RU2278415C1 - Method for radio communication between protected objects and centralized guard station - Google Patents

Abstract

FIELD: engineering of equipment for transmitting signals of periodical and emergency alarm, possible use for realization of radio communication between guard center and protected objects.

SUBSTANCE: in guard center for each protected object a necessity for sending control signal is estimated, binary signal code is generated and transmitted with a command message, which is received at protected object. In each protected object in binary code handshaking, controlling or alarming messages are generated and transmitted to guard center. In guard center on basis of received alarming message a non-standard event is detected and adequate decision is taken. During transmission from each protected object of any message, expected time interval is determined between moments of transmission start for current message and next message of current protected object and bearing frequency of next message, and also moments of receipt of new messages from each one of protected objects and bearing frequencies of these messages are recorded. During generation of messages, transition from logical zero to logical one is performed by appropriate shift of bearing f. during approach of current time to recorded moment of receipt of new message from one of protected objects, broadband signals receipt is performed, input frequencies band is transferred to lower frequencies spectrum, analog-digital conversion is performed and intervals of frequencies, close to frequencies, at which in expected message symbols of logical one and zero are to be transferred, are singled out. If expected message is not received, in singled out frequency areas measures are taken, adequate for measures when alarming message is received from protected object. If message is received, by means of serial shift of time interval of digital filtration, moments of bit changes in message are determined and also time offset from the beginning of message, received message is decoded and actions are performed, adequate for its content. It also checked, whether aforementioned actions require sending a control signal to protected object. If such a requirement is present, command message is formed, containing a controlling signal, and transferred at frequencies of logical zero and one in the message received by guard center. At protected object after finishing transmission of message during a preset time interval, receipt of command from guard center is expected at same frequencies, at which the last message was transmitted from protected object.

EFFECT: possible increase of effective radius of alarm signaling equipment, used for protecting objects, with consideration of real active limitations on radio frequency nominal values and power of transmitters emission.

6 cl, 3 dwg

Description

The invention relates to methods for transmitting control and alarm signals using radio communication systems with frequency hopping. Such methods can be used in equipment that establishes a radio link between a central security point (CC) and guarded objects, which can be both vehicles and real estate.

The radio communication systems used in this equipment are used to transmit command messages from the central monitoring station to any selected protected object and any acknowledged messages (confirming the receipt of the command message), control messages or alarm messages from any protected object to the central monitoring station. The most significant is the transmission of alarm messages to the central monitoring station, since the generation and transmission of alarm messages occurs in case of an emergency at the corresponding guarded object, for example, in case of fire or if unauthorized persons are exposed to the guarded object. Such unauthorized persons may be intruders who penetrated the protected object with the purpose of robbery.

Two main types of equipment for a radio communication system are known (from the point of view of organizing the transmission of any messages from a guarded object to a central monitoring station).

The first type includes such equipment of the radio communication system in which the moment of formation and transmission of the next message is not known at the guarded object and, as a rule, in the central monitoring station. The transmission of a specific message from the protected object occurs only after the occurrence of an event that causes subsequent transmission. For example, as soon as a fire alarm sensor is triggered, an alarm message about a fire is immediately generated and transmitted to the PCO. Such equipment of a radio communication system is described, for example, in patents DE No. 4337211, G 08 B 25/10, G 08 V 29/00, G 08 C 15/00, H 04 V 7/24; EP No. 0651361, G 08 B 25/10; RU No. 2244959, G 08 B 25/10, G 08 B 29/16, B 60 R 25/10. The advantages of such equipment of the radio communication system are the high speed of transmission of alarm messages and low load of the radio communication channel, since the transmission of a message occurs only when the corresponding event occurs, and such events are quite rare. However, this type of equipment of the radio communication system has certain disadvantages. If, during the intrusion of intruders, they were able to immediately (that is, before transmitting an alarm message) disable the transmitting device of the protected object, then there will be no obstacles for their further actions.

In the second type of equipment of the radio communication system at each guarded object, it is possible to determine in advance the moment of formation and transmission of the next message. And at the central monitoring station, with a certain degree of certainty, it is possible to predict the moments of receipt of the next messages from each of the protected objects. The number of messages transmitted to the central monitoring station from each guarded facility for such equipment of the radio communication system for each hour is very noticeable (usually from 15 to 30). Such equipment of a radio communication system is described, for example, in US patents No. 6188715, H 04 L 27/26; US No. 6,700,920, H 04 B 01/713; US No. 6870875, H 04 B 01/69. The equipment of this type of radio communication system has a number of drawbacks: the speed of transmitting alarm notifications is very low (the time from the fire detector to giving the appropriate alarm message can be several minutes), the download of the radio channel is quite high (with 100 guarded objects about 2,000 messages are received at the central monitoring station in hour). However, attackers face a much more difficult task when they invade a protected object. In the PCO, the termination of the transmission of messages from any protected object is considered as an alarm message about the intrusion of intruders. Therefore, it is not enough for an attacker to simply suppress the transmission of an alarm message; it is also necessary to form some artificial messages on the radio air, which in the central monitoring station should be taken for messages from this protected object, indicating its normal operation.

An object of the present invention relates specifically to the latter second type of apparatus of a radio communication system. And this equipment must be transmitted with real account of all the strict restrictions on the power and on the carrier frequency of the radio signal introduced in Russia.

