GB2391673A

GB2391673A - Wireless Audio Voice Monitor using Variable Bandwidth

Info

Publication number: GB2391673A
Application number: GB0218267A
Authority: GB
Inventors: Adrian D Charity; Douglas Ralph Ealey
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2002-08-06
Filing date: 2002-08-06
Publication date: 2004-02-11
Anticipated expiration: 2022-08-06
Also published as: EP1543483A1; GB0218267D0; DE60320428D1; ATE392686T1; WO2004015643A1; EP1543483B1; GB2391673B; AU2003242776A1

Abstract

A wireless audio monitor can remotely detect voice activity. A first portable radio transceiver 60 is reversibly switchable between a first narrow bandwidth audio receiving mode and a second wide bandwidth audio receiving mode. The first transceiver 60 is adapted to operate in the first narrow bandwidth audio receiving mode when listening for voice activity, and to communicate with a second transceiver 64 in wide bandwidth mode via a radio communication link when voice activity has been detected. The second transceiver 64 is adapted to indicate to a user the detection of voice activity by the first transceiver 60. The detection of voice can be optimised for infant voices 52, to enable the system to function as a baby monitor.

Description

(. 2391673

WIRELESS AUDIO MONITOR

Field of the Invention

5 Monitoring an audio environment via wireless devices.

Back round of the Invention g Monitoring of an audio environment via wireless devices 10 generally requires two components. The first component is a listening device. The listening device transmits from the intended area to the second component, which is a monitoring device. The monitoring device relays the audio signal to a user.

A typical device may in use provide constant audio monitoring. The transmitter simply broadcasts continuously, and control is limited to adjusting the volume of the monitoring device.

Published US patent application US-A-5774038 teaches, as an alternative, that the transmitter may be voice-activated.

This provides both a level of discrimination at the transmitter, and a reduction of power consumption, 25 increasing monitoring time.

However, there is still considerable scope to improve this monitoring arrangement, as the following description of the

invention makes clear.

Summar of Invention y The present invention provides means for remotely detecting voice activity.

( In a first aspect, the invention provides a communication system, as claimed in claim 1.

In a second aspect, the invention provides a method of 5 operating a communication system, as claimed in claim 18.

Further aspects are as claimed in the dependent claims.

Brief description of the Drawings

FIG. 1 shows the frequency characteristics of two modes of operation of the invention.

FIG. 2 shows an embodiment of a transceiver 2 in accordance 15 with the present invention.

FIG. 3 shows a preferred usage of a transceiver 60 in accordance with the present invention.

20 Detailed description of the invention

FIG. 1 shows the frequency characteristics of two modes of operation of the invention. There is a narrowband audio receiving mode 12. There is also a standard or unrestricted 25 audio receiving mode 10.

The use of the two modes shown in figure 1 will become apparent from the description below of the operation of the

invention. FIG. 2 shows an embodiment of a transceiver 2 in accordance with the present invention. The transceiver 2 of figure 2 can transmit speech from a user of the device. The transceiver 2 comprises a microphone 34 that provides a 35 signal and a reversibly switchable filter 46 that provides

either an unrestricted or narrowband version of the signal from the microphone 34. Hence the transceiver 2 of figure 2 is able to apply filters to the received sound that are of the general form shown in figure l.; The transceiver 2 also has a controller 20 and a memory 32.

Controller 20 may be a microprocessor.

Transmission circuit 22 transmits the signal from the 10 filter 46. Transmission circuit 22 transmits via switch 24 and antenna 26.

The transceiver 2 of figure 2 also comprises a display screen 42 and keypad 44, which serve as part of the user 15 interface circuitry of the transceiver. At least the keypad 44 portion of the user interface circuitry is activateable by the user. Voice activation of the transceiver, or other means of interaction with a user, may also be employed.

20 Signals received by the transceiver are routed by the switch 24 to receiving circuitry 28. From there, the received signals are routed to controller 20 and audio processing circuitry 38. A loudspeaker 40 is connected to audio circuit 38. Loudspeaker 40 forms a further part of 25 the user interface.

A data terminal 36 may be provided. Terminal 36 provides a signal comprising data for transmission by transmitter circuit 22, switch 24 and antenna 26.

In operation, the transceiver 2 is capable of storing in the memory 32 the data defining the modes of operation of the transceiver 2.

