JP7260605B2 - WAVEFORM OBSERVATION DEVICE AND TRANSMISSION PROPERTIES ACQUISITION METHOD - Google Patents

Description

The present invention relates to a waveform observation apparatus and transmission characteristic acquisition method, and more particularly to a waveform observation apparatus and transmission characteristic acquisition method capable of measuring frequency characteristics of a signal under measurement.

Conventionally, for example, waveform data of a signal under measurement input via an object under measurement is sequentially sampled at a predetermined cycle, the sampled waveform data are read out as appropriate, and an eye pattern is reproduced and displayed on a display screen to reproduce the waveform of the signal under measurement. A waveform observation device for observing is known.

A typical waveform observation device normally displays only the eye pattern display of the sampled signal under measurement, and observes the quality of the signal according to the waveform shape. Therefore, for example, when measuring the frequency characteristics of a device under test in a high-frequency circuit network (especially the S21 parameter, which is a frequency characteristic that is frequently measured), it is necessary to connect a vector network analyzer (VNA) as a separate device for measurement. be.

However, in order to measure the frequency characteristics of the device under test, a separate VNA must be prepared in addition to the waveform observation device, which raises the problem of increased measurement costs. In addition, each time a measurement item is changed, wiring such as a cable must be routed to a new device to change the measurement system, which complicates the measurement work.

Therefore, there has been proposed a waveform observation device capable of measuring frequency characteristics in addition to a general waveform observation function (see, for example, Patent Document 1).

Japanese Patent No. 5475484

The waveform observation apparatus disclosed in Patent Document 1 outputs a pattern signal of a pulse pattern arbitrarily selected from among random patterns of "0" and "1" having a unique period to the device under test as a test signal. It has a built-in pulse pattern generator (PPG).

Therefore, the waveform observation device disclosed in Patent Document 1 has a problem that the measurement of the frequency characteristics of the device under test is limited to the band of the built-in PPG. Moreover, since the waveform observation apparatus disclosed in Patent Document 1 itself has a built-in PPG, there is also a problem that the circuit in a device equipped with a PPG, such as an optical transceiver, cannot be measured as an object to be measured.

SUMMARY OF THE INVENTION The present invention has been made to solve such conventional problems, and is a waveform observation apparatus and transmission characteristic acquisition method capable of acquiring transmission characteristics of an object to be measured according to an arbitrary PPG band. intended to provide

In order to solve the above problems, a waveform observation apparatus according to the present invention provides waveform observation for obtaining discrete digital waveform data, which is time-series data, by sampling a signal under measurement based on a pattern signal from an arbitrary pulse pattern generator. reference waveform data for storing, as reference waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit without passing through the device under test. a storage unit, a loss-insertion waveform data storage unit that stores discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit via the device under test as loss-insertion waveform data; Fourier transforming the reference waveform data stored in the reference waveform data storage unit and the lossy insertion waveform data stored in the lossy insertion waveform data storage unit to generate a reference spectrum and a lossy insertion spectrum. a conversion unit, a difference calculation unit that calculates a difference between the reference spectrum and the loss insertion spectrum to acquire the transmission characteristics of the object under test, and the transmission characteristics of the object under measurement acquired by the difference calculation unit S parameter file output unit that converts to an S parameter file and outputs it, and the device under test consists of a known device whose transmission characteristics have been acquired by the difference calculation unit and an unknown device whose transmission characteristics are unknown a loss compensator for obtaining the transmission characteristics of the unknown device by subtracting the transmission characteristics of the known device from the transmission characteristics of the object under test obtained by the difference calculator; and a pattern from a certain pulse pattern generator. a loss insertion unit that adds the transmission characteristic of the device under test based on the signal to the reference spectrum based on the pattern signal from another pulse pattern generator to generate a pseudo loss insertion spectrum. be.

