EP0770977A1 - Procédé pour l'augmentation de la sécurité de transmission d'un dispositif d'alarme radio - Google Patents

Procédé pour l'augmentation de la sécurité de transmission d'un dispositif d'alarme radio Download PDF

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Publication number
EP0770977A1
EP0770977A1 EP96116835A EP96116835A EP0770977A1 EP 0770977 A1 EP0770977 A1 EP 0770977A1 EP 96116835 A EP96116835 A EP 96116835A EP 96116835 A EP96116835 A EP 96116835A EP 0770977 A1 EP0770977 A1 EP 0770977A1
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EP
European Patent Office
Prior art keywords
radio
radio signals
antennas
central unit
data telegrams
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP96116835A
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German (de)
English (en)
Inventor
Werner Grundig E.M.V. Müller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Grundig AG
Original Assignee
Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH filed Critical Grundig EMV Elektromechanische Versuchsanstalt Max Grundig GmbH
Publication of EP0770977A1 publication Critical patent/EP0770977A1/fr
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/16—Security signalling or alarm systems, e.g. redundant systems

Definitions

  • the invention relates to a method for increasing transmission security in a radio alarm system according to the preamble of claim 1.
  • Alarm systems have become a valuable aid when monitoring apartments or buildings. Fire, theft, burglary and robbery are reported without delay.
  • the individual components of an alarm system perform the following tasks:
  • An alarm is recognized by detectors (detectors), which have different sensors depending on the type of detector (e.g. fire, broken glass or water detector).
  • detectors detectors
  • the signals generated by one or more detectors are evaluated in a central unit. On the basis of the detector signals and additional status variables, a decision is made in the central unit whether an alarm should occur. This can then be done by forwarding an alarm signal to the police or by activating acoustic and / or visual alarm devices (sirens, alarm lights, etc.).
  • a very high level of interference immunity of the alarm system is achieved by the line-based implementation, but very high expenditure is required, in particular when the line network is retrofitted.
  • radio alarm systems are increasingly being used, the components of which are connected via radio links.
  • These radio alarm systems consist of a central unit with a power supply, a radio receiver and an alarm device as well as outdoor units with a mains-independent power supply, a detector and a radio transmitter.
  • the outdoor units are connected to the central unit by sending data telegrams.
  • the data telegrams contain code numbers that uniquely identify the outdoor units. Depending on the number of bits used for this, more or fewer code numbers can be assigned.
  • the transmitters of the outdoor units only send data telegrams if the detectors determine a malfunction. These data telegrams are repeated at short intervals until the fault has been remedied.
  • the transmitters of the outdoor units can send special data telegrams as status messages at fixed time intervals.
  • the data telegrams for status reporting are generated and transmitted in the outdoor units at intervals of up to several hours, which means that the central unit can monitor the proper functioning of the outdoor units.
  • further bits can be added to the data telegrams.
  • a radio alarm system that is easy to install afterwards and has increased interference immunity of the radio links is known from EP 0 293 627 A1, in which a radio transmission method for the transmission of information between a central unit and a number of external units is described. The same radio frequency is used for bidirectional radio transmission. All outdoor units, which include the detectors as well as transmitters and receivers, are first of all checked at the same time as a sum check whether they have switched on their transmitter for the transmission of information. If at least one switched-on transmitter is recognized, the outdoor units are polled one after the other in a time-division multiplex procedure. For this purpose, the outdoor units are assigned unique code numbers that are predefined or set using switches. The code numbers are part of data telegrams that are exchanged between the central unit and the outdoor units.
  • the known radio alarm system has the disadvantage that malfunctions or alarm triggers can be caused very easily from the outside with appropriate technical equipment but also with an identical external unit, since only a single radio frequency is used.
  • Such interference signals can also come from identical radio alarm systems operated in the neighborhood.
  • each of the individual messages from the outdoor units is transmitted by means of at least two radio signals with different carrier frequencies. If it is determined in a received data telegram that it cannot belong to one of the outdoor units of the alarm system, the reception field strength is checked to see whether it exceeds a predetermined maximum value. If the check of all radio signals for all carrier frequencies used is positive in the manner described above, an alarm message is triggered. In particular, the blocking of the entire alarm system by means of a strong jammer is prevented.
  • DE 44 08 268 A1 discloses a method for increasing the interference immunity of a radio alarm system. To avoid a false alarm, all radio signals whose field strength is below a threshold value set during commissioning are not evaluated.
  • This method has the disadvantage that if the antennas of the radio alarm system are positioned unfavorably, certain outdoor units cannot establish a radio connection to the central unit. This either triggers a false alarm or the radio alarm system cannot be armed or the corresponding outdoor unit cannot trigger an alarm.
