Network measurement device and delay time correction method thereof

Abstract

To provide a network measurement device capable of improving time accuracy of delay measurement for each frame in a network under measurement with a configuration which is simple and does not require a change of hardware.SOLUTION: A control unit 10 determines a difference between time information from a GNSS reception unit 5 and time information from a main body clock 7, and a deviation by an elapsed time of the time information from the main body clock 7, from captured data acquired by connecting an output port 11 and an input port 12 in a shortest manner. The control unit causes a delay measurement unit 3 to measure a delay time, causes a capture unit 4 to obtain captured data, and corrects the delay time obtained from the captured data by the difference between time information from the GNSS reception unit 5 and time information from the main body clock 7 and the deviation by the elapsed time of the time information from the main body clock 7, and corrects the corrected delay time by a maximum value and a minimum value of the delay time measured by the delay measurement unit 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a network measurement device that performs various measurements on a network as a device under test (DUT). [Background technology]

[0002] The network is used as the object under test, and the delay within the network is measured for each frame in the network under test.

[0003] Patent document 1 describes a time transmission system in which time synchronization packets are sent and received between time synchronization devices via a transmission device, and the time of the time synchronization devices is synchronized based on the time information of the sending and receiving.The transmission device measures the internal delay between the time synchronization packet input to the device and the time synchronization packet output from the device, adds the measured internal delay to the packet following the time synchronization packet, and synchronizes the time by correcting the time information added to the time synchronization packet with the internal delay. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 116201 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the delay within a transmission device is calculated from the time of its internal clock, and if the maximum frequency deviation of the internal clock is large, the time accuracy of the delay measurement becomes insufficient.

[0006] Therefore, an object of the present invention is to provide a network measurement device that can improve the time accuracy of delay measurement for each frame in a network under measurement, with a simple configuration that does not require any hardware changes. [Means for solving the problem]

[0007] The network measurement device of the present invention includes a GNSS receiver (5) that acquires time information from radio waves from GNSS (Global Navigation Satellite System) satellites, a main body clock (7) that generates time information using the frequency oscillated by an oscillator, a frame generator (2) that generates a data frame as a test signal corresponding to the communication standard of a device under test (100), sets time information from the GNSS receiver in the payload of the test signal of the generated data frame, and transmits the generated data frame from an output port (11) to the device under test, a delay measurement unit (3) that calculates a delay time within the device under test from the time information in the payload of the data frame as a test signal input from the device under test to an input port (12) and the reception time based on the time information from the GNSS receiver, and measures maximum and minimum values ​​of the delay time within a predetermined time, and a delay measurement unit (4) that captures the data frame as a test signal input from the device under test to the input port and transmits the data frame to the main body clock (7). The device is equipped with a capture unit (4) that stores the captured data together with time information from the clock, and a control unit (10) that calculates the difference between the time information from the GNSS receiving unit and the time information from the main body clock and the deviation due to the elapsed time of the time information of the main body clock from the captured data obtained by connecting the output port and the input port at the shortest distance, measures the delay time using the delay measurement unit, and acquires the capture data using the capture unit, corrects the delay time within the measured object for each data frame calculated from the capture data using the difference between the time information from the GNSS receiving unit and the time information from the main body clock and the deviation due to the elapsed time of the time information of the main body clock, and corrects the corrected delay time using the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

[0008] With this configuration, the delay time within the DUT for each data frame is calculated from the capture data acquired by the capture unit, and is corrected by the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation due to the elapsed time of the time information from the main unit clock, and is further corrected by the maximum and minimum values ​​of the delay time measured by the delay measurement unit.This makes it possible to improve the time accuracy of delay measurements for each frame in the network under test.