With this configuration, the waveform observation apparatus according to the present invention uses the PPG independent of the waveform observation apparatus as the signal source of the signal under measurement. can be acquired (S21 parameter).
In addition, with this configuration, the waveform observation apparatus according to the present invention can convert the S21 parameters of the device under test into an S parameter file and output it. It can be applied to various measurement devices such as analysis devices.
Further, with this configuration, the waveform observation apparatus according to the present invention can acquire the S21 parameter of the unknown device by subtracting the S21 parameter of the known device from the S21 parameter of the device under test. Desired transmission characteristics can be obtained.
In addition, with this configuration, the waveform observation apparatus according to the present invention adds the S21 parameter of the device under test based on the pattern signal from one PPG to the reference spectrum based on the pattern signal from another PPG to generate a pseudo spectrum. A loss insertion spectrum can be generated. For example, the waveform observation apparatus according to the present invention acquires the S21 parameter with an arbitrary loss board as a device under test, and stores it in the reference spectrum of another PPG included in a device such as an optical transceiver. Margin testing can be done by adding the S21 parameter as a loss.

Further, the waveform observation apparatus according to the present invention performs an inverse Fourier transform on the transmission characteristic of the object under test acquired by the difference calculation unit or the pseudo loss insertion spectrum generated by the loss insertion unit, The configuration may further include an inverse Fourier transform section that generates waveform data of the device under test.

With this configuration, the waveform observation apparatus according to the present invention performs an inverse Fourier transform on the S21 parameter of the object under test acquired by the difference calculation unit, thereby obtaining a Waveform data of the device under test can be generated by eliminating the effects of loss factors. Further, the waveform observation apparatus according to the present invention can acquire PPG waveform data with a pseudo loss element added by inverse Fourier transforming the pseudo loss insertion spectrum.

In addition, the waveform observation apparatus according to the present invention is arranged such that the reference waveform data, the loss insertion waveform data, the reference spectrum, the loss insertion spectrum, the transmission characteristic, and the object under test are controlled in accordance with an operation input to the operation unit. The configuration may further include a display control unit that controls display of any one or more of the waveform data in the display unit.

With this configuration, the waveform observation apparatus according to the present invention provides reference waveform data, loss-insertion waveform data, reference spectrum, loss-insertion spectrum, S21 parameter, and inverse Fourier transform unit in response to user's operation input to the operation unit. Since any one or more of the waveform data of the device under test generated by is controlled to be displayed on the display unit, the user can confirm these waveform data and spectra.

Further, the transmission characteristic acquisition method according to the present invention includes a waveform observation unit that samples a signal under measurement based on a pattern signal from an arbitrary pulse pattern generator and acquires discrete digital waveform data that is time-series data. A transmission characteristic acquisition method using an observation device, wherein discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit without passing through the object under measurement is stored as reference waveform data. a waveform data storage step; and a loss-inserted waveform data storage step of storing, as loss-inserted waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observing section through the device under test. and Fourier transforming the reference waveform data stored in the reference waveform data storage step and the lossy insertion waveform data stored in the lossy insertion waveform data storage step to generate a reference spectrum and a lossy insertion spectrum. a Fourier transform step of calculating a difference between the reference spectrum and the loss insertion spectrum to obtain the transmission characteristics of the object under test; and a step of calculating the difference of the object under test obtained by an S-parameter file output step of converting the transmission characteristics into an S-parameter file and outputting the same; and the object to be measured includes a known device whose transmission characteristics have already been acquired by the difference calculation step and an unknown device whose transmission characteristics are unknown. a loss compensation step of obtaining the transmission characteristics of the unknown device by subtracting the transmission characteristics of the known device from the transmission characteristics of the object under test obtained by the difference calculation step; a loss insertion step of adding the transmission characteristic of the device under test based on the pattern signal of the pulse pattern generator to the reference spectrum based on the pattern signal from another pulse pattern generator to generate a pseudo loss insertion spectrum Configuration.

