GB2406240A - Baby monitoring system - Google Patents

Abstract

A transmitting unit 10 for a baby alarm system comprises means 30 for detecting sound in a local environment in which a child or baby is located, means 20,40 for determining whether a detected sound is significant, means 90 for storing two telephone numbers, and means 20,50 operable, in response to a significant sound, to automatically dial one of the numbers to instigate a telecommunications session with a remote receiver unit via a telecommunications network. If a call cannot be instigated with a first of the two telephone numbers, the system attempts to contact the second number. The user may set threshold levels for the volume and/or duration of sound which instigates dialling of the number(s). Dialling may also be triggered in response to additional sensors monitoring smoke, temperature and orientation of the child or baby. The transmitting unit may be connected to the telecommunications network via a PSTN connection or via a mobile telephone, in which case it may either be interfaced with the mobile telephone or may be integrated into a mobile telephone. In the mobile phone arrangement, discontinuous transmission mode (DTX) may be used to switch off radio transmission between speech pauses.

Description

MONITORING SYSTEM

FIELD OF THE INVENTION

This invention relates to monitoring systems, arid in particular to transmitting units for such systems. A particularly preferred embodiment of the invention relates to a transmitter unit for a monitoring system of the type more commonly known as a "baby alarm".

BACKGROUND TO THE INVENTION

As is well known in the art, "baby alarms" of the type aforementioned are typically used when a child is sleeping to enable a carer (such as a parent or other person charged with ensuring the well being of the child) to monitor that child without having to be in the same room as the child.

Such systems typically comprise a transmitter unit which is placed in use in a sleeping child's room (preferably relatively close to the child), and a receiver unit which is placed in use near to the carer. Typically, the transmitter unit of the system includes a microphone and the receiver unit includes a loudspeaker, and the arrangement is such that sound generated by the child is transmitted to the receiving unit for replay to the carer so that the carer is made aware if, for example, the child should wake and start crying.

A variety of different models of "baby alarm" have previously been proposed. One such alarm includes a receiver unit that is provided with a rotary volume dial so that the carer can adjust the volume of sound replayed by the loudspeaker in the receiver unit. To avoid problems of the carer inadvertently switching the volume to a level which is inaudible, the receiver unit includes a visual sound level meter which provides an indication of the level of sound in the child's room. This arrangement allows the carer to easily determine whether a sound generated in the child's room is merely background noise of no consequence, or a noise that may be indicative of a problem.

To facilitate the easy identification of different sound levels in the child's room it has been proposed to subdivide the level meter into a number of differently coloured zones: a green zone indicative of inconsequential sound levels, an amber zone indicative of louder noises, and a red zone indicative of a relatively loud noise in the child's room which could indicate that the child has awakened and started crying.

In the light of more recent concerns regarding conditions such as Sudden Infant Death Syndrome (SIDS), it has been proposed to interface such baby alarms with a variety of additional sensors to monitor factors such as the temperature of the child, the heart rate of the child, and even whether the child is sleeping on its chest or back.

As the transmitter and receiver units of these previously proposed baby alarms are designed to be used in different rooms of a house, it is typically the case that they are configured to communicate wirelessly with one another.

One previously proposed system is configured in such a way that the transmitter unit modulates a signal with the audio signal and sends the modulated signal to the receiver unit via the mains electrical circuit of the house in which the system is located. Whilst this system works fairly well in a domestic environment, it does mean that the carer cannot stray too far from a power socket. In a non-domestic environment, however, this system may well not function as different floors of a hotel, for example, may well have separate and discreet power circuits.

Another previously proposed system employs a radio frequency transceiver in the transmitter unit that is configured to send an analogue radio frequency signal to the receiver unit. This system avoids problems that can occur when using the circuit-based system, but suffers from the disadvantage that the range of the system is relatively limited. A further, rather disconcerting, disadvantage is that the receiver unit of this system can inadvertently pick up signals from transmitter units of similar systems used in other households in the immediate vicinity.

To combat these problems of range and interference, it has more recently been proposed to utilise a digital wireless link between the transmitter unit and the receiver unit. It is believed that one such previously proposed system employs a DECT (Digital Enhanced Cordless Telecommunications) protocol, and is claimed to provide a range of in excess of 200 metres between the transmitter and receiver units.

Even more recently, it has become relatively commonplace to provide - in a domestic DECT telephone installation - an intercom function whereby a person using one handset of the installation can converse with another person using a different handset of the installation. This intercom function can additionally be configured for use as a baby alarm system.

In a normal domestic environment, these previously proposed systems have proved to function adequately. However, a number of problems have been become apparent when carers attempt to use such systems outside of a domestic environment, for example whilst staying in a hotel.

For example, as aforementioned, the fact that different floors may well be on different circuits has meant that a eater cannot rely on a circuit based alarm system to function properly. Similarly, the range and interference problems associated with traditional analogue radio systems are such that they are typically useless unless the receiver can be placed relatively close to the transmitter.

The range of digital wireless baby alarms (such as the aforementioned DECT system, and omer protocol alarm systems) is much improved (as compared to older analogue systems) and generally acceptable when the transmitter and receiver units are at the same or similar elevation. However, it has been noted that the range achievable is much more limited when the transmitter and receiver units are at different elevations - as may happen if a carer were to be relaxing in a restaurant of a hotel with their child asleep in a room several floors above them.

The distance between the cater and the child in such a scenario may be significantly less than the quoted range of the system (typically in the order of several hundred metres), but despite this it can still be impossible to pick up the signal from the transmitter unit. We are not sure why this problem occurs, but it may result from the typically markedly different construction styles of a domestic building (where the floors typically comprise no more than joists and floorboards), and a commercial building such as a hotel where the floors may be made from steel reinforced concrete. Several floors of steel reinforced concrete will doubtless represent a far greater barrier to the transmission of signals than a corresponding number of domestic floors.

