RU2805775C1 - Astronomical time signal generator for stand-alone digital seismometers - Google Patents

Abstract

FIELD: seismology.

SUBSTANCE: seismic signal receivers used to create seismic data recording systems. The claimed device contains a GPS receiver and a logical level converter. Additionally, a clock generator is introduced into the device, a controller for maintaining the parameters of the second mark, which has a program contained in it, which ensures that the period of signals of the second marks, if any, is measured, it is stored in the internal memory of this controller and the signals of the second marks are reproduced at its output when the signals stop receiving second marks from the GPS receiver.

EFFECT: increased reliability and expanded scope of the driver.

1 cl, 8 dwg

Description

The invention relates to seismology, and more precisely to equipment for seismic research, and can be used to create seismic data recording systems.

A known astronomical time signal generator for autonomous digital seismometers, containing a GPS receiver [1].

The disadvantage of the known device is that it provides an accurate reference of the recorded seismic signal to astronomical time only if there is a stable connection between the GPS receiver and the satellites of this system. This condition is not always met, for example, in dense clouds. Loss of synchronization can last for days, which is completely unacceptable, especially during long-term seismic monitoring.

An astronomical time signal generator for autonomous digital seismometers is also known, containing a GPS receiver, a logical level matching unit, the input of which is connected to the output of identifying the second marks of the GPS receiver [2].

This shaper also has low reliability for the same reasons as [1].

The closest technical solution to the proposed one and adopted as a prototype is an astronomical time signal generator for autonomous digital seismometers, containing a GPS receiver, a logical level matching block, the input of which is connected to the output of identifying the second marks of the GPS receiver [3].

The disadvantages of the known technical solution also include low reliability, because Such an astronomical time signal generator for autonomous digital seismometers, when communication with GPS satellites is lost, ceases to produce synchronizing pulses of the second marks, and also provides distorted information at the output of the identification of the second mark.

In addition, the known technical solution has a narrow scope, since it cannot work in conditions where there is no connection at all with GPS satellites, for example, when conducting seismic research in a deep mine.

The purpose of the invention is to increase the reliability and expand the scope of application of the device for synchronizing seismic data with astronomical time.

This goal is achieved by the fact that the device for synchronizing seismic data with astronomical time contains a highly stable clock generator, a controller for maintaining the parameters of the second mark, a controller for maintaining the identification of second marks, the clock input of which is connected to the clock input of the controller for maintaining the parameters of the second mark and the output of the clock generator, interrupt input controller for maintaining the second mark parameters is connected to the output of the second mark of the GPS receiver, and the output is connected to the interrupt input of the controller for maintaining the identification of the second mark and is the output of the second mark of the shaper, the output of which identifies the second mark is the output of the controller for maintaining the identification of the second mark, the input of the identification of the second mark of which is connected with the output of the logical level matching block, and the controller for maintaining the second mark parameters has a program contained in it, which provides measurement of the period of the second mark signals if they are present at the interrupt input of this controller, storing the period of the second mark signals in the internal memory of this controller and reproducing these signals on output of the controller for maintaining the parameters of the second mark when the receipt of signals of the second marks from the GPS receiver stops, and the controller for maintaining the identification of the second marks has a program contained in it that ensures the reception of messages about the time of the current second mark in the presence of second marks from the GPS receiver, the calculation of the time of the second mark when stopping the second marks from the GPS receiver and issuing identification information about the current second mark at the output of this controller in the format of a protocol message from the GPS receiver.

The set of essential features of this technical solution: “a highly stable clock generator, a controller for maintaining the second mark parameters, a controller for maintaining the identification of the second mark, the clock input of which is connected to the clock input of the controller for maintaining the second mark parameters and the output of the clock generator, the interrupt input of the controller for maintaining the second mark parameters is connected to the output of the second marks of the GPS receiver, and the output is connected to the interrupt input of the controller for maintaining the identification of second marks and is the output of the second marks of the shaper, the output of which identifies the second marks is the output of the controller for maintaining the identification of second marks, the input of which identifies the second marks is connected to the output of the logical level matching block, Moreover, the second mark parameters maintenance controller has a program contained in it, which ensures measurement of the period of seconds marks signals if they are present at the interrupt input of this controller, storage of the period of seconds marks signals in the internal memory of this controller and reproduction of these signals at the output of the second mark parameters maintenance controller when when the receipt of seconds marks signals from the GPS receiver stops, and the controller for maintaining the identification of second marks has a program included in it, which ensures the reception of messages about the time of the current second mark in the presence of second marks from the GPS receiver, the calculation of the time of the second mark when the seconds marks stop from the GPS receiver, and issuance of identification information about the current second mark at the output of this controller in the format of a protocol message of the GPS receiver - ensures the formation at the output of the second mark of the astronomical time generator for autonomous digital seismometers of second mark pulses, accompanied by reliable identification information at the identification output of the second mark of the shaper in case of loss of connection of the GPS receiver with GPS satellites, which increases the reliability of the shaper.