So, for example, if the guarded object is a vehicle, then GOST R 41.97-99 sets restrictions on the frequency and power of radio signals in the alarm equipment:

- carrier frequency (433.92 MHz ± 0.2%);

- maximum radiation power of 25 mW.

However, to ensure the competitiveness of the sold wireless alarm equipment, the manufacturer requires that the user of the alarm equipment do not issue special permits for the purchase and use of this equipment. Issuing permissions creates inconvenience for the user, which leads to the fact that the user refuses to purchase such equipment from this manufacturer and is looking for another manufacturer.

For alarm equipment that can be used in Russia without official authorization, the State Commission for Radio Frequencies (SCRF) by decision No. 7/5 of 04/02/2001 limited the ratings of the used radio frequencies (433.92 MHz ± 0.2%) and power ( up to 5 mW when installed on vehicles and up to 10 mW for other protected facilities).

With such small signal powers, the distance of protected objects from the central monitoring station should be several hundred meters. This is not enough to build effective wireless alarm equipment.

The traditional way to increase the distance of protected objects from the central monitoring station is to use the relay of signals of protected objects. However, the construction of a network of repeaters causes additional costs for construction work and, in addition, requires the permission of the State Radio Frequency Service and permits from owners of structures on which repeaters are installed.

One of the promising methods providing the possibility of transmitting messages from protected objects to a central monitoring station without using an extensive network of repeaters is the use of "jumping" frequencies in transmitted messages (Frequency hopping). Based on the application of this method, centralized security systems are described in the aforementioned patents-analogues: US No. 6188715, Н 04 L 27/26; US 6,700,920; H 04 B 01/713; US No. 6870875, H 04 B 01/69. It should be noted that the use of "jumping" frequencies makes it difficult for an attacker to form artificial messages on the air. In order for the artificial communication in the PCO to be perceived as a message from this protected object, indicating its normal operation, this artificial message should not only begin at the appropriate time, but also should be transmitted at the appropriate carrier frequency.

In addition, the use of “jumping” frequencies significantly reduces the likelihood that a pair of messages will be lost due to the coincidence of the transmission time intervals: for the loss of a pair of messages, the proximity of their carrier frequencies is also needed. However, if you do not control the choice of transmission start times and carrier frequencies, then loss of message pairs cannot be avoided.

Let's say that messages from a hundred of protected objects come to the PCO. Moreover, for each protected object, the time interval from the beginning of the transmission of any message to the beginning of the transmission of the next message is set within two to four minutes (with a hundred equally probable choices). Suppose further that the number of equally probable carrier frequency selection options for each message is one thousand. Then, every hour in the central monitoring station, two to three pairs of messages generated by different protected objects will be lost.

In one of the well-known technical solutions (in US patent No. 6870875, Н 04 В 01/69), measures were taken to select the moments of the beginning of the transmission of messages and carrier frequencies in order to avoid loss of message pairs due to their overlap (in time and carrier frequency). The method of operation of this technical solution is the closest to the claimed method. The technical solution for this patent is selected as a prototype of the proposed method.

The implementation of this method under the conditions in Russia of the restrictions on the range of radio frequencies and capacities does not allow to increase the coverage area of the equipment to more than (0.5-1.0) km. This is not enough for products intended for free market sale.

The present invention is aimed at improving the prototype, taking into account the current restrictions in Russia on the range of radio frequencies and powers.

The subject of this invention is a radio communication method between guarded objects and a central monitoring station, in which the central monitoring station identifies the need for a corresponding control signal for each protected object, generates a binary code for this control signal and transmits it over the air as part of a command message received at the corresponding protected object, in each of the protected objects they form in binary code and transmit acknowledgment, control or alarm messages to the PCO via radio, moreover, the acknowledgment message A message is generated after receiving a command message from the PCA, an alarm message - after an alarm event is detected at the guarded object, and a control message - if there are no conditions for the generation of an acknowledgment and alarm message, the alarm event is detected in the PCC, which caused the alarm message to be generated, and make a decision adequate to the disturbing event that occurred, when transmitting from each protected object any message - acknowledging, monitoring or alarming - determined dissolved expected time interval T between the instants of beginning of the transmission of this and the next message of the protected object and the carrier frequency F of the next message, wherein to select the expected time T intervals using three matched to all protected objects of the indicator: the minimum allowable time T _MIN range, maximum allowable interval the time T _MAX, and a step Δ _T of the timing interval and for selecting the carrier frequency F of the next message is also used for all three matching protected objects indicator: E imalno allowable frequency F _min, the maximum frequency F _MAKC and step frequency Δ _F grid, determining the expected time interval T is carried out by selecting a preset for each protected object pseudorandom algorithm equiprobable selecting number K _T within 0≤K _T ≤ (T _{MAX MIN} -T) / Δ _T and using the relation T = T _MIN + _T Δ _T K, and determining a carrier frequency F of the next message is performed by selecting a similar pre-set for each protected object algorithm pse equiprobable-random selection of K _F within 0≤K _F ≤ _{(F MAKC} -F _min) / Δ _F and utilization ratio F = F _F K _MIN + Δ _F, - wherein, in each one of the ARC is stored preset for protected objects pseudo-random equiprobable key algorithms and use these algorithms to determine and subsequently memorize the time of arrival of next messages from each of the protected objects and the carrier frequencies of these messages, when forming messages, they switch from a logical zero to a logical unit by shifting the carrier frequency F by an integer number K of steps Δ _{F of} the frequency grid that exceeds unity and constant for all protected objects, when the current time approaches the remembered time of the next message from one of the protected objects, they receive broadband signals, transfer the input frequency band to region of lower frequencies, carry out analog-to-digital conversion and digital filtering methods, taking into account the transfer of the input frequency band, allocate frequency intervals close those frequencies at which symbols of logical zero and logical units should be transmitted in the expected message, and if there is no reception of the expected message in the allocated frequency areas, measures are taken that are adequate to the measures taken when an alarm message is received from the corresponding protected object, if the message is received by successive shift the digital filtering time interval per step shorter than the transmission time interval of one bit in the message, the moments of the change in the bits in the message and sd are determined at the start time of the message, caused by the mismatch of the reference frequency of the generators in the monitoring station and the protected object, decrypt the received message and perform actions adequate to its content and taking into account the conditions that occur in the central monitoring station, check whether these actions require a control signal to be sent to the protected object, and if there is such a requirement, a command message is generated containing the required control signal, and it is transmitted at frequencies of logical zero and logical unit in the received AEC message as amended and, taking into account the mismatch between the reference frequency of the generators in the CCA and the protected object established when the message was received, and at the guarded object, after the end of the transmission of each message, a command from the CCA is expected to be received for a predetermined time interval at the same frequencies at which the last transmitted from this guarded object message.