The most apparent problem faced by a carer wishing to make use of a DECT telephone installation as a baby alarm outside of the domestic environment (for example whilst they are away on holiday) is that it is highly inconvenient to transport one's domestic telephone installation from one locale to another, particularly when one considers the fact that doing this would deprive the home of a telephone system that may well include other functionality such as an answering machine. Accordingly, it is apparent that whilst it might conceptually be possible for a carer to take their domestic telephone installation away with them on holiday, it is not in any way a practical proposition.

In view of the above, it would be an advantage if a monitoring system could be constructed that avoided these problems.

Summary of the Invention

As suggested above, an aim of the present invention is to alleviate the problems aforementioned, and with this aim in mind a first aspect of the invention provides a transmitting unit for use in a monitoring system such as a so-called baby alarm, the transmitting unit comprising means for detecting sound in a local environment in which a child or baby is located, means for determining whether a detected sound is significant, means for storing two telephone numbers, and means operable - in the event that a detected sound is determined to be significant - to automatically dial one of said two stored telephone numbers to instigate a telecommunications session with a remote system receiver unit via a public telecommunications network, the arrangement being such that said dialling means is operable to dial the other of said two telephone numbers in the event that a telecommunications session with a remote system receiver cannot be instigated using said one telephone s number.

The scope of the present invention also extends to a baby alarm system comprising a transmitting unit as aforementioned, and a receiving unit which is operable to participate in a telecommunications session with said transmitting unit.

These aspects of the invention are advantageous in that as the transmitter unit is operable to interface with a receiver unit via a telecommunications network, so the alarm system is capable of functioning in all regions where access to a telecommunications network is available irrespective of any difference in elevation (or indeed the range) between the transmitter and receiver units. Furthermore, the provision of a unit which is operable to dial two (or more) stored telephone numbers avoids any problems that might occur in the event that a telecommunications session cannot be instigated with a receiver unit at one of the two numbers.

Preferred features of embodiments of the invention are set out in the claims and elsewhere in the application.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic block-diagram of the core components of a preferred first embodiment of the invention; Fig. 2 is a schematic representation of illustrative thresholding circuitry; Fig. 3 is a schematic representation of alternative illustrative thresholding circuitry; Figs. 4, 5 and 6 are flow diagrams illustrating the functionality of the transmitter unit; and Fig. 7 is a modification of the functionality depicted schematically in Figs.4,5and6.

Fig. 8 is a schematic illustration of a second embodiment of the invention; Fig. 9 is a schematic representation of the core components of the embodiment depicted in Fig. 8; Fig. 10 is a schematic depiction of a third embodiment of the present invention implemented as a mobile telephone, and Fig. 11 is a schematic depiction of a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various preferred embodiments of the present invention will now be described by way of example only. It is envisaged that the first of these embodiments will be configured as a unit that is capable of being placed next to or near a child being monitored and being plugged into a socket outlet of a telecommunications network. The second of these embodiments is configured as a unit that plugs directly into a mobile telephone, the third of these embodiments is configured as a hardware and software modification of an existing mobile telephone, and the fourth of these embodiments is configured as software which may be executed by the processor of a mobile telephone.

It will be understood by those persons skilled in the art that these embodiments are merely illustrative, and that the teachings of the invention may be implemented in any of a number of different ways. As such it is important to bear in mind that the invention in its broadest terms relates to a transmitter unit of a baby alarm system which is configured to communicate with a receiver unit by means of a telecommunications network.

Referring now to Fig. 1 of the accompanying drawings, a transmitter unit 10 in accordance with a preferred first embodiment of the invention is based around a system processor 20 that is operable to co-ordinate functioning of the unit. A suitable processor may be, for example, one of the large range of "programmable system on chip" (PSoC) processors manufactured and sold by Cypress Semiconductor Corporation of 198 Champion Ct., San Jose, CA 95134, USA.

The transmitter unit, as will later be described, is intended for use with a remote receiver unit of the system. Such a unit may comprise, for example, a mobile or landline telephone (connected to a PSTN or a PBX), or indeed any device with telephonic capabilities.

A sound detector 30, such as a microphone, is coupled by way of thresholding circuitry 40, to the system processor. When the unit 10 is active, the sound detector is operable to pick up sounds in the room in which the unit is placed, and to generate an analogue signal that is passed to the thresholding circuitry 40 for determination as to whether a detected sound is "sigruficant".

By the term "significant" we mean that the detected sound is of a level (and preferably also of a duration) that has been preset, or indeed selected by the caret, as being representative of a level of sound in the room that they would wish to be notified about. That level of sound may be indicative, for example, of a level achieved by a crying child or baby.

The operation of illustrative thresholding circuitry will later be described in detail. At this juncture, however, it is worth noting that it will be apparent to those persons of ordinary skill in the art that the functionality (or indeed the circuitry) provided by the thresholding circuitry may be incorporated into the system processor as opposed to being provided by discrete electronic components.

The system processor 20 is also coupled to a dedicated communications processor 50 that is operable to instigate and terminate a telecommunications session with a remote receiver unit of the system. The communications processor is coupled to a communications interface 60 which may comprise, for example, an industry standard RJ11 port or equivalent. In one implementation, a cable can be plugged into the interface and into a wall socket (not shown) of a telephone system to permit the processor to access a telecommunications network, such as the PSTN for example.

Whilst this arrangement is preferred, it will nevertheless be apparent that the "interface" 60 could simply comprise a lead with an appropriate plug (such as a Type 431A UK standard line plug) provided on the end. The "interface" could then be plugged directly into the wall socket to provide access to the telecommunications network.

In either case, as the unit is designed to automatically call the carer, it is necessary to provide some means of switching the unit between "offhook" and "on-hook" states, as required. There are many different ways of achieving this, and one preferred option is to provide a relay that is operable to switch the unit between on- and off-hook states.

In a highly preferred embodiment, the communications processor is selected from the UBA2050 range of one-chip telephone integrated circuits manufactured and sold by Philips Semiconductors (a division of Philips Electronics NV) located in Eindhoven, the Netherlands. In general terms, the UBA2050 family of processors offer all speech and line interface functions, dialing and nuger functions required in electronic telephone sets.