  • the present invention has for its object to provide a method for operating a radio alarm system with improved transmission security, which eliminates the disadvantages of radio alarm systems known from the prior art.
  • the method should also be able to be used for radio alarm systems with low transmission power.
  • each outdoor unit and the central unit have at least two antennas, which have different directional characteristics and are spatially offset from one another, whereby a uniform field strength distribution can be achieved.
  • no special alignment of transmitting or receiving antennas is required, and during installation there are no requirements for mounting the transmitting or receiving antennas.
  • influences on the transmission channel can be minimized by using at least two antennas with different directional characteristics, which are also arranged at different locations.
  • a radio alarm system operated according to claim 2 has the advantage that interference on the transmission channel can be corrected very well again by correlating the data telegrams of the radio signals sent and received by means of different antennas.
  • a radio alarm system operated according to claim 3 has the advantage that an antenna multiplex can be carried out, through which an improved reception and thus an increased transmission security can be achieved, in particular if the polarization of the transmission signal is influenced in the transmission channel.
  • An advantage of the method according to claims 4 and 5 is that, despite narrowband interference on the carrier frequencies used by the radio alarm system, an exchange of data telegrams is possible.
  • An advantage of the method according to claim 8 is that carrier frequencies which have already been recognized as being disturbed are no longer used for the transmission of data telegrams and that an alarm message is issued when no undisturbed carrier frequencies are available.
  • a radio alarm system operated according to the method of claim 9 has the advantage that the ability to influence the alarm system by evaluating and emulating the data telegrams is reduced by using a coding algorithm in the external units and the central unit.
  • the invention is explained in more detail below on the basis of an embodiment of a radio alarm system.
  • the single figure shows the basic structure of a radio alarm system operating according to the method according to the invention.
  • the radio alarm system has several outdoor units A1 to An and a central unit Z.
  • the external units A1 to An each have a detector, a computing unit, a battery or a rechargeable battery and a transmitter with two associated antennas An1 and An2, one or both antennas being able to be selected for reception via an antenna switch.
  • At least two antennas are provided for each outdoor unit, which have different directional characteristics and are spatially offset from one another.
  • the computing units which can be formed, for example, by microcomputers, evaluate the signals from the detectors and control the respective outdoor unit.
  • the central unit Z comprises a receiver 2 with associated antennas I1 and I2, a demodulator 3 for extracting the digital data telegrams and a computing unit 4 which evaluates the data telegrams and controls the receiver 2.
  • the computing unit 3 can be formed, for example, by a microcomputer with an associated memory.
  • antennas I1 and I2 can be selected individually or together for transmission / reception via an antenna switch.
  • the transmitters of the outdoor units A1 to An send their data telegrams via the connected antennas An1 and An2. These are chosen so that due to the respective directional characteristics of the antennas An1 and An2, when the transmission signal is superimposed on the transmission channel, an as uniform as possible electromagnetic field (Coulomb field) arises, in which the reception field strength only depends on the distance between the transmission and reception antennas.
  • Coulomb field electromagnetic field
  • the transmission security is further increased in that the transmitting and receiving antennas are arranged offset in three-dimensional space. Interference due to multi-path reception and other location-dependent interference can thus be largely avoided. Due to the doubling of the transmit and receive antennas, the transmission channels can be quadrupled, from transmit antenna 1 to receive antenna 1 and 2 and from transmit antenna 2 to receive antenna 1 and 2. This increases the effort for additional antennas in outdoor units A1 to An and central unit Z linearly, while the number of transmission channels and thus the improvement in transmission security is growing quadratically.
  • the received signals of the individual antennas are also correlated with one another in the receiver, as a result of which the signal components, in particular the data telegram, which are identically present in the two received signals, are amplified and the non-identical signal components, in particular noise, are attenuated.
  • a runtime compensation can also be carried out in order to take into account the different runtimes of the received signal on the differently long transmission channels. The correlation and the runtime compensation are carried out by the computing unit 3 of the central unit Z and the data telegram obtained therefrom is evaluated.
  • an algorithm is stored in the transmitter and receiver, which is processed by the control unit and takes into account which antenna was used to receive a valid data telegram with the higher reception field strength.
  • the external units A1 to An send data telegrams several times, the data telegrams with at least two different carrier frequencies be modulated and sent.