Particular features of the invention are as follows.

In the PCO, when determining the time of arrival of the next message from the protected object under consideration, the expected time interval for receiving the next message is compared with the previously expected time intervals for receiving messages from other protected objects, the presence of overlapping of these intervals on the expected time interval for receiving the next message taking into account the duration of the additional time interval filing a command message, if such an overlap is detected, the presence of proximity is not checked uschih frequency and fixed proximity carriers form change command for the given protected object formation time and / or the carrier frequency of the next message, and then stored in the central station and the corrected parameters of the protected object.

Using the commands generated in the PCA, the time interval T between the moments when the transmission of this and the next message starts from the corresponding protected object is increased to the maximum allowable value T _MAX .

Digital filtering of messages in the central monitoring station is carried out using the fast Fourier transform.

When using the fast Fourier transform, an acceptable frequency overlap is established in adjacent spectral regions, at least a step Δ _{F of} the frequency grid.

In the structure of each message, a synchronization marker, an information block made using error-correcting coding, and a checksum are distinguished.

The objective of the invention is the creation of a technology that provides an increase in the range of the known alarm equipment used in the protection of vehicles and real estate, taking into account the actual restrictions on the nominal values of the used radio frequencies and radiation powers of the transmitters.

The technical result of the invention is the creation of a sufficiently simple in technical implementation and not having restrictions for the free market sale of system equipment designed to work in alarm systems.

The invention is illustrated using the drawings shown in figures 1-3.

Figure 1 explains the concept of the proposed method of radio communication between protected objects and PTOs.

Figure 2 shows the structural diagram of an example of a technical implementation of the equipment of the protected object.

Figure 3 shows the structural diagram of an example of a technical implementation of the equipment of the central monitoring station.

Figure 1-3 used the following notation: 1 - sensor; 2 - object control unit; 3 - object receiver; 4 - node pseudo-random selection; 5 - object frequency register; 6 - object time register; 7 - object time counter; 8 is a coincidence diagram; 9 - object driver of the message; 10 - auxiliary time register; 11 - current time counter; 12 is a first comparison diagram; 13 is a block of pseudo-random selection nodes; 14 - auxiliary address register; 15 - central frequency register; 16 - central time register; 17 - heterodyne receiver; 18 - analog-to-digital Converter; 19 is a block of digital filters; 20 - auxiliary frequency register; 21 - a crucial unit; 22 - central control unit; 23 - buffer memory; 24 is a second comparison diagram; 25 - shaper command message.

The equipment of the guarded facility is installed on the corresponding guarded property or in a vehicle. In this case, the structure of an example of technical implementation of the equipment of the protected object (figure 2) includes sensors 1, the outputs of which are connected to the object control unit 2. The corresponding outputs of the object control unit 2 are connected to the input of the node 4 of the pseudo-random selection, to the first input of the object register 6 times, to the first and second inputs of the object counter 7 times and to the first input of the object shaper 9 messages configured to transmit the corresponding messages over the air to the central monitoring station . The outputs of the object register 6 and the object counter 7 are connected to the corresponding inputs of the matching circuit 8, the output of which is connected to the first input of the object control unit 2 and to the second input of the object driver 9 messages. The third input of the object driver 9 of the message is connected to the output of the object register 5 of the frequency and connected to the input of the object receiver 3, configured to receive the corresponding command messages from the central monitoring station via radio. Moreover, the output of the object receiver 3 is connected to the second input of the object control unit 2, and the outputs of the node 4 of the pseudo-random selection are connected respectively to the second input of the object register 6 of the time and to the input of the object register 5 of the frequency.

