Patent Description:
<CIT> titled as "Spatial Mapping of Audio Playback Devices in a Listening Environment" discloses a method and apparatus for spatial mapping of two or more audio playback devices in a listening environment.

<CIT> titled as "Delay estimation for acoustic echo cancellation" discloses a technology for estimating a delay between a far-end audio signal and a near-end audio signal for acoustic echo cancellation.

There are solutions that exist which can connect multiple wireless speakers for audio play including subwoofers, but they only work by the same manufacturer that was specifically designed to do as such. These products are incapable to connect to a competitor product as an example.

Existing subwoofers are not considered "portable", nor are they designed as such. Subwoofers are generally too heavy and large to be considered portable. Additionally, subwoofers are powered from an AC outlet, or by being hard-wired in an automobile to receive <NUM>-16V.

A need exists to provide better bass for audio systems that is portable, battery powered, and easy to connect to existing third party Bluetooth audio systems. Users of this technology will have the ability to pair this subwoofer device to their existing Bluetooth speakers, their car audio system provided it is Bluetooth enabled, or any other Bluetooth audio systems without the need for professional installation.

Aftermarket solutions are available to complement an automotive stereo system whereby the consumer would have to install a subwoofer by themselves or use a professional service because it usually requires dismantling portions of the automobile to route cables and install 3rd party electronics such as an amplifier. To many automobile owners, they do not have the experience or knowledge for installing aftermarket electronics, or do not want to pay the high costs for installation fees. In most cases when leasing an automobile, manipulating the automobile with aftermarket electronics will violate the lease agreement.

An object of an embodiment of the present invention is to provide a Bluetooth speaker, such as subwoofer, that is configured to receive a Bluetooth signal, produce sound, and connect via Bluetooth to an audio system, such as to a Bluetooth speaker, vehicle audio system, home theater system, or Smart TV, the invention defined in the appended claims.

The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings wherein like reference numerals identify like elements in which:.

While this invention may be susceptible to embodiment in different forms, there are shown in the drawings and will be described herein in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated.

<FIG> is a block diagram of a device that is configured to receive a wireless signal, produce sound, and connect wirelessly to an audio system, such as another speaker or the audio system of a vehicle. Specifically, a preferred embodiment of the present invention is shown, wherein the device comprises a portable, battery-operated Bluetooth subwoofer <NUM> that is in accordance with a preferred embodiment of the present invention.

As shown, the portable, battery-operated Bluetooth subwoofer <NUM> comprises at least one wireless sink, such as a Bluetooth signal receiver <NUM>. The Bluetooth signal receiver <NUM> is configured to receive a wireless signal, such as a Bluetooth signal from a mobile phone. As such, music, for example, can be sent wirelessly from the mobile phone to the subwoofer <NUM>. The subwoofer <NUM> includes a signal processor <NUM> (such as a Digital Signal Processor (DSP)) that is configured to receive a digital audio signal <NUM> from the Bluetooth signal receiver <NUM>. The subwoofer <NUM> also includes at least one wireless source, such as a Bluetooth signal transmitter <NUM> that is configured to receive signals <NUM> from the signal processor <NUM> and wirelessly transmit a Bluetooth signal, i.e., to an audio system, such as to another speaker (as shown in <FIG>, described more fully later hereinbelow) or to the audio system of a vehicle (as shown in <FIG>, described more fully later hereinbelow).

As shown in <FIG>, the subwoofer <NUM> also preferably includes a digital audio buffer <NUM> that is configured to receive signals <NUM> from the signal processor <NUM>, at least one microphone <NUM>, and synchronizing circuitry <NUM> that is configured to receive signals <NUM>, <NUM> from both the at least one microphone <NUM> and the digital audio buffer <NUM>. An amplifier <NUM> is preferably provided and the digital audio buffer <NUM> is configured to receive signals <NUM> from the synchronizing circuitry <NUM>, provide signals <NUM> to the amplifier <NUM>, and the amplifier <NUM> is configured to drive at least one speaker <NUM> to produce sound.

As shown in <FIG>, at least one user-interactive control, such as one or more knobs and/or switches <NUM>, may be provided as being connected to the signal processor <NUM>, wherein the at least one user-interactive control is adjustable by user, for example, to set the crossover frequency, phase, etc., wherein such controls are common user adjustments in subwoofer applications. Furthermore, the portable, battery-operated Bluetooth subwoofer <NUM> may include one or more inputs, lights, buttons, etc. which are standard in the industry and therefore have been omitted from the drawings, for clarity.

