Acoustic communication

Abstract

The present invention relates to an electronic device including an acoustic transducer for transmitting an acoustic signal at a predetermined frequency toward a second electronic device, the device including an inertial measurement unit configured to measure changes in orientation and motion of the device relative to the second device, the device also having a computing unit configured to calculate a Doppler shift resulting from the motion, and adjusting transmit and / or receive frequencies according to the calculated Doppler shift.

Description

[Technical Field]

[0001] The present invention relates to electronic devices that communicate at least in part using audio signals, and in particular ultrasonic signals. [Background technology]

[0002] It is known to use time-of-flight measurements to track objects for touchless interaction with a computing device equipped with an ultrasonic transmitter and several receivers. Indeed, various proposals for such tracking have been made, for example, in U.S. Patent Application US 2006 / 0161871 by Apple, which specifically relates to input to a handheld device by a user's finger. However, these proposals have drawbacks. In particular, they can be susceptible to interference from echoes generated by other objects and from active noise sources.

[0003] Interference is particularly problematic in acoustic tracking systems due to the wider dispersion characteristics and speed of sound waves.

[0004] US10331166 describes this situation, where two or more devices, particularly mobile devices, attempt to use acoustic input systems within hearing range of each other. They may interfere with each other, especially when they are configured to transmit similar or identical acoustic signals to each other (e.g., in the same frequency range). US10331166 proposes a solution whereby the two devices can interact by one receiving an acoustic signal from the other and acting on it. One simplified example might be for the second device to alert the user to the presence of another user (of the first device) in the vicinity, for example, any identifiable user or thing, or any thing with an identification in the phone book of the second device.

[0005] In the notice of rejection, the examiner is of the opinion that the present application lacks an inventive step over JP2015185950A(D1) and US2019 / 0204408 A1(D2).

[0006] In JP2015185950A and US2019 / 0204408, Doppler shift calculations are used to adjust for relative motion in communications based on acoustic signals. In JP2015185950A, a global positioning system, reflected electromagnetic waves, or the like is used to measure position and velocity, which is then used to adapt the frequency of the acoustic signal. In US2019 / 0204408, the Doppler shift is measured based on signals between two devices, thus requiring an already established relationship between the two devices. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] US 2006 / 0161871 [Patent Document 2] US10331166 [Patent Document 3] JP2015185950A(D1) [Patent Document 4] US2019 / 0204408 A1(D2) [Patent Document 5] NO20221245[P6567] [Patent Document 6] NO20221246[P6728] [Patent Document 7] NO2022147

[6750] Summary of the Invention [Problem to be solved by the invention]

[0008] Prior art solutions, however, are still prone to interference and loss of contact between devices, especially for mobile devices moving relative to each other. It is therefore an object of the present invention to improve the accessibility and stability of acoustic communication between at least two devices. This is achieved as set out in the accompanying claims. [Means for solving the problem]

[0009] The present invention will be described primarily with respect to the use of inertial measurements in each mobile phone. Inertial or accelerometer measurements do not monitor relative velocity or position, unlike direct measurements of relative velocity that adjust signals when measuring change, the magnitude of the change. Therefore, the present invention simply compensates for changes in relative motion when a change in motion or position is registered by one of the devices.

[0010] Thus, the present invention addresses the problem of devices moving relative to one another. When using ultrasound signals, the motion may be large enough to change the frequency received by the device due to a Doppler shift. To eliminate environmental noise, a narrow frequency range may be advantageous, but the Doppler effect is more pronounced in a narrow frequency range.

[0011] Also, when more than one frequency is used to transmit acoustic signals, as described, for example, in NO20221245 [P6567], the signals typically need to be separated by 150-200 Hz to avoid frequency overlap when devices move relative to each other. Compensating for relative motion alleviates this problem and allows for more efficient use of the frequency range, for example, allowing for more parallel signals at different frequencies.

[0012] In accordance with the present invention, the transmitted acoustic signal is intentionally varied with the movement of the device in a particular direction to eliminate or significantly reduce the Doppler effect observed by the receiving device.

