GB2510117A

GB2510117A - Active noise cancellation system with orientation sensor to determine ANC microphone selection

Info

Publication number: GB2510117A
Application number: GB1301197.8A
Authority: GB
Inventors: Mark Griffin; Edna O'dowd
Original assignee: ODG TECHNOLOGIES Ltd
Current assignee: ODG TECHNOLOGIES Ltd
Priority date: 2013-01-23
Filing date: 2013-01-23
Publication date: 2014-07-30
Also published as: GB201301197D0

Abstract

Portable radio handset (1) comprising master unit (3) connected to slave unit (5) with first and second microphones (9,11) operating as primary and secondary microphones in an active noise cancellation (ANC) system depending on the orientation of the slave unit which is detected using an orientation sensor (13). First and second microphones are interchangeable so either can operate as the primary or secondary microphone. Orientation sensor may comprise an accelerometer, tilt switch, gyroscope, or manually-operated switch. First and second microphones may be mounted at either end and/or side of the slave unit. A visual indicator (LED) may show which microphone is operating as the primary microphone. Orientation sensor may enter a configuration mode for a predetermined time period, with fixed orientation set on time expiry, until re-configuration (reset or next start-up). Primary microphone may the one closest to the users mouth, with secondary microphone sensing ambient background noise. The system is intended for use in the portable radio handsets used by the emergency services (police, fire, ambulance / paramedics) for clear, high quality audio communication with control centre dispatchers. Master unit may be worn on a belt around the waist with slave unit attached to the chest region.

Description

"A portable radio handset"

Introduction

This invention relates to a portable radio handset.

Portable radio handsets are commonly used by members of the emergency services including police officers, fire brigade personnel and paramedics. Typically, the portable radios are worn by these individuals when they are away from the police station, fire station or hospital to allow communication between a dispatcher in a control centre and the individual. In this way, the individuals can be contacted by the dispatcher, receive instructions and be asked to attend the scene of a crime or the scene of an emergency.

Similarly, the individual can use the portable radio handsets to call the dispatcher requesting backup, update the dispatcher on the state of the emergency or request instruction from the dispatcher. The portable radio handsets comprise a master unit, often referred to as a portable radio, which is commonly, although not exclusively, worn on a belt around the wearer's waist and a slave unit, often referred to as a remote speaker microphone, which is commonly, although not exclusively, worn on a lapel adjacent the wearer's chest.

Communication via portable radio handsets is less than ideal due to the often poor audio quality of the communications. In particular, if the individual using the portable radio handset is in an area with a high level of ambient noise, it can be difficult if not impossible for the dispatcher to sufficiently distinguish the voice of the individual from the background noise. In order to improve the audio quality of the communications to the control centre, it is beneficial to implement active noise cancellation in the portable radio handset. Active noise cancellation in the portable radio handset will filter out at least some of the ambient noise from the communications to the control centre thereby making the communications to the control centre more intelligible for the dispatcher.

There is however a problem with the known portable radio handsets with active noise cancellation in that in certain cases, the active noise cancellation is not effective or is not operating close to its full potential due to the manner in which the portable radio handset is held by the individual or carried about their person.

It is an object of the present invention to provide a portable radio handset that overcomes at least some of the problems with the known portable radio handsets. In particular, it is an object of the invention to provide a portable radio handset with effective noise cancellation.

Statements of Invention

According to the invention there is provided a portable radio handset comprising a master unit and a slave unit, the slave unit comprising a first microphone and a second microphone, one of which operates as a primary microphone in a noise cancellation circuit of the slave unit and the other of which operates as a secondary microphone in the noise cancellation circuit of the slave unit, and in which the first microphone and the second microphone are interchangeable so that either of the first microphone and the second microphone can operate as either of the primary microphone and the secondary microphone of the noise cancellation circuit, and in which there is provided an orientation sensor to detect the orientation of the slave unit and means responsive to the orientation sensor to designate one of the first microphone and the second microphone as the primary microphone of the noise cancellation circuit and designate the other of the first microphone and the second microphone as the secondary microphone of the noise cancellation circuit.

