Systems and methods for controlling access

Abstract

The present invention relates to a system and method for establishing a wireless connection between a mobile first device and a second device, the system and method including: a first device configured for wireless communication using a known communication protocol; a second device including an acoustic transmitter configured to transmit acoustic signals in an ultrasonic range; a first device including at least two transducers, at least one of which is an acoustic receiver configured to receive signals in the ultrasonic range; a first device configured to measure and calculate its motion relative to the second device based at least in part on the acoustic signals received by the receiver; and a first device configured to initiate wireless communication when the motion of the first device is within a determined range relative to the second device.

Description

[Technical Field]

[0001] The present invention relates to a system and method for controlling access to external devices, such as a Wi-Fi system or an external speaker system. [Background technology]

[0002] Public areas such as stores, coffee shops, hotels, and restaurants often offer WiFi access to their customers. However, the signal is often strong enough to be received outside the area, making it difficult to restrict access to the intended area and user. Various authentication methods exist to restrict access to only customers, such as WPA / Password sign-in within a location, user subscription login, login coupons, etc. Most of these methods lack a concept of presence to restrict service to on-premises customers. In other words, anyone, given authentication credentials, can often gain access simply by being within WiFi range. Therefore, there is a need for a way to control access to areas within WiFi range. Similar problems pertain to other types of wireless systems, such as Bluetooth, used for local control of devices.

[0003] Another problem is that the number of devices is increasing, making selection more difficult. Typically, this means selecting a particular device from a list of devices in a menu, where the sometimes displayed device identifiers can be confusing to the user.

[0004] U.S. Patent No. 10,331,166 describes a method for two or more devices to determine their relative position and orientation based on ultrasonic signals transmitted between them. Using one speaker and two microphones on each device, positioning can be performed in 2D, such as on a tabletop. By adding more transducers, this method can be generalized to operate in 3D. Wireless communication (Bluetooth or WiFi) may be used to add communication capacity between devices and provide further possibilities for device synchronization. However, this solution does not prevent unnecessary connections in more complex situations involving a larger number of devices. U.S. Patent Application Publication No. 2021 / 0400417 describes an audio system that allows different devices to determine their relative position and orientation. Similarly, EP 3968295 describes two devices being able to measure the relative position between them. Additionally, WiFi or similar technology may be used to initiate communication between devices in separate operations. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 10,331,166 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0400417 [Patent Document 3] EP3968295 [Patent Document 4] WO2022189140 [Patent Document 5] U.S. Patent Application No. 2013 / 322214 [Patent Document 6] NO20221247 Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore a further object of the present invention to provide a solution for selecting the correct device among all available devices in a room. This is achieved as specified in the appended claims. [Means for solving the problem]

[0007] The present invention is therefore based on the understanding that many devices have at least one speaker for generating acoustic signals, thus constituting a sound source in addition to electromagnetic communication, and that most mobile devices have at least one, but usually three or more, microphones in addition to a transducer for electromagnetic communication.

[0008] Most speakers and acoustic transducers are capable of transmitting and receiving signals in the near ultrasonic range, just outside the audible range. Wavelengths in the ultrasonic range are also relatively short, so two acoustic sensors placed a few millimeters apart can be configured to detect the difference in reception time between two received signals, e.g., by phase difference. Using two transducers, the direction from the receiver to the source can thus be calculated. Based on the direction, the device may then choose which of the fixed devices in the area to connect to.

[0009] Thus, the present invention is configured to use acoustic signals to measure movement and to use this movement to initiate communication when the direction of movement is related to a direction towards a second device.

[0010] In one embodiment, the invention may involve the use of an inertial measurement unit (IMU) and / or magnetometer (compass) on devices such as smartphones and tablets, which in combination with the device's movement may be used to: 1. Improving the accuracy and robustness of the position estimate in general. Filtering and smoothing of the position estimate, as well as outlier detection and removal, is one such use. 2. Resolving ambiguities in location estimation. 3. Providing new capabilities for estimating more location parameters with a limited number of acoustic transducers on each device. 4. Improving robustness when one or more of the acoustic transducers are obstructed or affected by objects in the nearby environment, such as a grasping hand. 5. Allowing the positioning system to be activated only when necessary, i.e., after the device has been moved, thereby saving power. 6. Using a stored map of previously detected and located devices, such as IoT devices, in a room as a prior for where the device will be located the next time you enter the room with a mobile device, such as a smartphone. A magnetometer can be used to make a rough initial estimate of the orientation of the mobile device relative to the room.

[0011] In many cases, one of the devices will have the role of being the primary device that wants to map the locations of all other devices (i.e., secondary devices) in its environment, and the other devices can be assumed to be ignorant of the other devices around it. An example of this would be a smartphone (primary device) being used to control IoT devices around it, and the smartphone wanting to know the distance and direction to different IoT devices. In other cases, all devices may want to know about all other devices and their relative positions. An example of this would be a mesh of sensors placed within an area such as a building. In this case, all devices are equal, so the concept of primary or secondary devices is not necessary.

