Network measurement device and its delay time correction method

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 using a network as a device under test (DUT).

Background Art

[0002] Measurements are being made of the delay within the network for each frame in the DUT network, with the network serving as the DUT.

[0003] Patent Document 1 describes a time transmission system in which time synchronization packets are transmitted and received between time synchronization devices via a transmission device, and the times of the time synchronization devices are synchronized based on the time information of the transmission and reception. In this system, the in-device delay from when a time synchronization packet input to the transmission device is output from the device is measured, the measured in-device delay is added to a packet following the time synchronization packet, and the time information given to the time synchronization packet is corrected by the in-device delay to synchronize the times.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the in-device delay measured by the transmission device is calculated from the time based on the internal clock. If the maximum frequency deviation of the internal clock is large, there is a problem that 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 the DUT network with a simple configuration that does not require hardware modification. [Means for solving the problem]

[0007] The network measurement device of the present invention includes a GNSS receiving unit (5) that acquires time information from radio waves from a GNSS (Global Navigation Satellite System) satellite, a main unit clock (7) that generates time information based on the frequency oscillated by an oscillator, a frame generation unit (2) that generates a data frame as a test signal corresponding to the communication standard of the object under test (100), sets the time information from the GNSS receiving unit in the payload of the test signal of the generated data frame and transmits it to the object under test from the output port (11), a delay measurement unit (3) that calculates the delay time within the object under test from the time information of the payload of the data frame as a test signal input from the object under test to the input port (12) and the reception time based on the time information of the GNSS receiving unit, and measures the maximum and minimum values ​​of the delay time over a predetermined period of time, a capture unit (4) that captures the data frame as a test signal input from the object under test to the input port and saves it as captured data together with the time information from the main unit clock, and connects the output port and the input port in the shortest possible distance. The frame generation unit transmits a data frame as a test signal, which is then stored in the capture unit. From the captured data, the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation of the time information from the main unit clock due to the elapsed time are determined. The output port and the input port are connected to the object under test, and the frame generation unit transmits a data frame as a test signal. The delay measurement unit measures the delay time, and the capture unit captures the data keep The system includes a control unit (10) that corrects the delay time within the object under measurement for each data frame obtained from the captured data 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 then corrects the corrected delay time by the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

[0008] With this configuration, the capture unit keepThe delay time within the object under test is determined from the captured data, corrected by the difference between the time information from the GNSS receiver and the time information from the main unit clock, and by the deviation due to the elapsed time of the time information from the main unit clock. Furthermore, it is corrected by the maximum and minimum values ​​of the delay time measured by the delay measurement unit. This improves the time accuracy of frame-by-frame delay measurement in the network under test.

[0009] Furthermore, the delay time correction method of the present invention is a delay time correction method for a network measuring device comprising: a GNSS receiving unit (5) that acquires time information from radio waves from a GNSS satellite; a main unit clock (7) that generates time information based on the frequency oscillated by an oscillator; a frame generation unit (2) that generates a data frame as a test signal corresponding to the communication standard of the object under test (100), sets the time information from the GNSS receiving unit in the payload of the test signal of the generated data frame, and transmits it to the object under test from the output port (11); a delay measurement unit (3) that calculates the delay time within the object under test from the time information of the payload of the data frame as a test signal input from the object under test to the input port (12) and the reception time based on the time information of the GNSS receiving unit, and measures the maximum and minimum values ​​of the delay time over a predetermined period of time; and a capture unit (4) that captures the data frame as a test signal input from the object under test to the input port and saves it as captured data together with the time information from the main unit clock, wherein the output port and the input port are connected in the shortest possible distance. The frame generation unit transmits a data frame as a test signal, which is then stored in the capture unit. The steps include: determining the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation of the time information from the main unit clock due to the elapsed time, from the captured data; The output port and the input port are connected to the object under test, and the frame generation unit transmits a data frame as a test signal. The delay measurement unit measures the delay time, and the capture unit captures the data keepThe system includes the steps of: correcting the delay time within the object under measurement for each data frame obtained from the captured data 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 correcting the corrected delay time by the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

