KR19980038351A - High Precision Visual Synchronizer and Control Method Using Ground Position Measurement System (GPS) - Google Patents

Abstract

The present invention provides a high-precision time synchronization device using a ground position measurement system for outputting a predetermined frequency output from the precision visual oscillation circuit to the 1PPS received from a GPS satellite in a high performance microprocessor unit (MPU) programmatically and accurately. The control method is related.

To this end, an antenna for receiving a 1PPS visual signal emitted from a GPS satellite, a GPS receiver connected to the antenna for outputting 1PPS and various data, a precision visual oscillation circuit generating a 10MHz main clock, and a system by a predetermined program Control and count the main clock of 10MHz and 1PPS of the GPS receiver, synchronize and output the main controller to synchronize with each other, initialize the system and display the reception of 1PPS from the GPS satellites, the output of 1PPs and 10MHz, and alarm in case of system failure The reset and display unit which generates the signal outputs the synchronized 1PPS and the frequency of 10MHz, and configures the output drive to be able to communicate with other external devices and applies the mobile communication to precisely synchronize the time of each base station. It is to prevent the disconnection of the mobile terminal from the other party, the present invention also Communications in addition to the would also be usefully applied, etc. power systems, metrology, distributed processing systems, and optical networks.

Description

High Precision Visual Synchronizer and Control Method Using Ground Position Measurement System (GPS)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high precision time synchronization device using a ground positioning system (GPS: `` GPS '') and a control method thereof, in particular, in a 1PPS and a precision visual oscillation circuit received from a GPS satellite. The present invention relates to a high-precision time synchronizer using a ground position measuring system for precisely synchronizing and outputting a predetermined frequency output in a high performance microprocessor unit (MPU) and a control method thereof.

The high-precision visual synchronization device described in the present invention is applicable to mobile communication field, power system, metrology, distributed processing system and optical communication network with a wide range of applications. The technical scope of the system field is as follows.

First, it is installed in a base station of code division multiple access (CDMA) used in personal communication service (PCS), which is currently expected to be used in Korea, and is used for mobile communication using code division multiple access. In this case, high-precision visual synchronization is essential.

For example, if a user moves from one place to another during communication, if the system is not synchronized between the two base stations, it may cause a fatal error such as disconnection, as well as code division multiple access communication. The number of users of wireless mobile communication is increasing exponentially every year, so the importance is very high.

Therefore, in Korea, standards are not set for each mobile communication as a protocol problem, so it is necessary to prepare a separate base station according to the communication method. Therefore, it is necessary to prepare for this. Most high-precision time synchronizers include time division including code division multiple access. Developments are being made for the telecommunications market such as Time Division Multiple Access (TDMA) and Paging.

Secondly, precision time synchronizers can be installed in power-related systems, and the most common one can be used to synchronize the tagging / logging subsystems for each system and accident time.

That is, the interconnected wires of the unexpected situation occurs, these errors are detected quickly and can FT IU of each system to cope with unless such disconnection (FTIU: Fault transient lnterface Unit) is a time logging in a precisely synchronized state (Time Tagging) This requires a time synchronizer with a relatively high precision, and can also aid in the processing of sequential control and management data.

In addition, the power system is applied to various fields such as RTU (Remote Terminal Unit) of SCADA (Supervisory Control And Data Acquisition) system and stable control of power system.

Therefore, the high-precision time synchronizer applied to the above fields requires a reference time in Universal Time Coordinated (UTC), and the reference time signal is received from a GPS satellite.

That is, a 1PPS (Pulse Per Second) time signal transmitted from a GPS satellite is transmitted based on the time of the U.S. standard time through two cesium atomic clocks and two rubidium atomic clocks mounted in the satellite itself.

Looking at the precise time synchronization device using the 1PPS transmitted from the conventional GPS satellites as follows.

Prior art 1

Figure 1 (a) is composed of a time synchronization device using Hewlett Packard's Smart Clock (SnnrtClock) technology, processing a low-cost oscillator as a reference signal and at the same time combines the GPS satellite 1PPS as an external signal, high precision and low price At the same time, in the case of Holdover mode, in which the external reference signal 1PPS is incapable of receiving, the error tolerance is already provided in a value predicted in the normal state, and the operation method is the external of the oscillator and the 1PPS. The microprocessor compares the reference signal and returns the error value to the oscillator to improve the accuracy by adjusting the oscillator frequency.

