Communication system, in particular for alarms and method for its operation

Technical field

p0001The invention relates to a communication system, in particular for alarm systems interlinked hazard detectors and a method for operating such a communication system and a communication terminal which uses the method, for use in the communication system.

State of the art

p0002In fixed communications systems, it comes in both wired as well as leadless transmission links, even after a carefully executed installation, by changes in the transmission paths repeatedly to deterioration of the transmission quality and the failure of communication. In radio links, this is often due to changes in the environment such as new furniture or walls, which have a higher signal attenuation or reflections result. In wired systems usually creeping short circuits or interruptions lead to the communication lines due to reflections and increased attenuation in degraded communications. Especially with security systems such as hazard alert systems for reporting against hazards such. As smoke, fire and gas secure communications among system participants is necessary. From the<patcit id="pcit0001" dnum="US4754261A"><text>US 4,754,261</text></patcit> in this respect is an alarm system is known in which the receivers are housed in an installation mode during system installation, in which the received signal is disturbed at the receiver and, therefore, a reception signal of higher quality than is required in normal operation. When the receiver in the installation mode can receive all the channels of the system a quality replacement for the communication is assumed during normal operation. The<patcit id="pcit0002" dnum="EP0874341A"><text>EP0874341</text></patcit> proposes to the front against the installation of an alarm system to reduce the transmission power compared to normal operation while. Receivers are installed, are varied in their position until a position is found where the can be received with a lower transmit power signals transmitted.

p0003Both systems are limited during the installation of the system the communication range and can detect only in this phase faults. You also need to download additional switching elements in the transmission or reception circuit that can switch between different power levels when sending or receiving, and are related. The Range Control inflexible and limited to the installation mode. In the from of<patcit id="pcit0003" dnum="US5801626A"><text>US 5,801,626</text></patcit> become known system can recognize transmission interference even after the installation phase. To check an undisturbed reception Separate heartbeats are sent. When receiving a signal, the signal strength is measured and determines whether there is a monitoring signal. If the received signal is a supervisory signal, then the measured signal strength is compared to a fixed threshold value. If the measured signal strength the threshold, then the monitor signal is discarded and not answered. With all other signals, the reception strength is disregarded. Even from the<patcit id="pcit0004" dnum="US20110014910A"><text>US 2011/0014910</text></patcit> It is known to measure the signal strength of a signal and to compare it with a threshold value. The threshold value is here, however, determined in the receiving device based on the signal strength, which is measured during the reception of at least part of the signal z. B. the preamble. Exceeds the signal strength of the threshold values ​​determined by the measurement values ​​themselves, then the signal is processed, otherwise it is discarded. Although the latter reduces the disturbing influence of neighboring systems, is not carried out but error-prone if z. B. will be the first signal receive a weak signal, and therefore the threshold is determined too low, in addition, the range can not be influenced in a targeted and flexible again.

Object of the invention

p0004The invention is therefore based on the object, a method of operation, a communication system and a communication terminal for communication in particular specify in hazard detection systems, which do not have the disadvantages of the prior art, or at least mitigate.

Description of the Invention

p0005The object is achieved, according to the features of the claims and will be described in more detail below.

p0006In an inventive method for operating a communication system, is to control the communication range, a limit value for the signal strength of a receiver provided in a telegram to be transmitted. For this, select a sending system participant z. B. a smoke detector as a function of its mode of operation or the type of the receiving device a limit, and adds it z. B. in the header of a to be sent a telegram. The limit can be provided in the form of a reception field strength value (RSSI) or even as a relative value of a relative scale of z. B. 0-10. A lower limit can be selected for., During an installation mode, while in an alarm possibly even the maximum possible value is chosen. but it is also conceivable, even after installation in general to specify a low value to avoid disturbing neighboring systems, which have the same address range. Once the message completed, and the limit is inserted, the message is sent. All recipients within the physical range can receive the transmitted telegram. Upon receiving a telegram, the receiver simultaneously determine the reception strength with which the message is received. This they can do z. B. by means of a built-in most radio chips RSSI function (Received Signal Strength Indication). Even during the reception or shortly thereafter, the limit value for the signal strength from the message is extracted and compared with the reception strength during the reception. Where it is clear from this comparison that the measured reception strength falls below the threshold, the message is discarded, or canceled if necessary the ongoing reception. Before comparing the reception strength with the threshold value, a comparison of its own recipient address with the address of the recipient can take place, to which the message is addressed, if necessary. If this already determined that the addresses do not match, then the comparison of the reception strength may be omitted with the limit if necessary, because the message is discarded anyway. Preferably, the limit value is to be sent for the reception strength in the same telegram with the reception strength of the limit value is compared.