[0009] The delay time correction method of the present invention includes a GNSS receiver (5) that acquires time information from radio waves from GNSS satellites, a main clock (7) that generates time information using the frequency oscillated by an oscillator, a frame generator (2) that generates a data frame as a test signal corresponding to a communication standard of a device under test (100), sets time information from the GNSS receiver in the payload of the test signal of the generated data frame, and transmits the generated data frame from an output port (11) to the device under test, a delay measurement unit (3) that calculates a delay time within the device under test from the time information in the payload of the data frame as a test signal input from the device under test to an input port (12) and the reception time based on the time information from the GNSS receiver, and measures maximum and minimum values ​​of the delay time within a predetermined time, and a delay measurement unit (4) that captures the data frame as a test signal input from the device under test to the input port, and calculates the time information from the main clock in the payload of the test signal. and a capture unit (4) that stores both the time information from the GNSS receiving unit and the time information from the main body clock as capture data, the method comprising the steps of: determining, from the capture data obtained by connecting the output port and the input port at the shortest distance, the difference between the time information from the GNSS receiving unit and the time information from the main body clock, and the deviation due to the elapsed time of the time information of the main body clock; measuring the delay time with the delay measurement unit and acquiring the capture data with the capture unit; correcting the delay time within the device under test for each data frame determined from the capture data with the difference between the time information from the GNSS receiving unit and the time information from the main body clock, and the deviation due to the elapsed time of the time information of the main body clock; and correcting the corrected delay time with the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

[0010] With this configuration, the delay time within the DUT for each data frame is calculated from the capture data acquired by the capture unit, and is corrected by the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation due to the elapsed time of the time information from the main unit clock, and is further corrected by the maximum and minimum values ​​of the delay time measured by the delay measurement unit.This makes it possible to improve the time accuracy of delay measurements for each frame in the network under test. [Effects of the Invention]

[0011] The present invention can provide a network measurement device that can improve the time accuracy of delay measurement for each frame in a network under measurement, with a simple configuration and without requiring any hardware changes. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram of a network measurement device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing an example of changes in delay time due to correction of a network measurement device according to an embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart illustrating the procedure of the delay time correction process of the network measurement device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a network measurement device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0014] In FIG. 1, a network measurement device 1 according to an embodiment of the present invention is connected to a network as a DUT 100 via a wired connection such as an Ethernet (registered trademark) cable, and performs a measurement test on the DUT 100.

[0015] The network measurement device 1 includes a frame generation unit 2, a delay measurement unit 3, a capture unit 4, a GNSS reception unit 5, a GNSS antenna 6, a main unit clock 7, an operation unit 8, a display unit 9, and a control unit 10. In this embodiment, the GNSS will be described using, for example, GPS (Global Positioning System). Galileo, BeiDou, GLONASS, etc. can also be used as the GNSS.

[0016] The frame generator 2 generates a data frame as a test signal that conforms to the communication standard of the DUT 100 , and transmits the generated data frame test signal from the output port 11 to the DUT 100 .

[0017] The delay measurement unit 3 receives a data frame as a test signal input from the DUT 100 to the input port 12, and measures the delay within the DUT 100 from the received data frame.

[0018] The capture unit 4 captures a data frame as a test signal input from the DUT 100 to the input port 12, and stores it as captured data.

[0019] The GNSS receiver 5 receives radio waves from GNSS satellites via the GNSS antenna 6, obtains the current time from information contained in the received radio waves, and outputs it to the frame generator 2 and the delay measurer 3.

[0020] The main body clock 7 generates time information using, for example, a temperature compensated crystal oscillator (TCXO) and outputs it to the capture unit 4.

[0021] The operation unit 8 is configured with input devices such as a keyboard, a mouse, and a touch panel, and outputs information input by operation to the control unit 10.

[0022] The display unit 9 is configured, for example, with an image display device such as a liquid crystal display, and displays images for inputting information required for setting up the measurement, images showing the status during the measurement, and the like.

[0023] The control unit 10 is composed of a computer unit having, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory, a hard disk drive, an input port, and an output port.

[0024] This computer unit is configured so that the CPU can control devices connected to the input and output ports by executing an OS (Operating System) stored in a hard disk drive, for example.

[0025] The network measurement device 1 measures the delay time of each data frame as the delay measurement of the DUT 100, and outputs the maximum, minimum and average values ​​for each second, for example.

[0026] When delay measurement is selected, for example, by an operation input to the operation unit 8, the control unit 10 instructs the frame generation unit 2 to generate and transmit a data frame as a test signal, and instructs the delay measurement unit 3 to measure the delay.