The system processor is also coupled to a keypad 70 which is operable, in a manner to later be described, to permit a carer to input data to the transmitter unit. An advantage of using one of the aforementioned UBA2050 range of processors is that these processors each include a keypad, and as such a "separate" keypad need not be provided. In the preferred embodiment, the keypad includes twelve touch-tone telephone keys arranged in a standard layout, as well as a test key, a set-up key, and two "telephone number" keys (the function of which will later be described).

In a highly preferred embodiment, the system processor is coupled to a keypad illuminator 80 which is operable to illuminate the keypad 70 so that carers can use the unit in relative low light levels (as might occur in a room lit only by a nightlight for example).

The processor 20 is also coupled to a memory 90 for storing data input to the unit via the aforementioned keypad 70, as well as to an information display 100 and a warning display 110. The information display may comprise, for example, a sixteen character LCD display, and the warning display will typically comprise one or more - probably coloured - light emitting diodes.

The transmitting unit 10 is powered by an appropriate power source 120. In the preferred embodiment, power for the unit is provided by one or more batteries. These batteries may be rechargeable, and if so the unit is preferably configured so that the batteries may be recharged by placing the unit on top of an appropriate charger unit that is coupled to the mains power supply. Such an arrangement is convenient as it negates the need for the carer to remove batteries from the unit for recharging. As an alternative, the unit may be provided with an appropriate power supply socket to permit it to be coupled directly to the mains power supply. As a yet further alternative, the unit may be arranged to be powered by the mains power supply in which case the "power source" 120 will include a transformer and other conventional components known to those of ordinary skill in the art.

In a highly preferred arrangement, the warning display is configured to illuminate in the event that the power levels of the unit should drop below a predetermined minimum. The unit may even be configured to initiate a telecommunications session with the carer in the event the power levels should drop.

As shown in Fig. 1, a system clock 130 is coupled to the processor, and the processor uses signals from the clock for a number of different functions - each of which is to be later described.

A final, optional, component of the unit 10 is an input / output interface 140. This interface is provided to allow the cater to connect the unit to one or more additional sensing devices, such as a temperature sensor, a smoke detector or one of the aforementioned baby mats that allow the carer to monitor the orientation of the child or baby in their bed. If a temperature sensor, for example, is connected then the system processor may be configured to contact the carer if the temperature in the room should exceed a given value or drop below a given value.

In general terms, the transmitter unit of the preferred embodiment is configured to dial one or more of at least two telephone numbers input to the unit by a carer in the event that the sound level in the room should exceed a given threshold (or indeed in the event that another optional sensor should be triggered). The telephone numbers may identify, for example, a mobile telephone carried by the carer, a landline telephone that the carer knows that they will be near, or an extension number of a private exchange (such as that which one might find in a hotel).

In the preferred arrangement, the transmitter unit is arranged to contact the carer if the sound level (or other trigger) exceeds a predetermined level for a predetermined time In the preferred embodiment, these thresholds are user set during "set-up" of the unit prior to use, although it is conceivable that they may instead be pre-programrned into the unit.

Figs. 2 and 3 illustrate two schematic, and illustrative, examples of appropriate thresholding circuitry that may form the basis of the "thresholding circuitry" 40 depicted in Fig. 1.

Referring now to Fig. 2, in this arrangement the threshold voltage level VREF is controlled by the system processor 20. It is envisaged that the cater may be asked, during "set-up", to select a trigger level from, say, one to ten - each trigger level being associated with a different voltage. Once an appropriate level has been selected the processor can then stepup or step down the reference voltage VREF to provide the threshold voltage corresponding to the level selected by the carer.

The sound detector 30 is operable to output analogue audio signals, and these analogue signals are passed to a rectifier 150 where they are converted to a DC voltage level. The DC voltage output by the rectifier 150 is fed to a comparator 160, and the comparator 160 is operable to compare the DC input voltage from the rectifier with the aforementioned reference voltage VREF. If the DC input voltage should exceed VREF then a signal is sent to the system processor 20, and the processor starts a timer. If the DC input voltage should continue to exceed VREF for a predetermined period of time, the processor determines that the noise level detected is "significant", and proceeds in a manner to be later described. If the DC input level should drop to less than VREF the processor stops and resets the timer and determines the noise to have been insignificant.

As aforementioned, the carer can - in the preferred embodiment at least select the time for which the noise must persist before they are contacted by the transmitter unit. In an alternative implementation, the unit may be preset to contact the carer is the noise should persist for a given period of time, or indeed may be preset to contact the carer on each occasion the noise levels rise above the threshold represented by VREF.

Referring now to Fig. 3, in this arrangement the thresholding circuitry of Fig. 2 is modified by the addition of a variable resistor (or potentiometer) 170. In this implementation, VREF is constant and the carer is capable of setting the voltage reference level V'REF against which the DC sound level voltage signal will be compared by means of the variable resistor 170.

In a highly preferred implementation, the variable resistor may take the form of a thumbwheel that can be rotated to vary the resistance between a minimum resistance (where V'REF will be relatively high) and a maximum resistance (where VIREF will be relatively low). The thumbwheel may be switched to an "off" position where most - if not all - of the components of the unit are disconnected from the power source 120. This allows the carer to switch the unit off when not required. In a particularly preferred embodiment, the memory will continue to be powered by the power source even when the unit is switched off in order to save the carer from having to input telephone numbers on each occasion that the unit is switched on.

In each of the arrangements depicted in Figs. 2 and 3 it is preferred that the system processor is configured to start two timers on sensing of a "significant" noise. The first timer, as aforementioned, defines the length of time for which a significant noise must persist before the carer is contacted.

The second timer is configured to be very much shorter and is designed so that the first timer does not reset if there should be a pause between successive noises made by the child. The second timer may be of the order of a few seconds, and be configured to reset on each occasion that a significant noise is generated when the first timer is running. If the second timer should expire before a second significant noise is made, the controller assumes that the child has stopped making "significant" noises and resets the first timer.

This arrangement is advantageous in that it prevents the first timer from resetting in the event of a short pause between noises made by the child.

