KR20110082678A - Time syncronization method between radio vibration measuring systems using revision signal - Google Patents

Abstract

PURPOSE: A time synchronizing method which uses a calibration signal in a wireless vibration measuring system is provided to detect a delay time of a wireless transmitter. CONSTITUTION: An A/D converting unit(S20) converts an analog signal into a digital signal. The converted signal is stored in FIFO RAM. A transmitter transmits a packet. A counter signal is generated after initializing the packet.

Description

Time Synchronization Method between Radio Vibration Measuring Systems Using Revision Signal}

The present invention relates to a time synchronization method for enabling synchronization between wireless transmitters in a real-time wireless vibration measurement system. In particular, the present invention relates to a radio wave error and a wireless signal generated by a wireless environment of a WLAN. Considering the control speed error between the main board of the transmitter and the DAQ board, a counter is configured at the OS level to generate a reference time so that the wireless receiver can improve the time delay of each wireless transmitter and use the calculated time delay. The present invention relates to a time synchronization technology between wireless vibration measurement systems that receive data packets transmitted from wireless transmitters, temporarily store them through an internal memory buffer, remove time delays, and synchronize each wireless transmitter.

Related technologies include a time synchronization method for a wireless sensor network (Korean Patent No. 10-0682541), a low power routing method using a time synchronization method and a reservation method in a wireless sensor network, and an apparatus for performing the same (Korea Patent Publication No. 10). -2009-0006757), a wireless sensor network time synchronization method (Korean Patent Laid-Open Publication No. 10-2009-0105731), and a wireless communication packet synchronizer and a method thereof (Korean Registration No. 10-07704206).

In case of using NTP (Network Time Protocol) server in network environment, wired network can be synchronized with 1msec precision and wired network with 10msec precision.

Since the real-time wireless vibration measurement system of the present invention aims at synchronization of a vibration signal which is a dynamic signal, it is necessary to have a higher precision. For example, when sampling is measured at 100 Hz, the sampling period is 0.00390625 seconds, and synchronization accuracy of 3 msec or less is required. However, since NTP server supports more than 10msec precision, it is difficult to match synchronization.

In general, time synchronization methods are essential in distributed systems such as wireless sensor networks. However, the time delay that occurs in wireless communication, the time delay that occurs in the timer of each node, the time delay caused by interrupts, the time delay caused by the switching method of the WLAN, the time delay caused by the switching method of the WLAN, etc. Various factors influence the time delay.

The real-time wireless vibration measurement system collects data from each wireless transmitter, which is connected to a wireless router serving a 2.4GHz wireless LAN and a piezoelectric accelerometer to perform internal analog and digital signal processing tasks. And, it consists of a wireless receiver for performing the vibration signal analysis. Time delays that can occur in wireless instrumentation systems can distort phase information in all the analyzes required, especially for vibrating wire measurements.

1 is a block diagram showing a synchronization method of a wireless communication system according to the prior art.

The server 10 transmits the absolute time of the server, and the client 20 removes the time difference according to the transmission speed by configuring the synchronization by applying the received time.

2 is a block diagram illustrating a time delay occurring in a wireless communication system.

In the network shown in FIG. 2, a time delay occurs according to the command transmission rate. In particular, in the case of the wireless network shown in FIG. 2, a time delay occurs according to the radio sensitivity. The wireless receiver 30 receives a radio signal, and the main boards # 1, # 2 (41, 51), and the DA1 # 1 (41) and the DAQ # 2 (42) perform analog-to-digital conversion. In the case of a radio transmitter in which the radio sensitivity is located at a different position, as shown in the figure, a delay of δ1, δ'1 between the main board # 1 41 and the DAQ board # 1 42 of the radio transmitter 40 is shown. In this case, a delay of δ2 and δ'2 may occur even at a control speed between the main board # 2 51 and the DAQ board # 2 52 of the wireless transmitter 50.

Where δ1 is the radio wave error occurring in the wireless environment,

       δ2: control speed error between boards,

       δ'1: radio wave error occurring in a wireless environment,

       δ'2: The board-to-board control error rate.

Therefore, in the present invention, when transmitting data from each of the four channel-based wireless transmitters, in addition to the channel data, each wireless transmitter also transmits a calibration signal to the wireless receiver to make a delay time with other wireless transmitters using the absolute time as the reference wireless transmitter. It is an object of the present invention to provide a time synchronization technique between wireless vibration measurement systems using a calibration signal to be detected.

In order to achieve the above object, the present invention passes through an A / D conversion unit for receiving an analog signal and converting it into a digital signal, storing the digitally converted signal in a FIFO (first in, first out) RAM (S30), and transmitting a packet. And performing a process of generating a counter signal by initializing from the outside.

According to the present invention, the time synchronization method for the wireless network is improved to reduce the time error that may occur in the communication path, thereby enabling the synchronization between the wireless transmitter and the receiver distributed more quickly and accurately on the wireless network.

In addition, the calibration signal can be dynamically changed and used according to the sampling cycle according to the precision, which has the advantage of achieving synchronization according to the vibration measurement frequency.