FIG. 3 shows a preferred usage of a transceiver 60 in accordance with the present invention. An infant SO emits a sound 52 that is detected by the transceiver 60. If the sound exceeds a threshold determined by controller 62 of 5 transceiver 60, a signal is transmitted.

The first transceiver 60 contains reversibly switchable audio receiving modes, the first being a narrow-bandwidth audio receiving mode, and the second an unrestricted audio 10 receiving mode.

A second of possibly many transceivers 64 receives the transmission of the first transceiver 60. Transceiver 64 provides a call alert and/or vibrates to alert user 54.

15 User 54 may then send a command using the second transceiver 64 to change modes of operation of the first transceiver 60.

The general operation of the invention is therefore clear, 20 from the above example. Below a more detailed description

of two preferred embodiments is given.

Description of Exemplary Embodiments

25 Embodiment 1: Figure 3 illustrates the scenario of the first preferred embodiment. In this embodiment an infant 50 emits a sound 52 that is detected by the transceiver 60. If the sound 30 exceeds a threshold determined by controller 62 of transceiver 60, a signal is transmitted.

In this embodiment a second transceiver 64 receives the transmission of the first transceiver 60 and provides a 35 call alert and/or vibrates to alert user 54. In this

embodiment, user 54 may then send a command using the second transceiver 64 to change modes of operation of the first transceiver 60. Additional optional transceivers are not shown for simplicity. -

In this embodiment, the first narrow bandwidth audio receiving mode is designed to be most sensitive to infant voice frequencies, in accordance with figure 1. See plot 12 -

of figure 1. It would be expected that this mode would be 10 the default monitoring mode in this embodiment. -

Employing either the first narrow-bandwidth audio receiving mode, or the second unrestricted audio receiving mode, the -

first transceiver 60 would employ a voice level threshold 15 based on comparison between current signal levels and long term or prior signal levels constituting background noise.

This threshold level may optionally be made user adjustable.

20 The first narrow-bandwidth audio receiving mode can operate a with a bandwidth that is optimal for detecting the frequencies of an infant. These frequencies may be those in which the volume of sound is greatest when a baby is crying. In comparison to a prior art listening device of

25 broader bandwidth: (i) This narrow bandwidth may help to screen out noises other than a babies' cries, making more precise the selection of instances at which a listening adult is -

notified of noise at the baby's location; 30 (ii) It may also require less battery power to operate in the narrow-bandwidth receiving mode; (iii)Finally, the first and second portable units 60 and 64 may also require less battery power, because the first unit 60 will be triggered less often to communicate 35 with the second transceiver 64.

Upon detecting speech that exceeds the voice level threshold, the first transceiver 60 may automatically employ any or all of the following modes of operation: 5 (i) The first transceiver 60 transmits audio for a limited period of time following voice activity detection; (ii) The first transceiver 60 changes its transmission mode from voice-detection based transmission to 10 continuous transmission; (iii) The first transceiver 60 changes its audio receiving mode from the narrow bandwidth audio receiving mode to the unrestricted audio receiving mode, or vice versa, depending on the current audio receiving mode.

Any automatic change of mode may optionally last for only a limited period, before reverting to the previous mode.

The second transceiver 64 can be reversibly changed between 20 indicating voice detection and continuously monitoring the transmissions of the first transceiver 60, either by the user by direct intervention, setting an automatic mode change, or under control of the first transceiver 60 via a wireless radio link.

The second transceiver 64 may additionally remotely control modes of the first transceiver 60, either as a consequence of user intervention, or automatically. These modes may comprise any or all of the following: 30 (i) The second transceiver 64 can remotely alter the transmission mode of the first transceiver between voice-

detection based transmission and continuous transmission; (ii) The second transceiver 64 can remotely alter the audio receiving mode of the first transceiver between a narrow

bandwidth audio receiving mode and an unrestricted audio receiving mode;! (iii) The second transceiver 64 can remotely alter the level of gain applied to the audio signal in the first! 5 transceiver.

Any remote change of mode may optionally last for only a limited period, before reverting to the previous mode. r 10 In this embodiment, it is envisaged that the first and second transceivers are functionally interchangeable, with each comprising the necessary means to perform the role of either first or second transceiver as described herein.

15 Embodiment 2: The second preferred embodiment is similar to embodiment 1, except that the transceivers are based upon current portable two-way radios. This second embodiment provides 20 the additional benefit of multiple selectable transmission channels. This allows many transceiver pairs or groups to I operate independently, within a locality where only a single-frequency transmission capability would cause interference between monitoring activities.