Preferably, the signal processor <NUM> is configured to effectively feed the low frequencies to the digital audio buffer <NUM> for eventual output via the at least one speaker <NUM>, and is configured to feed mid and high frequencies to the Bluetooth signal transmitter <NUM> which is paired to another audio system such as another speaker (as shown in <FIG>, described more fully later hereinbelow) or the audio system of a vehicle (as shown in <FIG>, described more fully later hereinbelow), which plays the mid and high frequencies.

Regardless, in order to calibrate (or synchronize) the low frequencies to the other audio system, preferably the subwoofer <NUM> is configured to use the at least one microphone <NUM> which feeds the signal <NUM> back into the synchronizing circuitry <NUM>. The synchronizing circuitry <NUM> is configured to determine the overall delay and point to the memory address in the digital audio buffer <NUM> as to where the low frequency digital audio signal <NUM> matches the incoming audio received via the microphone <NUM>. The signal <NUM> is then fed into the amplifier <NUM> for playing through the at least one speaker <NUM>. Preferably, the subwoofer <NUM> is configured to provide that the overall delay accuracy is acceptable, for example less than <NUM> milliseconds.

Calibration (or synchronization) is preferably accomplished in synchronizing circuitry <NUM> comprising digital circuitry, a programmed field programmable gate array, or a programmed digital signal processor, that performs a cross correlation of signal <NUM> from at least one microphone <NUM>, with signal <NUM> delayed as signal <NUM>. Cross correlation is a well-studied and well-documented mathematical algorithm. Mathematically equivalent techniques such as convolution via application of finite impulse response filters with programmable coefficients may be desirable depending on the specific implementation of synchronizing circuitry <NUM>. The calculated sample number (time) location of the peak of the cross correlation ("X" in <NUM>, relative to "<NUM>" delay at <NUM>, in <FIG>), with sufficient confidence, is used to control digital audio buffer <NUM>, to delay signal <NUM> to the amplifier and the signal to line out <NUM>, as required.

Confidence in calibration is preferably calculated by comparing the "Y" value in <NUM> and <NUM> of the peak of the cross correlations in <FIG>, respectively, to the "Y" value in <NUM> and <NUM> of the next highest peaks, and also by comparing the peak Y values to the mean Y value of the cross correlation being evaluated. If the peak is sufficiently greater than the next highest peak, and also sufficiently greater than the mean, as exemplified by <FIG>, the calculation is used to configure the delay. If the peak is not sufficiently greater than the next highest peak, or not sufficiently greater than the mean, with both cases exemplified by <FIG>, the result is presumed erroneous, discarded, and the calculation is repeated.

Accuracy of calibration is preferably improved by delaying the signal <NUM>, yielding a more useful signal <NUM> for the cross correlation comparison with signal <NUM>. This delay may be <NUM>, fixed, or calculated from previous calibration attempts.

Accuracy of calibration is preferably also improved by filtering signals <NUM> and <NUM> according to those frequencies which can be easily detected by at least one microphone <NUM>, are presumed easily reproduced by speakers receiving signals from transmitter(s) <NUM> and <NUM>, and not reproduced by speakers <NUM> or (presumably) <NUM>.

Preferably, the subwoofer <NUM> is configured to be battery-operated and therefore, as shown in <FIG>, includes a battery <NUM>, associated internal power management circuitry <NUM>, and the subwoofer <NUM> is configured to be charged using an external wall charger <NUM>. Of course, the subwoofer <NUM> can instead (or in addition) be configured to be hard-wired, such as to the power system of an automobile.

Instead of a single Bluetooth transmitter <NUM>, additional Bluetooth transmitters (represented by dots <NUM> in <FIG>) can be provided as receiving signals <NUM> from the signal processor <NUM> such that the subwoofer <NUM> is configured to simultaneously connect (and transmit) to multiple Bluetooth speakers, such as to create a <NUM> surround system.

Instead of, or in addition to, providing signals <NUM> to the amplifier <NUM> for driving the speaker <NUM>, the digital audio buffer <NUM> can provide signals to a line out <NUM> that can be connected to an external active speaker <NUM>, such as to a powered external subwoofer or to an amplifier that is connected to a passive subwoofer. In fact, the amplifier <NUM> and speaker <NUM> can be omitted entirely from the device <NUM> and just the line out <NUM> be provided. Alternatively, or in addition, an amplifier <NUM> can be provided inside the device <NUM> to provide a powered output to amplifier output <NUM> that can be connected to an external passive speaker <NUM>, such as a passive speaker or subwoofer. Any one or more of these alternatives can be implemented - i.e., internal amplifier <NUM> and speaker <NUM>, line out <NUM>, internal amplifier <NUM> and amplifier output <NUM>.