[0027] The frame generator 2 generates a data frame as a test signal, sets the time from the GNSS receiver 5 as the transmission time in the payload, and transmits the data frame to the DUT 100 .

[0028] The delay measurement unit 3 calculates the delay time as the difference between the transmission time set in the payload of the data frame received from the DUT 100 and the reception time based on the time from the GNSS receiver 5, and outputs the maximum, minimum, and average values ​​of the delay time per second to the control unit 10.

[0029] The control unit 10 displays the delay measurement data received from the delay measurement unit 3 on the display unit 9 as a graph or the like.

[0030] This delay time is a highly accurate delay time, as both the transmission time and the reception time are calculated from the highly accurate time from the GNSS receiver 5.

[0031] Here, there is a demand to measure not only the maximum, minimum, and average values ​​within a given time period, but also the delay time for each data frame. However, measuring the delay time for each data frame requires modifying the delay measurement unit 3. Modifying the delay measurement unit 3 is time-consuming and costly, and therefore not easily implemented.

[0032] For this reason, in this embodiment, the delay time for each data frame is measured using the capture data from the capture unit 4.

[0033] However, since the time of the captured data is generated by the TCXO of the main clock 7, the maximum frequency deviation is on the order of several ppm, with the actual value being 1 ppm or less, and the time accuracy of delay measurement is insufficient.

[0034] In this embodiment, the accuracy of the delay time from the capture data is improved by correcting the frequency fluctuation of the main body clock 7.

[0035] First, prepare data for calibration. Connect the output port 11 and the input port 12 with the shortest Ethernet cable, for example, about 20 cm, transmit a data frame as a test signal, and obtain capture data for about one minute using the capture unit 4.

[0036] The calibration data must be acquired every time the network measurement device 1 is turned off or the connected interface is changed.

[0037] The control unit 10 obtains the delay time for each data frame from the value of a delay measurement counter indicating the transmission time in the payload and the reception time of the data frame of the capture data, using the capture data as calibration data.

[0038] The control unit 10 calculates the average value of the calculated delay times, for example, every second, and calculates the change (slope) of the average value over time.

[0039] The calibration data is considered to have almost zero delay because it connects output port 11 and input port 12 via the shortest route. Therefore, the difference between the average and minimum values ​​of the measured delay time per second is the original difference (offset) between the time of the GNSS receiver 5 and the main clock 7, and the slope of the average value per second is considered to be the frequency deviation of the TCXO of the main clock 7.

[0040] Thereafter, the device is connected to the DUT 100 to be measured, and similarly transmits a data frame as a test signal for about one minute, causing the delay measurement unit 3 to measure the delay and the capture unit 4 to acquire capture data.

[0041] The control unit 10 calculates the delay time for each data frame from the measured capture data, based on the value of a counter for delay measurement indicating the transmission time within the payload, and the reception time of the data frame of the capture data.

[0042] The control unit 10 performs correction by subtracting the offset value and the value corresponding to the slope obtained from the calibration data from the obtained delay time.

[0043] For example, as shown in FIG. 2, the measured delay time data before correction shows that the delay time increases over time, but the slope becomes gentler after correction using calibration data.

[0044] The control unit 10 corrects the delay time corrected using the calibration data using the actual measurement data measured by the delay measurement unit 3.

[0045] The control unit 10 corrects the one-second delay time based on the difference between the maximum and minimum values ​​of the actual measurement data for one second and the maximum and minimum values ​​of the delay time for one second calculated from the corresponding corrected capture data. The control unit 10 corrects the one-second delay time, for example, by using the average value of the difference between the maximum values ​​and the minimum values.

[0046] By performing such correction using actual measurement data, it is possible to obtain highly accurate delay time data that is not affected by the measurement time, as shown in Figure 2.

[0047] The delay time correction process performed by the network measurement device 1 according to this embodiment configured as described above will be described with reference to Fig. 3. The delay time correction process described below is executed when the user operates the operation unit 8 to select delay time measurement.

[0048] In step S1, the control unit 10 obtains a value corresponding to the offset value and the slope from the calibration data. After executing the process of step S1, the control unit 10 executes the process of step S2.