Further, in the method for obtaining transmission characteristics according to the present invention, the transmission characteristics of the object under test obtained by the difference calculation step or the pseudo loss insertion spectrum generated by the loss insertion step are subjected to an inverse Fourier transform. and an inverse Fourier transform step of generating waveform data of the device under test .
Further, in the transmission characteristic acquisition method according to the present invention, the reference waveform data, the loss-insertion waveform data, the reference spectrum, the loss-insertion spectrum, the transmission characteristics, and the measured The configuration may further include a display control step of controlling display of any one or more of the waveform data of the object on the display unit.

SUMMARY OF THE INVENTION The present invention provides a waveform observing apparatus and a method for acquiring transmission characteristics that can acquire transmission characteristics of an object to be measured according to an arbitrary PPG band.

1 is a block diagram showing the configuration of a waveform observation device according to an embodiment of the present invention; FIG. 3 is a block diagram showing a configuration when using a PPG built in an optical transceiver as the PPG in this embodiment; FIG. 2 is a diagram for explaining the operation of a waveform observing section in FIG. 1; FIG. (a) is a diagram showing an example of an eye pattern when the signal under measurement is input from the PPG to the waveform observation section without passing through the device under test; FIG. 10 is a diagram showing an example of an eye pattern when a signal is input to the waveform observing section; (a) is a graph showing a reference spectrum generated by the Fourier transform unit in FIG. 1, and (b) is a graph showing a loss insertion spectrum generated by the Fourier transform unit in FIG. 6 is a graph showing an example of the S21 parameter of the device under test obtained by subtracting the reference spectrum shown in FIG. 5(a) from the loss insertion spectrum shown in FIG. 5(b); 5 is a graph showing the result of measuring the S21 parameter of the device under test with the waveform observation device of the present embodiment and the result of measuring the S21 parameter of the device under test with the VNA, superimposed on each other. 1 is a block diagram showing a configuration example of an object to be measured; FIG. 4 is a flow chart showing processing of a transmission characteristic acquisition method using the waveform observation device according to the embodiment of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a waveform observation device and a transmission characteristic acquisition method according to the present invention will be described below with reference to the drawings.

A waveform observation apparatus 1 according to an embodiment of the present invention shown in FIG. 1 observes the waveform of a signal under measurement based on a pattern signal from an arbitrary PPG 100. , a waveform data processing unit 30 , an operation unit 40 , and a display unit 50 .

The PPG 100 is provided separately from the waveform observation apparatus 1. For example, the PPG 100 may be an independent form of a signal generator, or a DSP (DSP) mounted on various devices such as an optical transceiver. It may be in the form of a chip built in a digital signal processor).

The PPG 100 outputs a pattern signal such as an NRZ PRBS (Pseudorandom Binary Sequence) pattern. The PPG 100 also outputs pattern signals such as PAM4 PRBS patterns and SSPRQ (Short Stress Pattern Random Quaternary) patterns. Alternatively, the PPG 100 may output a pattern signal such as a fixed pattern or an arbitrary programmable pattern. Furthermore, the PPG 100 generates a synchronous clock synchronized with the pattern signal as described above, and outputs this synchronous clock to the waveform observing section 10 as a trigger signal.

DUT 200 is, for example, a passive device such as a cable, a connector, a filter, or a loss board having a predetermined loss. Examples of transmission standards that the device under test 200 supports include IEEE802.3 and OIF-CEI. Furthermore, the device under test 200 may be a passive circuit or the like arranged after the built-in PPG in various devices such as an optical transceiver.

FIG. 2 is a diagram showing a configuration example when the PPG built into the optical transceiver 60 is used as the PPG 100 in this embodiment. An MCB (Module Compliance Board) 61 is an evaluation board for transmitting and receiving electrical signals output from the optical transceiver 60 and has a port (not shown) for inserting the optical transceiver 60 .

Returning to FIG. 1, the waveform observation section 10 samples the signal under measurement in response to a trigger signal from the PPG 100, and acquires discrete digital waveform data, which is time-series data of the signal under measurement. 11 and a sampling signal generator 12 .