By having such a portable radio handset, the orientation of the slave unit will be detected and based on the orientation of the slave unit, the configuration of primary and secondary microphones that will provide the best noise cancellation will be determined.

The first and second microphones of the slave unit will then be configured as either the primary or secondary microphone of the noise cancellation circuit according to the preferred configuration. In this way, the noise cancellation circuit will be effective and the communications from the individual to the control centre will be legible more often.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor comprises an accelerometer mounted on the slave unit. This is seen as a particularly effective and reliable way of detecting the orientation of the slave unit. The accelerometer will preferably be a six axis accelerometer and will be able to detect with ease the manner in which the slave unit is mounted about the individual.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor comprises of a gyroscope.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor comprises a switch operable to indicate the orientation of the slave unit. As an alternative to the accelerometer, a simple switch can be used to determine the orientation of the slave unit. For example, the switch may determine whether the slave unit is mounted upright (with the interconnecting cable run directly down from the slave unit to the master unit) or upside down (with the interconnecting cable run up over the shoulder and down the individuals back before being connected to the master unit) and once this is known, it may be possible to determine the correct microphone to use as the primary microphone and which microphone to use as the secondary microphone.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor comprises a tilt switch.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor comprises a manually operated switch to indicate the orientation of the slave unit. If preferred, there may be provided a manually operated switch to indicate the orientation of the slave unit and this will be considered to be the orientation sensor. The manually operated switch could be provided on the slave unit or the master unit if preferred.

In one embodiment of the invention there is provided a portable radio handset in which the first microphone is mounted adjacent one end of the slave unit and the second microphone is mounted adjacent another end of the slave unit opposite the end at which the first microphone is mounted. By separating the microphones in this way, the separation between the primary and secondary microphones will be at its maximum leading to good detection and filtration of ambient noise. Furthermore, it will be possible to mount the slave unit in a variety of different ways and still obtain good noise cancellation performance.

In one embodiment of the invention there is provided a portable radio handset in which the first microphone is mounted adjacent one side of the slave unit and the second microphone is mounted adjacent another side of the slave unit opposite the side at which the first microphone is mounted. By separating the microphones in this way, the separation between the primary and secondary microphones will lead to good detection and filtration of ambient noise. Furthermore, it will be possible to mount the slave unit in a variety of different ways and still obtain good noise cancellation performance.

In one embodiment of the invention there is provided a portable radio handset in which there is provided a visual indicator to show which microphone is currently operating as the primary microphone. This is seen as useful in those circumstances where the slave unit may be detached from the individual's clothing before or during a communication. In this way, the individual can determine whether they are speaking into the correct microphone of the slave unit. It is preferable to talk into the primary microphone of the noise cancellation circuit for best performance of the noise cancellation circuit and by having a visual indicator, the individual can tell whether or not they are talking into the primary microphone.

In one embodiment of the invention there is provided a portable radio handset in which the orientation sensor enters into a configuration mode for a predetermined period of time to determine the orientation of the slave unit and once the predetermined period of time expires, the orientation sensor sets the orientation of the slave unit in a fixed orientation until the orientation unit is placed into a configuration mode once more. In this way, if the orientation of the slave unit relative to the earth should change but the orientation of the slave unit relative to the individual wearing the slave unit does not change, for example, if the individual should bend over forwards, the configuration of the microphones will not change. What is important is that the microphone that is nearest the mouth of the individual wearing the slave unit is used as the primary microphone. The device could enter into configuration mode each time it is powered up so depowering the device will effectively reset the device and place it into configuration mode the next time the device is powered up.

Detailed Description of the Invention

The invention will now be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings, in which:-Figure 1 is a diagrammatic representation of the portable radio handset according to the invention being worn by an individual in a first configuration; Figure 2 is a diagrammatic repiesentation of the portable radio handset according to the invention being worn by an individual in a second configuration; Figure 3 is a diagrammatic repiesentation of the portable radio handset according to the invention being worn by an individual in a third configuration; and Figure 4 is a diagrammatic representation of the portable radio handset according to the invention being worn by an individual in a fourth configuration.

