement. For example, even when the jitter tolerance point is 1E-12 or less, it can be predicted in the same time as the conventional jitter tolerance measurement. The jitter tolerance point of a desired bit error rate including can be predicted in a short time.

  Although the best mode of the jitter tolerance measuring apparatus and jitter tolerance measuring method according to the present invention has been described above, the present invention is not limited by the description and drawings according to this mode. That is, it is a matter of course that all other forms, examples, operation techniques, and the like made by those skilled in the art based on this form are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Jitter tolerance measuring apparatus 2 Jitter generation part 2a Modulation signal generator 2b Jitter signal generator 3 Jitter measurement part 3a Operation part 3b Control part 3ba Error rate prediction means 3bb Jitter amplitude control means 4 Measurement object ER1, ER2, ER3 Reference error rate

Claims (2)

In a jitter tolerance measuring apparatus (1) for measuring a jitter tolerance point at a predetermined bit error rate,
Select one of the search methods from among the up search that increases the jitter amount by a predetermined step width, the down word that decreases the jitter amount by a predetermined step width, and the binary that changes the jitter amount while dividing the search interval in half. Bit error rate 1E-6> Upward reference bit error rate ER1> Binary reference bit error rate ER2> Downward reference bit error rate ER3 in accordance with the selected search method An operation unit (3a) for setting a reference bit error rate and setting a bit error rate to be predicted;
The value of the sine jitter amplitude is driven toward the reference error rate corresponding to the search method selected by the operation unit, and the minimum two values are obtained based on the measurement result in the preset calculation range of the measurement result obtained by this tracking. A jitter tolerance characterized by comprising a control section (3b) that obtains a virtual straight line using multiplication and predicts an intersection of the virtual straight line and the bit error rate set by the operation section as a jitter tolerance point. measuring device. In a jitter tolerance measurement method for measuring a jitter tolerance point at a predetermined bit error rate,
The search method is selected from among an upward that increases the jitter amount by a predetermined step width, a downward that decreases the jitter amount by a predetermined step width, and a binary that changes the jitter amount while dividing the search interval in half. Steps,
Bit error rate 1E-6> Reference bit error rate ER1 of the above> Reference bit error rate ER2 of the binary> Reference bit error rate ER3 of the down word is satisfied according to the selected search method. Setting a reference bit error rate;
Setting the bit error rate you want to predict;
The value of the sine jitter amplitude is driven toward the reference error rate corresponding to the selected search method, and the least square method is used based on the measurement result of the preset calculation range of the measurement result obtained by this tracking. A jitter tolerance measuring method comprising: obtaining a virtual straight line and predicting an intersection between the virtual straight line and the set bit error rate as a jitter tolerance point.

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