As an alternative to the use of two timers, the system could use a single timer and be configured to sample the output of the comparator at regular intervals, the child being deemed to have ceased making noise if no "significant" sound is detected during a number of successive samples whilst the first timer is running. As a yet further alternative, the system could be configured to SD successive samples for a predetermined period of time, and determine a "significant" sound to have occurred only if the summed sampled levels exceed a much higher threshold (typically equally to V'REF multiplied by the number of samples taken).

Adjustable thresholding is, in any event, a well-known technique, and as such a variety of alternative arrangements will be immediately apparent to those of ordinary skill in the art.

To set-up the unit for use, the carer must provide a power source (by charging the batteries or plugging the unit into the mains power supply, for example), and input two telephone numbers into the unit.

In the preferred embodiment, the carer inputs a first phone number by pressing the first of the aforementioned "phone number" keys, and typing in the number (including any access codes and/or country / area codes) into the unit. As the number is typed into the unit, the digits are displayed on the aforementioned infonnation display 100 so that the carer can check that they have been input correctly. Once all of the numbers have been input, the carer then presses the input number key a second time to store the input number in the memory 90.

This process is then repeated for the second number, and is initiated by the carer pressing the second of the aforementioned "phone number" keys.

In the preferred embodiment where a thumbwheel is provided to set V'REF, the carer completes the set-up process by pressing the "set-up" key and inputting a time period (in seconds) for which the noise must persist before the system processor of the unit automatically dials one or more of the inputted numbers. Once an appropriate time period has been inputted, the carer presses the "set-up" key once more to store the selected time period in the memory. If the carer should forget, or choose not to input a time period for which the noise must persist before they are contact, then it is preferred for the unit to default to a predetermined time period, say 20 or 30 seconds.

In the embodiment where VREF is set electronically, the abovementioned "set-up" procedure may also prompt the carer to indicate, for example on a scale of 1 to 10, at which point the carer wishes a generated sound to be determined to be significant.

In a highly preferred arrangement, the carer is able to test the unit prior to use by pressing the aforementioned "test" button. If the carer should opt to press this button, then the unit is configured to dial first the first telephone number input to the unit, and then the second number input to the unit so that the carer can check that the unit is functioning correctly.

In another highly preferred arrangement, the aforementioned warning display is configured to illuminate if, in a test mode, the care should make a noise that exceeds their chosen threshold level. In this way the carer can determine whether a selected threshold level is appropriate before leaving the child. As an alternative to illuminating the warning display, the unit may instead be configured to provide a measure of the ambient background noise in the room on the information display (perhaps in terms of the aforementioned scale of 1 to 10), thereby assisting the carer in picking a threshold level that is appropriate having regard to the ambient noise of the room in which the child is sleeping.

The processors of the unit implement the aforementioned functionality by means of appropriate software stored in memory and executed by the processors. Figs. 4, 5 and 6 provide a schematic illustration, in the form of a flow diagram, of the functionality provided by the software.

Referring now to Fig. 4, before using the unit the carer must set (step 200) the trigger threshold level, the time for which a noise must persist before being deemed to be significant, and the telephone numbers that the unit will dial in the event of a significant noise being detected.

Once these variables have been set the unit starts monitoring (step 202), and compares (in step 204) the level of sound detected by the sound detector with the threshold level set by the carer in step 200. If the sound level detected should exceed the pre-set threshold level (step 205), the unit starts a first timer in step 206. If the sound level detected should be less than the pre-set threshold level (as determined in step 205), the unit continues to monitor the sounds levels in the room in step 204. Once the first timer has been set in step 206, the unit continues in step

208 to compare the detected sound level with the pre-set threshold. If the detected sound level should drop below the threshold, the unit determines that the child has now stopped making a noise, resets the first timer in step 210 and processing reverts to step 204 aforementioned.

If, in step 208, the detected sound level is determined to still exceed the threshold, a check is made in step 212 to determine whether the first timer (set in step 206) has expired). The first timer corresponds to the amount of time, input by the carer in step 200, for which detected noise must persist at a level above the threshold for it to be deemed to be significant.

If the 1st timer has not yet expired, processing reverts to step 208 aforementioned. If the 1st timer has expired, the 1st timer is reset in step 214, a "number of attempts" variable is set to zero (step 215), and the first telephone number (inputted in step 200 aforementioned) is retrieved from the memory in step 216.

The unit then activates the aforementioned relay to go "off-hook" (step 218), and the communications processor determines in step 220 whether a dial tone is present.

If no dial tone can be detected, the unit activates the relay to go "on hook" and resets (step 222). The unit then waits for a relatively short predetermined amount of time (step 224) - say in the order of ten seconds before reverting to step 218.

If a dial tone is detected in step 220, the unit dials (in step 226 - Fig. 5) the telephone number retrieved in step 216, and starts a second timer in step 228. The unit then checks in step 230 whether the call placed to the retrieved number has been answered. It is anticipated that the second timer will be set to be something in the region of 20 to 30 seconds.

If the call has not been answered, the unit checks in step 232 whether the second timer has expired, and if the second timer has not expired reverts to checking whether the call has been answered in step 230. If the second timer has expired, it is reset in step 234 and the "number of attempts" variable (previously set to zero) is incremented by one in step 236.

In the preferred embodiment, the unit is configured to try each of the two input numbers twice, but it will be appreciated that a greater number of attempts may be provided for if desired. It is even conceivable that the carer may be able to select how many attempts are made to contact an inputted telephone number.

A check is then made, in step 238, to determine whether the "number of attempts" variable is equal to two. If the number of attempts is less than two, processing reverts to step 222 (Fig. 4) aforementioned. If the number of attempts is determined to be equal to two, processing continues at "C" in Fig. 6. This further processing will later be described in detail.

If the call should be answered in step 230, the unit resets the second timer in step 240, and starts a third timer in step 242. The unit then connects the microphone to the remote receiver unit in step 244 to permit the carer to listen to the sound that has been deemed to be significant.