Prior art 2

Figure 1 (b) is a form of independent isochronous maintenance block for improving the isochronism between each frequency in the improved technique of Hewlett Packard's company, unlike the prior art 1, this method is within l × 10 ^-10 within at least one day Because the frequency can be adjusted up to, combining GPS clock with rubidium or high-quality crystal oscillator can achieve stability enough to approach cesium's performance, and the part of the isochronous maintenance block is the frequency repeater.

Prior Art 3

Figure 1 (c) of another conventional technology (PRS: Prinnry Reference Systems (PRS) of the Datum (MTUM) company), and compared to the conventional mobile communication market market such as ATM (ATM: Asynchronous Transfer Mode) It is a product for telecommunication or wireless communication network, and is similar to Hewlett-Packard's HP55300A.

In other words, DATUM's PRS (PRS) uses the main clock oscillator portion not only rubidium but also a crystal oscillator, and uses GPS as an external reference reception signal.

Such a conventional time synchronizer shown in FIGS. 1A to 1D mainly relies on hardware to maintain time synchronization and isochronousness, which not only complicates the system itself but also increases the volume of the product itself. It becomes very large and also maintains a high price in terms of price. Therefore, it is not universalized, and there is a problem of deterioration in reliability as a visual synchronizer by having a large variation in precision.

The present invention is to solve the problems of the above, it is to be output in synchronization with the 1PPS transmitted from the GPS satellite 10MHz main clock generated in the precision time oscillation circuit by a program set in a high precision microprocessor unit Thus, when applied to the mobile communication it is an object of the present invention to precisely synchronize the time of each base station to prevent the disconnection of the mobile terminal in the call state.

Another object of the present invention is to maintain the main clock synchronization through the prediction value of the timeout (Overtime) according to environmental factors in the microprocessor unit in the case of a holdover state in which 1PPS is not received from the GPS receiver. By doing so, the time of each base station can be synchronized even when a fatal error of the GPS receiver occurs.

Another object of the present invention is to send a correction data value to the precision time oscillator circuit when the 10 MHz main clock is not exactly synchronized with 1 PPS transmitted from the GPS satellite so that the 10 MHz main clock is constantly output. 1PPS can be synchronized exactly, and the current operation mode and status of the system is displayed on the display device, as well as the compactness of the product according to the simple configuration and low-cost spread.

In order to achieve the above object, the present invention provides an antenna for receiving a visual signal of 1PPS radiated from a GPS satellite, and connected to the antenna to output 1PPS, and whether the 1PPS is received, a back-up voltage detection signal, and a year. A GPS receiver for outputting data on month and day, the main controller being connected to an output terminal of the GPS receiver to control the system by a predetermined program and counting and correcting the main clocks during 1PPS of the GPS receiver and synchronously outputting the same; A precision visual oscillation circuit connected between the input and output terminals of the main control unit to generate a 1 MHz main clock constantly, connected to the output terminal of the main control unit to initialize the system and receiving 1PPS from the GPS satellites, and outputting 1PPS and 10MHz. A reset and display unit for displaying an alarm when a system error occurs, and 1PPS synchronized with the output terminal of the main control unit. It consists of an output drive that outputs a frequency of 10MHz and allows communication with other external devices.

In addition, the present invention, when the system is powered on, initializes the system, executes the self-diagnosis mode and determines whether there is an abnormality of the system, and then sends an alarm and prepares the system according to the abnormality, and 1PPS from the GPS receiver. GPS satellite that outputs the clock based on previous data by recognizing whether the time signal is received and turning on the corresponding display lamp in lock mode when 1PPS is received, and holding over mode when 1PPS is not received. Signal receiving process; If the lock mode is determined in the above process, the main clock is counted. If the main clock is counted a predetermined number of times during the 1PPS, the corresponding lamp is turned on to indicate that the main clock is synchronized. It is judged that it is not composed of synchronization and correction process of increasing or decreasing the output frequency of the precision visual oscillation circuit.

1A to 1C are schematic diagrams of a conventional time synchronizer.

2 is an overall block diagram of a time synchronizer according to the present invention.