In addition, when conducting seismic research in places where there is basically no connection with GPS satellites, for example, in a mine, you can first link the shaper to astronomical time on the earth's surface, and then move the shaper into the mine and connect it to a seismometer instead of a GPS receiver . Thus, the astronomical time signal generator for autonomous digital seismometers has the ability to operate in places inaccessible to GPS satellite signals, which expands its scope of application.

In fig. Figure 1 shows a block diagram of an astronomical time signal generator for autonomous digital seismometers; FIG. 2 is an example of the algorithm for the operation of the main program contained in the controller for maintaining the parameters of the second mark, in Fig. 3 – an example of an algorithm for a subroutine for processing an interrupt caused by the rising edge of the second mark signal at the interrupt input of the controller for maintaining the second mark parameters, in FIG. 4 is an example of an algorithm for the operation of a subroutine for processing interrupts caused by the timer of the controller for maintaining the parameters of the second marks when this timer reaches the time period of the pulses of the second marks, contained in the controller for maintaining the parameters of the second marks, in FIG. 5 is an example of the algorithm of operation of the subroutine for processing interrupts caused by the timer of the controller for maintaining the second mark parameters when this timer reaches the duration of the second mark pulse contained in the controller for maintaining the second mark parameters, in FIG. 6 is a timing diagram explaining the operation of the controller for maintaining the parameters of the second mark, in FIG. 7 is an example of the algorithm for the operation of the main program contained in the controller for maintaining the identification of seconds; in FIG. 8 is an example of an algorithm for a subroutine for processing an interrupt caused by a rising edge of the signal at the interrupt input of the controller for maintaining the identification of second marks.

The astronomical time signal generator for digital seismometers (Fig. 1) contains a GPS receiver 1, a logical level matching block 2, a highly stable clock generator 3, a controller 4 for maintaining second mark parameters, a controller 5 for maintaining the identification of second marks, the clock input of which is connected to the output of the clock generator 3 and with the clock input of controller 4, the interrupt input of which is connected to the output of 6 second marks of the GPS receiver 1, and the output of controller 4 is connected to the interrupt input of controller 5 and is the output of 7 second marks of the shaper, the output 8 of identification of second marks of which is the output of controller 5, the second mark identification input of which is connected to the output of block 2 for matching logical levels, the input of which is connected to the second mark identification output of GPS receiver 1.

The device works as follows.

After turning on the power, the GPS receiver 1 takes some time to establish communication with satellites. After the connection is established, at output 6, GPS receiver 1 generates a second mark pulse every second, the rising edge of which coincides with the beginning of the second of astronomical time. At the same time, at the second mark identification output of the GPS receiver 1, each second mark pulse is accompanied by a serial code in the RS-232 electrical signal standard, containing information about its time [1]. Logical level matching block 2 converts the levels of electrical signals corresponding to the RS-232 standard into standard logical levels of TTL/CMOS microcircuits.

After turning on the power, controller 4 proceeds to execute its main program (Fig. 2). Initialization of controller 4 consists of performing the following operations:

1. Setting at the output of controller 4 (output 7 of the shaper) the value of the logical signal level VPPS = 0;

2. enabling interrupts when a rising edge of the signal arrives at the interrupt input of controller 4 (setting the value of the variable ICIE1=1);

3. permission to capture the contents of the controller 4 timer at the moment the rising edge of the signal arrives at the interrupt input of this controller 4 and save this captured content in the ICR timer capture register;

4. disable timer comparison interrupts on channel A (OCIE1A=0);

5. Loading the value of the integer part of the variable N=t into the OCR1B timer comparison register_dl.*f_gene., Where t_dl.- approximate duration of the second mark pulse generated by the GPS receiver 1 (usually t_dl.300 ms), and f_{gene. -}clock generator frequency 3;

6. enabling interrupts compared to controller 4 timer on channel B (OCIE1B=1);

1. disable interrupts in comparison of controller 4 timer via channel A (OCIE1A=0);

2. assigning the value i=0 to variable i.

After initialization, the main program contained in controller 4 enters an endless loop without performing any operations. Exit from this loop is possible only to some interrupt handling routine when a corresponding interrupt request occurs.