Here, the signal under measurement is either a pattern signal directly input from PPG 100 to waveform observation section 10 without via device under test 200, or a pattern signal input from PPG 100 to waveform observation section 10 via device under test 200. pattern signal. When the pattern signal from the PPG 100 is directly input to the waveform observing section 10 without passing through the device under test 200, the PPG 100 and the waveform observing section 10 are connected by a low-loss cable whose frequency characteristics are guaranteed. preferably

The sampler 11 samples the input signal under measurement each time it receives a sampling signal generated by the sampling signal generator 12 , converts it into discrete digital waveform data that is time-series data, and stores it in the waveform data storage 20 . Output.

A trigger signal from the PPG 100 is input to the sampling signal generator 12 . As shown in FIG. 3, the sampling signal generation unit 12 generates a sampling signal having a sampling period Ts longer than an integral multiple of the waveform repetition period Ta of the signal under measurement by a predetermined time resolution ΔT from the timing at which the trigger signal is received. Occur. A sampling signal generated by the sampling signal generator 12 is input to the sampler 11 . With this sampling signal, the sampling position is gradually shifted by ΔT with reference to a specific phase of the periodic waveform of the signal under measurement, so the sampler 11 can restore the waveform of the signal under measurement with a time resolution of ΔT.

The bottom of FIG. 3 shows an example in which the signal under measurement restored with the time resolution ΔT is displayed as a time-series waveform (pulse pattern). If displayed, an eye pattern is obtained. Note that the sampling period Ts and the period of the trigger signal can be set by operating the operation unit 40 .

The discrete digital waveform data acquired by the sampler 11 is displayed on the display unit 50 as eye patterns or time-series waveforms. FIG. 4(a) shows an example of an eye pattern when the signal under measurement is input from the PPG 100 to the waveform observing section 10 without passing through the device under test 200. FIG. FIG. 4B shows an example of an eye pattern when the signal under measurement is input from the PPG 100 through the device under test 200 to the waveform observing section 10. FIG.

The trigger signal input to the sampling signal generator 12 may be extracted from the signal under measurement. In this case, the waveform observation apparatus 1 further includes a clock recovery circuit for recovering the clock component from the input signal under measurement, and a trigger signal synchronized with the rise or fall of the clock component of the signal under measurement is output from the clock recovery circuit. will occur.

The waveform data storage section 20 includes a reference waveform data storage section 21 and a lossy insertion waveform data storage section 22 . The reference waveform data storage unit 21 stores the discrete digital waveform data of the signal under measurement input from the PPG 100 to the waveform observation unit 10 without passing through the device under test 200 as reference waveform data. The loss-inserted waveform data storage unit 22 stores discrete digital waveform data of the signal under measurement input from the PPG 100 to the waveform observation unit 10 via the device under test 200 as loss-inserted waveform data.

The waveform data processing unit 30 includes, for example, a microcomputer or personal computer including a CPU, ROM, RAM, HDD, etc., and includes a Fourier transform unit 31, a difference calculation unit 32, an S parameter file output unit 33, a loss compensation unit 34, The functions of the loss insertion unit 35, the inverse Fourier transform unit 36, the transmission characteristic storage unit 37, and the display control unit 38 are realized. At least part of the waveform data processing unit 30 may be configured by a digital circuit such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), or may be configured by software by executing a predetermined program by a CPU. It is possible to Alternatively, at least part of the waveform data processing section 30 can be configured by appropriately combining hardware processing by a digital circuit and software processing by a predetermined program.

The Fourier transform unit 31 Fourier transforms (Fast Fourier Transform: FFT) the reference waveform data stored in the reference waveform data storage unit 21 to generate a reference spectrum. The Fourier transform unit 31 Fourier transforms the loss-insertion waveform data stored in the loss-insertion waveform data storage unit 22 to generate a loss-insertion spectrum. FIGS. 5(a) and 5(b) respectively show an example of the reference spectrum and the loss insertion spectrum. The reference spectrum and the loss insertion spectrum generated by the Fourier transform section 31 are stored in the transmission characteristic storage section 37 .