3 is a detailed circuit diagram of a main control unit which is a time synchronization device according to the present invention;

4 is a detailed view of a precise time oscillation circuit as a time synchronization device according to the present invention;

5 is a detailed view of a reset and display unit which is a time synchronizer according to the present invention.

6 is a detailed view of an output drive circuit as a time synchronizer according to the present invention.

7 is an overall operation flow chart of the time synchronizer according to the present invention.

8 is a timing diagram of each stage of the time synchronization device according to the present invention;

* Explanation of symbols for main parts of the drawings

10: antenna 20: GPS receiver

30: reset and display unit 31: reset switch

32: reset circuit 33: drive circuit

34: display unit 40: precision time oscillation circuit

41: D / A converter 42: variable voltage oscillator (VCO)

50: main controller 51: microprocessor unit (MPU)

52,53: 1st, 2nd ROM (ROM) 54,55: 1st, 2nd RAM

56: chip selector 70: output drive

71,72: first and second output unit 73: communication interface

100: GPS satellites

2 is a block diagram of a high-precision time synchronization device using a ground position measuring system according to the present invention, one side of the antenna 10 receiving the time signal emitted from the GPS satellite 100, one received time signal per second A GPS receiver 20 that outputs a pulse (hereinafter referred to as `` 1PPS '' (Pulse Per Second)) and outputs data regarding reception and back-up voltage detection and year, month, and day of the 1PPS is connected. It is.

In addition, on the output side of the GPS receiver 20, the entire system is controlled by a predetermined program, and the outputs of the precision time oscillation circuit 40 and the GPS receiver 20 are combined, counted, and corrected to accurately synchronize 10 MHz to 1 PPS. An output main controller 50 is connected.

In addition, one output terminal of the main controller 50 initializes the entire system and displays whether or not a time signal is received from the GPS and whether 1PPS is normally output by lighting a lamp, and resets to generate an alarm when a system abnormality occurs. And a display unit 30 are connected.

In addition, the other output terminal of the main control unit 50 outputs 1PPS and a frequency of 10MHz synchronized with each other and is provided with at least one communication port is connected to the output drive 70 that can communicate with other external devices, the main control unit One input terminal of 50 is connected with a precision time oscillation circuit 40 for constantly outputting a main clock of 10 MHz.

3 is a detailed circuit diagram of the main controller 50, which is a high-precision visual synchronization device using GPS according to the present invention, which controls the entire system and combines the outputs of the precision visual oscillation circuit 40 and the GPS receiver 20. A microprocessor unit (hereinafter referred to as `` MPU '') 51 which corrects and outputs 1 PPS and 10 MHz of the main clock accurately is provided, and one side of the MPU 51 stores the entire control program of the system. The first and second ROMs 52 and 53 are connected.

The other end of the MPU 51 is connected with first and second RAMs 54 and 55 for storing and reading data necessary for system operation, and the first and second ends of the MPU 51 are connected to one end of the MPU 51. The chip selectors 56 for enabling the two ROMs 52 and 53 and the first and second RAMs 54 and 55 are connected to each other.

4 is a detailed view of the precision time oscillation circuit 40 which is a time synchronization device according to the present invention, and a variable voltage oscillator 42 having a variable frequency output according to an applied voltage is connected to one input terminal of the MPU 51. Between the input terminal of the variable voltage oscillator 42 and the output terminal of the MPU 51, the correction data value transmitted from the MPU 51 is converted to analog so that the main clock output from the variable voltage oscillator 42 is 10 MHz. The D / A converter 41 applied to the voltage oscillator 42 is connected and comprised.

FIG. 5 is a detailed circuit diagram of the reset and display unit 30, which is a high-precision visual synchronization device using GPS according to the present invention, wherein an input terminal of one side of the MPU 51 initializes the entire system according to the connection of the switch 31 ( 32) is connected, and the output terminal of the MPU 51 is composed of a plurality of LEDs and alarms through the drive circuit 33, whether or not to receive the time signal from the GPS satellite 100, the normal output of 1PPS, alarm when a system abnormality occurs The display part 34 which generate | occur | produces this is connected and comprised.