p0007However, it is also conceivable that the limit value for the signal strength and the remaining data to be transmitted between two or more telegrams are divided. Particular preference is therefore to the limit are sent and received within the same message group, the limit applies to their telegrams. So the limit for a receive field strength could be sent, for example, in a message that applies to the subsequent or a series of subsequent frames. Preferably, the telegram containing the reception threshold for subsequent telegrams, to be confirmed with a higher power and / or redundant possibly even transmitted on different channels and / or must from the receiver before the subsequent telegrams are sent.

p0008The method of operating a communication system governs in particular the range of the communication and thus also represents a method of communicating. Here, in a preferred embodiment of the invention, the communication system is formed by an alarm system. The invention therefore also relates to a method for communicating in an alarm system. Such a warning system often consists of at least one device such as a hazard warning center for receiving messages and from detectors with sensors for risk parameters such as smoke, the detector having at least one transmitter for transmitting alarm or status messages. A preferred type of alarm system is made up of several interlinked hazard detectors, each hazard detector is fitted next to sensors and transmitters with receivers and alarm and display means. Also in this method provides a system participants, especially a hazard detector, a threshold for a received level in a telegram to be sent. Then, the message is sent and can be particularly welcomed by a second system participants a hazard detector. While receiving the telegram, the reception strength z. B. is calculated as the RSSI value and compared to the limit value of a previously received message, but preferably with the threshold received from the same telegram. If it is determined in this comparison that the signal strength drops below the limit, then the message is discarded.

p0009The invention also relates to a communication system with at least one sending system participant who is especially configured to send alarm signals and with at least one receiving system participant who is particularly adapted to receive alarm signals. The sending system participant includes a first range-control that provides the receiving system participants a limit on the signal strength in a telegram. The receiving system participant includes a second range-control, which comprises a measuring device for the reception strength of the received telegrams and a comparator. The comparator is configured to compare the measured upon reception of a telegram reception strength to the limit, but this was provided by the sending system participants in a telegram sent previously, bevozugt in the same telegram. The second range-control is further configured to reject the received message when the measured reception strength drops below the limit. In this case, a transmitting system participants also receive appropriate devices and a receiving system participants include the corresponding devices for sending.

p0010In a preferred embodiment of the inventive communication system, the communication system is formed by an alarm system, in which the system participants themselves communicating to z. B. status and alarm messages to exchange particular hazard alarm to each other and finally users of the system. Such a warning system consisting of at least two interlinked hazard detectors which are particularly adapted to detect and report of smoke, temperature, fire and / or gases. Each of these hazard detector includes a transmitter and a receiver and a first and second range control. The first range-control is adapted to provide a threshold for a received level in a telegram to be sent. The second range-control comprises a first measuring device for the reception strength of the received telegrams and a comparator. The comparator is configured to compare the measured upon reception of a telegram reception strength with the first of the range control of the sending hazard detector in a previously transmitted but preferably provided in the same telegram limit. The second range-control is adapted to discard the received message when the measured reception strength drops below the limit.

p0011Finally, the invention relates to a communication terminal which is formed in a preferred embodiment as a danger detector with one or more sensors. In the embodiment as hazard detectors, the sensors are especially adapted risk parameters such as smoke, temperature, fire and / or gas to detect. The communication terminal according to the invention has a transmitter, a receiver and a controller, and a first and a second range-control. The first range-control unit is designed to provide a threshold for a received level in a telegram to be sent. The second range-control includes a measuring device for the reception strength of telegrams received and comparing means. The comparator is in turn set up, but the measured upon reception of a telegram reception strength with the first of the range control of a transmitting hazard detector in a telegram sent beforehand preferably in the same telegram compare provided limit. The second range-control or the control means are adapted to discard the received message when the measured reception strength drops below the limit.

