DE69726793T2 - Automatic alarm system with monitoring signal analysis - Google Patents

Description

BACKGROUND THE INVENTION

The present invention relates on a receiving station for use in a communication system and on a process for testing an effective power range in a communication system.

Most wireless radio frequency (RF) security systems available today such as those made by ADEMCO generally use a variety of transmitter products that share information Receiver / controller send. The transferred Information usually describes the state of various transducers assigned to each transmitter are, such as smoke, motion, glass breakage, shock and vibration detectors, Door, window and Floor mat switch etc. These transmitter products are designed that they're inexpensive and are generally broadcast-only, as opposed to Transceivers or transceivers that are significantly expensive are. To meet the basic requirements of regulators fulfill, have to the transmitters send periodic monitoring transmission signals for control purposes, to ensure the correct operation of all Monitor transmitters in a given system. The monitoring signal (as well as an alarm signal) has a unique identification code, who is embedded in his data message and serves the Control Panel to announce which specific sending device this monitoring message (or Alarm message) has sent. If a monitoring signal from the receiver unit has been correctly received and recorded, the transmitter identification code generally for further processing to the control panel cleverly.

For lifesaving applications the wireless RF system must also comply with even stricter regulations such as UL864 from Underwriters Laboratories. This Regulation also requires that the transmission power level of the monitoring signal by at least 3 dB or by another equivalent Means among those of transmission of the alarm signal (the normal non-monitoring signal) to ensure that the alarm signal has an effective power range above that of the periodic monitoring signals owns all transmitters in the system.

To use transmitter-only products that would send an alarm signal exactly at the maximum permissible level, and around that power level during the periodic monitoring signal transmission to cut at least 3 dB there are substantial additional costs for each transmitter product. Further were most of the broadcast circuits before the appearance of the regulations such as the UL864 requirement, which is why everyone is currently on transmission circuits on the market despite the fact that she already everyone else applicable UL and FCC requirements as well as other official Meet requirements, redesigned and need to be replaced.

US-A-4 754 261 discloses an apparatus for Evaluation of the installation of components of a wireless Alram system. A central station can receive alarm signals from several satellite stations. While During installation, the central station can be put into an installation mode manually in which a characteristic of the received alarm signal attenuated is going to trigger of the alarm a received signal of higher quality than in a normal operating mode is required.

It would therefore be in a first Aspect advantageous to use an alarm system that the transmission power level of the monitoring signal effective is reduced by at least 3 dB below that of the normal alarm signal and This ensures that the alarm signal goes on without modification existing commercial Transmitters have an effective 3 dB minimum range above that the periodic monitoring signals all transmitters in the system.

As an alternative, it would be in a second aspect also advantageous to use an alarm system that has an automatic Check of the received monitoring signal without its reception sensitivity or other operating parameters for subsequent Change news and instead, such tests on the first captured monitoring message to execute in real time. It would be therefore advantageous to use an alarm system that includes the system monitoring messages sensitivity to a normal alarm signal and This ensures that the alarm signal goes on without modification already commercially available Senders an effective range above that of the periodic surveillance messages of all transmitters in the system.

Alternatively, it would be a third Aspect also advantageous, an alarm system that is a method of Measure the signal strength of received messages, uses and the measured signal strength with a predetermined threshold that must be exceeded so that the monitoring message as valid is believed to compare.

It is therefore an object of the first aspect of the present invention to provide a communication system which is suitable for use with an alarm system and which effectively reduces the monitoring signal strength without actually modifying the monitoring signal generated by the transmitter. It is another object of the first aspect of the present invention, a method for modification provide an operating parameter of the receiver such that the receiver sensitivity is changed during a monitoring transmission sequence in order to achieve these goals. It is yet another object of the first aspect of the present invention to prevent, by logic, that the transmitter identification code is sent from that transmitter to the system controller during a multi-message monitoring transmit sequence after one of those messages has been correctly received at normal sensitivity level and if none of the subsequent monitoring messages from the same transmitter have been correctly received during the same transmission sequence with a reduced sensitivity level. It is still another object of the first aspect of the present invention to allow logic to transmit the transmitter identification code from that transmitter to the system controller during a multi-message monitoring transmit sequence after one of those messages has been correctly received at normal sensitivity level and if one the subsequent monitoring messages from the same transmitter during the same transmission sequence with reduced sensitivity level was correctly received. It is still another object of the first aspect of the present invention to provide the application of an effective maximum time limit within which the receiver sensitivity can be kept in the reduced state to ensure that all subsequent normal alarm transmissions are received and processed at full receiver sensitivity. It is a still further object of the first aspect of the present invention to automatically allow one or more transmitter identification codes, regardless of whether they are surveillance or alarm broadcasts, to be sent to the control system if they are within the maximum period during which the receiver sensitivity is in is kept in its reduced state, received correctly.

It is a task of the second aspect the present invention to provide two signal paths in the receiver, so a surveillance message can be received at a sensitivity level that compares the sensitivity at which the alarm messages are received, is lower. It is yet another task of the second Aspect of the present invention to prevent by logic the transmitter identification code during a surveillance broadcast is sent from that transmitter to the control panel when a monitoring message is received high sensitivity level has been received correctly, however not received correctly with reduced sensitivity level is. It is yet another task of the second aspect of the present invention, by logic to allow the transmitter identification code is sent to the control panel when both a monitoring message Received correctly at both high and low sensitivity levels has been. It is yet another task of the second aspect of the present invention to ensure that alarm messages always received at high sensitivity level and sent to the system control become.