6 is a detailed circuit diagram of the output drive circuit 70, which is a high-precision time synchronization device using GPS according to the present invention, wherein the first and second output units 71 output 1PPS and 10MHz to the output terminal of the MPU 51, respectively. 72 is connected and one or more communication interfaces 73 capable of various types of communication with the outside are connected.

Here, the first and second output units 71 and 72 may be formed of first and second NOR gates NOR1 and NOR2, respectively, 1PPS at one end of the first NOR gate NOR1, and 10 MHz may be the first. It is applied to each of the two-north gates NOR2, and the enable signal is applied from the MPU 51 to the other ends of the first and second north gates NOR1 and NOR2.

7 is an overall operation flowchart of the high precision time synchronizer using GPS according to the present invention, and FIG. 8 is an input / output timing diagram of the high precision time synchronizer using GPS according to the present invention.

Looking at the operation of the present invention made as described above are as follows.

First, the overall operation of the present invention will be described with reference to FIG. 2, and the 1PPS time signal of the GPS satellite 100 provides the time of the U.S. standard time through two cesium atomic clocks and two rubidium atomic clocks mounted in the satellite itself. It is sent out as a standard.

Therefore, the visual signal transmitted from the GPS satellite 100 is transmitted to the GPS receiver 20 through the antenna 10, thereby outputting 1PPS, and receiving the visual signal transmitted from the GPS satellite 100 and back-up voltage. Each data relating to the detection and the year, month, and day is outputted to the main controller 50, while the main clock of 10 MHz is output from the precision time oscillator circuit 40 to be transmitted to the main controller 50.

On the other hand, the main controller 50 performs a series of programs shown in FIG. 7 according to the input state of the 1PPS transmitted from the GPS receiver 20 and the 10MHz main clock transmitted from the precision time oscillator circuit 40 to control sequentially. At the same time, by combining, counting, and calibrating, 1PPS and 10MHz are accurately synchronized, and then 1PPS and 10MHz are output.

Therefore, 10 MHz is accurately synchronized with 1 PPS at the main controller 50, and the frequency of each of the synchronized 1 PPS and 10 MHz is output through the output drive 70, while at the main controller 50, the signals of 1 PPS and 10 MHz are output. When is normally output is reset and sends a control signal to the display unit 30 to turn on the corresponding LED and at the same time, when receiving a visual signal from the GPS satellite 100, the LED lights and an alarm occurs when a system abnormality occurs.

Therefore, when 1PPS and 10MHz outputted in synchronization with the main control unit 50 are provided to the base station of the mobile communication of the code division multiple access (CDMA), the time synchronization occurs for each base station, and the call is moved from the base station to the other base station. The disconnection of the terminal during communication is eliminated.

The operation of the high-precision time synchronizer using GPS according to the present invention operated as outlined above will be described in more detail with reference to FIGS. 2 to 8.

First, when power is supplied to the system, the main controller 50 initializes the system in the MPU 51 (S1), and then executes a self-diagnosis mode (S2) to test whether there is a problem with the system.

At this time, if it is determined that there is no abnormality in the system (S3), the ready state of generating 1PPS using 10MHz, which is the main clock output from the precision time oscillation circuit 40 until the time signal 1PPS is received from the GPS satellite 100. On the other hand, when it is determined that there is an abnormality in the system after executing the self-diagnosis mode, the control signal is sent to the drive circuit 33 of the reset and display unit 30 shown in FIG. The system initial process (S1) for transmitting the built-in alarm is performed.

In this state, as described above, two cesium atomic clocks and two rubidium atomic clocks mounted in the GPS satellite 100 itself are transmitted on the basis of the Universal Time Coordinated Universal Time (UTC). The antenna 10 is transmitted to the GPS receiver 20.

Meanwhile, the GPS receiver 20 receives the time signal from the GPS satellite 100 and outputs 1PPS that generates one pulse per second as shown in FIG. 8A, while receiving the time signal from the GPS satellite 100. Each data relating to whether or not, back-up voltage detection, and year, month, and day are transmitted to the main controller 50.

In addition, when power is supplied to the system, the MPU 51 sends a predetermined data value to the D / A converter 41 of the precision time oscillation circuit 40 shown in FIG. As a value is applied to the variable voltage oscillator 42, a main clock of 10 MHz is output, which is applied to the main controller 50 again.