The difference calculator 32 calculates the difference between the reference spectrum generated by the Fourier transform unit 31 and the loss insertion spectrum, and obtains the transmission characteristic (S21 parameter) of the device under test 200 . FIG. 6 shows an example of the S21 parameter of the device under test 200 obtained by subtracting the reference spectrum shown in FIG. 5(a) from the loss insertion spectrum shown in FIG. 5(b) by the difference calculator 32. there is The S21 parameter of the device under test 200 acquired by the difference calculator 32 is stored in the transmission characteristic storage 37 .

FIG. 7 is a graph showing the result of measuring the S21 parameter of the device under test 200 with the waveform observing apparatus 1 of this embodiment and the result of measuring the S21 parameter of the device under test 200 with the VNA. The measurement results of the S21 parameter by the waveform observation device 1 of this embodiment are in good agreement with the measurement results of the VNA in the low frequency band up to about 15 GHz, and the frequency characteristics tend to attenuate toward the high frequency band. showing. The waveform observation apparatus 1 of this embodiment has the advantage that the S21 parameter of the device under test 200 can be easily measured at low cost without preparing an expensive VNA.

The S parameter file output unit 33 outputs the S21 parameter data of the device under test 200 acquired by the difference calculation unit 32 and stored in the transmission characteristic storage unit 37 in a known S parameter file format that can be read and written by a personal computer or the like. data and output as an S parameter file. The S parameter file output from the S parameter file output unit 33 may be stored in the transmission characteristic storage unit 37, or may be stored in an external storage device such as a hard disk device, a magnetic tape, a disk, an optical disk, or a magneto-optical disk. , ROM, PROM, VCD, DVD, or other computer-readable recording medium. The S-parameter file output from the S-parameter file output unit 33 can also be applied to various measurement devices such as other waveform observation devices and signal analysis devices.

In this manner, the waveform observation apparatus 1 of the present embodiment eliminates the influence of loss elements other than the device under test 200 existing between the PPG 100 and the waveform observation device 1, and obtains the S21 parameter of the device under test 200. can be extracted.

If the device under test 200 is composed of one or more known devices whose S21 parameters have already been acquired by the difference calculator 32 and one or more unknown devices whose S21 parameters are unknown, the loss compensator 34 determines whether the difference calculator 32 By subtracting the S21 parameters of one or more known devices from the S21 parameters of the device under test 200 obtained by , the S21 parameters of one or more unknown devices are obtained.

FIG. 8 shows an example of a measurement system in which device under test 200 consists of two known devices 200A and one unknown device 200B. The two known devices 200A are, for example, two cables connecting one unknown device 200B to the PPG 100 and the waveform observing apparatus 1. FIG. In this case, the loss compensator 34 subtracts the S21 parameters of the two known devices 200A from the S21 parameters of the device under test 200 to obtain the S21 parameters of the unknown device 200B. Here, the S21 parameters of the two known devices 200A are read from the transmission characteristic storage section 37 according to the user's operation input to the operation section 40. FIG. Note that the S21 parameters of the unknown device 200B acquired by the loss compensation unit 34 may be stored in the transmission characteristic storage unit 37.

The loss insertion unit 35 adds the S21 parameter of the device under test 200 obtained based on the pattern signal from a certain PPG 100 to the reference spectrum obtained based on the pattern signal from the other PPG 100' to generate a pseudo It is possible to generate a loss-insertion spectrum with Here, the S21 parameters of the device under test 200 obtained based on the pattern signal from a certain PPG 100 are read out from the transmission characteristic storage section 37 according to the operation input to the operation section 40 by the user. The pseudo loss insertion spectrum generated by the loss insertion section 35 may be stored in the transmission characteristic storage section 37.