It is a task of the third aspect the invention by logic to prevent the transmitter identification code while a surveillance broadcast is sent from that transmitter to the control panel when the received signal levels of a monitoring message does not exceed the predetermined threshold. It's one more time further object of the third aspect of the present invention, through logic to allow the transmitter identification code to be sent to the Control Panel is sent when the received signal level of a monitoring message exceeds the predetermined threshold. It is yet another object of the third aspect of the present Invention to ensure that alarm messages are always at maximum Sensitivity received and sent to the control system d. that is, alarm messages are received at full sensitivity and are not subject to the specified threshold. It is yet another task of the third aspect of the present Invention to provide a method using data formats can work in which multiple messages for each broadcast event are sent, the format containing a specific bit, the a monitoring message indicates, and can use single or multiple messages.

It is yet another task all aspects of the present invention, an effective method to distinguish between surveillance broadcasts and provide normal alarm broadcasts.

SUMMARY THE INVENTION

According to the present invention, a receiving station is provided for use in a communication system, the receiving station comprising receiving means for receiving signals from a remote transmitting station and being operable to determine whether there is an effective power range for receiving signals, and characterized is to test by control means which can determine whether a signal received by the remote transmitter is of a surveillance or non-monitor type and in response to the identification of a monitor signal to determine whether a non-monitor signal from the remote transmitter exceeds the effective power range over the Monitoring signal. Further features are set out in claims 2 to 8 and 12 to 14 which is to be used to direct attention. In addition, a communication system is provided which contains a receiving station as mentioned above. Further features of the communication system are set out in claims 10 and 11. There is also provided an alarm system which includes the above-mentioned communication system.

• (1) Empfangen eines Signals von der entfernten Sendestation;
• (2) Feststellen, ob das Signal von einem Überwachungs- oder Nichtüberwachungstyp ist; und
• (3) wenn das Signal von einem Überwachungstyp ist, Ausführen eines Tests, um festzustellen, ob ein Nichtüberwachungssignal von der entfernten Sendestation den Effektivleistungsbereich über dem Überwachungssignal hätte.

According to a further aspect of the present invention, there is provided a method for checking an effective power range in a communication system, which comprises a receiving station with receiving means for receiving signals of a monitoring and a non-monitoring type from at least one remote transmitting station, the method comprising the following steps:

• (1) receiving a signal from the remote transmitter station;
• (2) determining whether the signal is of a surveillance or non-surveillance type; and
• (3) if the signal is of a monitor type, test to see if a non-monitor signal from the remote transmitter station would have the effective power range above the monitor signal.

Further steps are in claims 18 to 31 to which attention is hereby drawn should.

A first aspect of the present Invention is based on the premise that instead of lowering it the maximum allowable Performance of periodic monitoring signal transmissions is an equivalent mean, the receiver sensitivity by one Reduce the amount that is equivalent to reducing the transmission power by 3 dB, however only during the reception of monitoring signals, and full receiver sensitivity to be provided when non-surveillance alarm signals be received.

The first request to the recipient is in this first aspect of the invention that he has the ability must have the reception sensitivity by at least 3 dB change, to the applicable regulatory Requirements. The receiver implemented in the present invention an intermediate frequency receiver while the to change its sensitivity used circuitry professionals in the field of Narrow band, short range, RF intermediate frequency receivers are well known is and not closer here needs to be discussed. It should only be mentioned that the receiver sensitivity between two specified values, the logical 1 or the logical 0 state of a microprocessor output connected to that part of the receiver circuits which the receiver sensitivity determines, is connected, changed becomes. this makes possible a control of receiver sensitivity through the microprocessor software.

The first requirement for the recipient is that he has the ability must have signals at two different sensitivity levels to receive, which must differ by at least 3 dB to applicable regulatory Requirements. The receiver implemented in the present invention uses an intermediate frequency architecture, although it is clear to those skilled in the art that all types of recipients can nevertheless be used in this invention. It It is important to note that by introducing a Threshold or cut level in the video processing circuit after demodulating the incoming RF signal and reducing it on its original Baseband content cheapest is controlled. The video processing circuit gives two baseband signals from that except that one of the signals opposite the another signal is 3 dB higher Threshold has been subjected to are similar. These two Baseband signals are routed to input ports of a microprocessor, thereby this with two signal inputs is delivered that receive at different sensitivities become. It is clear to experts that sensitivity control the cheapest for the baseband Procedure is, although creating two different paths on an earlier one Point in the receiver possible, although less desirable for reasons of cost and scope, is. The signal received at high sensitivity is used by the microprocessor used to control and synchronization information during a introductory section (preamble) receive the message, with the control information then passed through The microprocessor used the following data and clock the CRC portions of the message into both microprocessor input ports. The signal received at the port with reduced sensitivity is stored in the RAM of the microprocessor. That at the connection with High sensitivity received signal will be after correct CRC checked, determining whether the message is of the surveillance type or not. If the message is a non-watch message it is forwarded directly to the control console for further processing. If the CRC is correct and the message is of the surveillance type, the messages are sent via Connection with reduced sensitivity data stored in RAM read and the CRC calculated, this rcht then if they correct and with that received at the high sensitivity connector Message is identical (correlated) for further processing the control is forwarded. If the CRC is wrong or the saved message does not match the high-sensitivity message, the message is not further processed and the surveillance broadcast received only incorrectly.