Each two-way radio's controller would be modified with the control options and modes outlined above, in connection with embodiment 1 of the invention. The two-way radios would be equipped with an audio filter that could provide 30 the two bandwidths lo and 12 shown in figure 1. The twoway radios would be able to switch between these filter modes, as described above in connection with embodiment 1.

Claims

( Claims

1. A system for remotely detecting voice activity, comprising:! at least a first (60) and a second (64) portable radio transceiver, the first transceiver being reversibly switchable between a first narrow-bandwidth audio receiving mode (12), and a second unrestricted audio receiving mode 10 (10);

the first transceiver (60) being adapted to operate in the first narrowbandwidth audio receiving mode when listening for voice activity, and to communicate with the second 15 transceiver (64) via a wireless radio communication link when voice activity has been detected; the second transceiver (64) being adapted to indicate to a user the detection of voice activity (52) by the first 20 transceiver (60).

2. A system according to claim 1, wherein the first narrow bandwidth audio receiving mode (12) of the first transceiver (60) is band-limited to favour infant voice 25 frequencies.

3. A system according to claim 1 or claim 2, wherein the voice activity detection of the first transceiver (60) employs a threshold mechanism that is dependent on the 30 level of background noise.

4. A system according to claim 3, wherein the sensitivity of the voice activity detection threshold can be adjusted by a user.!

5. A system according to any previous claim, wherein the first transceiver transmits audio for a limited period of time following voice activity detection.

5 6. A system according to any previous claim, wherein the second transceiver indicates the detection of voice activity by the first transceiver by call alert or vibration. 10 7. A system according to any of claims 1 to 6, wherein the first transceiver is adapted to automatically change its mode of operation upon the detection of voice.

8. A system according to claim 7, wherein the first 15 transceiver automatically changes its transmission mode, the change being from voicedetection based transmission to continuous transmission.

9. A system according to claim 7, wherein the first 20 transceiver automatically changes its audio receiving mode, the change being from a narrow bandwidth audio receiving mode to an unrestricted audio receiving mode.

10. A system according to any of claims 7 to 9, wherein 25 the first transceiver automatically changes modes for a limited time period, before reverting to the previous mode.

11. A system according to any previous claim, wherein a -

mode of the second transceiver is reversibly changeable 30 between indicating voice activity detection by the first transceiver and monitoring the audio transmission of the first transceiver, the change of mode being either: (i) By manual intervention of a user of the second transceiver, or

( (ii) Under control of the first transceiver, via a wireless radio link.

12. A system according to any previous claim, wherein the 5 second transceiver can remotely alter modes of the first transceiver, via a wireless radio communication link.

13. A system according to claim 12, wherein the second transceiver can remotely alter the transmission mode of the 10 first transceiver, the change being from voice-detection based transmission to continuous transmission.

14. A system according to claim 12 or 13, wherein the second transceiver can remotely alter the audio receiving 15 mode of the first transceiver, the change being from a narrow bandwidth audio receiving mode to an unrestricted audio receiving mode.

15. A system according to any of claims 12 to 14, wherein 20 the second transceiver can remotely alter the audio receiving mode of the first transceiver, the change being the level of gain applied to the audio signal.

16. A system according to any of claims 12 to 15, wherein 25 the first transceiver reverts from the remotely altered mode to the previous mode after a limited time period.

17. A system according to any previous claim, wherein each of the first transceiver and second transceiver comprise 30 the necessary means to perform the role of either first or second transceiver.

( 18. A method for remotely detecting voice activity, comprising the provision of at least a first (60) and a second (64) portable radio transceiver, the first transceiver being reversibly switchable between a first 5 narrow bandwidth audio receiving mode (12), and a second unrestricted audio receiving mode (10), whereby in operation: (i) The first transceiver (60) listens in the first narrow bandwidth audio receiving mode (12), when 10 listening for voice activity; (ii) The first transceiver (60) communicates with the second transceiver (64) via a wireless radio communication link, when voice activity has been detected; and: 15 (iii) The second transceiver (64) indicates to a user the detection of voice activity by the first transceiver (60).

19. A method according to claim 18, wherein the first 20 narrow bandwidth audio receiving mode (12) is band-limited to favour infant voice frequencies. t 20. A method according to claim 18, wherein the first transceiver provides an automatic change of a mode of 25 operation upon the detection of voice. 2 21. A method according to any of claims 18 to 20, wherein the second transceiver provides a remote alteration of a mode of the first transceiver, via a wireless radio 30 communication link.

