GB2502974A

GB2502974A - Identifying RF interference in a social alarm system

Info

Publication number: GB2502974A
Application number: GB201210271A
Authority: GB
Inventors: Christopher Anthony Burns
Original assignee: Tunstall Group Ltd
Current assignee: Tunstall Group Ltd
Priority date: 2012-06-11
Filing date: 2012-06-11
Publication date: 2013-12-18
Anticipated expiration: 2032-06-11
Also published as: GB2502974B; GB201210271D0

Abstract

Â A social alarm system (10,fig.1) monitors the safety and wellbeing of a person in their home or dwelling. The social alarm system includes a client unit 100. The client unit 100 includes an antenna 160 for receiving radio frequency signals from at least one or more peripheral devices 110,120, and unrecognised sources. A signal strength detector unit 130 measures a signal strength of the received RF signals to provide a received signal strength indicator (RSSI) value. A blocking detector unit 140 is arranged to indentify RF interference based on the RSSI value from the signal strength detector unit. A controller 150 is arranged to report an RF interference incident based on the blocking detector identifying the RF interference. The peripheral devices 110,120 may comprise a remote personal trigger such as a pendant, or a sensor such as an occupancy sensor, fall detector, and/or environmental sensors. The social alarm system may be arranged to communicate with a remote monitoring centre in the event of an alarm being triggered. The invention is particularly suited to confirming the functionality of the system in the presence of RF interference.

Description

SOCIAL ALARM CLIENT UNIT

AND MONITORING METHOD

BACKGROUND

Technical Field

The present invention relates in general to a social alarm system and to a monitoring method of a social alarm client unit.

Description of Related Art

A social alarm system monitors the safety and wellbeing of a client in their dwelling.

A social alarm client unit is installed in the dwelling and is arranged to initiate an alarm call to a remote monitoring centre apparatus when an alarm event is detected. As particular examples, the alarm may be triggered by the client pressing an alarm button on the social alarm client unit itself or on a remote personal trigger such as pendant.

In the event of an alarm being triggered, an operator using a terminal at the remote monitoring centre is able to open a voice communication path and talk with the client via the client unit. The voice communication path is useful in order to immediately reassure the client and asses their need for further care.

It is important to confirm that the system is functioning correctly. In particular, a difficulty arises concerning radio frequency (RF) interference in the vicinity of the client unit. This RF interference may impede the operation of the client unit, possibly to the extent that the client unit is unable to perform wireless signalling with local peripheral devices such as the personal remote trigger. Ultimately, severe RF interference may mean that an alarm call cannot be raised when needed. Therefore, it is desired to provide an effective, reliable and cost-effective mechanism for maintaining viable operation of the social alarm client unit.

Generally, it is desired to address one or more of the disadvantages associated with the related art, whether those disadvantages are specifically discussed herein or will be otherwise appreciated by the skilled person from reading the following description.

SUMMARY OF THE INVENTION

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

In one example aspect there is provided method of radio frequency monitoring performed in a social alarm client unit. The method includes receiving radio frequency signals at least from one or more peripheral devices and from unrecognised sources; measuring a signal strength of the received RF signals to provide a received signal strength indicator (RSSI) value; indentifying RF interference based on the RSSI value in relation to the RF signals from unrecognised sources; and signalling an RF interference incident based on identifying the RE interference.

In one example aspect there is provided a social alarm client unit having an antenna arranged to receive radio frequency signals at least from one or more peripheral devices. A signal strength detector unit is arranged to measure a signal strength of the received RE signals to provide a received signal strength indicator (RSSI) value. A blocking detector unit is arranged to indentify RF interference based on the RSSI value from the signal strength detector unit, and a controller is arranged to report an RE interference incident based on the blocking detector identifying the RE interference.

In one example, the signals from the one or more peripherals are detected based on pairing information. In one example, the received RE signals are decoded, by decoding signals from the one or more peripherals associated with the client unit as the recognised radio frequency signals. In one example, signals from one or more peripherals associated with other social alarm client units, which may be operating in the vicinity, are also decoded and treated as the recognised radio frequency signals. These recognised RF signals are not detected as RE interference.