A third aspect of the present Invention is based on the premise an RSSI (received signal strength indication) signal that the signal strength of the received signal and determining whether the received signal Signal a monitoring signal or a non-watch signal is. If it is determined that the received signal is a supervisory signal is determined whether the generated RSSI signal over a predetermined threshold value, the received signal then as valid received monitoring signal processed when the RSSI signal is over is the predetermined threshold. The received signal is not processed as a valid monitoring signal, if the generated RSSI signal is not above a predetermined threshold lies. If it is determined that the received signal is a non-surveillance signal then it will be without determining if it is over the predetermined threshold, as part of a valid received Not monitoring signal processed.

SUMMARY THE DRAWING

1 Figure 3 is a block diagram of the preferred embodiment of all three aspects of the present invention;

2 Figure 12 is a timing diagram of the monitoring and alarm messages processed by the preferred embodiment of all three aspects of the present invention;

3 Fig. 3 is a timing diagram of reduced receiver sensitivity performed by the preferred embodiment of the first aspect of the present invention;

4 Figure 3 is a flowchart of the operation of the preferred embodiment of the first aspect of the present invention;

5 Figure 3 is a block diagram of the receiver / control unit in accordance with the preferred embodiment of the first aspect of the present invention;

6 Figure 3 is a block diagram of the receiver / control unit in accordance with the preferred embodiment of the second aspect of the present invention;

7 Figure 3 is a flowchart of the operation of the preferred embodiment of the second aspect of the present invention;

8th FIG. 10 is a circuit diagram of the processing section of the block diagram of FIG 6 ;

9 Figure 3 is a block diagram of the receiver / control unit in accordance with the preferred embodiment of the third aspect of the present invention;

10 Figure 3 is a flowchart of the operation of the preferred embodiment of the third aspect of the present invention; and

11 FIG. 10 is a circuit diagram of the processing section of the block diagram of FIG 9 ,

PRECISE DESCRIPTION THE PREFERRED EMBODIMENT

The following discussion of the overall system and the monitoring and alarm messages applies to all three aspects of the present invention. In 1 is an alarm system 2 shown which is a receiver / control unit 6 includes that with multiple remote facilities 4 , each of which contains an alarm sensor and a data transmission unit. The alarm sensors are well known in the art and include, for example, motion detectors, fire or smoke sensors, glass break sensors, door and window entry sensors and the like. In the preferred embodiment, the alarm system operates 2 in a so-called "wireless" manner by transmitting electromagnetic waves (especially at high frequency) between the remote devices 4 and the receiver / control unit 6 , The transmitter units used in all remote facilities 4 are also known per se and send monitoring and alarm message signals, described below, by modulating a radio frequency (RF) signal (e.g. 345 MHz). The modulated RF signal is from the receiver / control unit 6 received, processed and decoded so that the control unit with data from the remote devices 4 is cared for and can react accordingly; z. By sounding an alarm speaker, calling the police or fire department, etc. A more detailed description of this type of wireless alarm system can be found in U.S. Patent No. 4,754,261 to Marino, assigned to the assignee of the present invention, and incorporated herein by reference is included.

The removed facilities 4 are configured to send monitoring signals and alarm signals according to protocols that are known per se. The monitor signals are used to ensure that everyone in the system 2 configured remote facility 4 really with the receiver / control unit 6 is connected to periodic "test signals" to the receiver / control unit 6 to deliver. Because a remote facility 4 With this type of system, an alarm signal may only be sent at the time of an emergency (e.g. when a window assigned to the sensor is broken), it is imperative that the system 2 a periodic process to ensure that a facility 4 really with the receiver / control unit 6 connected, operates so that potential problems can be dealt with immediately.

Therefore, for monitoring purposes, from any remote facility 4 periodically a monitoring signal to the receiver / control unit in the system 6 Posted. A surveillance broadcast sequence generally consists of a simple pentad, ie a single group of five idens table messages, as in section A of 2 is shown. Each message has a duration of approximately 20 ms and is repeated every 100 ms, as in 2 is shown. A normal non-surveillance alarm signal, which is generally only sent when the state of the alarm sensor changes (e.g. when a door is opened), consists of a double pentad, i.e. two groups of five identical messages that are timed are separated by about 1 second. This is in section B of 2 shown.

Each identical message has a length of 64 bits and contains a 16-bit preamble, 24 bits for the transmitter serial number or for keypad data, a single 8-bit status byte and a 16-bit CRC (Cyclic Redundancy Character), such as in section C of 2 is shown. The status byte contains 8 data bits, which are in section D of 2 are shown as D1-D8 and carry specific information. In this case, D8 = 1 means that the received message comes from a transmitter capable of generating surveillance broadcasts, whereupon D1-D4 represent the state of up to 4 sensor inputs to that transmitter, D5 the state of the battery of that transmitter indicates and D6 = 1 means that the received message is part of a monitoring simple pentad transmission. In this way, the receiver circuitry is supplied with coded information from the transmitter unit, which enables it to determine whether the message is part of a monitoring signal or part of a normal non-monitoring alarm signal.

In the first aspect of the invention, according to which the receiver detects that the present message is part of a monitoring pentad, the sensitivity of the receiver is immediately reduced. 3 shows how the receiver sensitivity is changed while receiving a monitoring pentad. Starting with the full receiver sensitivity, the first message of the pentad is received and analyzed correctly. If it is determined that this message is a monitor message (ie D6 = 1), the message is temporarily stored in a receiver buffer memory and the receiver sensitivity is immediately reduced by at least 3 dB below the full level. The reduced sensitivity level remains in effect until a subsequent monitoring message that corresponds to the first message received at the full sensitivity level is correctly received at this reduced level, or until a predetermined time period of 600 ms has elapsed, whichever occurs first. If, during this reduced sensitivity interval, a surveillance broadcast is successfully received that does not match the one that initiated the interval (ie, the message stored in the receiver), the surveillance message for the mismatched sender ID is immediately on for further processing the control unit sent.