A check is then made, in step 246, to see whether the third timer has expired. If the timer has not yet expired, processing reverts to step 244 aforementioned. If the third timer has expired, the third timer is reset in step 248, the unit goes "on-hook" (i.e. terminates the telecommunications session with the remote receiver unit) and resets (step 250), and processing reverts to step 204 (Fig. 4) aforementioned.

It is anticipated that the third timer will be preset to a duration of something in the order of a minute. This will provide the cater with sufficient time to determine whether noise detected is in fact significant.

In a modification of this arrangement, the unit may be configured to introduce a delay, say in the order of a minute or so, after step 246 and before recommencing monitoring in step 204.

If the check undertaken in Step 238 should indicate that two attempts to contact the carer at the first number have been made, processing continues at "C" in Fig. 6, and the unit retrieves the inputted second telephone number in step 252 and resets the "number of attempts" variable to zero (step 253).

The unit then goes "off-hook" in step 254, and a check is made in step 256 to see whether a dial tone can be detected. If no dial tone can be detected, the unit goes "on-hook" and resets in step 257, pauses in step 258 (say for ten seconds or so) before reverting to step 254 aforementioned.

If a dial tone is detected in step 256, the unit dials the inputted second telephone number in step 260, starts a fourth timer in step 262, and checks in step 264 if the call has been answered. It is anticipated that the fourth timer will be set to be something in the region of 20 to 30 seconds.

If the call has not been answered, the unit checks in step 266 whether the fourth timer has expired, and if the fourth timer has not expired reverts to checking whether the call has been answered in step 264. If the fourth timer has expired, it is reset in step 268 and the "number of attempts" variable (previously set to zero) is incremented by one in step 270.

A check is then made, in step 272, to determine whether the "number of attempts" variable is equal to two. If the number of attempts is less than two, processing reverts to step 257 aforementioned. If the number of attempts is determined to be equal to two, the unit goes "on-hook" and resets (step 274), and reverts to monitoring for "significant" sound in step 204 (Fig. 4).

If the call should be answered in step 264, the unit resets the fourth timer in step 276, and starts a fifth timer in step 278. The unit then connects the microphone to the remote receiver unit in step 280 to permit the carer to listen to the sound that has been deemed to be significant.

A check is then made, in step 282, to see whether the timer has expired. If the timer has not yet expired, processing reverts to step 280 aforementioned. If the timer has expired, the timer is reset in step 284, processing reverts to step 274 aforementioned, and thence to step 204 (Fig. 4).

It is anticipated that the fifth timer will be preset to a duration of something in the order of a minute. This will provide the carer with sufficient time to determine whether noise detected is in fact significant.

In a modification of this arrangement, the unit may be configured to introduce a delay, say in the order of a minute or so, after step 274 and before recommencing monitoring in step 204.

It will be appreciated from the above, that the unit of the preferred embodiment provides an effective means to monitor a child, and to alert a carer in the event that the child should start making a noise that is deemed by the carer to be significant. Of particular note is the fact that the unit will try two telephone numbers (chosen by the carer) before reverting to monitoring the child. It is relatively unlikely, in the event that two different numbers are input by the carer, that a connection cannot be made to either number, and as such the unit provides an effective means to monitor the well being of the child.

It will also be appreciated that the particular arrangement employed includes a number of safeguards that help to reduce the frequency with which a carer is contacted in the event of detected noise. These safeguards should help avoid problems associated with a carer being contacted following a noise which persisted only for a relatively short amount of time, or being repeatedly contacted in a relatively short period of time. Such contact may be considered to be undesirable given that the carer is likely to have to pay for each call made by the unit.

A farther modification is depicted schematically in Fig. 7. In this modification, as depicted, further steps are provided following the comparison step 204 of Fig. 4.

The first of these steps comprises a check to determine whether a call has been placed to the unit (step 286). If an incoming call is detected, the unit automatically goes "off-hook" in step 288, starts a timer in step 290, and connects the microphone to the caller (step 292) so that the caller (typically the carer) can listen for sounds in the room.

Following connection of the microphone to the caller, the unit checks in step 294 for expiration of the timer set in step 290. Once the timer has expired, it is reset in step 296, the unit goes "on-hook" and resets (step 298), and processing continues in step 205 (Fig. 4) aforementioned.

This modification of the system is advantageous as it allows a carer to call into the unit and listen to any sounds in the room in which the child has been placed. In other words, the carer is permitted to remotely monitor the child without having to wait for the unit to contact the carer following the detection of a significant noise. It is also advantageous in that it allows persons other than the carer to call in and check on the child from a remote location.

It will be apparent from the above, that the teachings of the present invention provide an effective means to avoid some or all of the problems afflicting the prior art. In particular, it will be apparent that a baby alarm which is configured to contact a carer by means of a telecommunications network effectively avoids the range problems that have plagued previously proposed devices.

As mentioned above, the teachings of the invention may be implemented in a number of different embodiments, a second of which will now be described.

In the first embodiment of the invention, the transmitting unit will most probably be configured as a unit which interfaces with a socket outlet of a telecommunications network. In the second embodiment of the invention, the transmitting unit is configured to interface with a mobile telephone to provide access to the telecommunications network.

This embodiment may be implemented by means of a connector which is adapted to plug at one end into the unit and at the other end into an appropriate input/output interface of a mobile telephone. In a highly preferred arrangement, the communications processor of the unit will be configured to detect whether the unit is plugged into a socket outlet or a mobile telephone and configure the signals sent by the unit as appropriate for interfacing with the network. Such modifications are well known to those skilled in the art of telecommunications and for brevity will not be further described herein.

In a modification of this embodiment depicted in Fig. 8, the transmitter unit 300 itself is configured to plug directly into an input/output port of a mobile telephone 301.

As shown, the telephone 301 comprises a display 302, an aerial 304 and a plurality of keys 306 arranged in a keypad. The keys, as is known in the art, can be arranged as so-called hard keys with one predetermined function or alternatively they can be arranged as soft-keys which have a plurality of functions depending on the particular operating mode of the telephone. The telephone 301 is provided with a microphone 308 and a loudspeaker 310 for input of user speech and generation of audio signals for relaying to a user. An infra-red inputloutput port 312 is also provided to permit infrared optical data signals to be received from and/or transmitted to other mobile telephones which are also equipped with an appropriate port.