  • the transmission can be carried out simultaneously with one transmitter per carrier frequency in each outdoor unit A1 to An or in succession with a single transmitter, which can be set to the different carrier frequencies.
  • the order in which the different carrier frequencies are set can be fixed or can be changed.
  • the receiver 2 present in the central unit Z can likewise have a plurality of individual receivers for the simultaneous reception of a plurality of carrier frequencies used, or a single receiver which scans the carrier frequencies used in accordance with a specific scheme.
  • a receiver 2 in the central unit Z is assumed which scans the carrier frequencies used one after the other.
  • the receiver 2 is tuned by the microcomputer 4 via the connection 5.
  • the transmitters of the outdoor units A1 to An send the carrier frequencies used one after the other in time.
  • the respective outdoor unit A1 to An is triggered, so that a data telegram is sent by the transmitter S.
  • This radio signal is received by the receiver 2 of the central unit Z and a value characterizing the reception field strength is output to the microcomputer 4 via the data line 6.
  • the microcomputer 4 receives the data telegram just received from the output of the demodulator 3. This is evaluated in the microcomputer, which determines the code number of the sending outdoor unit.
  • the microcomputer 4 then stores the value of the reception field strength together with the code number.
  • a code number for the carrier frequency set on the receiver 2 can also be stored. If this is additionally stored, exact statements can be made about the interference of each individual carrier frequency for each outdoor unit A 1 to An.
  • this carrier frequency is stored in the central unit Z and is no longer used for further radio connections to the outdoor units A1 to An. If it is possible to manually set one or more carrier frequencies used in the outdoor units, the carrier frequencies that are too disturbed (or the least disturbed) are displayed on a display unit of the central unit Z and the user has the option of making corresponding settings on the outdoor units A1 to An manually to be carried out so that the outdoor units A1 to An only use carrier frequencies which are not excessively disturbed.
  • the carrier frequency to be set by outdoor units A1 to An is transmitted from the central unit to outdoor units A1 to An in a special data telegram.
  • a carrier frequency is then selected which is used to transmit the data telegrams to the central unit Z and this carrier frequency is transmitted to the central unit Z in a special data telegram on a specific carrier frequency.
  • a simplified embodiment can be formed if, instead of as described above for each outdoor unit and each carrier frequency, the microcomputer 3 stores only the smallest of all detected reception field strengths.
  • the reception field strength of all incoming radio signals is determined in the receiver 2 and the determined value is passed on to the microcomputer 4.
  • the receiver 2 is tuned to the first carrier frequency for a certain period of time.
  • the period of time for which the receiver 2 is set to a frequency is usefully longer than the period of use of a frequency by the transmitters of the outdoor units (e.g. three times the period).
  • the microcomputer 4 sets the receiver 2 to the next carrier frequency to be received via the line 5, etc. If a signal is received whose reception field strength is greater than the value described above, the data telegram demodulated by the demodulator 3 is evaluated by the microcomputer 4.
  • the voting time may be extended in order to be able to receive the data telegram completely. Then the receiver is tuned to the next frequency, etc.
  • the point in time at which the radio signal was received, the carrier frequency, the reception field strength and the signal originating from the demodulator 3 are stored by the microcomputer 4. This information can be evaluated, for example, by the operator of the radio alarm system in order to detect manipulation attempts by third parties.
  • the carrier frequency recognized as disturbed in this way is no longer used for establishing a connection between central unit Z and an external unit.
  • the central units Z automatically inform the branch offices which carrier frequencies are not to be used. These are stored in the branch offices.
  • a display unit of the central unit Z shows which carrier frequencies should not be used. The user can then manually set the unwanted or desired carrier frequencies at the individual branch offices.
  • the data telegrams in the outdoor units are split into several sub-blocks in order to Modulate sub-blocks on different carrier frequencies.
  • the sub-blocks of the data telegrams are reassembled in the central unit in accordance with the split that has been carried out.
  • the data telegrams can be encoded in the outdoor units for each data telegram using a predetermined algorithm.
  • the affiliation of the received data telegrams is checked in the central unit using the same algorithm.
  • each valid data telegram is not a minimum value above an interference noise present in the transmission channel, e.g. Noise or malfunction, an alarm is triggered in the armed state, otherwise the arming is prevented.
  • the received field strength of each valid received data telegram as well as the field strength of the noise is determined at periodic intervals.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Alarm Systems (AREA)
EP96116835A 1995-10-23 1996-10-19 Procédé pour l'augmentation de la sécurité de transmission d'un dispositif d'alarme radio Ceased EP0770977A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19539312 1995-10-23
DE1995139312 DE19539312A1 (de) 1995-10-23 1995-10-23 Verfahren zur Erhöhung der Übertragungssicherheit bei Funkalarmanlagen