Another embodiment may provide that more than one microphone <NUM> be provided, as represented by the multiple dots indicated with reference numeral <NUM>, such as to provide for improved noise cancelation.

The portable subwoofer <NUM> is configured to connect to any Bluetooth device that is capable of streaming audio. Common examples include a mobile phone, tablet, personal computer, etc. In the present disclosure, a mobile phone is merely used as an example.

<FIG> depicts a standard method of connecting a mobile phone <NUM> to a conventional Bluetooth speaker <NUM>. The mobile phone <NUM> is considered the "source," and the Bluetooth speaker <NUM> is considered the "sink. " Audio data streams from the mobile phone <NUM> to the Bluetooth speaker <NUM>. The Bluetooth speaker <NUM> receives the signal, processes it, and amplifies the signal to the speaker, thus creating audio sound.

<FIG> illustrates the same solution using the portable subwoofer <NUM> shown in <FIG> and described hereinabove. As shown in <FIG>, the mobile phone <NUM> connects to the portable subwoofer <NUM> via Bluetooth as a "source. " The portable subwoofer <NUM> is a "sink" to the mobile phone <NUM>, and is also a "source" to the Bluetooth speaker <NUM>. The Bluetooth speaker <NUM> is a "sink" relative to the portable subwoofer <NUM>. Essentially, the portable subwoofer <NUM> is configured to receive the audio signal from the mobile phone <NUM>, process the signal, route the low frequencies to the internal amplifier <NUM> (see <FIG>) which powers the internal subwoofer loudspeaker <NUM> (see <FIG>), and route the mid and high frequencies to the "source" portion which is then effectively broadcast to the Bluetooth speaker <NUM> (see <FIG>). Both portable subwoofer <NUM> and Bluetooth speaker <NUM> are synchronized (i.e., using the at least one microphone <NUM> and the synchronizing circuitry <NUM> shown in <FIG>) such that the sound being emitted will not have audible delays.

When pairing to a portable Bluetooth speaker <NUM>, the portable subwoofer <NUM> must be positioned within range of the source mobile phone <NUM> and the Bluetooth speaker <NUM>. The user will then pair the mobile phone <NUM> to the portable subwoofer <NUM> via Bluetooth. The portable subwoofer <NUM> will pair to the Bluetooth speaker <NUM>, and once connected, the user will stream audio through their mobile phone <NUM>.

The portable subwoofer <NUM> may be configured to use a Class <NUM> Bluetooth power level, which is currently the most common class for Bluetooth audio products. Its range is typically about ten meters or thirty-two feet. Alternatively, the portable subwoofer <NUM> may be configured to work in other classes, such as a Class <NUM> Bluetooth power level.

<FIG> depicts a standard method of connecting a mobile phone <NUM> to a conventional Bluetooth enabled car radio (aka "head unit") <NUM>. The mobile phone <NUM> is considered the "source," and the head unit <NUM> is considered the "sink. " Audio data streams from the mobile phone <NUM> to the head unit <NUM>. The head unit <NUM> receives the signal, processes it, and amplifies the signal to the speakers <NUM> in the car, thus creating audio sound.

<FIG> illustrates the same solution using the portable subwoofer <NUM> shown in <FIG> and described hereinabove. As shown in <FIG>, the mobile phone <NUM> connects to the portable subwoofer <NUM> via Bluetooth as a "source. " The portable subwoofer <NUM> is a "sink" to the mobile phone <NUM>, and is also a "source" to the car stereo (i.e., the head unit) <NUM>. The head unit <NUM> is a "sink" relative to the portable subwoofer <NUM>. Essentially, the portable subwoofer <NUM> is configured to receive the audio signal from the mobile phone <NUM>, process the signal, route the low frequencies to the internal amplifier (<NUM> in <FIG>) which powers the internal subwoofer loudspeaker (<NUM> in <FIG>), and route the mid and high frequencies to the "source" portion which is then effectively broadcast to the head unit <NUM>. Both portable subwoofer <NUM> and head unit <NUM> are synchronized (i.e., using the at least one microphone <NUM> and synchronizing circuitry <NUM> shown in <FIG>) such that the sound being emitted will not have audible delays.