The inverse Fourier transform section 36 generates waveform data of the device under test 200 by inverse Fourier transforming (IFFT) the S21 parameter of the device under test 200 acquired by the difference calculating section 32 . ing. Further, the inverse Fourier transform section 36 may perform an inverse Fourier transform on the pseudo loss insertion spectrum generated by the loss insertion section 35 to generate waveform data of the pseudo device under test 200 . The waveform data generated by the inverse Fourier transform section 36 may be stored in the waveform data storage section 20 .

For example, using the waveform observation device 1 of the present embodiment, the S21 parameter of the loss board having the frequency characteristics specified by the transmission standards such as IEEE802.3 and OIF-CEI is acquired in advance, and the other PPG 100 ′ reference A pseudo loss insertion spectrum can be generated by adding the S21 parameter of the loss board to the spectrum. Furthermore, using the waveform observation device 1 of the present embodiment, the pseudo loss insertion spectrum can be converted into waveform data by the inverse Fourier transform section 36 . This makes it possible, for example, to simulate addition of loss to other PPG 100' without attaching actual loss boards having various frequency characteristics to other PPG 100'.

The display control unit 38 controls the reference waveform data, the loss-insertion waveform data, the reference spectrum, the loss-insertion spectrum, the S21 parameter, and the subject generated by the inverse Fourier transform unit 36 in response to the operation input to the operation unit 40 by the user. Any one or more of the waveform data of the measurement object 200 are controlled to be displayed on the display section 50 .

The operation unit 40 is for receiving an operation input by the user, and is configured by a touch panel including a touch sensor for detecting a contact position by a touch operation on an input surface corresponding to the display screen of the display unit 50, for example. . When the user touches the position of a specific item displayed on the display screen with a finger or a stylus, the operation unit 40 recognizes the match between the position detected by the touch sensor on the display screen and the position of the item. As a result, a signal for executing the function assigned to each item is output to the display control unit 38 . The operation unit 40 may be operably displayed on the display unit 50, or may include an input device such as a keyboard or mouse.

By the user's operation input to the operation unit 40, settings related to sampling of the signal under measurement, selection of waveform data and spectrum stored in each storage unit, selection of waveform data and spectrum to be displayed on the display unit 50, and the like can be performed. It is possible.

The display unit 50 is composed of a display device such as a liquid crystal display or a CRT, and displays the reference waveform data, the loss insertion waveform data, the reference spectrum, the loss insertion spectrum, and the S21 parameter of the device under test 200 based on display control by the display control unit 38. , and waveform data of the device under test 200 are displayed on the display screen. Furthermore, the display unit 50 displays operation targets such as buttons, soft keys, pull-down menus, and text boxes for setting various conditions.

A transmission characteristic acquisition method using the waveform observation device 1 will be described below with reference to the flowchart of FIG.

First, the user connects the PPG 100 and the waveform observing apparatus 1 without the device under test 200 (step S1).

Next, the waveform observing section 10 acquires the reference waveform data before loss insertion of the signal under measurement which is input from the PPG 100 without passing through the device under test 200 . The acquired reference waveform data is stored in the storage unit 21 (reference waveform data storage step S2).

Next, the user connects the PPG 100 and the waveform observing apparatus 1 via the device under test 200 (step S3).

Next, the waveform observation section 10 acquires the loss-inserted waveform data of the signal under measurement input from the PPG 100 via the device under test 200 after loss insertion. The acquired lossy insertion waveform data is stored in the storage unit 21 (lossy insertion waveform data storage step S4).

Next, the Fourier transform unit 31 Fourier transforms the reference waveform data stored in the reference waveform data storage unit 21 in the reference waveform data storage step S2 to generate a reference spectrum. The Fourier transform unit 31 Fourier transforms the loss-insertion waveform data stored in the loss-insertion waveform data storage unit 22 in the loss-insertion waveform data storage step S4 to generate a loss-insertion spectrum (Fourier transform step S5).

Next, the difference calculator 32 calculates the difference between the reference spectrum generated in the Fourier transform step S5 and the loss insertion spectrum, and obtains the S21 parameter of the device under test 200 (difference calculation step S6).