Another remote device may be operating during the time that the receiver has reduced sensitivity due to the detection of reception of a monitor signal 4 received a signal (alarm signal or monitoring signal). This means that a second received signal can be interleaved with a first received signal. In order for the receiver to process the interleaved second signal correctly, the time-out period used to wait for the next monitoring message must be greater than the time for a pentad, but less than the time before the second pentad of an alarm transmission can begin. This ensures reception of the (second) broadcast at full sensitivity level even if it occurs somewhat later than a nested first surveillance broadcast, since a double pentad is always assigned to alarm broadcasts, but only single pentads are used for surveillance broadcasts. Out 2 it can be seen that this time period is greater than 400 ms (to at least allow the last of the remaining four messages to be captured), but less than 1 second (to bring the receiver back to full sensitivity before the next pentad if the transmission is double Pentad is) must be. Therefore, a duration of 600 ms is used in this embodiment.

A typical scenario is in 3 shown, in which the first monitoring message leads to a reduction in the receiver sensitivity level and the second monitoring message, which matches the first message, is correctly received. In this case, the correct reception of the monitoring message for that particular transmitter has been established with a reduced sensitivity level, which is why the receiver is allowed to send the monitoring message for that transmitter ID to the controller. However goes out 3 also shows that the lowered sensitivity level continues if the second message, the third message, etc. are not received correctly due to the reduced sensitivity. If all four of the remaining messages are not received correctly at this reduced level, the required range for that sender is considered inappropriate. In this case, the monitoring message for that sender ID is not sent to the controller. The controller is therefore only ready to receive those monitoring messages via transmitter ID in the system that can be received with a reduced sensitivity level, which means that the UL864 requirement is met.

This operational flow of this first aspect of the present invention is illustrated by the in 4 shown flowchart shown, in step S 1, the (RF) input signal is processed to provide a digital data signal. In step S2 digital data signal decoded to analyze status bit D6 and determine whether the message concerns monitoring or a non-monitoring alarm. If it is determined in step S3 that the message relates to non-monitoring, the message is sent to the controller for processing in step S4 and the process is ended. However, if it is determined that the message is a monitoring message, it is stored in a temporary buffer in step S5 and the receiver sensitivity is reduced by 3 dB in step S6. A time trigger cycle, which, as explained above, is 600 ms in the preferred embodiment, is then initiated in step S7. The process loops through steps S8 and S11 until the time trigger is due in step S8 or until a new message is received in step S11.

If the time trigger is due without a new message being received while the receiver is in the reduced sensitivity state, the stored message is ignored in step S9, the receiver sensitivity is increased to normal again in step S10 and the process is ended. In this case, since the monitoring message was not correctly received and captured while the receiver was in the reduced sensitivity state, the transmitter ID assigned to that monitoring message is actually discarded, which is why the receiver / control unit is never informed of its initial reception at full sensitivity level , Thus, although the monitor signal was strong enough to be detected at normal sensitivity levels, it could not be received if the signal strength was effectively reduced by 3 dB, which is why the UL864 test for that remote device 4 failed.

If, however, a new one in step S11 Message is received is analyzed in step S12 to determine whether they're the temporary Buffer stored message is equal; d. i.e. whether they are of the same Sending device originates or whether it comes from another sending device has been received whose message stream is actually with that of the original received message is nested. If the news from another transmitter comes, it is sent to the controller in step S13 (since they received successfully when the sensitivity level was lowered ) and the waiting state is continued with steps S8 and S11. The time trigger is not reset since the recipient the next surveillance message, that matches the one that initiated the sensitivity reduction is waiting. So the receiver sensitivity becomes if within the time trigger period no new message that matches the saved message, received, increased to normal and the process ends, ignoring the stored message becomes.

However, if determined in step S12 the new message matches the saved message, is the test passed, which is why the message in step S14 Further processing is sent to the control. The receiver sensitivity is increased back to normal and the process is complete.

5 shows the block diagram for the receiver / control unit 6 of the first aspect of the present invention. An RF signal is sent to the antenna 20 received by the subsystem 22 filtered and through the subsystem 24 in conjunction with a 355.7 MHz oscillator 26 demodulated using techniques that are known per se. A demodulated baseband video signal 28 becomes a video processor circuit 30 performed, which has a programmable sensitivity to achieve the objectives of this invention. See U.S. Patent No. 4,754,261 for more details. A microprocessor 32 with one for storing the by the schedule of 4 embodied program suitable ROM block 34 is with the video processor 30 connected to provide suitable control signals for controlling the receiver sensitivity. In particular, if the microprocessor determines that a message is a monitoring message, the status of the control signal 36 changed to indicate to the video processor that the sensitivity of the receiver unit should be reduced by 3 dB. This control signal is switched again in accordance with the processing described above to reset the receiver sensitivity to normal if necessary.

The transmitter identification data, together with other data belonging to the operation of the alarm system, are processed via the ECP data bus for further processing, as described above 38 , the interface with four lines, which comprise a ground line and a power line as well as data transmission and data reception lines according to techniques known per se, to the control unit (not shown here).

The control signal 40 allows, if desired, manual control of the receiver sensitivity via the keypad 8th or the like to put the system in a test mode for device installation purposes as described in the above-mentioned Patent No. 4,754,261.