The equipment of the central monitoring station is installed in general for all protected objects of the central monitoring station. At the same time, the heterodyne receiver 17 made with the possibility of receiving messages from protected objects is included in the example of technical implementation of the PCO equipment (Fig. 3). The output of the heterodyne receiver 17 through an analog-to-digital converter 18 is connected to the first input of the digital filter block 19. The second input of the digital filter block 19 is connected to the first input of the block 13 of the pseudo-random selection nodes and to the output of the first comparison circuit 12. The first input of the first comparison circuit is connected to the output of the current time counter 11, and the second input is connected to the output of the auxiliary time register 10 and to the first input of the central control unit 22, the second input of which is connected to the first output of the digital filter unit 19. The second output of the digital filter unit 19 through the decision unit 21 is connected to the third input of the Central control unit 22. In this case, the second input of the block 13 of pseudo-random selection nodes is connected to the output of the auxiliary address register 14. The first output of the block 13 of pseudo-random selection nodes is connected through the central frequency register 15 to the fourth input of the central control unit 22. The second output of the block 13 of pseudo-random selection nodes is connected to the first input of the central time register 16, the output of which is connected to the fifth input of the central control unit 22, the sixth input of which is connected to the output of the second comparison circuit 24. The first input of the second comparison circuit 24 is connected to the first output of the buffer memory 23, the first input of which is connected to the second input of the second comparison circuit 24 and to the first output of the central control unit 22. The second output of the central control unit 22 is connected to the input of the command message generator 25 configured to transmit command messages for the respective protected objects over the air. The seventh input of the central control unit 22 is connected to the second output of the buffer memory 23, the second input of which is connected to the third output of the central control unit 22, the fourth output of which is connected to the second input of the central time register 16. The third, fourth and fifth outputs of the buffer memory 23 are connected to the inputs of the auxiliary time register 10, the auxiliary address register 14 and the auxiliary frequency register 20, respectively. The output of the auxiliary frequency register 20 is connected to the third input of the digital filter unit 19.

Sensors 1 are technical means of security and fire alarms, designed to detect a fire at a guarded object or to detect the penetration (attempt of penetration) of unauthorized persons to a guarded object, as well as to detect the fact of exposure to a guarded object that exceeds the normalized level. That is, the sensors 1 detect alarm events at the guarded object. Upon detection of alarm events, the sensors 1 generate the corresponding alarm notifications. In addition, the sensors 1 can also generate control and diagnostic alerts. The types and basic characteristics of technical means of fire and security alarms are widely known in scientific and technical literature (for example, "Directory of engineering and technical workers and electricians of technical means of security and fire alarms", Moscow, Ministry of Internal Affairs, GUVO, 1997).

The object control unit 2, the decision unit 21, the central control unit 22 and the second comparison circuit 24 can be performed, for example, according to the programmable controller circuits.

As an analog-to-digital Converter 18 can be used with standard commercially available chips.

Block 19 of digital filters can be made on the basis of digital filtering nodes of an integrating type using the fast Fourier transform method.

The structure of the equipment of each guarded object includes a special pseudo-random selection node 4 designed specifically for this guarded object. It allows pseudo-random selection of the carrier frequency of the next message and the time interval between sending this message and sending the previous message. For simplicity of presentation, we can assume that the node 4 of the pseudo-random choice is a permanent non-volatile storage device (although in practice the choice of the hardware implementation of the node 4 of the pseudo-random choice can be extremely wide). For this embodiment, the pseudo-random selection node 4, the pseudo-random selection node block 13 is a set of storage devices, the contents of each of which completely coincides with the contents of the pseudo-random selection node 4 (which is part of the corresponding protected object). Block 13 nodes of the pseudo-random selection is made with the possibility of selecting a specific storage device according to the contents of the auxiliary address register 14.

As the object receiver 3, you can use the receiver of any known type, for example superheterodyne with a variable frequency of the local oscillator.

The heterodyne receiver 17 must be configured to transmit the input frequency band to lower frequency (eg, sound) frequencies when receiving radio signals.

The object driver of the message 9 and the driver 25 of the command message are configured to generate signals in the desired frequency band with a corresponding (external to them) selection of the carrier frequency. With this in mind, the object message shaper 9 and command message shaper 25 can be performed according to the standard transmitter scheme with the selected modulation type as the serial code of the message to be transmitted.

The remaining nodes and blocks of the considered hardware implementation of the proposed method are standard digital elements that are widely described in the technical literature and available on the commercial market.

The centralized security system described above works as follows.

At a certain distance (for example, no more than 20 km) from the central monitoring station, a number of protected objects are located (Fig. 1). Such protected objects may be vehicles or real estate. Each of the protected objects is connected via a corresponding radio channel with a central monitoring station. The central monitoring station generates individual control signals for each protected object transmitted by the binary code over the air as part of the so-called command messages. After receiving the command message at the corresponding guarded object, an acknowledgment message is generated confirming the receipt of the command message.

At protected sites, disturbing events can occur, which include, for example, a fire or an attack on this protected object by intruders. Security equipment located at this guarded facility detects alarm events and then sends the corresponding alarm message to the central monitoring station. According to the decrypted alarm message, the PCO determines which alarm event occurred at the guarded object and take adequate measures, for example, in case of fire, send a fire brigade to the appropriate address.