[0012] 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]

[0013] [Figure 1] FIG. 1 is a diagram illustrating the concept of the present invention. [Figure 2] FIG. 1 illustrates a method performed in accordance with the present invention. [Figure 3] FIG. 1 illustrates an example where a primary device, shown as a laptop, has identified the locations of two mobile phones. DETAILED DESCRIPTION OF THE INVENTION

[0014] As shown in Figure 1, which illustrates a preferred embodiment of the present invention, the system includes a first stationary device 1 including an ultrasonic transmitter 2 that transmits an acoustic signal 2a. The system also includes a wireless communication unit such as WiFi, Bluetooth, etc., as described below. It should be noted that the term "stationary device" is understood as a device that has a defined position or movement relative to the mobile device, allowing the user to point the mobile device towards the stationary device.

[0015] The portable device 3 in this case comprises two microphones 4a, 4b capable of receiving ultrasonic signals. The microphones are positioned at a distance C from each other and therefore receive acoustic signals propagated over different propagation paths A, B. Both microphones 4a, 4b are connected to a processor 5 configured to compare the signals from the microphones, in a manner known per se. In the example shown, the microphones 4a, 4b are positioned at the bottom of a mobile phone, and when the mobile phone is pointed towards the first fixed device 1, the signals at the microphones 4a, 4b will have the same propagation distance and therefore will be in phase.

[0016] If the processor 5 finds that the signals received at the microphones are in phase, the device 3 may determine that the first stationary device 1 is selected and may begin a connection routine, which may include confirmation at a user interface, using a screen, by moving the mobile device in a predetermined manner or by approaching the stationary device.

[0017] In the illustrated example, a second fixed device 11 is also shown including a speaker 12 emitting an ultrasonic signal, but in this case the propagation paths A', B' are different and therefore this device is not selected.

[0018] Other embodiments may be envisioned, such as positioning a microphone along the mobile device in a pointed direction, with the orientation determined as a predetermined phase difference. Alternatively, the mobile device combines signals from one microphone and, for example, a WiFi receiver. The acoustic signal may simply be a sine wave, but is preferably a coded or combined signal to avoid ambiguity in identifying devices in different directions or configured to be accessible by the system. It may also be possible to measure the time delay when a fixed device retransmits a signal emitted by the mobile device requesting connection, although this may be more complicated than locally measuring the acoustic phase difference. The acoustic sensor or microphone may also be combined with other sensors, such as inertial measurements using an IMU 6 to detect movement 6a of the device 3, which may be communicated to the processor 5 and potentially used to detect movements, movement patterns, or gestures that can be used to confirm selection, for example, by moving toward the selected fixed device, rotating the device 3, etc. The detected movement may therefore include both translational and rotational movement, detected, for example, by a compass, gyro, etc.

[0019] Once the mobile device identifies a fixed device 1, the wireless signal from the device must be identified, for example, by moving toward the fixed device and monitoring the distance, as described above. A wireless connection can be obtained, for example, if the acoustic signal from the fixed device is encoded with a code corresponding to the identification of the fixed device. The mobile device can then request access to the particular fixed device.

[0020] Since the actual ultrasound message is constrained to the room in which the access point is transmitting due to the physical properties of ultrasound, as described in WO2022189140 or US Patent Application No. 2013 / 322214, the ultrasound message may contain information about how to connect to the wireless network handled by the wireless access point.

[0021] The message may include SSID and corresponding password information that allows the recipient of the ultrasound message to seamlessly connect to the wireless network. Although the information extracted from the ultrasound message is not used to automatically connect to a wireless network, these ultrasound messages may be used to select an associated wireless access point.

[0022] For example, in one embodiment involving a small cellular base station, transmitting ultrasound from a cellular base station (CBS) allows a user equipment (UE) to filter out all CBSs outside the space or room the UE is currently in. In apartment buildings where multiple CBSs are installed, it can be a challenge for the UE to select a preferred CBS. If the CBSs can transmit ultrasound messages and the UE can receive them, the messages can be used by the UE to connect to a CBS in the same room, rather than, for example, the CBS with the highest signal strength.

[0023] The ultrasound message may include additional information about the cellular network, including cost, QoS parameters, etc., allowing the UE to make an informed decision about whether to connect via the CBS. It is also possible for the UE and CBS to exchange multiple ultrasound messages. The messages may be used to send secure messages between devices to verify that the UE is authorized to connect to the CBS. The messages may also be used to measure the distance between devices, as described in Norwegian Application No. 20221247. Based on these distance measurements, either the UE or the CBS may not allow the UE to connect to the cellular network via the CBS. There may also be other conditions that control when or if the UE is authorized to connect to the CBS.

[0024] The fixed devices mentioned above may also be devices setting up ad-hoc wireless networks, such as laptops, tablets, or smartphones, in a mesh network configured to seamlessly connect other nearby devices. One possible solution is to use WiFi Direct, where a WiFi Direct group owner can send ultrasonic messages to nearby devices, allowing recipients of the ultrasonic messages to seamlessly connect to the wireless network. This enables a scenario in which a group of people can set up an ad-hoc secure wireless network in a meeting room where they are located, providing, for example, a video conferencing system and allowing others to connect and participate in the meeting, for example, via screen sharing over a local or global network. In this case, it may also be advantageous to be able to measure the relative position and orientation between units, as described in NO20221247.