The preferred embodiment of the first aspect of the present invention has been described in terms of reducing receiver sensitivity to effect impaired transmit / receive function and thus test the operating range of the system to ensure that it complies with applicable regulatory requirements. Of course, this can also be implemented by modifying other operating parameters of the receiver to have similar Er to achieve results. For example, as in Marino U.S. Patent No. 4,754,261, mentioned above, the cut level of a conditioning circuit used in connection with the receiver may be changed as a result of the detection of a monitoring message or the baud rate of the receiver may be changed to meet a higher requirement system operation, etc.

It is also, although the preferred embodiment monitoring aspect of this first aspect of the present invention in a monitoring signal used, which are identical to each other, of course possible, monitoring messages to use that correlates with each other in a predetermined way instead of demanding that they be the same. Therefore surveillance messages be coded with identifiers that represent the transmission source, differ from each other in different ways. The System can easily for adjusted the analysis of the relationship among surveillance messages to determine if they are really correlated, and thus determine whether they were broadcast from the same source, and where appropriate to allow further processing of the message.

Although in this embodiment for surveillance broadcasts individual groups of five identical News and for normal alarm broadcasts two groups of five identical messages could be used other schemes can also be used. For example two or more identical or different messages per group for surveillance broadcasts and an equal or greater number of identical or different messages per more than one group for the normal alarm broadcasts. Moreover can also the length and the periodicity of the programs may be different and still with the ones disclosed here Procedures be consistent.

The second aspect will now be described in more detail. Again shows 1 the block diagram of the system used by this second aspect of the invention; however, the (in 6 shown) receiver / control unit 6a instead of the receiver / control unit 6 of the first aspect of the invention. It is also related to 2 the message format used by the second aspect of the present invention, which operates as described above. In this second aspect, during the preamble section of a received message, the microprocessor decoding algorithm determines the necessary control information that is necessary for the subsequent decoding of the data portion and the CRC of the message. This control and the initial decoding are performed using the high sensitivity connector of the in 6 microprocessor shown determined.

If the microprocessor in the receiver of 6 decoding a non-watchdog (D6 = 0) message at the high sensitivity port is immediately sent to the control console, while when a watchdog message (D6 = 1) is decoded the microprocessor checks the RAM buffer, which receives the data received at reduced sensitivity contains. This data has been clocked into the buffer using the control information derived from the message at the high sensitivity port. If the monitoring message in the buffer is correlated (identical) to the message received at the high sensitivity port, the message is sent to the control panel. If the correlation is not accurate, this particular monitoring message will fail and will not be sent to the control panel. Thus, alarm messages (non-surveillance messages) are received at full sensitivity, while all surveillance messages are subjected to an additional threshold to ensure an adequate system area.

This process is relied on for his Success on neither sending multiple surveillance or alarm messages with each alarm event this procedure is still carried out by multiple transmissions adversely affected.

It is clear to experts that it depends on the signal traffic density may require sufficient RAM to be provided to compare several low-sensitivity messages to buffer with the high sensitivity counterpart.

6 shows the block diagram for the receiver / control unit 6a of this second aspect of the present invention, The Receiver 6a includes an antenna selection circuit 20a , an RF filter 22a , a low noise amplifier 24a , a second RF filter 26a , a mixer 28a , a local oscillator 30a , an intermediate frequency (IF) filter 321, an intermediate frequency (IF) amplification and demodulation circuit 34a and a video filter 36a all of which are well known in the field of RF receivers. In addition, a demodulated baseband video signal from the video filter 36a to a video processing circuit 38a and a threshold circuit 40a led, which serves to provide two outputs that have been subjected to different sensitivity thresholds. These data outputs are with two input ports of a microprocessor 42a connected. An appropriately designed buffer follows the connection with reduced sensitivity 44a , which stores the received data if it should come from a monitoring signal and a correlation is also required.

Now the schedule of 7 Referred. The input signal is received and processed by the above-mentioned components, two data signals being derived; one with full or normal receiver sensitivity, which is connected to connection I2 in the microprocessor is entered, and a second signal with reduced sensitivity, which is input into the microprocessor at connection I3. The low sensitivity data message is stored in the RAM buffer 44a saved. At the same time, the microprocessor on I2 examines the D6 bit of the full sensitivity signal input. If it is determined that it is a non-watch signal, that in RAM 44a Stored data message ignored with reduced sensitivity and the message sent with full sensitivity from I2 to the controller. However, if it is determined that the complete received data message is of the monitor type, the microprocessor compares 42a those in RAM 44a stored low sensitivity message with the full sensitivity message, and if they are correlated the test is passed and the message is sent to the controller. However, if it is determined that the signals are not correlated, they are ignored and the test is considered failed, so the controller is not provided with information that the monitoring message has been received.

In the preferred embodiment this second aspect of the invention becomes the correlation of the monitor signal with reduced sensitivity with the monitoring signal at full Sensitivity determined when the two signals match. However, given a system, it can of course be a tolerable level of Give variance, if desired, in the comparison routine considered can be.

The preferred embodiment this second aspect of the invention is described in terms of a system in which a single message was sent for each send event and the message contains a specific bit that a monitoring message designated. It’s clear to experts that a message is often repeated, to increase the likelihood of reception, and that no specific bit must be included. With this type of system a surveillance broadcast of an alarm broadcast by the number of repetitions one Message can be distinguished. There are regulatory requirements that a monitoring message less often is repeated as an alarm message. Detects in these cases the system described in the present invention by counting the Number of repetitions of a received message, whether a message of the surveillance type is before deciding whether to compare low-sensitivity and high sensitivity messages are performed.