The telephone comprises a female part of an input/output interface connector (not shown) into which a male part 314 of a compatible inputloutput connector on the transmitter unit 300 can be plugged.

Connection of the male and female connectors allows signals to be passed between the transmitter unit and the telephone, and may optionally also permit the transmitter unit to be powered by the battery pack (not shown) of the telephone.

The transmitter unit further comprises at least one LED 316 that is configured to illuminate when the unit is powered, and a thumbwheel 318 that can be manipulated by the carer to set the threshold volume above which a noise may be considered to be significant if it persists for a given period of time.

Fig. 9 is a schematic representation of key components of the embodiment depicted in Fig. 1. As shown the telephone 301 includes a central control unit or processor 320 that, at least in general terms, is operable to control operation of the telephone. Coupled to the processor 320 is a radio unit 322 and timing control circuitry 324 that together are operable to control the transmission and reception of telecommunications signals to and from other telecommunications telephones or from telecommunications networks to which the telephone can connect via the aerial 304.

A removable data storage device or subscriber identity module (SIM) 326 is provided for data and program storage. The data will usually comprise the IMSI (which uniquely identifies the telephone), and other information such as a set of telephone numbers stored on the phone by the user. Software programs may also be stored on the SIM as part of the so- called SIM toolkit (or SIM application toolkit as it is otherwise known).

Coupled to the processor 320 is the display 302, and signals can be sent from the processor to the display in order to convey messages, instructions, and other information to a user of the telephone. The processor is also coupled to the keypad 306 for data input by a user to the telephone.

Sound (for example user speech) picked up by the microphone 308 is processed by a speech processor 328 (for example to remove non transmittable frequencies), and a coder/decoder (CODEC) 330 that is operable to convert analogue signals generated by the microphone 308 into digital data for subsequent processing. The speech processor 328 and CODEC 330 are also operable to process received digital data and convert it into appropriate audio signals for relaying to a user by means of the loudspeaker 310.

Also coupled to the processor 320 is a ring generator 332 which is operable to generate one of a variety of different alerts which are used to alert a user of the telephone as to when a call, a message or other information is received at the telephone. In this particular case the ring generator is operable to generate appropriate signals to drive a vibrating buzzer 334, to illuminate an LED 336 (or bank of illumination devices) or to generate a ring signal for relay to the user via the loudspeaker 310. Typically, a user of the telephone is able to select which of these alert options are most preferable for their current ambient environment. In a highly preferred arrangement, the telephone is configured to disable the buzzer and the generation of a ring signal when the transmitting unit 300 is plugged into the telephone 301.

The transmitting unit 300 includes thresholding circuitry 338 that is gettable by means of the thumbwheel 318 aforementioned. The thresholding circuitry is coupled to a processor 340, and via the processor 340 to the interface 314. The processor is coupled to the LED 316 aforementioned.

The transmitting unit includes memory 339 which is coupled to the processor 340, and is configured to store variables such as - for example - the contact numbers that the carer wishes the unit to dial in the event of a significant noise, or the time for which a noise must persist before it is deemed significant.

The transmitting unit may optionally comprise a microphone 342, as a sound sensing device, coupled to the thresholding circuitry. As an altemative, the processor 340 may be configured to process signals from the microphone 308 of the telephone proper. The transmitting unit may also comprise a power source. Alternatively, as aforementioned, the transmitting unit may be configured to draw power from a battery pack 344 of the telephone proper.

The telephone and transmitting unit operate under the control of software which replicates the functionality described above in connection with Figs. 4 to 7 of the accompanying drawings. The processors 320, 340 of the telephone and transmitting unit can co-operate to execute the software (for example in a master/slave configuration), or alternatively the bulk of the processing may be undertaken by one or other of the two processors. Such variations will be immediately apparent to those persons of ordinary skill in the art, and as such will not further be described herein.

Fig. 10 is a modification of the embodiment depicted in Fig. 9, where the functionality of the telephone and separate transmitting unit is replicated in hardware and software as a mobile telephone, such as a GSM or UMTS compatible telephone. The majority of the components of the telephone are the same as those illustrated in Fig. 9, and these components will be referenced with the same numerals as those used above in connection with the

description of Fig. 9.

As shown the phone 301 comprises a display 302, an aerial 304 and a plurality of keys 306 arranged in a keypad, a microphone 308 and a loudspeaker 301 for input of user speech and generation of audio signals for relaying to a user. An infra-red input/output port 312 is provided to permit the reception andlor transmission of infrared optical data signals.

The telephone 301 includes a central control unit or processor 320, and coupled to the processor 320 is a radio unit 322 and timing control circuitry 324 that are operable to control the transmission and reception of telecommunications signals. The display 302 is also coupled to the processor 320, and signals can be sent from the processor to the display in order to convey messages, instructions, and other infonnation to a user of the telephone.

The processor is also coupled to the keypad 306 (for data input by a user to the telephone), and to a ring generator 332 which is operable to generate one of a variety of different alerts which are used to alert a user of the telephone as to when a call, a message or other information is received at the telephone. In this particular case the ring generator is operable to generate appropriate signals to drive a vibrating buzzer 334, an LED or equivalent illumination device 336 or to generate a ring signal for relay to the user via the loudspeaker 310.

A microphone 308 is provided, and is operable to convert sound signals (such as user speech for example) from the phone's ambient environment into analogue AC electrical signals that are subsequently passed to a speech processor 328 for processing, and a coder/decoder (CODEC) 330 that is operable to convert the analogue signals generated by the microphone 308 into digital data for subsequent processing. The speech processor 328 and CODEC 330 are also operable to process received digital data and convert it into appropriate analogue audio signals for relaying to a user by means of the loudspeaker 310.