Next, the S parameter file output unit 33 converts the S21 parameter data of the device under test 200 acquired in the difference calculation step S6 and stored in the transmission characteristic storage unit 37 into S parameter file format data. Output as a parameter file (S parameter file output step S7).

As described above, the waveform observing apparatus 1 according to the present embodiment uses the PPG 100 independent of the waveform observing apparatus 1 as the signal source of the signal under measurement. Accordingly, the S21 parameter of the device under test 200 can be obtained.

Further, the waveform observation apparatus 1 according to the present embodiment generates a reference spectrum from the reference waveform data stored in the reference waveform data storage unit 21, and also generates a loss-insertion spectrum from the loss-insertion waveform data stored in the loss-insertion waveform data storage unit 22. It is designed to generate a spectrum. For this reason, the waveform data measurement timing and the spectrum acquisition timing do not have to be the same. It is possible to calculate the S21 parameter of the device under test 200 from the loss insertion waveform data. In other words, the waveform observing apparatus 1 according to the present embodiment can acquire the S21 parameter of the device under test 200 at arbitrary timing without being affected by errors due to reconnection.

Further, since the waveform observation apparatus 1 according to the present embodiment can convert the S21 parameters of the device under test 200 into an S parameter file and output it, for example, the S parameter file can be used by other waveform observation apparatuses and signal analysis. It can be applied to various measuring devices such as devices.

In addition, the waveform observation apparatus 1 according to the present embodiment can acquire the S21 parameter of the unknown device 200B by subtracting the S21 parameter of the known device 200A from the S21 parameter of the device under test 200, thereby canceling the loss in the measurement system. desired transmission characteristics can be obtained.

Further, the waveform observing apparatus 1 according to the present embodiment adds the S21 parameter of the device under test 200 based on the pattern signal from a certain PPG 100 to the reference spectrum based on the pattern signal from the other PPG 100' to obtain a pseudo A loss insertion spectrum can be generated. For example, the waveform observation apparatus 1 according to the present embodiment acquires S21 parameters with an arbitrary loss board as the device under test 200, and uses the arbitrary loss board as the reference spectrum of another PPG 100' included in a device such as an optical transceiver. A margin test can be performed by adding the S21 parameter obtained from as a loss.

In addition, the waveform observation apparatus 1 according to the present embodiment performs an inverse Fourier transform on the S21 parameter of the device under test 200 acquired by the difference calculation unit 32 to obtain Waveform data of the device under test 200 can be generated by eliminating the effects of loss factors other than the device under test 200 . Further, the waveform observation apparatus 1 according to the present embodiment can obtain waveform data of the PPG 100' with a pseudo loss element added by inverse Fourier transforming the pseudo loss insertion spectrum.

In addition, the waveform observation apparatus 1 according to the present embodiment performs reference waveform data, loss-insertion waveform data, reference spectrum, loss-insertion spectrum, S21 parameters, and inverse Fourier transform in accordance with user's operation input to the operation unit 40. Since one or more of the waveform data of the device under test 200 generated by the unit 36 are controlled to be displayed on the display unit 50, the user can confirm these waveform data and spectra.

1 waveform observation device 10 waveform observation unit 20 waveform data storage unit 21 reference waveform data storage unit 22 loss insertion waveform data storage unit 30 waveform data processing unit 31 Fourier transform unit 32 difference calculation unit 33 S parameter file output unit 34 loss compensation unit 35 Loss insertion unit 36 Inverse Fourier transform unit 37 Transmission characteristic storage unit 38 Display control unit 40 Operation unit 50 Display unit 100, 100' PPG
200 DUT 200A, 200B Device

Claims (6)