8th shows the circuit diagram of the dashed portion of 6 , An integrated IF / demodulator circuit 34 , in the preferred embodiment a Philips NE614, uses the IF input signal and delivers a demodulated data signal to the low pass filter at its output 36a , which is formed by R1 and C1. The low pass filter 36a reduces the noise component of the video output signal. The filtered video signal is then DC coupled through a capacitor C2 to the non-inverting inputs of the U3 and U4 comparators (LM339), which quantize the signal to a logic level necessary for input to the microprocessor 42a suitable is. The combination of R4 and R5 forms a voltage divider that defines a cut level for the reference voltage applied to the inverting input of the U3 comparator. Capacitor C3 provides a DC ground for the U3 comparator reference input.

The to the inverting input of the comparator U4 is applied by introducing a additional Current over modified the resistance Ry. Thus the reference voltage is on U4 shifted by an amount determined by the values of Rx and Ry is determined. Generally Ry is much larger than Rx or can pass through a real power source to be replaced.

The output signals of each comparator U3, U4 are at the input connections I2 and I3 of the microprocessor 42a entered. The microprocessor in the preferred embodiment is a COP881 available from National Semiconductor. In particular, the output signal from U3 is fed to connection I2 of the microprocessor and corresponds to the normal sensitivity signal. The output signal from U4, which has been subjected to a higher comparison threshold compared to that at U3, is fed to the connection I3 of the microprocessor. This represents the low sensitivity input signal that is used for subsequent comparison, if desired, in an internal RAM 44a is stored as described above.

The microprocessor 42a can optionally control the threshold value applied to U4 via a transistor switch TR1 and Rz, which in the optional control circuit of 8th are shown. If desired, the threshold voltage applied to the inverting input of the comparator U4 can be changed by programming a suitable data bit D0. When D0 is at logic low, transistor TR1 turns off and the threshold applied to U4 remains unchanged. However, when the D0 bit is set to logic high, the transistor TR1 turns on and the reference voltage at U4 is changed according to the value of the resistor Rz. Thus, the threshold described here for analyzing monitoring signals can be changed by software control and can be changed for a specific data message received by a transmitter. This can be expanded further by, for example, several control circuits connected in parallel with the reference voltage input of U4 46a be used. The resistance Rz on any additional control circuit 46 can by another, from the microprocessor 42a output bit (e.g. D1, D2, etc.) can be controlled. Thus, by programming the appropriate bit to control the desired control circuit 46a and accordingly changing the reference voltage, a graduated threshold may be available for use with different environments.

The third aspect of the present invention will now be described in more detail. Again shows 1 the block diagram of the system used by this third aspect of the invention; however, the receiver / control unit 6b instead of the receiver / control unit 6a of the second aspect of the invention. It is also related to 2 the message format used by the second aspect of the present invention, which operates as described above. In this third aspect, during the introductory portion of a received message, a decoding algorithm implemented with a microprocessor determines the necessary control information necessary for the subsequent decoding of the data portion and the CRC of the message.

9 shows the block diagram for the receiver / control unit 6b of this third aspect of the present invention. The receiver / control unit 6b resembles the receiver / control unit 6a , which is why the same reference numerals are used for the same components. So the recipient includes 6a an antenna selection circuit 20a , an RF filter 22a , a low noise amplifier 24a , a second RF filter 26a , a mixer 28a , a local oscillator 30a , an intermediate frequency (IF) filter 321, an intermediate frequency (IF) amplification and demodulation circuit 34a and a video filter 36a all of which are well known in the field of RF receivers. In addition, a demodulated baseband video signal from the video filter 36a to a video processing circuit 38b guided. The video processing circuit 38b provides an RSSI (received signal strength indication) signal 39 in analog format, which is characteristic of the signal strength of the received signal. RSSI measurement circuits are known per se and are described, for example, in US Pat. Nos. 4,620,114, 5,390,365 and 5,423,064. The video processing circuit 38b also gives the processed receive signal to a connection I3 on the microprocessor 42a out. The analog RSSI signal 39 is by an A / D converter 40b , which is known per se, processed, the resulting digital data word, which is characteristic of the signal strength of the received signal, is input to the connection G5 for further processing. An appropriately designed RAM buffer follows the A / D port 44a which stores the RSSI digital data word if it has been determined that the data message is on the signal 41 is of the surveillance type and further processing is required.

Now the schedule of 10 Referred. The input signal is received and processed by the above-mentioned RF components, whereby two data signals are derived; the real data signal 41 which is connected to connector I3 in the microprocessor 42a is entered, and the digital RSSI signal data word, which is entered serially into the microprocessor at connection G5. The RSSI data word is then in the internal RAM buffer 44a saved. At the same time, the microprocessor on I3 examines the D6 bit of the signal input. If it is determined that it is a non-watch (alarm) signal, it will be in RAM 44a saved RSSI word ignored and the message from I3 sent to the controller. However, if it is determined that the received data message is of the monitor type, the microprocessor compares 42a that in RAM 44a stored RSSI word with a predetermined threshold, which is in a non-volatile buffer 45 is stored, and if the RSSI word is above the predetermined threshold value, the test is passed and the monitoring message is sent to the controller. However, if it is determined that the RSSI word is not above the predetermined threshold, the received signal is ignored and the test is considered failed, so the controller is not provided with information that the monitoring message has been received. Thus, the transmitter identification data and other status data are sent to the control system if the message is of the alarm type or if it is of the monitoring type and has been received with the appropriate signal level.