[0049] In step S2, the control unit 10 causes the delay measurement unit 3 to measure the delay time and causes the capture unit 4 to acquire capture data. After executing the process of step S2, the control unit 10 executes the process of step S3.

[0050] In step S3, the control unit 10 corrects the delay time for each data frame calculated from the captured data using a value corresponding to the offset value and the slope. After executing the process of step S3, the control unit 10 executes the process of step S4.

[0051] In step S4, the control unit 10 corrects the corrected delay time with the maximum and minimum values ​​of the delay time measured by the delay measurement unit 3. After executing the process of step S4, the control unit 10 ends the delay time correction process.

[0052] As described above, in the embodiment described above, the control unit 10 calculates the delay time within the DUT 100 for each data frame from the capture data acquired by the capture unit 4, and performs correction using a value corresponding to the offset value and slope calculated from the calibration data, and further performs correction using the maximum and minimum values ​​of the actual measurement data measured by the delay measurement unit 3.

[0053] This makes it possible to improve the time accuracy of delay measurement for each frame in the network under measurement with a simple configuration that does not require any hardware changes.

[0054] In this embodiment, measurements are performed using one network measurement device 1, but the same can be achieved by using two network measurement devices 1 as the transmitting and receiving sides.

[0055] Furthermore, in this embodiment, delay time correction and the like are performed by the control unit 10, but it is also possible to connect a personal computer to the network measurement device 1 and perform delay time correction and the like using software on the personal computer.

[0056] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0057] 1. Network measurement equipment 2. Frame Generation Unit 3. Delay measurement section 4 Capture section 5 GNSS receiver 7. Main unit clock 10 Control Unit 11 output ports 12 input ports 100 DUT (device under test)

Claims

1. a GNSS receiver (5) that acquires time information from radio waves from GNSS satellites; A main clock (7) that generates time information based on the frequency of the oscillator; a frame generating unit (2) that generates a data frame as a test signal corresponding to a communication standard of the device under test (100), sets time information from the GNSS receiving unit in the payload of the test signal of the generated data frame, and transmits the data frame from an output port (11) to the device under test; a delay measurement unit (3) that calculates a delay time within the device under test from time information of a payload of a data frame as a test signal input from the device under test to an input port (12) and a reception time based on time information from the GNSS receiving unit, and measures the maximum and minimum values ​​of the delay time within a predetermined time; a capture unit (4) that captures a data frame as a test signal input from the device under test to the input port and stores the captured data together with time information based on the main body clock; From the capture data acquired by connecting the output port and the input port at the shortest distance, a difference between the time information from the GNSS receiving unit and the time information from the main body clock and a deviation due to elapsed time of the time information from the main body clock are calculated; a control unit (10) that causes the delay measurement unit to measure the delay time and the capture unit to acquire the capture data, corrects the delay time within the measured object for each data frame calculated from the capture data using the difference between the time information from the GNSS receiving unit and the time information from the main body clock and the deviation due to the elapsed time of the time information from the main body clock, and corrects the corrected delay time using the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

2. a frame generation unit (2) that generates a data frame as a test signal corresponding to a communication standard of a device under test (100), sets time information from the GNSS receiving unit in the payload of the test signal of the generated data frame, and transmits the data frame from an output port (11) to the device under test; a delay measurement unit (3) that calculates a delay time within the device under test from the time information in the payload of the data frame as a test signal input from the device under test to an input port (12) and the reception time based on the time information from the GNSS receiving unit, and measures maximum and minimum values ​​of the delay time within a predetermined time; and a capture unit (4) that captures the data frame as a test signal input from the device under test to the input port and stores it as capture data together with the time information from the device under test clock, A step of calculating a difference between the time information by the GNSS receiving unit and the time information by the main body clock and a deviation due to elapsed time of the time information of the main body clock from the capture data obtained by connecting the output port and the input port in the shortest way; a step of measuring a delay time using the delay measurement unit, acquiring the capture data using the capture unit, and correcting the delay time within the device under test for each data frame obtained from the capture data using a difference between the time information from the GNSS receiving unit and the time information from the main body clock and a deviation due to elapsed time of the time information from the main body clock; and correcting the corrected delay time with the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

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