[0013] The present invention will now be described with reference to the accompanying drawings, which illustrate the invention by way of example. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 illustrates the concept of the present invention using two electronic devices communicating as described in US10331166. [Figure 2a] FIG. 1 illustrates relative motion vectors between two devices. [Figure 2b] FIG. 1 illustrates relative motion vectors between two devices. DETAILED DESCRIPTION OF THE INVENTION

[0015] 1, electronic devices 100, 101 include acoustic components for transmitting and receiving acoustic signals 102, which may be a single sine wave or a signal with multiple frequencies, for encoding and transmitting data between electronic devices. The acoustic signals 102 may also be used as identifiable acoustic signals with a fixed set of frequencies that the receiving device utilizes for proper handling during reception processing.

[0016] If a first electronic device 100 is transmitting a sinusoidal signal from a transmitter 108 at frequency F1 in a direction 103 towards a second device 101 that is capable of receiving the transmitted signal with at least one acoustic receiver 104, 105 while moving from or towards the second device 101, the second device will observe, due to the Doppler effect, another frequency F2 that is different from the F1 frequency that the first device was transmitting. This typically means that the Doppler effect needs to be taken into account when two electronic devices 100, 101, at least one of which is a mobile phone or tablet, use an acoustic signal having one or more frequency components to transfer information from one mobile device to another, using the intention of the acoustic signal or a particular acoustic signal having frequency F1.

[0017] Essentially, the original frequency or frequencies of the acoustic signal may change slightly when it is received. The F2 frequency may be lower or higher than the originally transmitted frequency F1. How much lower or higher depends on how fast the first device is moving toward the second device. If both devices are moving toward or away from each other, the Doppler shift of the transmitted frequency depends on the relative speed of the two devices. While this specification describes two devices communicating using acoustic signals, the invention may be used with multiple devices.

[0018] There are situations where Doppler shift causes problems in identifying the exact frequency that a first device was using. If an exact frequency is used to transfer information (i.e., bits, numbers, symbols, characters, data, etc.) between a first and second device, it is easier if the devices are stationary; there is no Doppler shift in the acoustic signal, but the observed frequency at the receiver does not change. Working with a constant frequency at the receiver has a clear advantage over solutions where the frequency changes only slightly because the first device is moving.

[0019] Typically, embedded sensors such as accelerometers and gyroscopes, or other six-degree-of-freedom sensors, are found throughout mobile devices. According to the present invention, at least the mobile device 100 includes such sensors and is configured to detect the direction and momentum towards a second device 101 that is transmitting data using acoustic signals (e.g., ultrasonic signals). This solution is described in detail in US10331166. As an alternative to using inertial measurements in each device, it may also be contemplated to use wider bandwidth signals transmitted and received by the devices to immediately measure any changes in the distance between the devices based on time-of-flight measurements; the different type of sensor is hereinafter referred to as an inertial measurement unit (IMU).

[0020] Once the first device 100 knows the direction 103 to the second device 101, the first device 100 can use its IMU sensors to continuously detect its own velocity in the direction of the second device and dynamically adjust the frequency of the acoustic signal to eliminate or significantly reduce the observed Doppler shift due to the second device. Even if the first device is not moving directly towards the second device, the velocity can be split into two components: velocity towards the second device and velocity perpendicular to the direction of the second device.

[0021] This is shown in Figure 2a, where the total momentum V of the first device has a component Vd directed towards the second device 101, and the transmitted signal frequency is adjusted according to Vd so that the second device 101 receives the predetermined frequency.

[0022] If the second device is also moving, as shown in Figure 2b, the first device must continuously track its direction to the second device and simultaneously calculate its own velocity in the direction of the second device in order to adjust the acoustic signal and its frequency accordingly to eliminate or reduce Doppler effects. If the second device is also moving while receiving data from the first device, the second device must detect its direction to the first device and calculate its own velocity in that direction. Using this velocity estimate, the second device can adjust the frequency components used to sample the incoming acoustic signal, significantly reducing the observed Doppler effects. If the first device is not moving, the frequency components of the acoustic signal transmitted toward the second device will not be adjusted in response to Doppler effects due to the stationary first device.