[0010] With this configuration, the capture unit keep The delay time within the object under test is determined from the captured data, corrected by the difference between the time information from the GNSS receiver and the time information from the main unit clock, and by the deviation due to the elapsed time of the time information from the main unit clock. Furthermore, it is corrected by the maximum and minimum values ​​of the delay time measured by the delay measurement unit. This improves the time accuracy of frame-by-frame delay measurement in the network under test. [Effects of the Invention]

[0011] The present invention provides a network measurement device that can improve the time accuracy of frame-by-frame delay measurement in a network under test, without requiring hardware changes and with a simple configuration. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a block diagram of a network measurement device according to one embodiment of the present invention. [Figure 2] Figure 2 is a graph showing an example of the change in delay time due to the correction of a network measurement device according to one embodiment of the present invention. [Figure 3] Figure 3 is a flowchart illustrating the procedure for delay time correction processing of a network measurement device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0013] Hereinafter, a network measuring 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 by wire via an Ethernet (registered trademark) cable or the like, 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 body clock 7, an operation unit 8, a display unit 9, and a control unit 10. In this embodiment, for example, GPS (Global Positioning System) is used as the GNSS for explanation. It is also possible to use Galileo, BeiDou, GLONASS, etc. as the GNSS.

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

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

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

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

[0020] [[ID=

[26] ] 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 composed of input devices such as a keyboard, a mouse, a touch panel, etc., and outputs the operation input information, etc. to the control unit 10.

[0022] The display unit 9 is composed of an image display device such as a liquid crystal display, etc., and displays an image for inputting information necessary for measurement settings, an image indicating the state during measurement, etc.

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

[0024] This computer unit can control the devices connected to the input port and the output port by the CPU executing the OS (Operating System) stored in the hard disk device, for example. [[ID=十六]]

[0025] [[ID=十七]] The network measurement device 1 measures the delay time for each data frame as the delay measurement of the DUT 100, and outputs, for example, the maximum value, the minimum value, and the average value every 1 second.

[0026] When delay measurement is selected by an operation input to the operation unit 8, for example, 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 perform delay measurement.

[0027] The frame generation unit 2 generates a data frame as a test signal, sets the time from the GNSS reception unit 5 as the transmission time in the payload, and transmits it 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 unit 5, and outputs the maximum, minimum, and average values ​​of the delay time for each second to the control unit 10.

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

[0030] This delay time is calculated from highly accurate time data from the GNSS receiver unit 5, including both the transmission and reception times, resulting in a highly accurate delay time.

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

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

[0033] However, because the TCXO of the main unit clock 7 is the source of the captured data's time signature, the maximum frequency deviation is only a few ppm, and the actual value is less than 1 ppm, resulting in insufficient time accuracy for delay measurement.

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

[0035] First, prepare the data for calibration. Connect the output port 11 and the input port 12 with an Ethernet cable as short as possible, for example, about 20 cm long, and have the device transmit a data frame as a test signal. The capture unit 4 will then acquire the capture data for about 1 minute.

[0036] Calibration data needs to be acquired each time the power to the network measurement device 1 is turned off or the connected interface is changed.

[0037] The control unit 10 uses the captured data as calibration data to determine the delay time for each data frame from the value of a delay measurement counter representing the transmission time in the payload and the reception time of the data frame of the captured data.

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

[0039] Since the calibration data is obtained by connecting output port 11 and input port 12 with the shortest possible connection, the delay is considered to be almost zero. Therefore, the difference between the average and minimum values ​​of the measured delay time every second is considered to be the original difference (offset) between the time of the GNSS receiver 5 and the main unit clock 7, and the slope of the average value every second is considered to be the frequency deviation of the TCXO of the main unit clock 7.

[0040] Subsequently, the system is connected to the DUT100 to be measured, and a data frame is transmitted as a test signal for about one minute. The delay measurement unit 3 performs delay measurement, and the capture unit 4 acquires the captured data.

[0041] The control unit 10 uses the measured capture data to determine the delay time for each data frame from the value of a delay measurement counter representing the transmission time in the payload and the reception time of the data frame of the captured 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] As shown in Figure 2, for example, the measured delay time, before correction, shows an increase in delay time over time, but the slope becomes gentler after correction with calibration data.