However, if the guarded object was attacked by intruders, it is necessary to reckon with the fact that the security equipment at the guarded object can be suppressed, for example, mechanically broken and destroyed by the use of firearms and explosives. Therefore, an alarming message about an attack by attackers may not reach the PCO. In the security system under consideration, it is provided that each of the messages of a certain i-th guarded object is supplied and, accordingly, arrives at the central monitoring station at strictly defined time points (t _{i, 1} , t _{i, 2} ... t _{i, p} , t _{i, p + 1} ...). These time points are calculated both in each guarded object and in the central monitoring station. When transmitting (at time t _{i, p} ) the next message using the pseudo-random equally probable algorithm, the time interval T is determined between the start of transmission of this message and the start of transmission of the following message:

The algorithm for the pseudo-random equiprobable choice of the time interval T is special for each of the protected objects, however, each of the algorithms for the pseudo-random equiprobable choice of the time interval T for the protected object is also known in the central monitoring station. Common to all algorithms for pseudo-random equiprobable choice of the time interval T are three parameters:

T _MIN - the minimum allowable time interval;

T _MAX - the maximum allowable time interval;

Δ _T is the time interval selection step.

Thus, the choice of the time interval T is reduced to the choice of an integer K _T in the range from 0 to (T _MAX- T _MIN ) / Δ _T. At the same time, pseudo-random equiprobable selection algorithms should provide an equal probability of choosing any of the integers within the given limits. Formula (1) is converted to the form:

The binary code of each message is transmitted on a pseudo-randomly selected carrier frequency F. Algorithms for the pseudo-random equiprobable selection of the carrier frequency F are specific for each of the protected objects, however, each of the algorithms for the pseudo-random equiprobable choice of the carrier frequency F for the protected object is also known in the PCO. Common to all algorithms for pseudo-random equiprobable selection of the carrier frequency F are three parameters:

F _MIN - the minimum allowable carrier frequency;

F _MAKC - maximum allowable carrier frequency;

Δ _F is the step of the frequency grid.

The pseudo-random selection of the carrier frequency F is reduced to the choice of an integer K _F ranging from 0 to (F _MAKC -F _MIN ) / Δ _F. At the same time, pseudo-random equiprobable selection algorithms should provide an equal probability of choosing any of the integers within the given limits. The carrier frequency F is determined by the formula:

When transmitting, frequency modulation is used. For example, a logical zero is transmitted at a carrier frequency F, and a logical unit is transmitted at a frequency F + K · Δ _F. The integer K is a common constant value for both all protected objects, and for the central monitoring station. For example, K = 2.

If at a certain point in time at a certain carrier frequency the PCO did not receive messages from the corresponding protected object, then this event of the PCO equates to the receipt of an alarm message about an attack by attackers on this protected object. Therefore, if at any secured object at the moment selected for sending a message, there are no conditions for the formation and submission of an acknowledgment or alarm message, then this protected object generates a so-called control message. Its admission to the central monitoring station indicates only that the corresponding protected object is in a normal state. Of course, the control message may also contain some additional information, for example, that the voltage of the battery has dropped significantly and is close to the allowable limit. However, it should be noted that the content of any message does not relate to the subject of this patent and will not be considered. Only the presence of four types of messages in the system is essential: command, acknowledgment, control and alarm.

Moreover, the structure of each message contains:

- synchronization marker;

- information block (made, for example, using error-correcting coding);

- check sum.

The number of bits in each type of message is strictly constant. The duration of the transmission of each discharge is the same.

Let us now consider in more detail the operation of the equipment (Fig. 2) installed on protected objects.

A number of sensors 1 are installed at the guarded object (vehicle or real estate), each of which implements the assigned security function directly for it in the security zone established for it. For example, one of the sensors 1 can make sure that the garage door is closed and maintains its integrity in a secured summer cottage. Another sensor 1 monitors the integrity and closed state of one of the windows of the house, etc. The task of the sensors 1 is to fix certain events (including disturbing events) and transmit information about these events to the object control unit 2 (which can be, for example, a specially programmed microcontroller).

A signal from the object receiver 3 also arrives at the object control unit 2 (when any command message from the central monitoring station arrives at this protected object).

The object control unit 2 according to the information received from the sensors 1 and from the object receiver 3, prepares a message code (acknowledging, monitoring or alarm) to be transmitted next. After the set minimum acceptable time interval (T _MIN ) passes from the moment the last message starts transmission, the object control unit 2 issues a command to the pseudo-random selection node 4. By this command, the node 4 pseudo-random selection transmits:

- on the object register 5 frequency code K _F carrier frequency of the next message;

- to the object register 6 times the code K _{T the} expected time interval T between transmitted messages. With the minimum allowable content of the object register 6 times (for example, all logical zeros), the minimum allowable time interval T _{MIN is} set between the transmitted messages, and with the maximum allowable contents of the object register 6 times (for example, all logical units) the maximum allowable time interval T _{MAX is established} between transmitted messages.

In addition, the object control unit 2 resets the object time counter 7 and starts to send counting signals to it with a period equal to the time interval selection step Δ _T. The equality of the contents of the object time counter 7 to the contents of the object register 6 time means that the set expected time interval T has passed from the moment of the previous message. Matching circuit 8 establishes the coincidence of the contents of the object counter 7 time and the object register 6 time, and then sends a signal to the object shaper 9 messages to the object control unit 2.