Establishing a connection with satellites by the GPS receiver 1 usually takes about 10 seconds. During this time, the main program of controller 4 manages to complete initialization and enter an endless loop, waiting for interrupt requests. After the GPS receiver 1 establishes communication with satellites, pulses of second marks begin to appear at its output 6 (Fig. 6), the rising edges of which coincide with the beginning of the seconds of astronomical time. The first second mark after the GPS receiver 1 establishes communication with satellites appears at time t ₀ (Fig. 6). At the same moment in time, the rising edge of the second mark pulse will arrive at the interrupt input of controller 4, which will cause a corresponding interrupt request in this controller 4. At this request, controller 4 will interrupt the execution of the main program (Fig. 2) and proceed to execute the processing subroutine corresponding to the request interrupt (Fig. 3), which first resets the timer of controller 4 (the timer of controller 4, after the reset, begins to count the clock cycles of generator 3 from zero). After this, the interrupt subroutine (Fig. 3) sets VPPS = 1 (logical level “1” at the output of controller 4 and, which is the same, at the output of the 7 second mark of the shaper (Fig. 6). Thus, the rising edge of the pulse at the output The 7 second mark of the shaper will repeat the rising edge of the second mark pulse at the output of the 6 second mark of the GPS receiver 1.

Strictly speaking, the rising edge at the output 7 of the shaper will lag several clock cycles of the clock generator 3 from the rising edge of the second mark pulse at the output 6 of the GPS receiver 1. The higher the frequency of the master oscillator 3, the more insignificant this difference between the times of the rising edges. So, if f _gen. =10 MHz, then the difference between the fronts will not exceed tenths of a microsecond. And, since the time error of the rising edge of the second mark pulse at output 6 of the GPS receiver 1 is 1 μs, the discrepancy between the rising edges of the signals at outputs 6 and 7 can be neglected.

After the formation of a rising edge at the output of controller 4, the interrupt processing subroutine (Fig. 3) checks the value of the variable i, set during initialization i=0. If still i=0, then the subroutine changes the value of the variable to i=1 and returns to the same place in the main program from where the interrupt was called, i.e., into the endless loop of the main program (Fig. 2).

Because when initializing controller 4, only interrupts were allowed on the rising edge of the signal at the interrupt input of that controller 4 and compared to channel B of the timer of this one; t of controller 4. At the same time, the number N corresponding to time t was written to the comparison register on channel B of the timer of this controller 4 _. 300 ms, which means that the timer, having counted up to N cycles of clock generator 3, will issue a request for an interrupt compared to channel B of the timer. After resetting the timer at time t ₀ , the next rising edge of the second mark pulse can arrive at the controller’s interrupt input no earlier than 1 s later, and the timer of controller 4 is configured so that it will give an interrupt request compared to channel B after time t _{for .} 300 ms, i.e. before the arrival of the rising edge of the second mark pulse (Fig. 6). Thus, at time t ₀ + _tdl. The timer of controller 4 produces a request for an interruption in comparison on channel B, the processing of which occurs in accordance with the algorithm (Fig. 5). Having entered the timer comparison interrupt processing via channel B, the corresponding subroutine sets the signal value VPPS = 0 at the output of controller 4, i.e., at the output of the shaper, thereby completing the formation of a second mark pulse at the output 7 of the shaper for the moment t ₀ ( Fig. 6).After setting VPPS=0, the timer continues further counting time in clock cycles of generator 3, and the interrupt subroutine (Fig. 5) returns to the endless loop of the main program (Fig. 2) of controller 4, where the next interrupt request is again waited for . If this request again turns out to be a request for an interrupt compared to channel B, then the program will exit to process this interrupt and, without changing anything, will return to the main program, since VPPS = 0 already. If the rising edge of the next pulse of the second mark arrives earlier (time t ₁ (Fig. 6), then controller 4 will first capture the time of the rising edge and save this time in the ICR timer register. Since the last reset of the timer is before the rising edge of the second the second mark signal at time t ₁ was produced by the rising edge of the first second mark signal at time t ₀ (Figs. 2 and 6), then the ICR timer register will store the value corresponding to the time T=t ₁ -t ₀ , where T- period of repetition of pulses of second marks. After capturing the timer time, a request for interruption will arise on the rising edge of the signal at the interrupt input of controller 4, which will lead to a transition from the endless loop of the main program (Fig. 2) to the interrupt processing subroutine (Fig. 3), in accordance with the algorithm of which the program resets the timer, setting logical “1” VPPS = 1 at the output of controller 4, i.e. at output 7 of the driver (time t ₁ (Fig. 6)). Since during the execution of the interrupt subroutine (Fig. 3) when processing the first pulse of the second mark received at time t ₀ , the value of the variable i changed to i = 1, then the subroutine for processing the interrupt when the second pulse of the second mark arrived at time t ₁ (Fig. 3) after checking the value of i, it will proceed to check whether the timer interrupt on channel A is enabled or not, which is determined by the value of the OCIE1A variable. If OCIE1A=1, then this interrupt is enabled, if OCIE1A=0 - not. If the specified interrupt is not enabled, then the subroutine (Fig. 3) confirms i=1 and returns to the endless loop of the main program (Fig. 2). If, when checking OCIE1A, it turns out that OCIE1A = 0, then the subroutine transfers the captured time value T from the ICR capture register to the OCR1A comparison register on channel A, enables timer comparison interrupts on channel A (OCIE1A = 1), disables rising interrupts edge of the signal at the interrupt input (ICIE1=0) of controller 4.