Referring to Figure 1, there is shown a silhouette of an individual, foi example a police officer, that carries on their person a portable radio handset, indicated generally by the reference numeral 1. The portable radio handset I comprises a master unit 3 and a slave unit 5 connected to the master unit by way of a cable 7. The slave unit 5 comprises a microphone 9, 11 and a speaker (not shown) and the slave unit 5 is located close to the face of the individual so that it can be used by the individual for communication with a control centre (not shown).

More specifically, the slave unit 5 comprises a pair of microphones, a first microphone 9 and a second microphone 11, and an orientation sensor, in this case an accelerometer 13 mounted therein for determining the orientation of the slave unit 5. The first microphone 9 and the second microphone 11 are interchangeable so that either of the first microphone and the second microphone can operate as either of a primary microphone and a secondary microphone of a noise cancellation circuit. The first microphone 9 is mounted adjacent one end of the slave unit and the second microphone 11 is located adjacent the other! opposite end of the slave unit.

In use, the accelerometer 13 determines the orientation of the slave unitS in which it is mounted, and there is provided means responsive to the accelerometer 13 that appoints one of the first microphone 9 and the second microphone 11 as the primary microphone of the noise cancellation circuit, and appoints the other of the first microphone 9 and the second microphone 11 as the secondary microphone of the noise cancellation circuit.

Typically, the microphone that is closest to the individual's mouth will be used as the primary microphone of the noise cancellation circuit as it will receive the clearest speech signal from the individual and the other microphone is used as the secondary microphone. Therefore, in the embodiment shown in Figure 1, the first microphone 9 located adjacent the top of the slave unit and indicated in solid line is designated as the primary microphone and the second microphone 11 located adjacent the bottom of the slave unit and indicated in broken line is designated as the secondary microphone.

However, this is only one way in which the portable radio handset is carried about their person.

Referring to Figure 2, there is shown another common way in which the portable radio handsets are carried about the person of an individual. The master unit 3 is worn on a belt as is the norm and the slave unit 5 is attached to a lapel or other suitable anchorage point on the chest of the individual. However, in Figure 2, the cable 7 between the master unit 3 and the slave unit 5 is led up the individual's back and over their shoulder in order to prevent the cable 7 being snagged and getting in the way. When the cable 7 is led over the shoulder in such a manner, the slave unit is typically upside down compared to the configuration shown in Figure 1. Therefore, the microphone 11 will now be closest to the mouth of the individual. The accelerometer 13, detecting the orientation of the slave unit, will cause the second microphone 11, now shown in solid line, to be designated as the primary microphone of the noise cancellation circuit and will cause the first microphone 9, now shown in dashed outline, to be designated as the secondary microphone of the noise cancellation circuit.

It can be seen from Figures 1 and 2 that the microphone closest to the mouth of the individual will be selected as the primary microphone of the noise cancellation circuit and the microphone furthest away from the mouth of the individual will be designated as the secondary microphone. The accelerometer 13 will detect the orientation of the slave unit and determine from that orientation which microphone 9, 11 is better suited for use as the primary microphone of the noise cancellation circuit and which microphone 9, 11 is better suited as the secondary microphone of the noise cancellation circuit. In certain circumstances, it may not be possible to determine with certainty which microphone is closest to the mouth of the individual or indeed the microphones may be equidistant from the mouth of the individual using the microphone, for example if the slave unit is mounted horizontally. The choice of microphone is based on orientation and how the unit is typically used. In the case where the slave unit is horizontal the algorithm to determine the designation of the microphone will currently chose microphone 9 as the primary and microphone 11 as the secondary.

In the embodiments shown in Figures 1 and 2, both of the microphones 9, 11 are located at the same side of the slave unit S but at opposite ends of the slave unit. It is envisaged that the microphones 9, 11 may be located on opposite sides of the slave unit 5 as well as or instead of being located at opposite ends of the slave unit in which case it may be preferable to use the microphone that is further away from the mouth of the individual but on an exposed side of the slave unit S if it is likely to obtain a better audio signal from the individual. For example, in the embodiment shown in Figure 2, if the second microphone 11 was in fact located towards the rear face of the slave unit (in other words, up against the body of the individual) it may be preferable to use that microphone 11 as the secondary microphone of the noise cancellation circuit and the other microphone 9 as the primary microphone of the noise cancellation circuit. The accelerometer, which in this case is a six axis accelerometer, will be able to detect the orientation of the slave unit and make such a determination.