Coupled between the CODEC 330 and the microphone 308 is level sensing logic 346 which is operable, in the preferred embodiment, to continuously monitor the AC analogue electrical signal output by the microphone 308 as it picks up sound from its surrounding envirorunent. The level sensing logic, and software to be later described, are configured to implement the baby monitoring functionality aforementioned.

The level sensing logic 346 comprises a rectifier 348 which is operable to convert AC analogue audio signals from the microphone 308 into a DC voltage signal that rises and falls with the amplitude of the AC audio signal, and hence with the volume of the audio signals detected by the microphone.

The output of the rectifier 348 is connected to an input of a comparator 350 that is operable to compare the DC voltage signal output by the rectifier with a reference voltage VRef supplied at another input of the comparator 350.

If the voltage level output by the rectifier 348 is greater than the voltage level of the reference voltage VRef, a high volume alert signal is sent by the comparator 350 to the processor 320 to indicate that the volume of the audio signal received by the microphone 308 has risen above the volume level represented by the predetemmined reference voltage VRef.

The processor 320 comprises a baby monitor (BM) 352. In the preferred embodiment, the BM is implemented by software executed by the processor 320. It will be appreciated, however, that the functionality of the BM could of course be provided by hardware (such as one or more application specific integrated circuits (ASICs) for example) wired to the processor 320. The BM, in software form, could form part of a so-called SIM Toolkit (or SIM Application toolkit as it is sometimes known) or part of the software provided in the mobile telephone.

When the telephone is set in a "baby monitor" mode, the BM 352, on receipt of a high volume alert signal from the comparator 350, starts an internal timer and continues to monitor the output from the comparator 350 (as described previously). If the level of the DC signal from the rectifier 348 does not fall below the reference voltage VRef before the timer expires, the BM 352 determines that the sound detected is "significant" and proceeds to attempt to contact the carer by automatically initiating a telecommunications session as aforementioned.

If the level of the DC signal from the rectifier 348 falls below the reference voltage VRef before the timer expires, the BM 352 determines that there has been a temporary increase in the level of input audio, takes no action to contact the carer and resets the timer.

As with the embodiment depicted in Fig. 9, the functionality of the software and hardware replicates the functionality above described in connection with Figs. 4 to 7 of the accompanying drawings, and as such the embodiment depicted in Fig. 10 should be read as providing any or all of the IS features above described in connection with Figs. 4 to 7. For brevity this functionality will not further be described herein.

Despite this, it will nevertheless be appreciated by those persons skilled in the art that the teachings of this embodiment provide an effective baby monitor by means of relatively minor modifications to an existing mobile telephone.

Fig. 11 is a schematic illustration of a mobile telephone in accordance with a fourth embodiment of the present invention. As before, components of the telephone shown schematically in Fig 11 that are common to the telephone shown in Figs. 9 and 10 are referenced with the same reference numerals.

The apparatus of Fig 11 is based on a modification of a prior art mobile telephone of the type which is capable of operating in a so-called discontinuous transmission (DTX) mode.

Discontinuous transmission is used in mobile telecommunications systems to switch the radio transmitter offbetween speech pauses. The use of DTX saves power in the mobile telephone and thus increases the life of the telephone's battery power supply. DTX also reduces interference levels to improve transmission quality.

Some prior art DTX systems, instead of completely switching the transmission off during speech pauses, generate parameters that characterise the background noise, and send these parameters over the air interface at a low rate in Silence Descriptor (SID) frames. The parameters are used at the receive side to regenerate background noise (referred to in the art as "comfort noise") which reflects, as well as possible, the spectral and temporal content of the background noise at the transmit side. The parameters that characterize the background noise are referred to as comfort noise (CN) parameters. The comfort noise parameters typically include a subset of speech coding parameters: in particular synthesis filter coefficients and gain parameters.

In a typical implementation of a DTX transmission system, a "voice activity detection" (VAD) algorithm is employed to distinguish between "user speech and noise" and "noise without user speech". Further details of VAD algorithms are explained in GSM recommendation: GSM 06.82 "Voice Activity Detection (VAD) for Enhanced Full Rate (EFR) speech channels" (the contents of which are incorporated herein by reference), and are not further discussed here.

In prior art DTX systems, the VAD is configured to identify when "noise without user speech" occurs and take appropriate steps. The teachings of this embodiment employ a modified VAD that is configured to identify when "user speech and noise" occurs and to take appropriate steps - it being apparent to those persons skilled in the art that such "user speech and noise" is indicative in the scenario of a baby monitor as potentially being as a result of a "significant" noise. In simple terms, the VAD may be thought of as providing a relatively sophisticated form of thresholding, and as such any thresholding software or hardware may be substituted therefor without departing from the scope of the present invention. In any event, the modifications required to a commonly available VAD will be immediately apparent to those persons skilled in the art.

The telephone 301 shown in Fig 11 comprises a processor 320 and a modified voice activity detection (VAD) module 354. The VAD module 354 may be implemented in hardware either as a discrete component or as part of the speech processor 328, or more preferably - as shown schematically in Fig 11 - may be implemented as a computer program (or algorithm) executed by the processor 320.

The telephone is also provided with a baby monitor unit (BM) 352 (as before described) that in the preferred embodiment is also implemented as software executable by the processor. Once again, as an alternative to a software solution, the BM 352 could of course be implemented as hardware either as a discrete component or as part of another component of the telephone 301.

The BM and VAD software modules can be configured to provide the functionality described above in connection with Figs. 4 to 7, and as such the teachings of this aspect of the invention provide a software solution to the problems aforementioned.

As will be immediately apparent, this is particularly advantageous in that suitable software may be loaded onto any compatible telephone to provide a baby monitor with the aforementioned features and functionality.

In a highly preferred arrangement the software could be configured to be downdoadable from a web site.

It will also be understood, that modifications may be made to the embodiments herein described without departing from the spirit and scope of the invention claimed.