When pairing to a car stereo <NUM>, the portable subwoofer <NUM> would be set within range of the source mobile phone <NUM> and the car stereo <NUM>. The user will pair the mobile phone <NUM> to the portable subwoofer <NUM> via Bluetooth, and the portable subwoofer <NUM> will pair to the car stereo <NUM>. Once connected the user will stream audio through their mobile phone.

The portable subwoofer <NUM> preferably has similar features as existing subwoofers in order to 'tune' the sound levels to match the environment or product it is paired to. This preferably includes, for example, volume levels, cross over frequency, and phase.

The portable subwoofer <NUM> is also configured to synchronize the sound with the other audio device (a portable Bluetooth speaker, car stereo, etc.) so the user will hear the music without any delay between the low frequencies from the portable subwoofer <NUM>, and the mid/high frequencies from the other audio device.

The portable subwoofer <NUM> is configured to pair via Bluetooth from any device capable of streaming Bluetooth audio and act as the "sink. " The portable subwoofer <NUM> is also configured to pair via Bluetooth to other audio equipment capable of streaming Bluetooth audio and act as the "source.

The portable subwoofer <NUM> is also preferably configured to filter the audio signal output to "split" the signals in two streams. One which will be low frequencies to the portable subwoofer <NUM>, the other will wirelessly stream to the other device intended for the mid and high frequencies.

The portable subwoofer <NUM> is also preferably configured to synchronize the audio signal going to the portable subwoofer <NUM> and the unit playing mid/high frequencies such that the user will not hear delays between the two units playing the audio stream.

Preferably, the portable subwoofer <NUM> is configured to be portable in which the size and weight is small enough for a person to carry, is portable in which it operates with rechargeable batteries inside the unit, thus not needing any other power source such as AC outlet, or automobile power system.

To enhance existing audio systems that do not have sufficient bass, such as portable Bluetooth speakers, and car stereos without subwoofers, the portable subwoofer <NUM> is able to accomplish this with the ability to pair to a device capable of streaming Bluetooth audio such as a mobile phone, split the audio such that the portable subwoofer <NUM> will produce louder bass and send the mid/high frequencies to the existing audio system to create a fuller sound. It is portable by not just size and weight, but also because the unit is battery powered and does not need an AC outlet or power direct from an automobile to operate.

Although the present disclosure is directed to Bluetooth as being the standard of wireless communication used by the device and systems disclosed herein, the device and related systems can be configured to receive and transmit data using other standards and frequencies.

Furthermore, while the device has been described as being a subwoofer, the device can be provided as being, for example, a full range speaker which is capable of producing lows, highs and mid frequencies. As such, the "at least one speaker" <NUM> disclosed herein can actually be multiple speakers, such as three speakers, wherein the signal processor <NUM> is configured to send different frequencies to different amplifiers associated with different speakers.

Claim 1:
A portable device (<NUM>) comprising: a wireless sink (<NUM>); a signal processor (<NUM>); a wireless source (<NUM>); at least one microphone (<NUM>) configured to receive audio from outside the portable device; and at least one of at least one speaker (<NUM>) and a line out (<NUM>), wherein the device is configured to receive a wireless signal using the wireless sink, process the signal using the signal processor, and transmit a wireless signal using the wireless source depending on what audio is received from the at least one microphone, and wherein the portable device is configured to at least one of emit sound using the at least one speaker and provide signals to the line out depending on what audio is received from the at least one microphone, wherein the portable device further comprises:
a digital audio buffer (<NUM>) configured to receive signals from the signal processor;
wherein the portable device is characterised in that it comprises a synchronizing circuitry (<NUM>) configured to receive signals from both the at least one microphone and the digital audio buffer, wherein the synchronizing circuitry is configured to employ cross correlation to effect calibration of the device; and
an amplifier (<NUM>),
wherein the digital audio buffer is configured to receive signals from the synchronizing circuitry and provide signals to the amplifier;
wherein the portable device is configured to:
add a delay if, after comparing peaks of a cross correlation of signals received by the synchronizing circuitry, it is determined that a highest peak is sufficiently greater than a next highest peak, and also sufficiently greater than a mean of the cross correlation of the signals received by the synchronizing circuitry ; and
not add a delay and instead repeat a calculation if it is determined that the highest peak of the cross correlation is not sufficiently greater than the next highest peak, or not sufficiently greater than the mean,
wherein the amplifier is configured to drive said at least one speaker to produce sound, and
wherein the portable device is configured to improve an accuracy of calibration by filtering signals received by the synchronizing circuitry according to those frequencies which can be detected by the synchronizing circuitry using the at least one microphone.