Publications (1)

Publication Number Publication Date
EP0770977A1 true EP0770977A1 (fr) 1997-05-02

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EP96116835A Ceased EP0770977A1 (fr) 1995-10-23 1996-10-19 Procédé pour l'augmentation de la sécurité de transmission d'un dispositif d'alarme radio

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EP (1) EP0770977A1 (fr)
DE (1) DE19539312A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001018762A1 (fr) * 1999-09-07 2001-03-15 Ademco Microtech Limited Ameliorations apportees ou se rapportant a des systemes de detection

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6901066B1 (en) † 1999-05-13 2005-05-31 Honeywell International Inc. Wireless control network with scheduled time slots
DE10114313C2 (de) * 2001-03-23 2003-12-04 Siemens Gebaeudesicherheit Gmb Verfahren zur Funkübertragung in einem Gefahrenmeldesystem
DE10114314A1 (de) * 2001-03-23 2002-10-10 Siemens Gebaeudesicherheit Gmb Verfahren zur Funkübertragung in einem Gefahrenmeldesystem
DE10321204B3 (de) * 2003-05-12 2005-01-13 Siemens Ag Verfahren und Einrichtung zur Funktionsüberwachung von Funkübertragungswegen in einem Gefahrenmeldesystem
DE102006056465B4 (de) * 2006-11-28 2012-10-31 Thomas Schildknecht Verfahren und Vorrichtung zum Überwachen des Funkverkehrs innerhalb eines Raumes
FR2973546B1 (fr) 2011-03-31 2013-04-05 Finsecur Dispositif de declenchement d'alarme pour un systeme de securite
FR2973544B1 (fr) 2011-03-31 2013-11-15 Finsecur Dispositif de declenchement d'alarme pour un systeme de securite
WO2017072559A1 (fr) * 2015-10-30 2017-05-04 Ebs Sp. Z O.O. Système d'alarme et transmetteur d'alarme

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4109239A (en) * 1975-09-30 1978-08-22 Scientific-Atlanta, Inc. Radio frequency alarm system including transmitting, coding and decoding circuitry
JPS5577247A (en) * 1978-12-06 1980-06-10 Kokusai Electric Co Ltd Diversity transmitter-receiver
EP0293627A1 (fr) 1987-05-19 1988-12-07 Ascom Radiocom AG Méthode de transmission radio
EP0484880A2 (fr) 1990-11-05 1992-05-13 Norbert Schaaf Système radio d'alarme
DE4337211C1 (de) * 1993-10-30 1994-12-15 Grundig Emv Funkalarmanlage mit einer Funkstrecke zwischen den Außenstationen und der Zentraleinheit einer Alarmanlage
DE4408268A1 (de) 1994-03-11 1995-09-21 Grundig Emv Verfahren zur Erhöhung der Störsicherheit einer Funkalarmanlage

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2259430B (en) * 1991-09-07 1996-05-01 Motorola Ltd Radio receiver and transmitter providing diversity

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4109239A (en) * 1975-09-30 1978-08-22 Scientific-Atlanta, Inc. Radio frequency alarm system including transmitting, coding and decoding circuitry
JPS5577247A (en) * 1978-12-06 1980-06-10 Kokusai Electric Co Ltd Diversity transmitter-receiver
EP0293627A1 (fr) 1987-05-19 1988-12-07 Ascom Radiocom AG Méthode de transmission radio
EP0484880A2 (fr) 1990-11-05 1992-05-13 Norbert Schaaf Système radio d'alarme
DE4337211C1 (de) * 1993-10-30 1994-12-15 Grundig Emv Funkalarmanlage mit einer Funkstrecke zwischen den Außenstationen und der Zentraleinheit einer Alarmanlage
DE4408268A1 (de) 1994-03-11 1995-09-21 Grundig Emv Verfahren zur Erhöhung der Störsicherheit einer Funkalarmanlage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 4, no. 121 (E - 023) 27 August 1980 (1980-08-27) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001018762A1 (fr) * 1999-09-07 2001-03-15 Ademco Microtech Limited Ameliorations apportees ou se rapportant a des systemes de detection

Also Published As

Publication number Publication date
DE19539312A1 (de) 1997-04-24

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