In one example, both an alert threshold and a critical threshold are defined. An alert signal is provided when the RSSI level is above the alert threshold continuously for a defined period. A critical signal is provided when the RSSI level is above the critical threshold for the defined period. In one example, the alert level is lower than the critical level. In one example the alert level is about half of the critical level. In one example, an alert count of alert incidents and/or a critical count of critical incidents are maintained by considering the alert signal and the critical signal, respectively.

In one example, one or more reporting constraints are applied which inhibit further reporting of an alert incident and/or a critical incident. One example may include selectively generating a local announcement as an audible or visual warning from the client unit to warn that RF blocking has been detected and/or making a background call over a communications channel. In this way the alert incidents and/or the critical incidents may be notified to the user and/or registered with a remote monitoring server apparatus.

As will be discussed in more detail below, the example embodiments address many of the difficulties of the related art. At least some examples provide an improved mechanism for recognising RF interference. The example embodiments tolerate legitimate RF activity in the vicinity, while unwanted RF interference is judged with greater precision. These and other features and advantages will be appreciated further from the following example embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show how example embodiments may be carried into effect, reference will now be made to the accompanying drawings in which: Figure 1 is a schematic diagram of an example social alarm system; Figure 2 is a schematic diagram showing an example internal configuration of a social alarm client unit; Figure 3 is a bar graph as an example of detecting RF interference as performed within the client unit; Figure 4 is a flowchart showing an RF interference reporting function as performed by the client unit; and Figure 5 is a flowchart showing an RF interference reporting function as performed by the client unit.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

The example embodiments will be described particularly with reference to the social alarm system shown in the drawings. The apparatus and method may be applied in many specific implementations, as will be apparent to persons skilled in the art from the teachings herein.

Figure 1 is a schematic diagram showing an example social alarm system. In one example embodiment, the social alarm system 10 comprises a social alarm client unit 100 which is connected in use to social alarm server apparatus 200 at a monitoring centre through a communications channel 300. Suitably, the communications channel 300 is capable of carrying both voice (speech) and data signalling (e.g. using in-band audio tones such as DTMF tones).

As shown in Figure 1, the example client unit 100 has a simple and straightforward user interface suitable for use by a wide range of people of differing abilities. Typically the client unit 100 includes, inter a/ia, a readily identified "alarm" button 101. The client unit may also include a"cancel" button 102.

The client unit 100 may be used in combination with one or more local peripheral devices, such as with a personal radio trigger 110 and/or with one or more sensors 120.

The personal radio trigger 110 may be worn as a pendent or carried by the user about their person, worn on their wrist or on a belt, or attached to a key ring, for example. The personal radio trigger 110 includes an alarm button 111 so that the user may raise an alarm call in an emergency even when they are not in proximity to the client unit 100. The personal radio trigger 110 communicates with the client unit 100 over a short range wireless radio transmission.

The sensors 120 may include any suitable telecare sensor or combination of sensors.

The sensors 120 may include bed/chair occupancy sensors, pressure mats, a fall detector, and/or environmental sensors (e.g. carbon monoxide, natural gas), amongst others. Again, the sensors 120 communicate with the client unit 100 over short range wireless radio transmission.

Suitably, the client unit 100 and these local peripheral devices 110, 120 are each short range devices (SRD) according to ETSI EN300 220-2: 2010 which concerns radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW. For example, social alarms are allocated frequency ranges for transmit and receive of 169,475 MHz to 169,4875 MHz, 169,5875 MHz to 169,6000 MHz and 869,200 MHz to 869,250 MHz. The client unit 100 is suitably a "Category 1" radio receiver appropriate for highly reliable SRD communication media serving human life inherent systems that may result in a physical risk to a person. The EN50134 series of standards for Social Alarms are also relevant including particularly EN50134-2 for trigger devices and EN50134 -3 for the client unit.

Figure 2 is a schematic diagram showing an example internal configuration of the client unit 100. In this example. the client unit 100 comprises signal strength detector unit 130, a blocking detector unit 140, a controller 150 and an RF antenna 160.