1 is a block diagram showing a synchronization method of a wireless communication system according to the prior art.
2 is a block diagram illustrating a time delay occurring in a wireless communication system.
3 is a flowchart illustrating a time synchronization method of a wireless transmitter using a calibration signal according to the present invention.
4 is a view showing the shape of the calibration signal according to the present invention.
5 is a flowchart sequentially illustrating a flow of a time synchronization method of a wireless vibration measuring system using a calibration signal according to the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

3 is a flowchart illustrating a time synchronization method of a wireless transmitter using a calibration signal according to the present invention.

In the present invention, since a delay may occur for each wireless receiver because a difference in the control speed of the ADC converting an analog signal into a digital signal may occur when a delay occurs as shown in FIG. By generating a calibration signal operating in a system different from the control command of the wireless receiver allows the wireless receiver to calculate the time delay value between wireless transmitters.

As shown in FIG. 3, the time synchronization method of the wireless transmitter using the calibration signal according to the present invention receives an analog signal (S10) and converts it into a digital signal through an A / D converter (S20). It is stored in the FIFO (first-in-first-out) RAM (S30), and transmits the packet (S40), it is initialized from the outside (S50) and goes through the process of generating a counter signal (S60).

4 is a view showing the shape of the calibration signal according to the present invention.

As described in FIG. 3, the counter for synchronization is located at an application level (input signal size) to periodically generate a signal as shown in the drawing. The width of one clock is determined by the sampling frequency used for vibration measurement, and the length of one cycle and the total height of the clock have 16 bits, which is the resolution of the ADC.

5 is a flowchart sequentially illustrating a flow of a time synchronization method of a wireless vibration measuring system using a calibration signal according to the present invention.

As shown in FIGS. 3 and 4, a counter is generated in the wireless transmitter, and the wireless receiver receives the counter along with the sensor data from each transmitter to calculate a time delay. The BIOS value is calculated by comparing the clocks of # 2 and # 3 with the reference clock of the wireless transmitter # 1, which is calculated as time through a sampling period to recognize the time delay value of each wireless transmitter. The internal memory buffer removes data for a time delay and configures synchronization.

The flow of FIG. 5 is demonstrated.

First, the S100 converts an analog signal into a digital signal. Then, the counter power is applied (S110), the counter is reset by the user (S120), the counter is enabled (S130), the counter data and the signal data are stored in the FIFO RAM (S140), and the packet is transmitted ( S150). Here, the steps S110 to S150 are operations of the radio transmitter, and then a radio packet is received, and the transmitters # 1, # 2, and # 3 transmit a counter signal in consideration of the time delay (S160). Then, the transmitter counter signal is detected (S170), the counter delay time is calculated based on the transmitter # 1 (S180), and then the data corresponding to the delay time is removed (S190), and the synchronized data is displayed (S200). . Herein, operations S160 to S200 are operations of the wireless receiver.

According to the present invention, the time delay caused by the radio propagation error and the board control speed error may be changed at each communication connection since the A / D converter starts to asynchronously start the operation of the A / D converter. At the start of the measurement, the sensor's data is converted to digital data via an A / D converter, and independently of this, a calibration signal is generated inside the motherboard. The start and end of the A / D converter is controlled by the command of the wireless receiver, but since the calibration signal inside the main board is generated independently after the power is applied, the period delay between each wireless transmitter can be calculated regardless of the time delay. Can be. The detected time delay may be synchronized after data synchronization is performed in the internal memory of the wireless receiver to sequentially display data. Since the size of the data block to be transmitted can be changed according to the sampling rate of the radio transmitter, the width of the calibration signal is also dynamically changed in proportion to the sampling rate.

According to the present invention as described above, the time synchronization method for the wireless network is improved to reduce the time error that may occur on the communication path, thereby enabling the synchronization between the wireless transmitter and the receiver distributed more quickly and accurately on the wireless network.

In addition, the calibration signal can be dynamically changed and used according to the sampling cycle according to the precision, which has the advantage of achieving synchronization according to the vibration measurement frequency.

While an embodiment of the present invention has been described with reference to the drawings, the present invention is not limited thereto, and various modifications and variations are made by those skilled in the art without departing from the spirit and scope of the appended claims below. It is to be understood that such modifications and variations are intended to be included within the scope of the present invention.

10: server 20: client
30: radio receiver 40, 50: radio transmitter # 1, # 2
41, 51: Mainboard # 1, # 2 42, 52: DAQ # 1, # 2

Claims (3)

After receiving the analog signal and converting it into a digital signal, the digital converted signal is stored in a FIFO (first in, first out) RAM (S30), and the packet is transmitted. The external signal is initialized to generate a counter signal. Time synchronization method between the wireless vibration measurement system using a calibration signal, characterized in that it comprises the step of. Converts analog signals into digital signals at the wireless transmitter, applies counter power, resets the counter by the user, enables the counter, stores counter data and signal data in the FIFO RAM, transmits packets, Receive a packet; In the wireless receiver, transmitters # 1, # 2, and # 3 transmit a counter signal in consideration of time delay, detect a transmitter counter signal, calculate a counter delay time based on transmitter # 1, and then correspond to the delay time. And removing the data and displaying the synchronized data. The method of claim 2,
The BIOS value is calculated by comparing the clocks of the wireless transmitters # 2 and # 3 with the reference clock of the wireless transmitter # 1, and the time is calculated through the sampling period to recognize the time delay value of each wireless transmitter. A method of synchronizing time between wireless vibration measurement systems using a calibration signal, characterized in that to configure synchronization by removing data as much as a time delay through the internal memory buffer.

Images