The one for comparison with the measured The threshold used by RSSI word can be determined in different ways become. In one embodiment The RSSI threshold can be set at the factory using standard programming techniques have been preset. Alternatively, the RSSI threshold by the system installer who, during the initial Operation of the system performs measurements around that of the particular one Programmed to determine the corresponding correct threshold value become. Third, the microprocessor can use techniques known per se be configured to take certain measurements of received signals carries and an average threshold to be used accordingly sets.

11 shows the circuit diagram of the dashed portion of 9 , An integrated IF / demodulator circuit 34 , in the preferred embodiment a Philips NE614, uses the IF input signal and delivers a demodulated data signal to the low pass filter at its output 36a , which is formed by R1 and C1. The low pass filter 36a reduces the noise component of the video output signal. The filtered video signal then becomes the same via a capacitor C2 to the non-inverting inputs of the U3 comparator (LM339) current coupled, which quantizes the signal to a logic level, which is for input into the microprocessor 42a suitable is. The combination of R4 and R5 forms a voltage divider that defines a cut level for the reference voltage applied to the inverting input of the U3 comparator. Capacitor C3 provides a DC ground for the U3 comparator reference input.

The output signal of the comparator U3 is at I3 of the microprocessor 42a entered. The microprocessor in the preferred embodiment is a COP881 available from National Semiconductor. In particular, the output signal from U3 is led to connection I3 of the microprocessor and is at the normal sensitivity level.

The filtered demodulated data signal is also put into an analog-to-digital (A / D) circuit 40b entered, which delivers a digital output signal representative of the input signal according to techniques known per se. In the preferred embodiment. a Texas Instruments TLC549I is used. A serial digital data word is then on the G5 connector of the microprocessor 42a for storage in the internal RAM 44a and subsequent analysis as described above.

The preferred embodiment has been described with reference to a system in which each Sending event a single message is sent, with in the Message contains a specific bit to a monitoring message to call. It is clear to experts that a message is repeated frequently to increase the likelihood of reception, and that besides no specific bit has to be included. With this type of system can be a surveillance broadcast of an alarm broadcast by the number of repetitions one Message can be distinguished. There are regulatory requirements that a monitoring message less often is repeated as an alarm message. Detects in these cases the system described in the present invention by counting the Number of repetitions of a received message, whether a message of the surveillance type is before deciding whether to perform the RSSI analysis or not.

It may also be desirable to use the one described here automatic self test function of the present invention only on certain remote facilities rather than exercising at all. It means that official Requirements only stipulate that facilities or applications for Lifesaving can be tested in this way while other facilities do not have to meet such strict communication standards in the system. In such a system is the processing circuitry and -Software added intelligence to determine whether surveillance messages an exam and / or an analysis according to the present Invention are subject. This can be done by designating a Status bits in the message occur as a test / no-test bit, where a logical TRUE indicates that the transmission area is to be checked, and a logical FALSE indicates that the test will not run got to. Alternatively, the processor can implement a lookup table those with identity each device is programmed to pass the range test subject, and then use the facility identification code to access the table and the message accordingly to process.

Although the preferred embodiment have been described in connection with a wireless RF system the invention can also be readily applied to conventional ones wired systems such as local area networks (LANs) and the like applied, where necessary or desired, the operating range between the transmitter and receiver functions to test.

Claims (31)

