Microelectronic device for determining telecontrol signal pulse quality

. The application of electromagnetic relays in control systems on railway transport is very problematic. The solution of this problem is based on modelling processes and application of microelectronic devices. The functional scheme for different modes of operation of the telecontrol signal decryption device is developed and investigated. Graphs and algorithm of microelectronic unit operation are given.


Introduction
In existing systems of train traffic control on railway transport, dispatch control and monitoring devices for the state of railway automation and telemechanics objects are widely used.Such systems include dispatch centralisation "Luch", developed in 1976 and operated to date on the roads of JSC "Uzbekistan Temir Yullari".The objects of control and management of this system are station automation and telemechanics devices, which are divided into central station and line station devices.The signalling and communication centre replaced all the devices of the central station of dispatch centralisation with microprocessor devices of the "Dialogue" system, which was supposed to use a specialised safe microcomputer at the line stations.However, the high cost of safe computers was the main reason why it was necessary to refuse to use them at the line stations, thus, at the moment the devices of the central station of dispatch centralisation have been transferred to the microprocessor basis, and the devices of line stations remained in the old version, i.e., on the basis of rigid logic and with the use of electromagnetic relays [1][2][3][4].
In this connection, the most urgent task of transferring the operation of the line station devices to the microprocessor basis appeared.As a microcontroller was chosen a single-chip microcontroller of MICROCHIP company of PIC family.In spite of small dimensions, these microcontrollers have good enough software, besides, there are some developments in this matter and experience in realisation of functional possibilities of relay circuits, microelectronic microcontrollers.[1,2,[4][5][6][7][8][9][10][11][12][13][14][15][16].
In addition, these devices are quite well equipped with elements of the specialised debugging environment MPLAB.

Method
The purpose of this article is to solve innovative problems on the application of contactless devices in the existing relay system of block route centralisation, which will provide an increase in traffic safety by increasing the reliability, technical condition of devices, control.To achieve this goal the methods of refusal from hardware realisation of logic functions and transition to software solution of these dependencies, and also refusal from mechanical contacts and transition to microelectronic contactless switching devices were used [1,5,6,8,9,10,13].

Discussion
The devices of the line dispatch centralisation station of intermediate railway stations are functionally divided into two parts: receiving, by telecontrol signal, and transmitting, by telesignalling.This section considers the proposed algorithm for decoding the received telecontrol signal, the hardware part of which is based on a microcontroller.The signal receiver receives information in the form of 01Н, 02Н and 04Н the order of change of these data determines the quality of the received signal, i.e., at 01Н → 02Н; 02Н → 04Н; 04Н → 01Н corresponds to the accepted "1", and at 01Н → 04Н; 02Н → 01Н; 04Н → 02Н corresponds to the received "0".Therefore, to determine the quality of the received signal, it is necessary to compare it with the previous one, the value of which is reflected by the variable " у ".There are three subprograms in the programme, appropriately named "01", "02" and "04".After receiving a new signal, it is characterised by the variable "" х , is immediately analysed " у ", with subsequent reference to one of the listed subprogrammes.