Brief Description of Drawings

p0012The sole figure shows an inventive communication system with two communication terminals according to the invention which are designed as hazard detectors.

embodiment

p0013In the following, the invention will now be explained in more detail with reference to the single drawing. This exemplifies a communication system (1) in the form of a hazard detection system (1) the example here with more than one danger alarm devices (2) is shown. Alternatively, the system could also consist of a risk center (ggf.14) with one or more satellites for. B. hazard detector (2). The hazard detectors (2) are equipped with a control unit (9) which environmental measurements by means of sensors (10) and communicating with other risk alarm devices controls and coordinates. The control unit (9) takes over the analysis of the signals of the sensors (10). The hazard detectors (2) also include display and alerting means (13) may be displayed with which states z. B. disorders such as a low battery, the detector (2) and alarms. Here, a hazard warning lights (2) See both own states and alarms, as well as the other risk alarm device (2). For this, a danger alarm device (2) includes at least one receiver (3) with which it can receive appropriate information from other danger alarm devices (2). To send status and alert information Hazard detectors (2) also includes a transmitter (4). According to the invention the transmitter (4) is associated with a first range-control unit (5). The first range-control (5) inserts in selected, but preferably in each frame to be transmitted, the other danger alarms (2) or optionally sends the hazard detectors (2) to a control center, a limit on the reception strength of a, of the reception the telegram of a hazard detectors (2) or possibly a central office, is evaluated. The limit is preferably inserted in the header of a message. To receive messages from other hazard detectors (2) an inventive hazard detectors (2) includes a receiver (3). The receiver (3) is associated with a second range-control (6). In the figure is shown that the second range-control (6) contains a measuring device (7) for the reception strength with which a message is received and a comparison device (8). In practice, the measuring device (7) for the reception strength is usually be a part of the receiver (3), which represents the signal strength of the second range-control (6) z. B. in the form of an RSSI signal or -value available. Therefore here rather the logical and the physical map is shown. The comparator (8) compares the measured reception strength with the previously extracted from a message limit, the limit but is preferably extracted from a message previously sent from the same telegram. If it is determined in this comparison that the measured reception strength drops below the limit, the received message is discarded. In the event that the receipt of the telegram is still in progress, this can then be terminated immediately. Discarding of the message may take place in that the second range-control (6) the message does not pass to the control unit (9) or by emitting to the control unit (9) a signal indicative of the control unit (9), the just- received message can not be evaluated but discarded.

p0014The selection of the reception strength limits through the first range-control (5) is carried out based on different criteria. These include the various operating modes, states of the danger detector as faults, the device type to which a message is directed and the contents of the telegram itself. The first range-control (5) can choose a very low threshold for., During an installation mode in further operation is always exceeded. Here by a sufficient signal to noise ratio is maintained even when subsequent changes of the transmission characteristics. Moreover, it is also conceivable in the event of an alarm, which is in interlinked danger alarm devices (2) of all detectors (2) reproduced in the system (1) to provide a mute command with different ranges. If z. B. a mute command from a hazard detectors (2) sent who does not even recognize an alarm, then could the telegram containing the Mute command lower limit are provided, whereupon only detector (2) in the close this detector (2) terminate the alarm. However dignity of mute command from the detector (2) is sent, the detected an alarm itself, a high threshold can be selected, so all other detectors (2) terminate the alarm in the system (1). It is also conceivable all detectors (2) provide for a low limit in normal operation mode, so as not to interfere with neighboring systems (1) of the same type. By contrary to logical range unchanged physical reach it is also conceivable with a service tool (14) z. B. a laptop, a tablet PC or a smartphone with the right app which for monitoring the status of the individual in a system (1 ) present danger alarms (2) is to be used to receive all messages from a greater distance and evaluate to be limited by a reduced transmission power without. This service tool would then just ignore the limit.