The object control unit 2 remembers the moment the signal arrives at it from the coincidence circuit 8. This moment the object control unit 2 considers as the moment of the beginning of transmission of the next message, because the signal from the matching circuit 8, the object driver of the message 9 starts transmitting the next message to the air. When a message is sent to the radio, the carrier frequency F is used, the code of which (K _F ) arrives at the message generator 9 from the output of the frequency object register 5, and the serial message code received in the message generator 9 from the object control unit 2. Upon completion of the transmission of the message, the object control unit 2 turns off the object shaper 9 of the message and switches to the standby mode for receiving a command message, which can be received in the object block 2 from the object receiver 3. In this case, the carrier frequency of the expected command message is set for the object receiver 3 from the output of the object 5 frequency register. In a system that implements the proposed method, there is always a single protected object that transmits a message to the ARC at a given carrier frequency F. Therefore, a command message from the ARC (at the same carrier frequency F) is sent strictly to a specific protected object (no address is required). After receiving the command to the object control unit 2, this object control unit 2 starts working out the contents of the received command, carrying out the required actions.

These actions are not related to the subject of the invention and are not specifically considered with a single exception: a command to change the expected time interval T is received. According to this command, the maximum allowable time interval T _MAX must be forcibly set at the guarded object. Therefore, to work out this command after the next code K _{T is} received from the node 4 of the pseudo-random selection in the object register 6 of the time. the expected time interval T, from the object control unit 2 to the same object register 6 of the time a signal of forced installation in the object register 6 of the maximum content time (T _MAX- T _MIN ) / Δ _T.

Consider now the operation of the PCO equipment (figure 3). For simplicity, the block diagram of the central monitoring station equipment in the implementation example (Fig. 3) does not take into account the possibility of simultaneously receiving messages from several protected objects in the central monitoring station (when using separated carrier frequencies).

We begin the consideration of the operation of the PCO equipment at the expected time t _{i, p of} receiving the next message from some i-th guarded object. At this point in time, the contents recorded in the auxiliary time register 10 coincides with the current time of the central monitoring station, that is, with the counter 11 of the current time. This coincidence fixes the first comparison circuit 12 and generates a control signal supplied to block 13 of pseudo-random selection nodes. At the address arriving at the block 13 of the pseudo-random selection nodes from the auxiliary address register 14, in the block 13 of the pseudo-random selection nodes, the pseudo-random selection node whose operation algorithm corresponds to the operation algorithm of the pseudo-random selection node 4, which is part of the protected object, is received and received from which it is expected in PTsO. Thus, at the output of the block 13 of pseudo-random selection nodes, the set of signals appears that should be generated in the corresponding guarded object at the output of the pseudo-random selection node 4 during the formation of the next message. This set of signals goes to the central frequency register 15 and to the central time register 16.

At the moment in time t _{i, p} in the central monitoring station, the reception of a message from a certain i-th protected object should begin. This reception is carried out by the broadband heterodyne receiver 17. When receiving, a linear transfer of the input frequency region to the lower frequency region occurs. That is, as a result of the conversion, instead of the carrier frequency F, there appears a certain frequency F ₁ uniquely associated with it by a linear transformation. From the output of the heterodyne receiver 17, the signals are fed to an analog-to-digital converter 18, where they are converted to digital form. Next, the received signals are fed to the block 19 of digital filters. To the same block of digital filters 19 from the output of the auxiliary frequency register 20, the code of the expected frequency F ₁ is transmitted. Using this code, the digital filter unit 19 creates several digital filters corresponding to the frequency of the expected signals. For the above K = 2, you can limit yourself to five digital filters, the nominal frequencies of which are equal to:

F ₁ - the expected frequency of receiving logical zero;

F ₁ + 2 · Δ _F is the expected frequency of reception of a logical unit;

F ₁ + Δ _F - the expected frequency of receiving a logical zero, taking into account a possible error on "+ Δ _F " (or the expected frequency of receiving a logical unit, taking into account a possible error on "-Δ _F "),

F ₁ -Δ _F - the expected frequency of receiving logical zero, taking into account the possible error on "-Δ _F ";

F ₁ + 3 · Δ _F - the expected frequency of reception of a logical unit, taking into account the possible error on "+ Δ _F ".

In principle, using these five digital filters, a possible error of up to ± 3 · Δ _F can be detected: in this case, the signal will be on only one digital filter. Then it is necessary to rebuild the digital filters, for example, by correspondingly changing the expected reception frequency F ₁ .

The allocated frequency intervals must overlap to ensure the receipt of notifications near the boundaries of the intervals. The amount of overlap is determined when programming the operation of the block 19 of the digital filters. In the system hardware implemented by the applicant enterprise, the digital filter unit 19 was built on the basis of a fast Fourier transform.

From the output of digital filter block 19, the signal is sent to decision block 21. If at the expected time for receiving a message at the expected frequency there is no signal reception, then decision block 21 includes a warning about an alarm event: no messages from a specific protected object.

If the digital filter unit 19 detects the presence of a signal in the desired frequency range, then the integration intervals must be set in the digital filter unit 19, the beginning and end of each of which must correspond to the beginning and end of the discharge transmission in the message of the protected object. Setting integration intervals is carried out when receiving a synchronizing message marker.