The RF antenna 160 receives radio frequency signals, which are intended to come from the one or more peripheral devices 110, 120. However, the antenna 160 may also receive unwanted RF signals from other sources, i.e. not from the desired peripherals 110, 120. This RF interference thus reduces reliability of communication with the peripherals and/or causes communication with the peripherals to be blocked completely.

The signal strength detector unit 130 measures a signal strength of the received RF signal to provide a received signal strength indicator (RSSI). In an example embodiment, the RSSI value is provided as an analogue voltage value, e.g. from 0-5V, within a defined range.

In another example embodiment the RSSI value is provided as a digital value, e.g. 0-256.

The blocking detector 140 is arranged to indentify RF interference based on the RSSI value from the signal detector 130. In particular, the blocking detector 140 detects a blocking condition when a continuous blocking signal persists for 30 seconds or longer. More particularly, the blocking detector distinguishes between a recognised and an unrecognised radio frequency signal. As noted above, the client unit 120 is intended to communicate with one or more peripherals 110, 120. The client unit 120 is suitably paired with the peripherals 110, 120 such as by recording an identity of the peripherals 110, 120. Therefore, communications which originate from the peripherals 110, 120 are recognised and treated as wanted communications and are distinguished from RF interference.

Also, it is possible that other similar client units may be operating in the vicinity of the client unit. A shared building or a sheltered housing development may have several people in the vicinity all using similar client units. In this case, it is legitimate for these other client units to receive wireless signals from their respective peripherals and this can be considered acceptable use of this radio spectrum. Therefore, the blocking detector preferably distinguishes radio traffic of other client units as being recognised signals. The client unit can decode the received signals and notice that the signal is intended for another client unit based on the pairing information. The signal is then disregarded. However, signals from an unrecognised source cannot be decoded and recognised in this way, in which case the signal is considered to be an unrecognised signal and a potential instance of RF interference.

The controller 150 determines operations which are to be performed when RF blocking is detected by the blocking detector 140. In particular, the controller 150 is arranged to generate an audible or visual warning from the client unit 100 to warn the user that RF blocking has been detected. For example, a recorded spoken message may be played through the loudspeaker of the client unit such as radio blocking detected'. A visual warning may be provided through a visual display unit or by an LED status light (e.g. a flashing red light).

The example embodiments provide additional functionality concerning RF interference, in particular by providing additional information concerning RF interference. Also, the example system is more responsive and better able to inform the user and other concerned persons about RF blocking.

Figure 3 is a bar graph as an example of detecting RF interference as performed within the client unit.

In the example embodiments, the RSSI level is measured for example once per second and is accumulated into a 30 second moving average. Further, the blocking detector 140 defines an alert threshold VA and a critical threshold V. The alert threshold and the critical threshold may be configurable settings within the client unit. As an example, the alert threshold level is about 25% of the maximum RSSI level and the critical threshold level is about 50% of the maximum RSSI level.

In some examples, the alert and critical threshold levels are assessed considering the scale of the level measurement (above which it would saturate) and the operational conditions of the client unit. Thus the 25% and 50% levels may vary in other practical embodiments. The alert level may be set by considering the RSSI value at which RF interference becomes noticeable and starts to degrade performance of the client unit. The critical level may be set considering RF interference which significantly impedes communication with the client unit.

The alert level is set to be lower than the critical level. In one example the alert level is set to be about half of the critical level.

Where the blocking detector 140 determines that the RSSI level is above the alert threshold continuously for a defined period such as 30 seconds or longer, then the blocking detector 140 may provide an "alert" signal to the controller 150. Likewise, when the RSSI level stays above the critical threshold for a continuous defined period say of 30 seconds or more then a "critical' signal is provided to the controller 150.

Figure 4 is a flowchart showing an RF interference reporting function as performed by the client unit 100.

At step 401, an alert signal is provided as noted above.

At step 402 an alert count in increased to count the number of alert signals that have been generated within the client unit.

At step 403, one or more reporting constraints are considered. The reporting constraints inhibit further reporting of the alert incident, in particular so that the user is not fatigued by overly frequent reports or announcements. As one example, the alert incidents are not announced at all to the user.

At step 404 the client unit optionally provides an audible or visual alert message locally to warn the user that RF interference has been detected. As noted above, the audible announcement may be suppressed.