Therefore, the main controller 50 determines whether a 1PPS visual signal is received from the GPS receiver 20 (S5). If it is determined that the 1PPS is normally received during the determination, the main controller 50 recognizes the locked mode. By sending a control signal to the drive circuit 33 of the reset and display unit 30 of FIG. 5 to turn on (S6) the corresponding LED of the display unit 34 to inform that the normal state that the visual signal is received from the GPS satellite 100 do.

At this time, if it is determined that 1PPS is not received in the process of determining whether 1PPS is received from the GPS receiver 20 (S5), the MPU 51 clocks the previous data based on the holdover mode. GPS satellite signal reception process (L2) to output a (S7) is performed.

On the other hand, if it is determined that the locked mode in which 1PPS is received from the GPS receiver 20 in the GPS satellite signal reception process L2, the MPU 51 outputs the main clock of 10 MHz output from the precision time oscillation circuit 40 for 1PPS. If it is determined that the main clock is counted correctly 10 million times during 1PPS by counting (S8) as a built-in timer counter (S8), it is recognized that 10MHz is correctly synchronized to 1PPS.

Accordingly, the display unit 34 outputs 1PPS shown in FIG. 8A and 10MHz shown in FIG. 8B, and sends control signals to the drive circuit 33, which is the reset and display unit 30 of FIG. By lighting the corresponding LED of (S10), it indicates that 10MHz is correctly synchronized with 1PPS.

However, if the main clock is not counted correctly 10 million times during 1PPS when the counting step S9 is performed in the MPU 51, it may be determined that the main clock output from the precision time oscillation circuit 40 is not exactly 10 MHz during 1PPS. As shown in 4, data for increasing or decreasing the output frequency of the variable voltage oscillator 42 is outputted to the D / A converter 41 (S11).

Therefore, the D / A converter 41 converts and outputs the digital signal output from the MPU 51 to the voltage value of the analog signal, and the converted voltage value is applied to the variable voltage oscillator 42 so as to be applied to the input voltage. The proportional output frequency is increased or decreased, and the increased or decreased output frequency is supplied to the MPU 51 to return to the counting step S8 of FIG. 7 which counts the main clock output from the variable voltage oscillator 42 for 1 PPS. By executing the synchronization and output process L3, the main clock of the variable voltage oscillator 42 can be maintained at a constant 10 MHz at all times.

In the first and second ROMs 52 and 53 in FIG. 3, a program capable of executing the above-described process is stored. In the MPU 51, the first and second ROMs 52 and 53 are stored. It reads the programs stored in the sequential order so that 10MHz can be accurately synchronized and calibrated at 1PPS.

In addition, the first and second RAMs 54 and 55 are for temporarily storing data necessary during the above-described series of processes, and the chip selector 56 is required during program execution under the control of the MPU 51. In order to sequentially read data, the first and second ROMs 52 and 53 and the first and second RAMs 54 and 55 may be selectively enabled.

Next, referring to FIG. 6, a process in which 1PPS and 10MHz accurately synchronized in the MPU 51 are output through the output drive 70 is as follows.

First, 10 MHz is synchronized with 1 PPS, and then 1 PPS output from the MPU 51 is transmitted to one end of the first north gate NOR1 of the first output unit 71, and 10 MHz is the second output unit 72. Is applied to the second NOR gate NOR2.

At this time, the enable signal is output from the MPU 51 to the first and second north gates NOR1 and NOR2 so that the clocks of 1PPS and 10 MHz synchronized with each other are the first and second north gates NOR1 and NOR2. ) Output is made only when is enabled, so that it is possible to maintain isochronism by reducing the time error between 1PPS and 10MHz output signals, and to communicate with other external devices through one or more communication interfaces 73. .

On the other hand, when an abnormality occurs in a state in which the system is in operation or when the system is initialized as necessary, the reset circuit 32 is operated by transmitting the reset signal 32 to the MPU 51 when the switch 31 of FIG. 5 is turned on. As described above, the MPU 51 recognizes the reset signal and executes the step S1 of initializing the system of FIG. 7 to execute the above-described process again.