[0023] In the above description, the devices are primarily configured to detect motion and adjust signals to a common, global reference. For example, as described in NO20221246 [P6728], where the difference in propagation time for acoustic signals between at least one transducer, e.g., a speaker, on a first device and at least two transducers, e.g., microphones, on a second device is used to find relative position and / or orientation, and in NO2022147

[6750] , where communication between two devices begins with registration of motion on one device, if the devices are capable of calculating relative motion between the devices, they may be adapted to use a common Doppler-corrected frequency, for example, communicated using a wireless communication network.

[0024] If the applied frequency range is close to the audible range, the device may be configured so that movement towards the user will not bring the frequencies into the audible range.

[0025] In one embodiment of the present invention, the first device is a personal device (e.g., a smartwatch, smartphone, tablet, or laptop), and the second device is a video conferencing system in a confined space or room in an office building. The audio / video conferencing system may continuously send an acoustic signal containing some information about the conferencing system. If there is a motion or presence detection mechanism operating in the room or confined space, the system can start sending an acoustic signal containing information about the conferencing system when someone enters the detection area. If the first device needs to send some information about the first device or the user of the first device to the second device, the first device can do so using an acoustic signal with the Doppler effect removed or significantly reduced.

[0026] In another embodiment, if the first device does not have an embedded motion sensor with six degrees of freedom and therefore cannot detect its own velocity, the first device can use an acoustic signal from a second device, or send its own acoustic signal, to detect when the device becomes immobile by processing the received acoustic signal and identifying echoes produced by stationary objects near the first device from the probe signal at the acoustic receiver over a period of time, at which point the first device can begin transmitting its own data to the first device without worrying about the Doppler effect.

[0027] In brief, the present invention relates to a system including an electronic device and at least two devices, where the electronic device includes an acoustic transducer for transmitting an acoustic signal at a predetermined frequency toward a second electronic device. The device also includes a motion measurement device configured to measure direction and motion relative to the second device. The device includes a computing unit configured to calculate a Doppler shift resulting from the motion and adjusts the transmit and / or receive frequency according to the calculated Doppler shift to maintain the frequency relative to the second device or a stationary, global reference frame. Thus, the transmitter may adjust the transmitted frequency and / or the receiver may adjust a filter or sampling rate to receive the Doppler-shifted signal.

[0028] The acoustic signal is preferably in the ultrasonic range, and the device may be configured to avoid the audible acoustic range, which may be obtained by tuning the receiver instead of the transmitter frequency.

[0029] Two or more devices may be part of a communication system configured to measure relative motion between the devices and adjust a common acoustic frequency according to the measured relative motion. The devices may also include communication means configured to choose a frequency suitable for both devices. [Explanation of symbols]

[0030] 100 mobile devices 101 Second Device 102 Acoustic Signals 103 directions 104 Acoustic Receiver 105 Acoustic receiver 108 Transmitter

Claims

1. 1. An electronic device comprising an acoustic transducer for transmitting an acoustic signal at a predetermined frequency towards a second electronic device, the device comprising an inertial measurement unit configured to measure changes in orientation and movement of the device relative to the second device, the device having a computing unit configured to calculate a Doppler shift resulting from the movement, and adjusting the transmitted and / or received frequency according to the calculated Doppler shift.

2. The device of claim 1 , wherein the device also includes an acoustic receiver, and the computing unit is configured to adjust the sampling rate of the receiver according to the calculated Doppler shift.

3. The device of claim 1 , wherein the acoustic signal is in the ultrasonic range.

4. The device of claim 3 , wherein the computing unit is configured to avoid the acoustic range when adjusting the signal.

5. The device of claim 1 , wherein the device is configured to measure the motion relative to a stationary reference frame.

6. The device of claim 1 , wherein the inertial measurement unit comprises an accelerometer.

7. 10. A communication system comprising at least two devices according to claim 1, wherein the devices are configured to measure relative motion between the devices and adjust a common acoustic frequency according to the measured relative motion.

8. The system of claim 7 , wherein the devices include communication means configured to select a frequency suitable for both devices.

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