If the operation of the PCA equipment and the corresponding guarded object occurs completely synchronously, then the signal issued by the first comparison circuit 12 at the time t _{i, p} will indicate the beginning of message reception. However, it is impossible to achieve complete synchronization of the operation of various units of equipment in the absence of common synchronization signals. Therefore, a certain limited time shift is allowed between the beginning of the reception of the message and the beginning of the output signal of the first comparison circuit 12. The maximum permissible value of this shift ± δ can be estimated. That is, it can be considered acceptable that the reception of the message begins at any arbitrary moment in time ranging from t _{i, p} -δ to t _{i, p} + δ.

This limit period of time can, for example, be divided into a certain number of equal parts, determined by the program of operation of the digital filter unit 19, and select the moment the message begins to receive at the maximum of the integral function corresponding to finding the received signal in a certain frequency range. If, for example, logical zeros and logical units are transmitted alternately in the synchronization marker, then the signals will appear alternately at the outputs of one of the following filter pairs:

- with nominal frequencies F ₁ and F ₁ + 2 · Δ _F ,

- with nominal frequencies F ₁ + Δ _F and F ₁ + 3 · Δ _F ;

- with rated frequencies F ₁ -Δ _F and F ₁ + Δ _F.

The integration time in each of the digital filters is exactly equal to the time of receipt of one bit of the message. The more precisely the start and end of the integration time correspond to the start and end times of transmission of one bit of the message, the higher the integration result. From its maximum, it is possible to fairly accurately establish the correction τ, by which the moment t _{i, p} differs from the real moment t * _{i, p} , of the beginning of message reception. Thus, the estimated time t _{i, p of the} beginning of reception is recorded in the auxiliary time register 10, a correction τ to this time moment is set in the digital filter block 19, and the expected value T of the time interval between the filing of the considered message of this protected object is stored in the central time register 16 and by filing the next message from the same guarded facility. According to these data, the central control unit 22 calculates the expected time t _{i, p + 1 of} receiving the next message from the i-th guarded object. In addition, the central control unit 22 updates the expected frequency value of the next message recorded in the central frequency register 15.

Then, the central control unit 22 sequentially reads from the cells of the buffer memory 23 the values of the expected moments of receiving messages from each of the remaining protected objects. Using the second comparison circuit 24, each of the read values is compared with the calculated expected time t _{i, p + 1 of} receiving the next message from the i-th guarded object. If the comparison reveals the possibility of blocking the message from the i-th protected object (taking into account the fact that a command message can be transmitted immediately after the end of this message) with a message from some other protected object or with a command message, then the second comparison circuit 24 gives about this signal to the Central control unit 22. Based on this signal, the central control unit 22 sets in the central time register 16 the content corresponding to the maximum allowable interval between the messages from one source (for example, all logical units), and then repeats the calculation of the expected time t _{i, p + 1 of} receiving the next message from i -th guarded object, taking into account the change in the contents of the central register 16 time. In addition, the central control unit 22 remembers that upon receipt of a message from the i-th protected object, it is necessary to submit a command message about the postponement of the next message from the i-th protected object.

Upon completion of all checks carried out by the second comparison circuit 24, the central control unit 22 writes to the i-th cell of the buffer memory 23 the calculated values of the expected time t _{i, p + 1 of} receiving the next message from the i-th protected object and the carrier frequency of this message.

It should be noted that the message continues to be received from the i-th protected object. The message bits are sequentially delivered to the deciding unit 21, where the content of the message is evaluated essentially. Upon completion of the receipt of the message, the decision unit 21 transmits a signal corresponding to the received message to the central control unit 22.

In this case, it can be revealed that an alarm message has been received or a control message has been received instead of an acknowledgment message. In both cases, the central control unit 22 includes a corresponding alarm, according to which an adequate solution is developed in the central monitoring station. The development of a specific adequate solution does not relate to the subject of this patent.

After the signal about the received message is received in the central control unit 22, the central control unit 22 checks whether it is necessary to generate a command message for the i-th guarded object. Such a message may be, in particular, a command message about the postponement of the next message by the i-th protected object. If this command message does not need to be generated, then the central control unit 22 checks if there are any requirements for the formation of any other command message. If it is necessary to transmit a command message, the central control unit 22 includes a command message generator 25, which, on an adjusted carrier frequency, transmits over the air a serial code of the corresponding command message.

Upon completion of the transmission of the command message (or after the fact of the absence of the need for its transmission to be detected), the central control unit 22 starts sequential interrogation of the cells of the buffer memory 23. Using the second comparison circuit 24, the cell of the buffer memory 23 is detected, in which the smallest moment of the expected time of receipt of the message is recorded. After that, from the buffer memory 23 is overwritten:

- the moment of the expected time of arrival of the next message - in the auxiliary register 10 time;

- the expected carrier frequency to the auxiliary frequency register 20;

- the number of the buffer memory cell is in the auxiliary register 14 addresses.

After that, the central monitoring station is prepared to receive the next message from the protected object. The work of the PCO considered above is further completely repeated.

When using the proposed method retains all the positive properties of the prototype, however, the technical implementation of the proposed method is significantly simpler. This provides a significant increase in the signal-to-noise ratio due to the multiple narrowing of the passband of the receiving path in the PCO, which proportionally reduces the noise power in the received frequency band while maintaining the useful signal power.