Referring to Figure 3, there is shown a further way in which the portable radio handsets are carried about the person of an individual and used by the individual. The master unit 3 is worn on a belt of the individual as is the norm and the slave unit 5 is detached from the belt and held adjacent the mouth of the individual when in use. The orientation sensor 9 will determine the microphone most appropriate for use as the primary microphone and will designate that microphone 9 as the primary microphone and the other microphone 11 as the secondary microphone.

Referring to Figure 4, there is shown a further still way in which the portable radio handsets are carried about the person of an individual and used by the individual. The master unit 3 is worn on a belt of the individual as is the norm and the slave unit 5 is also worn on the belt of the individual, even when in use. The orientation sensor 9 will determine the microphone most appropriate for use as the primary microphone and will designate that microphone 9 as the primary microphone and the other microphone 11 as the secondary microphone.

In the embodiments described, an accelerometer has been used as the device suitable for use as the orientation sensor. However, other devices could also be used instead of or indeed as well as the accelerometer as the orientation sensor. For example, in the embodiment shown in Figure 3, it may be desirable to use a proximity sensor or heat sensor to detect which side of the slave unit and hence which microphone is likely to provide the best input as the primary microphone. As an alternative to the accelerometer, a switch or switches could be used. For example, one or more tilt switches could be located in the slave unit to detect the orientation of the slave unit and from the output of the switches, a decision may be made as to which microphone would be most appropriate for use as the primary microphone.

As a further alternative, the switch could be a manual switch provided on the master unit or the slave unit for manipulation by the individual so that they can indicate the orientation of the device and hence which microphone would be most suited as the primary microphone. In such a case the manual switch provides the function of the orientation sensor. A visual indicator such as a light emitting diode (LED) may be provided on either the master or the slave unit to indicate which microphone 9, 11 is currently the primary microphone. Preferably though, an orientation sensor that operates without requiring positive intervention by an individual would be provided.

In the embodiments described, a six axis accelerometer has been described in use with the slave unit. Instead of a six axis accelerometer, a single axis or a double axes accelerometer could be used instead or indeed a plurality of similar or different types of accelerometers could be used to implement the orientation sensor.

In the embodiments described, the portable radio handset 1 is described as having a cable 7 intermediate the master unit 3 and the slave unit 5. It will be understood that the slave unit 5 may communicate with the master unit 3 via a wireless communication link such as a Bluetooth ® or similar type wireless communication link and the cable will not be provided in some circumstances.

In addition to the foregoing, it is envisaged that the orientation sensor may enter into a configuration (set-up) mode for a predetermined period of time to determine the orientation of the slave unit. Once the predetermined period of time expires, the orientation sensor sets the orientation of the slave unit in a fixed orientation until the orientation unit is placed into a configuration mode once more. By a fixed orientation, what is meant is that the orientation sensor determines what the orientation of the slave unit is and determines that that is the orientation that is correct relative to the person wearing the portable radio handset and will designate the primary microphone and the secondary microphone on that basis. The designation of the primary and the secondary microphones is fixed and will not change until the orientation sensor enters into a configuration mode once more. Therefore, if the individual should change position resulting in a change in the orientation of the slave unit relative to the earth but not relative to the wearer, such as if the individual bends over or lies down, the designation of the microphones will not change. The portable radio handsets orientation sensor may be configured to enter into a configuration mode each time the portable radio handset is turned on.

According to an alternative embodiment of the invention, when using these radios and the remote speaker microphones, the user must press a button (known as the push-to-talk (PIT) button) which then opens a voice channel. While the PTT buttons is pressed, the device constantly monitors the orientation of the slave device. So in the unlikely event that the orientation changes while the user is talking, the designation of the microphones will change.

In this specification the terms "comprise, comprises, comprised and comprising" and the terms include, includes, included and including" are all deemed totally interchangeable and should be afforded the widest possible interpretation.

The invention is in no way limited to the embodiment hereinbefore described but may be varied in both construction and detail within the scope of the claims.