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

[0045] The control unit 10 corrects the 1-second delay time based on the difference between the maximum and minimum values ​​of the measured data per second and the maximum and minimum values ​​of the delay time per second obtained from the corresponding corrected captured data. For example, the control unit 10 corrects the 1-second delay time by the average value of the difference between the maximum and minimum values.

[0046] By performing corrections using such measured data, highly accurate delay time data can be obtained without being 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 explained with reference to Figure 3. The delay time correction process described below is executed when the measurement of delay time is selected by the user's operation on the operation unit 8.

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

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

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

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

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

[0053] This allows for improved time accuracy in frame-by-frame delay measurements in the network under test, without requiring hardware changes and with a simple configuration.

[0054] In this embodiment, measurements were performed using one network measurement device 1, but the same results can be achieved by using two network measurement devices 1, one as the transmitter and the other as the receiver.

[0055] Furthermore, in this embodiment, the control unit 10 performed delay time correction, etc., but a personal computer may be connected to the network measurement device 1, and the delay time correction, etc. may be performed by the software on the personal computer.

[0056] While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications can be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims. [Explanation of symbols]

[0057] 1. Network measurement device 2. Frame generation unit 3. Delay Measurement Unit 4 Capture section 5 GNSS receiver 7. Main 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 a GNSS satellite, The main clock (7) generates time information based on the frequency of the oscillator, A frame generation unit (2) generates a data frame as a test signal corresponding to the communication standard of the object under test (100), sets time information by the GNSS receiver in the payload of the test signal of the generated data frame, and transmits it to the object under test from the output port (11), A delay measurement unit (3) calculates the delay time within the object under test from the time information of the data frame payload as a test signal input from the object under test to the input port (12) and the reception time based on the time information of the GNSS receiver, and measures the maximum and minimum values ​​of the delay time over a predetermined period of time. A capture unit (4) captures a data frame as a test signal input from the object under test to the input port and saves it as captured data along with time information from the main unit clock. The output port and the input port are connected in the shortest possible way, and a data frame is transmitted from the frame generation unit as a test signal. From the captured data stored in the capture unit, the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation of the time information from the main unit clock due to the elapsed time are determined. A network measurement device comprising: an output port and an input port connected to the object under test, a frame generation unit transmitting a data frame as a test signal, a delay measurement unit measuring the delay time, a capture unit saving the captured data, a control unit (10) correcting the delay time within the object under test for each data frame obtained from the captured data 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 correcting the corrected delay time by the maximum and minimum values ​​of the delay time measured by the delay measurement unit.

2. A delay time correction method for a network measurement device comprising: a GNSS receiving unit (5) that acquires time information from radio waves from a GNSS satellite; a main unit clock (7) that generates time information based on the frequency oscillated by an oscillator; a frame generation unit (2) that generates a data frame as a test signal corresponding to the communication standard of the object under test (100), sets the time information from the GNSS receiving unit in the payload of the test signal of the generated data frame, and transmits it to the object under test from the output port (11); a delay measurement unit (3) that calculates the delay time within the object under test from the time information of the payload of the data frame as a test signal input from the object under test to the input port (12) and the reception time based on the time information of the GNSS receiving unit, and measures the maximum and minimum values ​​of the delay time over a predetermined period of time; and a capture unit (4) that captures the data frame as a test signal input from the object under test to the input port and saves it as captured data together with the time information from the main unit clock, wherein the method is described above. The output port and the input port are connected in the shortest possible way, and a data frame is transmitted from the frame generation unit as a test signal. From the captured data stored in the capture unit, the difference between the time information from the GNSS receiver and the time information from the main unit clock, and the deviation of the time information from the main unit clock due to the elapsed time are determined. The output port and the input port are connected to the object under test, a data frame is transmitted from the frame generation unit as a test signal, the delay time is measured by the delay measurement unit, the captured data is saved by the capture unit, and the delay time within the object under test for each data frame obtained from the captured data is corrected by the difference between the time information from the GNSS receiver unit 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. A delay time correction method comprising the step of 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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