As described above, the present invention enables the 10MHz of the main clock output from the precision time oscillation circuit to be accurately synchronized with the 1PPS output from the GPS receiver by a program set in the MPU of the main controller, and of course, 1PPS from the GPS receiver. If the MPU is not received, the MPU maintains the main clock synchronously through the predicted value of the timeout according to environmental factors, so that the time can be accurately synchronized within a certain allowable range even in the event of a fatal error of the GPS receiver. When applied to, it is possible to prevent the disconnection of the mobile terminal in the call state by synchronizing the time of each base station precisely at the same time, it can be provided at a low cost and small size of the product according to a simple configuration.

Claims (6)

An antenna 10 for receiving a 1PPS visual signal radiated from the GPS satellites 100 and connected to the antenna 10 to output 1PPS, and whether the 1PPS is received, a back-up voltage detection signal, and year / month. GPS receiver 20 for outputting data about the work, connected to the output terminal of the GPS receiver 20 controls the system by a predetermined program and counts and corrects the main clock for 1PPS of the GPS receiver 20 To the output terminal of the main control unit 50, the precision time oscillation circuit 40 is connected to the input and output terminals of the main control unit 50 to generate a 10MHz main clock constantly, Connected to initialize the system and display whether 1PPS received from the GPS satellite 100, 1PPS and 10MHz output, and reset and display unit 30 to generate an alarm in the event of a system error, the output terminal of the main control unit 50 1PPS and 10 synchronized to connect A high precision time synchronization device using a GPS (Ground Positioning System) consisting of an output drive 70 which outputs a frequency of MHz and allows communication with other external devices. The main controller 50 of claim 1 controls the entire system and counts and corrects the outputs of the precision time oscillation circuit 40 and the GPS receiver 20 using a digital timer in the MPU 51. Of the first and second ROMs 52 and 53 and the MPU 51, which are connected to one end of the MPU 51 to accurately output and synchronize 10 MHz to the MPU 51 and store various control programs of the system. First and second RAMs 54 and 55 connected to the other end to store and read data required during system operation, and connected to one output terminal of the MPU 51 to the first and second ROMs 52 ( 53) and a chip selector (56) for selectively enabling the first and second rams (54, 55), respectively. The D / A converter 41 and the D / A converter according to claim 1, wherein the precision time oscillation circuit 40 converts and outputs the correction data of the digital signal output from the MPU 51 into a voltage of an analog signal. A variable voltage oscillator 42 is connected between the output terminal of the 41 and the input terminal of the MPU 51 to vary the output frequency according to the applied voltage so that the main clock of constant 10 MHz is always output by the correction data. High-precision time synchronizer using the GPS system. The MPU 51 of claim 1, wherein the output drive circuit 70 is connected to one output terminal of the MPU 51 and outputs 1PPS and 10MHz, respectively, and the MPU 51. High precision time synchronization device using a ground position measuring system (GPS), characterized in that consisting of one or more communication interface (73) that is connected to the other output terminal of the various possible communication with the outside. The first and second output units 71 and 72 have first and second north gates NOR1 and NOR2, respectively, and 1PPS is on one side of the first north gate NOR1. 10 MHz is applied to one end of the second nor gate NOR2, and an enable signal is applied from the MPU 51 to the other ends of the first and second norm gates NOR1 and NOR2. High-precision time synchronizer using the GPS system, characterized in that. A high precision time synchronizer using a ground position measuring system including a GPS receiver, a main control unit with an MPU, a precision visual oscillation circuit, a reset and display unit, and an output drive, wherein the system is initialized when power is supplied to the system. After the diagnosis mode is executed, it is determined whether there is an abnormality of the system, and the system is in an initial process (L1) for operating an alarm or ready state according to the abnormality, and 1PPS is received after determining whether a 1PPS visual signal is received from the GPS receiver. In this case, the corresponding display lamp is turned on in the lock mode, and if 1PPS is not received, the GPS satellite signal receiving process (L2) of recognizing the holdover mode and outputting a clock based on previous data is determined. When the main clock is counted for a predetermined number of times during 1PPS, the corresponding lamp is turned on to indicate synchronization. High precision using ground position measurement system (GPS) consisting of synchronization and output process (L3) which increases or decreases the output frequency of precision visual oscillation circuit by determining that the main clock is not synchronized for a predetermined number of times during the 1PPS. Control method of time synchronizer.