A waveform observation device (1) comprising a waveform observation section (10) for sampling a signal under measurement based on a pattern signal from an arbitrary pulse pattern generator (100, 100') to acquire discrete digital waveform data as time-series data ) and
a reference waveform data storage unit (21) for storing, as reference waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit without passing through the device under test (200);
a loss-inserted waveform data storage unit (22) for storing, as loss-inserted waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit via the device under test;
Fourier transforming the reference waveform data stored in the reference waveform data storage unit and the lossy insertion waveform data stored in the lossy insertion waveform data storage unit to generate a reference spectrum and a lossy insertion spectrum. a conversion unit (31);
a difference calculator (32) for calculating the difference between the reference spectrum and the loss insertion spectrum to acquire the transmission characteristics of the object under test;
an S-parameter file output unit (33) that converts the transmission characteristics of the object to be measured obtained by the difference calculation unit into an S-parameter file and outputs the S-parameter file;
When the object to be measured includes a known device (200A) whose transmission characteristics have been obtained by the difference calculation unit and an unknown device (200B) whose transmission characteristics are unknown, the measurement object obtained by the difference calculation unit a loss compensator (34) for obtaining the transmission characteristics of the unknown device by subtracting the transmission characteristics of the known device from the transmission characteristics of the object to be measured;
The transmission characteristics of the object under test based on the pattern signal from a certain pulse pattern generator (100) are added to the reference spectrum based on the pattern signal from the other pulse pattern generator (100') to obtain a pseudo and a loss insertion section (35) for generating a loss insertion spectrum . generating waveform data of the device under test by inverse Fourier transforming the transmission characteristics of the device under test acquired by the difference calculator or the pseudo loss insertion spectrum generated by the loss insertion unit; The waveform observation device according to claim 1, further comprising a Fourier transform section (36) . Any one of the reference waveform data, the loss insertion waveform data, the reference spectrum, the loss insertion spectrum, the transmission characteristics, and the waveform data of the device under test according to an operation input to the operation unit (40) 3. The waveform observing apparatus according to claim 2, further comprising a display control section (38) for controlling display of one or more on the display section (50) . A waveform observation device ( 1) A transmission characteristic acquisition method using
a reference waveform data storage step (S2) of storing, as reference waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit without passing through the device under test (200);
a loss-inserted waveform data storage step (S4) of storing, as loss-inserted waveform data, discrete digital waveform data of the signal under measurement input from the pulse pattern generator to the waveform observation unit via the device under test;
Fourier transforming the reference waveform data stored in the reference waveform data storage step and the loss-inserted waveform data stored in the loss-insertion waveform data storage step to generate a reference spectrum and a loss-insertion spectrum. a conversion step (S5);
a difference calculation step (S6) of calculating the difference between the reference spectrum and the loss insertion spectrum to obtain the transmission characteristic of the object to be measured;
an S-parameter file output step (S7) for converting the transmission characteristics of the object to be measured obtained by the difference calculation step into an S-parameter file and outputting the S-parameter file;
When the object to be measured includes a known device (200A) whose transmission characteristics have already been obtained by the difference calculation step and an unknown device (200B) whose transmission characteristics are unknown, the object to be measured obtained by the difference calculation step a loss compensation step of obtaining the transmission characteristics of the unknown device by subtracting the transmission characteristics of the known device from the transmission characteristics of the measured object;
The transmission characteristics of the object under test based on the pattern signal from a certain pulse pattern generator (100) are added to the reference spectrum based on the pattern signal from the other pulse pattern generator (100') to obtain a pseudo and a loss insertion step of generating a loss insertion spectrum. generating waveform data of the device under test by inverse Fourier transforming the transmission characteristic of the device under test obtained by the difference calculating step or the pseudo loss insertion spectrum generated by the loss insertion step; 5. The transmission characteristic acquiring method according to claim 4, further comprising a Fourier transform step. Any one of the reference waveform data, the loss insertion waveform data, the reference spectrum, the loss insertion spectrum, the transmission characteristics, and the waveform data of the device under test according to an operation input to the operation unit (40) 6. The transmission characteristic acquisition method according to claim 5, further comprising a display control step of controlling display of one or more on a display unit (50).

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