Receiving station ( 6 ; 6a ; 6b ) for use in a communication system, the receiving station receiving means ( 20 ; 20a ) for receiving signals from a remote transmitting station and being operable to determine whether there is an effective power range for receiving signals, characterized by control means ( 30 . 32 ; 38a . 42a ; 38b . 42a ) that can determine whether a signal received by the remote station is of a surveillance or non-surveillance type and, in response to the identification of a monitor signal, test to determine whether a non-surveillance signal from the remote station would have the effective power range above the monitor signal , Receiving station according to claim 1, further comprising modification means ( 30 ) comprising of the tax funds ( 30 . 32 ; 38a . 42a ; 38b . 42a ) are controllable to include an operating parameter of the receiving station as part of the test ( 6 ; 6a ; 6b ) to modify. Receiving station according to Claim 2, in which if the receiving means ( 20 ; 20a ) a subsequent monitoring signal is received by the remote transmitting station, the test has been passed and the control means ( 30 . 32 ; 38a . 42a ; 38b . 42a ) the operating parameters of the receiving station ( 6 ; 6a ; 6b ) reset to normal and forward the monitoring signal for further processing. Receiving station according to Claim 2 or 3, in which the operating parameter of the receiving station ( 6 ; 6a ; 6b ) through the control means ( 30 . 32 ; 38a . 42a ; 38b . 42a ) remains modified if the receiving means ( 20 ; 20a ) receive a monitoring signal from another remote transmitting station. Receiving station according to Claim 4, in which the control means ( 30 . 32 ; 38a . 42a ; 38b . 42a ) determine that the test for the other remote transmitter station was passed if the monitor signal was successfully received from that station while the operating parameter was modified and passed it on for subsequent processing. Receiving station according to claim 2, 3, 4 or 5, in which the control means ( 30 . 32 ; 38a . 42a ; 38b . 42a ) the operating parameters of the receiving station ( 6 ; 6a ; 6b ) to normal when the receiving means ( 20 ; 20a ) have not received any further monitoring signal from the remote transmitting station within a predetermined period of time since the reception of the monitoring signal, the period of time being such that at least part of a non-monitoring signal can be received while the operating parameter is not modified. Receiving station according to one of Claims 2 to 6, in which the control means ( 30 . 32 ; 38a . 42a ; 38b . 42a a monitoring routine for monitoring the type of signal determined by the control means and for controlling the operating parameter of the receiving station ( 6 ; 6a ; 6b ) in response to the type. Receiving station according to one of Claims 2 to 7, in which the modification of the operating parameter by preventing the response of the receiving station ( 6 ; 6a ; 6b ), for example by reducing the input signal sensitivity. Communication system, with a receiving station ( 6 ; 6a ; 6b ) according to one of claims 1 to 8 and a plurality of remote transmitting stations ( 4 ), each of which comprises transmission means that transmit monitoring signals and non-monitoring signals. Communication system according to claim 9, wherein the monitoring signal and the subsequent monitoring signal are correlated with each other. Communication system according to claim 9, wherein the monitoring signal and the subsequent monitoring signal are the same. Receiving station ( 6a ) according to claim 1, further comprising means to be used for the test ( 38a . 42a ) which process an electrical output signal representing the monitoring signal at a first sensitivity level and at a second sensitivity level which is lower than the first, in order to subsequently compare them, with a difference between the first and the second sensitivity level Effective power range represented. Receiving station according to claim 11, further comprising means ( 42a ) that determine whether the electrical output signal is substantially the same or correlated at the first and second sensitivity levels, where substantial equality or correlation means the presence of the effective power range. Receiving station according to claim 1, further comprising means ( 38b ) which measure the strength of the monitoring signal received by the receiving means and compare this strength with a predetermined threshold value, the predetermined threshold value representing the effective power range. Communication system, with a receiving station ( 6b ) according to claim 12, 13 or 14 and a plurality of remote transmitting stations ( 4 ), each of which comprises transmission means that transmit monitoring signals and non-monitoring signals. Alarm system ( 2 ), which comprises a communication system according to one of claims 9 to 11 or claim 15 and in which each remote transmitting station ( 4 ) of the plurality of remote transmitting stations further comprises a corresponding alarm sensor, the arrangement being such that, in operation, each remote transmitter sends a non-monitoring signal when a signal is received from its corresponding alarm sensor, the receiving station triggering an alarm in response to the non-monitoring signal, and each remote transmitting station periodically sends a monitor signal to trigger the test to provide effective power range monitoring over time. Method for checking an effective power range in a communication system, which a receiving station ( 6 ; 6a ; 6b ) with receiving means for receiving signals of a monitoring and a non-monitoring type from at least one remote transmitting station ( 4 ), the method comprising the following steps: (1) receiving a signal from the remote transmitting station ( 4 ); (2) determining whether the signal is of a surveillance or non-surveillance type; and (3) if the signal is of a surveillance type, performing a test to determine if a non-surveillance signal from the remote transmitter station ( 4 ) would have the effective power range above the monitor signal. The method of claim 17, further comprising the The step includes sending a monitor signal periodically to trigger the test to monitor the signal power security area over time. The method of claim 17 or 18, wherein the test comprises the following steps: modifying an operating parameter of the receiving station ( 6 ; 6a ; 6b ) by an amount representing the effective power range and waiting for the reception of a subsequent monitoring signal from the remote transmitter station ( 4 ) while the operating parameter is modified. The method of claim 19, further comprising the step of: the operating parameter of the receiving station ( 6 ; 6a ; 6b ) is reset to normal if the subsequent monitoring signal comes from the same remote transmitting station as the monitoring signal. The method of claim 20, further comprising the step includes, in which the modified operating parameters are maintained will when a heartbeat is received by another remote transmitter. The method of claim 21, further comprising the following Steps include: Determine whether the other remote transmitter passed the test if the heartbeat signal from this Station was successfully received while operating parameters was modified, and relaying the signal for subsequent processing. The method of claim 19, 20, 21 or 22, the further includes the following steps: (a) Measuring a given one Time period from the reception of the monitoring signal and (b) defer the operating parameter of the receiving station to normal at the end of the predetermined period of time, if none from the remote transmitting station subsequent monitoring signal is received, the predetermined time period being such that at least part of a non-monitoring signal can be received while the operating parameter is not modified. Method according to one of claims 17 to 23, wherein the step of modifying the operating parameter comprises the step of responding to the receiving station ( 6 ) is prevented, for example by reducing the input signal sensitivity. The method of claim 17, wherein the test comprises comprises the following steps: processing an electrical output signal, that's the monitor signal represents at a first sensitivity level and at a second sensitivity level, which is lower than the first one and then compared, where a difference between the first and second sensitivity levels represents the effective power range. The method of claim 25, further comprising the step comprises, in which it is determined whether the electrical output signal substantially the same at the first and second sensitivity levels or is correlated, being the essential equality or correlation means the presence of the effective power range. The method of claim 26, further comprising the step where the signal is rejected, if there is no substantial equality or correlation. The method of claim 17, wherein the test comprises includes the steps of: measuring the strength of the heartbeat signal from is received by the receiving means, and comparing the strength with a predetermined threshold that represents the effective power range represents. The method of claim 28, further comprising the following Steps include: reject of the monitoring signal as not valid received when the strength is lower than the predetermined threshold, and providing an output signal to indicate that the test is from the remote Transmitter station has not been passed. A method according to any one of claims 17 to 29, further comprising the Includes step where all non-supervisory signals are accepted and for subsequent processing can be forwarded. The method of any one of claims 17 to 30, further comprising Includes step in which the monitoring and non-supervisory signals wirelessly using electromagnetic waves between the distant Transmitter station and the receiver be sent.