At the applicant enterprise, equipment was tested that implements radio communication methods corresponding to the prototype and the claimed technical solution. Tests have shown that when fulfilling the requirements of the above decision of the State Committee for Emergencies No. 7/5 of 04/02/2001, the use of the proposed technical solution allows, all other things being equal, to increase the maximum permissible distance between the guarded object and the PTOs more than twenty times.

Thus, the combination of known and newly introduced in the claimed method of actions on material objects allows us to solve the problem that the invention is aimed at, while ensuring the required technical result. The method is technically feasible and has novelty, which allows us to consider it as an invention.

Claims (6)

1. The method of radio communication between the guarded objects and the central security point, in which the centralized guard point for each guarded object identifies the need for the appropriate control signal, form a binary code for this control signal and transmit it over the air as part of a command message, which is received on the corresponding guarded in the object, in each of the protected objects they form in binary code and transmit to the central protection point over the air acknowledging, control or alarm messages, moreover, an acknowledgment message is generated after receiving a command message from the central security guard station, an alarm message - after an alarm event is detected at the guarded object, and a control message - in the absence of conditions for the generation of an acknowledgment and alarm message, in the central guard station, an alarm message is detected the event that caused the formation of the alarm message, and make a decision that is adequate to the alarm event that occurred during transmission e from each protected object of any message - acknowledging, monitoring or alarming - determine the expected time interval T between the moments of the beginning of the transmission of this and the next message of this protected object and the carrier frequency F of the next message, in order to select the expected time interval T use three matching for all protected objects indicator: the minimum allowable time interval T _min, the maximum time interval T _max, and step Δ _T of the timing interval and for selecting the carrier often s F next message also use three coincident for all protected objects of the indicator: the minimum permissible frequency F _m, the maximum frequency F _max, and step Δ _F grid of frequencies, determining the expected time interval T is carried out by selecting a preset for each protected object algorithm pseudorandom equiprobable selecting number K _T within 0≤K _T ≤ (T _max -T _min) / Δ _T and using the relation T = T _min + R Δ _{T T,} and determining a carrier frequency F of the next message is performed pU selecting it on a similar pre-set for each protected object pseudorandom algorithm equiprobable selecting number K _F within 0≤K ≤ _F (F _max -F _min) / Δ _F and utilization ratio F = F _min + Δ _{F F} K, wherein that at the centralized security point, each of the pseudorandom equally probable key algorithms previously set for the protected objects is stored and these algorithms are used to determine and subsequently memorize the time of arrival of the next messages from each of the protected objects and the carrier frequencies of these messages, when generating messages, they switch from a logical zero to a logical unit by shifting the carrier frequency F by an integer number K of steps Δ _{F of} the frequency grid that exceeds unity and constant for all protected objects when the current time approaches the stored At the time of the next message from one of the protected objects, they receive broadband signals, transfer the input frequency band to the lower frequency region, and perform analog-to-digital Digital conversion and digital filtering methods, taking into account the transfer of the input frequency band, distinguish frequency intervals close to those frequencies at which symbols of logical zero and logical units should be transmitted in the expected message, and if adequate reception of the expected message is not taken in the selected frequency regions, measures taken upon receipt of an alarm message from the corresponding protected object, if a message is received by successively shifting the time interval digital filtering by a step shorter than the transmission time of one bit in the message, the moments of the change in the bits in the message and the shift in time of the start of the message caused by the mismatch of the reference frequency of the generators in the central protection point and the protected object are determined, they decrypt the received message and perform actions adequate to it the content and taking into account the conditions that take place at the central security point, check whether these actions require a control signal to be sent to the protected object, and If there is such a requirement, a command message is generated containing the required control signal, and it is transmitted at frequencies of logical zero and logical units in the message received by the central security center, as amended, taking into account the mismatch of the reference frequency of the generators as part of the central security center and the guarded object, and at the guarded object, at the end of the transmission of each message, a command from the central point is awaited for a specified time interval security guard at the same frequencies at which the last message was transmitted from this protected facility. 2. The method according to claim 1, characterized in that at the point of centralized protection when determining the time of arrival of the next message from the protected object under consideration, the expected time interval for receiving the next message is compared with the previously expected time intervals for the receipt of messages from other protected objects, the presence of these intervals for the expected time interval for receiving the next message, taking into account the duration of the additional time interval for the command message I, the detection of such overlay proximity check for carrier frequency and at the established vicinity carriers form change command for the given protected object formation time and / or the carrier frequency of the next message, and then stored in a centralized security point and the corrected parameters of the protected object. 3. The method according to claim 2, characterized in that, with the help of the centralized guard formed in the paragraph, the teams increase to the maximum allowable value T _max the time interval T between the start of transmission of this and the next message from the corresponding guarded object. 4. The method according to claim 1, characterized in that the digital filtering of messages at a centralized security point is carried out using a fast Fourier transform. 5. The method according to claim 4, characterized in that when using the fast Fourier transform, an acceptable frequency overlap is established in adjacent spectral regions of at least a step Δ _{F of} the frequency grid. 6. The method according to claim 1, characterized in that in the structure of each message allocate a synchronizing marker, an information block made using noise-resistant coding, and a checksum.

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