All this means that now, when the timer reaches the time in its comparison register OCR1A, controller 4 will generate an interrupt request compared to channel A of the timer, and more interrupt requests will be generated on rising edges of signals at the interrupt input of controller 4 will not be. Then the interrupt handling subroutine confirms i=1 and returns to the endless loop of the main program (Fig. 2). After time tdl _. after the timer is reset by the interrupt subroutine on the rising edge of the signal at the interrupt input of controller 4 at time t ₁ , a request for interruption will arise in comparison with channel B of the timer. At this request, a transition will occur to the subroutine for processing the corresponding interrupt (Fig. 5), which will set VPPS = 0, thereby forming the falling edge of the second pulse of the second mark at output 7 of the shaper (Fig. 6). In this case, the timer of controller 4 will continue counting the time (clock pulses of generator 3) started at time t ₁ . Since the timer channel A comparison register (OCR1A) was overloaded from its capture register (ICR1) with the time value T of the period of the second marks, then after this time after t ₁ (moment t ₂ ) a request for an interruption in comparison will arise on the channel A timer, and controller 4 will exit the endless loop of the main program (Fig. 2) into the interrupt processing subroutine corresponding to the request (Fig. 4).

This subroutine resets the timer, sets “1” (VPPS=1) at time t ₂ , which is separated by the period T of the second-mark pulses from moment t ₁ at the output 7 of the shaper (Fig. 6). The timer of the controller 4 continues to count the clock cycles of the generator 3. Due to this, requests for interruptions (Figs. 4 and 5) will be generated cyclically and will ensure the generation of second pulses at the output 7 of the shaper, even if they are not present at the output 6 of the GPS receiver 1 (Fig. 6), i.e. when the GPS receiver 1 loses communication with satellites. It is obvious that the accuracy of the correspondence of the rising edges of the second marks at the output 7 of the shaper, generated by the interrupt processing subroutine (Fig. 4), to the beginning of the seconds of astronomical time is determined by the accuracy and stability of the generator 3. The use of a highly stable thermostated generator from Bliley BOV TJ-10M as generator 3 allows generation by the shaper at its output of 7 signals of second marks, the rising edge of which does not differ from the beginning of astronomical seconds by more than 1 μs when the connection of the GPS 1 receiver with the satellites is lost for at least a day.

Controllers 4, 5 can be Atmel AVR series controllers that have the necessary timers, external interrupt inputs and serial data input and output interfaces, for example AtTiny2313.

Initialization of the controller 5 when executing its main program (Fig. 7) also manages to occur before the GPS receiver 1 establishes communication with the satellites. Initialization of controller 5 consists of performing the following operations:

1. enabling interrupts (INT0=1) on the rising edge (ISC00=3) of the signal at the interrupt input of controller 5;

2. permission to receive identification information about the second marks (RxEn=1) to the identification input of the second marks of this controller 5;

3. prohibition of transmitting identification information about second marks (TxEn=0) through controller output 5.

After initialization, the main program (Fig. 7) of controller 5 checks the value of the variable TxEn and, if TxEn=0, which was set during initialization, the program returns to checking this variable, which does not change its value in the main program. Thus, the program goes into an endless loop, from which it can exit only upon an interrupt request, and if in the interrupt handling subroutine TxEn changes its value from TxEn=0 to TxEn=1 and with this value it will return to the same place in the main program.