For example, whilst the foregoing description mentions two "telephone number" keys in connection with the input of two telephone numbers, it will be apparent that a single key could be provided if desired - a carer using this single key to input the numbers. It will also be apparent that the system could be configured to store any number of telephone numbers in excess of two. As such, references herein to a system unit that stores two telephone numbers should not be read as restricting the scope of the invention to the storage of two, and only two, numbers.

For example, whilst Fig. 1 depicts the unit in terms of various discrete components, some or all of these components could be incorporated into one particular device - such as an application specific integrated circuit for example. It will also be apparent that the software functionality described above can alternatively be implemented in hardware.

It will also be appreciated that whilst in an envisaged system the transmitter unit will be operable to contact (i.e. instigate a telecommunications session with) a telephone (such as a mobile telephone, a landline telephone connected to the PSTN or a telephone connected to an extension of a PBX), the system may alternatively employ - as a receiver unit - any device with suitable telephonic capabilities. Such a device may comprise, for example, a personal computer equipped with appropriate hardware and software, or indeed a PDA with appropriate telephonic 1 5 capabilities.

It should also be noted that whilst particular combinations of featuresherein described have been specifically enumerated in the accompanying claims and elsewhere in the description, the scope of the invention is not so limited and instead extends to any combination or permutation of features described herein irrespective of whether or not that combination or permutation has explicitly been claimed.

Claims (32)

1. A transmitting unit for a baby alarm system, the transmitting unit comprising means for detecting sound in a local environment in which a child or baby is located, means for determining whether a detected sound is significant, means for storing two telephone numbers, and means operable in the event that a detected sound is detemmined to be significant - to automatically dial one of said two stored telephone numbers to instigate a telecommunications session with a remote system receiver unit via a telecommunications network, the arrangement being such that said dialling means is operable to automatically dial the other of said two telephone numbers in the event that a telecommunications session with a remote system receiver cannot be instigated using said one telephone number.

2. A transmitting unit as claimed in Claim 1, wherein a detected sound is determined to be significant if the level of sound detected exceeds a predetermined threshold.

3. A transmitting unit as claimed in Claim 2, wherein said threshold is user selectable or gettable.

4. A transmitting unit as claimed in Claim 1, wherein a detected sound is determined to be significant if the level of sound detected exceeds a predetermined threshold for a predetermined period of time.

5. A transmitting unit as claimed in Claim 3, wherein said threshold is user selectable or gettable.

6. A transmitting unit as claimed in Claim 4 or 5, wherein said predetermined period of time is user selectable or gettable.

7. A transmitting unit as claimed in any preceding claim, comprising an interface through which said instigating means is capable of instigating a said telecommunications session.

8. A transmitting unit as claimed in Claim 7, wherein said interface is an interface for direct connection to said telecommunications network.

9. A transmitting unit as claimed in claim 8, wherein said interface comprises a cable terminated with a connector, the cable being integral with the transmitting unit and the connector being configured to couple the cable to a telephone outlet point of a telecommunications system.

10. A transmitting unit according to Claim 9, wherein said connector comprises a Type 431A UK line plug.

11. A transmitting unit according to Claim 9, wherein said transmitter unit is configured to plug into a mobile telephone or other telephonic terminal, the interface being adapted to mate with a corresponding interface of a mobile telephone or other terminal.

12. A transmitting unit as claimed in Claim 7, wherein said interface is an interface for indirect connection to said telecommunications network.

13. A transmitting unit as claimed in Claim 12, wherein said interface comprises an RJ11 socket integral with the connecting unit, the socket being couplable to a telephone outlet point by means of a suitable cable terminated with appropriate connector plugs.

14. A transmitting unit as claimed in any preceding claim, wherein said telecommunications network comprises a wired network.

15. A transmitting unit as claimed in any preceding claim, wherein said telecommunications network comprises a wireless network.

16. A transmitting unit as claimed in claim 14, wherein said wired network comprises a PSTN (public switched telephone network) and/or a PBX (private branch exchange).

17. A transmitting unit as claimed in claim 15, wherein said wireless network comprises a GSM compatible network.

18. A transmitting unit for use as a baby alarm, the unit being operable to send signals to a receiving unit via a (public or private) telecommunications network by dialling one or more of a number of prestored telephone numbers.

19. A transmitting unit as claimed in any preceding claim, comprising an input / output port that is couplable to one or more additional sensing devices.

20. A transmitting unit as claimed in claim 19, wherein said one or more additional sensing devices are selected from a temperature sensor (such as a thermocouple), a smoke detector, and means for detecting the orientation of the child or baby.

21. A transmitting unit in accordance with any preceding claim configured as a mobile telephone.

22. A transmitting unit according to Claim 21, wherein the means for determining whether a detected sound is significant is implemented in hardware.

23. A transmitting unit according to Claim 21, wherein the means for determining whether a detected sound is significant is implemented in software.

24. A transmitter unit according to Claim 21, wherein the dialling means is implemented in hardware or software.

25. A baby alarm system comprising a transmitting unit as claimed in any of Claims 1 to 24, and a receiving unit capable of engaging in a telecommunications session with said transmitting unit.

26. A baby alarm system as claimed in claim 25, wherein said receiving unit comprises a telephone.

27. A baby alarm system as claimed in claim 26, wherein said telephone comprises a landline telephone connected to a private or public telecommunications network.

28. A baby alarm system as claimed in claim 26, wherein said telephone comprises a wireless telephone, such as a GSM compatible mobile telephone.

29. A transmitting unit for a baby alarm system substantially as hereinbefore described with reference to the accompanying drawings.

30. A baby alarm system substantially as hereinbefore described.

31. A method comprising the steps of: detecting sound in a local environment in which a child or baby is located, determining whether a detected sound is significant, storing two telephone numbers, and - in the event that a detected sound is determined to be significant automatically dialling one of said two stored telephone numbers to instigate a telecommunications session with a remote system receiver unit via a telecommunications network, the method further comprising the step of automatically dialling the other of said two telephone numbers in the event that a telecommunications session with a remote system receiver cannot be instigated using said one telephone number.

32. A computer program comprising one or more computer program portions which, when executed in an execution environment, are operable to implement the steps of the method claimed in Claim 31.