Moreover
"" х and "" y have 01Н, 02Н  and 04Н , and " z " received signal quality " " 0,1 z  .Provided " " " " хy  there is no receipt of information, if the condition is fulfilled " " " " хy  a new signal is received.Let " " " " хy  , and "" y 02Н  , then address to subroutine "02", where work is done to determine the quality of the received bit of information "z" according to the following algorithm, if  , then there is an error in receiving the signal.Let " " " " хy  , and " 4 " 0 Н y  , then refer to subprogram "04", where the following is done, if " " 02 " " 0.1H 1 хх     , then there is an error in receiving the signal.Let " " 02H " " 0.4H 1 хх     , then there is an error in receiving the signal.
The second method of determining the quality of the received signal based on bit-by-bit comparison is possible.This method is based on the application of Assembler commands BTFSC f,b analyses the quality of the bit with the number b of the register f to "0" if yes, then skip the next command.The BTFSS f,b command analyses the quality of the bit with the bit number b of the f register at "1" if yes, then skip the next command.Execution of the ratio " " " " хy  , is perceived as the beginning of reception, i.e. the last bits are analysed "" х and "" y for the presence of "0", if "0", then "" х , "" y are either 02H or 04H.The second bit is then checked "" х , if it's "0" then " " 04H х  , the second bit is checked "" y if «1», then " 2 " 0 Н y  "у"=02Н, hence there is a transition 02Н → 04Н and " "1 z  .If there is in the last bit "" х "1" it is assumed that " " 01H х  , and the last bit is analysed "" y , if "1" reception error, if "0", the second bit is analysed "" y , if "1" takes place "" = 02Н,01H → 0.2H "" = 1, if this condition is not fulfilled, then "" = 04Н,01H → 0.4H "" = 0.
Both methods have the right to exist, from the position of software implementation of the procedure for determining the quality of the received telecontrol signal, but if you follow the criterion, the simpler the commands used in the programme, the more reliable it should choose the last option, but from the position of simplicity of understanding the sequence of actions is preferred to the first option.To study the behaviour of the device it is necessary to develop and study its model and implement an algorithm for determining the quality of the telecontrol signal pulse, which will be implemented in the software of the microprocessorbased information reception unit of the "Luch" dispatch centralisation line station, currently operated on the railways of JSC "YTY".
Modelling the operation of the dispatch centralisation line station node in its various positions.In the existing systems of train traffic control on railway transport, dispatching devices for control and monitoring of railway automation and telemechanics objects are widely used.The devices of the linear dispatch centralisation point of intermediate railway stations are functionally divided into two parts -receiving, by telecontrol signal, and transmitting, by tele-signalling.Nowadays one of the most urgent tasks is the transfer of the line station devices on the microprocessor basis.This paper considers one of the methods of modelling the operation of the node, the linear point, designed for demodulation of the telecontrol signal [6,7,9,11,12].The solution to this problem is based on the use of Petri net theory, which is a very convenient tool for modelling [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].The linear point device has output values described by three bits of information and accepts one of three states 001, 010, 100.The value of the received signal quality 0 or 1 is determined by the transition direction.Petri net graph of such a device is shown in Fig. 1.This Petri net is described by a quaternion С = (, , , ).The position of the device is described by the set  = { 1 ,  2 ,  3 ,  4 ,  5 }, where  1 = 001, 2 = 010, 3 = 100; р4= the received information corresponds to "1" and 5 p = the received information corresponds to "0"; the device transition is described by a set of  = { 1 ,  2 ,  3 ,  4 ,  5 ,  6 }.I: T → P 5 is an input function -a mapping from transitions to position sets.О: T → P 5 there is an output function -mapping from transitions to position sets.Input and output functions are used to map positions into sets of transitions, as well as vice versa.For the Petri net of Fig. 1, the extended input and output functions are the system of equations (1).
Analysis of the state graph shows that the positions  = { 1 ,  2 ,  3 }, are equally accessible to each other, provided that the transition direction determines the received quality of the pulse  = { 4 ,  5 }.More developed Petri nets are the Petri nets whose positions are equipped with tokens.A chip is a primitive concept of Petri nets (similar to positions and transitions).Chips belong to positions and their number can change when Petri nets are executed, assigning chips to positions is called labelling.A transition is called resolved if The graph of the labelled Petri net of the linear point device is shown in Fig. 2, which models the operation of the device in determining the quality of the received signal.The system of equations reflecting the state of this graph is given in (2).Let us consider the operation of this graph.To start any transition, it is necessary that this transition has at least two tokens.Let's assume the following order of chips distribution.After receiving the next telecontrol signal, the line station device is in one of the equally available positions with one chip, namely from the set of  1 ,  2 ,  3 , only one of the transitions will have a chip that defines the last state of the receiver.When the signal arrives, two chips are written to the transitions free of chips at once.With this in mind, let's consider the operation of the device by examining the behaviour of the model.Assume that the last combination was "010", so one chip is in position  1 , according to the system algorithm, the next position can be either  2 , for the case of information bit transmission "0", or  3 in the case of transmitting a bit of information with quality "1".Let us consider the case when receiving information bit "1", in this case we place two chips in position  3 and the graph will take the form shown in Fig. 3.The analysis of the state of this graph shows that the start conditions are fulfilled only for the transition 6 this will determine that a single bit of information has been received, and another chip will be returned to position 3 p , since there is a function ( 3 ) = { 3 ,  6 } As a result, the graph will move to a stationary state and will take the form shown in Fig. 4, from which it follows that the last combination "100" was accepted and the chip is in position 3 p .Consider the variant of information reception with a pulse of zero quality.For this purpose, the code combination (010) must arrive, in this case two chips will be placed in position 1   p and the graph will take the form shown in Fig. 5.The analysis of the state of this graph shows that the start conditions are fulfilled only for the transition 2 t , which has an input function ( 2 ) = {2 1 ,  3 }, where position  1 has two chips, and position  3 has one chip that registers the previous state of the device.Starting this transition will result in moving the chips and changing the state of the graph, because there are output functions ( 2 ) = { 1 ,  5 } and input functions ( 1 ) = { 2 ,  5 } and ( 5 ) = { 1 ,  2 ,  3 }.Chips will be reallocated in the following sequence, a chip from position  3 , and two chips from the position  1 create the conditions to trigger the transition 2  t , which will cause the chips to move out of position  3 , one chip out of position  1 will go into position  5 this will determine that a zero bit of information has been received, and one more chip will return to position  1 , since there is a function ( 3 ) = { 3 ,  6 }.As a result, the graph moving to a stationary state will take the form shown in Fig. 2, from which it follows that the last combination "010" was taken and the chip is in position   Software development.The algorithm of the main programme is shown in Fig. 6.The presented sequence of actions of the main programme is performed by the microcontroller each time after power-on or reset.At power-on or after reset, the first thing is the primary initialisation.During the initial initialisation process, the clock, watchdog timer, reset circuitry, etc. are set.After the initial initialisation, the ports are first configured.Port A is configured for output, the fifth, sixth and seventh digits of port B for input, the remaining digits of port B for output.Then the interrupt is configured by changing the level on the given digits of port B(INT).Then the programme self-locks and stays in this state until the interrupt occurs.

Conclusion
The methodology of development and modelling of a microprocessor-based device to determine the quality of the received telecontrol signal is proposed.Its model is developed and investigated with the use of the Petri net graph, on the basis of which the algorithm and software are built, fully adequate to the functional properties of the existing relay device of the dispatch centralisation system.

Fig. 1 .
Fig.1.Petri net graph of the state of the TU signal decoder

t, 1 p, and two position chips 3 p 1 p, one chip out of position 3 p
which has an input function ( 6 ) = {2 3 ,  1 }.Start of this transition will lead to a change of the graph state, because there are output functions ( 6 ) = { 3 ,  4 } and input functions ( 4 ) = { 4 ,  5 ,  6 }and( 3 ) = { 3 ,  6 }.Chips will be reallocated in the following sequence, a chip from position create the conditions to trigger the transition 6 t , which will cause the chip to move out of position will go into position 4 p