22. A system substantially as hereinbefore described with reference to the accompanying drawings.

Amendments to the claims have been filed as follows Claims 1. A system for remotely detecting voice activity, comprising: at least a first (60) and a second (64) portable radio transceiver, the first transceiver being reversibly switchable between a first narrow-bandwidth audio receiving mode (12), and a second standard audio receiving mode (lo); the first transceiver (60) being adapted to operate in the first narrow-bandwidth audio receiving mode when listening for voice activity, and to communicate with the second transceiver (64) via a wireless radio communication link 15 when voice activity has been detected; the second transceiver (64) being adapted to indicate to a user the detection of voice activity (52) by the first transceiver (60); and wherein each of the first transceiver and second transceiver comprise the necessary means to perform the role of either first or second transceiver.

25 2. A system according to claim l, wherein the first narrow bandwidth audio receiving mode (12) of the first transceiver (60) is band-limited to favour infant voice frequencies. 30 3. A system according to claim or claim 2, wherein the voice activity detection of the first transceiver (60) employs a threshold mechanism that is dependent on the level of background noise.

( 4. A system according to claim 3, wherein the sensitivity of the voice activity detection threshold can be adjusted by a user.

5 5. A system according to any previous claim, wherein the first transceiver transmits audio for a limited period of time following voice activity detection.

6. A system according to any previous claim, wherein the 10 second transceiver indicates the detection of voice activity by the first transceiver by call alert or vibration.

7. A system according to any of claims 1 to 6, wherein 15 the first transceiver is adapted to automatically change its mode of operation upon the detection of voice.

8. A system according to claim 7, wherein the first transceiver automatically changes its transmission mode, 20 the change being from voice-detection based transmission to continuous transmission.

9. A system according to claim 7, wherein the first transceiver automatically changes its audio receiving mode, 25 the change being from a narrow bandwidth audio receiving mode to a standard audio receiving mode.

10. A system according to any of claims 7 to 9, wherein the first transceiver automatically changes modes for a 30 limited time period, before reverting to the previous mode.

11. A system according to any previous claim, wherein a mode of the second transceiver is reversibly changeable between indicating voice activity detection by the first

( 1'0 transceiver and monitoring the audio transmission of the first transceiver, the change of mode being either: (i) By manual intervention of a user of the second transceiver, or 5 (ii) Under control of the first transceiver, via a wireless radio link.

12. A system according to any previous claim, wherein the second transceiver can remotely alter modes of the first 10 transceiver, via a wireless radio communication link.

13. A system according to claim 12, wherein the second transceiver can remotely alter the transmission mode of the first transceiver, the change being from voice-detection 15 based transmission to continuous transmission.

14. A system according to claim 12 or 13, wherein the second transceiver can remotely alter the audio receiving mode of the first transceiver, the change being from a 20 narrow bandwidth audio receiving mode to a standard audio receiving mode.

15. system according to any of claims 12 to 14, wherein the second transceiver can remotely alter the audio 25 receiving mode of the first transceiver, the change being the level of gain applied to the audio signal.

16. A system according to any of claims 12 to 15, wherein the first transceiver reverts from the remotely altered 30 mode to the previous mode after a limited time period.

17. A method for remotely detecting voice activity, comprising the provision of at least a first (60) and a second (64) portable radio transceiver, the first 35 transceiver being reversibly switchable between a first

narrow bandwidth audio receiving mode (12), and a second standard audio receiving mode (10), whereby in operation: (i) The first transceiver (60) listens in the first narrow bandwidth audio receiving mode (12), when 5 listening for voice activity; (ii) The first transceiver (50) communicates with the D second transceiver (64) via a wireless radio communication link, when voice activity has been detected; and -

10 (iii) The second transceiver (64) indicates to a user the -

detection of voice activity by the first transceiver (60).

18. A method according to claim 17, wherein the first 15 narrow bandwidth audio receiving mode (12) is band-limited to favour infant voice frequencies.

19. A method according to claim 17, wherein the first transceiver provides an automatic change of a mode of 20 operation upon the detection of voice.

20. A method according to any of claims 17 to 19, wherein the second transceiver provides a remote alteration of a mode of the first transceiver, via a wireless radio 25 communication link.

21. A system substantially as hereinbefore described with reference to the accompanying drawings.