When a rising edge is received at the interrupt input of controller 5 from the output of controller 4 and, which is the same, from the output of the 7 second mark of the shaper in controller 5, a request for interruption will arise and the endless loop of the main program (Fig. 7) of controller 5 will exit in its interrupt routine (Fig. 8), which will first check the value of the RxEn variable. If RxEn=1, as was set during initialization, then the subroutine receives byte-by-byte identification information about the current second mark and writes it to successive memory addresses of controller 5.

Thus, the entire package of identification information of the second mark is written into the memory of the controller 5, byte by byte, in the form in which it arrives from the GPS receiver 1 through the converter 2. Among this identification information there is a byte indicating whether there was communication with satellites while receiving the identification information about a given second mark or not, i.e. whether the identification information about a given second mark can be considered reliable. Therefore, immediately after receiving the entire packet of identification information about the current second mark, the reliability of this packet is checked. If it turns out that the packet is unreliable, then it immediately returns to the place in the main program (Fig. 7) from which the interrupt subroutine was called (Fig. 8), without changing any values of the main program variables. Otherwise, before returning to the main program, RxEn=0 is set, which means that in the memory of the controller 5 there is reliable identification information about the current second mark.

If, after exiting to the interrupt handling subroutine (Fig. 8), the check of RxEn showed that RxEn = 0, then the subroutine reads bytes relating only to the time of the last second mark to the corresponding addresses of the controller memory, increases the value of this time by 1 second and writes to the same addresses, a new time value that will be used to generate a packet of identification information for the next second mark. After this, the sign TxEn=1 is set, and the main program returns to the endless loop (Fig. 7). In the interrupt subroutine (Fig. 8), the TxEn sign has changed from “0” to “1”, so the main program will exit the endless loop and proceed to byte-by-byte reading at successive addresses from the memory of identification information about the current second mark and the identification information created from the previous packet second mark, its transmission to the output of the controller 5 and output 8 of the driver.

Thus, when the GPS receiver 1 loses communication with the satellites, the controller 4 together with the generator 3 generates signals of second marks at the output 7 of the shaper, and the controller 5 generates, during the loss of communication with satellites, reliable identification information for the second marks at the output 8 of the shaper, which increases reliability operation of an astronomical time signal generator for autonomous digital seismometers.

In addition, when conducting seismological studies in places where GPS satellite signals are not available, the proposed shaper can first be synchronized with GPS satellites where such a connection is available, and then moved directly to the research site and used there instead of a GPS receiver. This allows us to achieve another goal of the invention - expanding the scope of application of the astronomical time signal generator for autonomous digital seismometers.

The proposed device was developed for carrying out precision seismological measurements within the framework of the implementation of project No. 122040400015-5 (FMWN-2022-0017) “Structural features and dynamics of the Earth’s interior - the crust, upper mantle and inner core according to seismic data” and was used in carrying out precision seismological measurements .

The work carried out confirmed the achievement of the proposed set of essential features of the stated objectives of the invention.

Bibliography

1. GARMIN. GPS 25 LP series GPS sensor boards GPS25-LVC, GPS25-LVS, GPS25-HVS. Technical Specification.

2. RF Patent No. 2400777, 09.27.2010, IPC: G01V 1/16 (2006. 01).

3. RF Patent No. 2435175, November 27, 2011, IPC: G01V 1/16 (2006. 01).

Claims (1)

An astronomical time signal generator for autonomous digital seismometers, containing a GPS receiver, a logical level matching unit, the input of which is connected to the identification output of the second marks of the GPS receiver, characterized in that in order to increase the reliability of the generator and expand the scope of its application, it contains a clock generator, a maintenance controller second mark parameters, second mark identification maintenance controller, the clock input of which is connected to the clock input of the second mark parameters maintenance controller and the output of the clock generator, the interrupt input of the second mark parameters maintenance controller is connected to the second mark output of the GPS receiver, and the output is connected to the interrupt input of the maintenance controller identification of second marks and is the output of the second marks of the shaper, the output of the identification of second marks of which is the output of the controller for maintaining the identification of second marks, the input of identification of the second marks of which is connected to the output of the logical level matching block, and the controller for maintaining the parameters of the second mark has a program contained in it that provides measuring the period of the second mark signals if they are present at the interrupt input of this controller, storing the period of the second mark signals in the internal memory of this controller and reproducing these signals at the output of the controller for maintaining the second mark parameters when the receipt of second mark signals from the GPS receiver stops, and the controller maintaining the identification of the second mark tags has a program included in it, which ensures the reception of messages about the time of the current second mark in the presence of second marks from the GPS receiver, the calculation of the time of the second mark when the second marks stop from the GPS receiver and the issuance of identification information about the current second mark at the output of this controller in protocol format GPS receiver messages.