At step 405, the unit is set to make a background call over the communications channel 300 and log the alert incident with the remote monitoring server apparatus 200. In the example embodiments, the background call is made by dialling out over a telephone line as the communications channel 300 and signalling to the server apparatus 200. Suitably, the client unit 100 distinguishes between a background call for non-urgent events and a foreground call for urgent events, such as where the user actively summons assistance by pressing the alarm button on the pendant 110 or an important event has occurred such as the fall detector 120 registering a fall. The background call may be given a lower priority than a foreground call.

Figure 5 is a flowchart showing an operation of the client unit in response to detecting a critical amount of RF interference.

A critical signal is generated in step 501. A critical count is increased in step 502. The relevant constraints are considered in step 503 and then, where appropriate, a local announcement is made in step 504 and/or a background call is made in step 505 to the monitoring centre to register this incident of RF interference at the defined critical level.

In an example embodiment, the user may set a first time constraint, such as by pressing the cancel button 102 in response to an announcement, which then prevents subsequent audible announcements for a defined period such as 24 hours. In this way the user can prevent frequent announcements which may otherwise become annoying.

A second time constraint may be set within the unit which constrains a minimum repetition period for an incident. For example, the minimum period may be set to register an incident no more than once every two hours. This minimum period also prevents the announcements becoming overly frequent and annoying for the user or simply ignored by the user.

A third time constraint may be set within the unit which constrains a minimum repetition period for calling the monitoring centre. For example, the minimum period may be set to make a call no more than once every twenty-four hours. This minimum period prevents the monitoring centre being overburdened by background incident calls.

Figure 6 is a table showing example configuration settings applied to the client unit. The configuration settings include the critical RSSl threshold and a critical mode suppression period in which the critical mode is suppressed until a next critical signal will be generated.

The critical mode suppression period is suitably set as a number of seconds, such as 60 seconds. The unit is also provided with an alert RSSI level and an alert mode suppression period, which is suitably for a number of hours. Separately, a call suppression period may be defined which determines a minimum time period until a next call is made over the communications channel 300. The call suppression period may be set separately and may be for example once per day or a number of days so that the remote monitoring apparatus is not overwhelmed with a large number of calls from a large number of client units.

Figure 7 is a table showing example information held within the client unit related to RF interference. As shown in Figure 7 the unit may hold a critical count as the number of times the critical signal has been generated since the count was last reset. Also, the unit may hold a time period since the last critical signal is generated, such as a number of hours or days. The time period is useful for confirming correct operation of the unit. The unit may also hold an alert count as the number of alert signals which have been generated since the last reset and a time period in hours since the last alert signal. The unit may also present a current RSSI level, which again is useful in diagnosing correct operation of the unit.

The settings and configurations of Figure 6 and the recorded parameters of Figure 7 are suitably reported from the client unit 100 to the remote monitoring server apparatus 200

periodically or as part of each background call.

Thus, the client unit is now better able to inform the user about potentially harmful RF interference in the vicinity of the client unit. The user is better informed and is better able to take action to reduce RF interference, such as moving the base unit to another location or investigating the cause of the RF interference. Likewise, the remote monitoring centre server apparatus 200 logs RF interference activity at each client unit and may inform operators accordingly, such as with an RF interference report to identify client units which are suffering from unusual levels of RF interference. Further, providing both RF alert and RF critical levels provides greater information concerning RF interference in the vicinity of the client units.

The industrial application of the present invention will be clear from the discussion above. Likewise, the many advantages of the invention will be apparent from these embodiments and/or from practicing the example embodiments of the invention.

Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

Claims

CLAIMS1. A monitoring method of a social alarm client unit, comprising: receiving radio frequency signals from one or more peripheral devices and from unrecognised sources; measuring a signal strength of the received RF signals to provide a received signal strength indicator (RSSI) value; indentifying RF interference based on the RSSI value in relation to the RF signals from unrecognised sources; and signalling an RF interference incident based on identifying the RF interference.
2. The method of claim 1, comprising detecting the signals from the one or more peripherals based on pairing information.
3. The method of claim 1 or 2, comprising decoding signals from the one or more peripherals associated with the client unit as the recognised radio frequency signals and further decoding signals from one or more peripherals associated with other social alarm client units as also being the recognised radio frequency signals.
4. The method of any preceding claim, comprising measuring the RSSI level once per interval and accumulating the measured RSSI level into moving average over a plurality of intervals.
5. The method of any preceding claim, comprising defining both an alert threshold and a critical threshold, and providing an alert signal when the RSSI level is above the alert threshold continuously for a defined period, and providing a critical signal when the RSSl level is above the critical threshold for the defined period.
6. The method of claim 5, comprising increasing an alert count of alert incidents and a critical count of critical incidents, respectively, in response to receiving the alert signal and the critical signal.
7. The method of claim 5 or 6, comprising applying one or more reporting constraints which inhibit further reporting of an alert incident or a critical incident and selectively generating a local announcement as an audible or visual warning from the client unit to warn that RE blocking has been detected and/or making a background call over a communications channel to register the alert incident and/or the critical incident with a remote monitoring server apparatus.
8. The method of claim 7, comprising applying a first time constraint in response to a user input which inhibits subsequent local announcements for a time period.
9. The method of claim 7 or 8, comprising applying a second time constraint which constrains a minimum repetition period for the incidents or announcements.
10. The method of claim 7, 8 or 9, comprising applying a third time constraint which constrains a minimum repetition period of making the background call.
11. A social alarm client unit, comprising: an antenna arranged to receive radio frequency signals at least from one or more peripheral devices; a signal strength detector unit arranged to measure a signal strength of the received RF signals to provide a received signal strength indicator (RSSI) value; a blocking detector unit arranged to indentify RF interference based on the RSSI value from the signal strength detector unit; and a controller arranged to report an RE interference incident based on the blocking detector identifying the RE interference.
12. The client unit of claim 11, wherein the blocking detector is arranged to distinguish between an unrecognised radio frequency signal as the RF interference and a recognised radio frequency signal which is not the RF interference.
13. The client unit of claim 11 or 12, wherein the blocking detector is arranged to determine signals from the one or more peripherals associated with the client unit as the recognised radio frequency signals.
14. The client unit of claim 13 wherein the blocking detector is further arranged to determine signals from one or more peripherals associated with other social alarm client units as being the recognised radio frequency signals.
15. The client unit of claim 13 or 14, wherein the blocking detector is arranged to detect the signals from the one or more peripherals based on pairing information.
16. The client unit of any of claim 11 to 15, wherein the signal strength detector unit measures the RSSI level once per interval and accumulates the measured RSSI level into moving average over a plurality of intervals.
17. The client unit of any of claims 11 to 16, wherein the blocking detector identifies RF interference when a continuous RF interference signal persists for a defined period or longer.
18. The client unit of any of claims 11 to 17, wherein the blocking detector defines both an alert threshold and a critical threshold.
19. The client unit of claim 18, wherein the blocking detector is arranged to provide an alert signal to the controller when the RSSI level is above the alert threshold continuously for a defined period, and to provide a critical signal when the RSSI level is above the critical threshold for a defined period.
20. The client unit of claim 19, wherein the controller is arranged to increase an alert count of alert incidents and a critical count of critical incidents, respectively, in response to receiving the alert signal and the critical signal from the blocking detector.
21 The client unit of claim 19 or 20, wherein the controller is arranged to apply one or more reporting constraints which inhibit further reporting of the alert incident or the critical incident and, where appropriate, generates a local announcement as an audible or visual warning from the client unit to warn that RF blocking has been detected and/or causes the client unit to make a background call over a communications channel to register the alert incident and/or the critical incident with a remote monitoring server apparatus.
22. The client unit of claim 21, wherein the controller is arranged to apply a first time constraint in response to a user input which inhibits subsequent local announcements for a time period, and/or a second time constraint which constrains a minimum repetition period for the incidents, and/or a third time constraint which constrains a minimum repetition period ofmaking the background call.
23. A social alarm system, comprising: a monitoring server apparatus; and a plurality of client units; wherein each of the client units is arranged as set forth in any of claims 11 to 22.