[0025] The transmission of ultrasonic messages may be limited to periods when the presence of someone (i.e., a user) or something (e.g., a robot, a dog, a cat, etc.) is detected by any available type of presence detector unit. This scheme may reduce overall message transmissions, thereby reducing the power consumption of the solution.

[0026] The fixed device may alternatively be a video conferencing system that allows others to connect and participate in the conference, for example by screen sharing over a local or global network. In this case, it may also be advantageous to be able to measure the relative position and orientation between the units, as described in NO20221247.

[0027] According to one embodiment of the present invention, it may improve the accuracy and robustness of the overall position estimation and save power by activating the sensor only when moving.

[0028] Figure 3 shows the case where a primary unit 31, such as a laptop or fixed device, has identified the location of two secondary units 33a, 33b, such as mobile phones, by using ultrasonic signalling between the units.

[0029] If either of the phones 33a, 33b is moved, it may be detected using the IMU sensors 36a, 36b, which detect motion including rotational and translational motion. The position should be updated immediately, and therefore positioning must be performed continuously. If the user is working on a laptop, the user's hands may occasionally block the ultrasound path, potentially resulting in large random errors in the estimation. However, continuous monitoring of the IMU (accelerometer and / or gyro) can indicate that the phone is not moving and the position should not be updated. If the phone is moved, inertial navigation may be used to estimate the phone's motion in six degrees of freedom (DOF), or only three DOF when the phone is on a table. A sensor fusion algorithm, such as a Kalman filter, may be used to regularize the phone's position estimate. In particular, when the phone is immediately to the left or right of the screen, the vertical position estimate may be very coarse, and vertical movement may be based largely on the IMU signal.

[0030] In practice, the system may allow the phone to report when it is moved up, down, rotated, etc., according to its frame of reference, and the primary and secondary devices may communicate to detect whether the devices are moved relative to one another. Thus, if the phone reports an upward movement and the primary device finds that the movement brings the two devices closer, the system also knows the relative orientation of the phones. If the movement is upward relative to the phone's frame of reference and the primary device finds that this movement brings it closer, the system may interpret this as a gesture requesting access to the primary device's communication protocol. Other definitions may be linked to moving the phone sideways or rotating the phone relative to the primary device, such as disconnecting or providing input to the primary device's software. More complex gestures may also be envisioned.

[0031] According to another aspect of the invention, the invention may be configured to resolve ambiguities in position estimates.

[0032] In some scenarios, there may be several ambiguous positions of the device that provide the same distance in the acoustic path, in which case it is not possible to determine in which of the ambiguous positions the device is located. In the example below, a central primary unit 31 has top and bottom microphones 34 and a top speaker 32. In this case, two peripheral smartphones, one to the left and one to the right of the primary device, may provide identical acoustic measurements if they are at the same distance. Alternatively, a combination of acoustic and electromagnetic measurements may be used to measure relative orientation, with at least one distance measured acoustically and a second distance measured using Bluetooth.

[0033] However, for example, if the right phone 33a is moved slightly to the left or right 6a, this movement can be measured using both the IMU on the phone and the ultrasound system on the primary device unit 31. For example, if the right phone reports to the primary device that it has moved slightly to the left in its own coordinate system, and the primary device measures that the peripheral phone is portrait-oriented and is moving closer, it knows that the peripheral is on the right. If it were on the left, it would have moved away from the primary device. The movement used for disambiguation can be the movement that occurred when the peripheral phone or primary device was first placed on the table. This concept can be used to resolve most cases of ambiguity.

[0034] The present invention may also provide new capabilities for estimating more position parameters with a limited number of acoustic transducers on each device.

[0035] In the general case of a handheld device, it has 6 DOF of motion: x, y, z for translation, and α, β, γ for rotation. To be able to position two devices with 6 DOF relative to each other, at least six independent measurements of the distance between the two devices are required. When the device is placed on a table, it has 3 DOF of motion: x, y, and α (azimuthal rotation).

[0036] Therefore, the present invention may actually follow the following scheme. One single general app will be used on the phone for all IoT devices. Compatible IoT devices in the environment are detected by emitting ultrasonic pulses. The direction to each detected device is obtained from the direction of arrival of the ultrasound signal. The phone connects to the desired device (e.g. Bluetooth) by being close to that device and / or making a gesture with the phone (which is recognized by the IMU on the phone). The connection is authenticated by the mobile device sending an ultrasound code requested by the IoT device. A device-specific GUI is sent to the phone via Bluetooth or other wireless channel. This should be a common standard, such as an html or pdf file. Control commands are sent via Bluetooth.

[0037] Compatible IoT devices in the environment are detected by their emitting ultrasonic pulses. 1) All compatible IoT devices send a standard ultrasonic pulse every n seconds at random times, simultaneously sending a signal over Bluetooth. 2) The mobile compares the time of the received ultrasonic pulse with Bluetooth, thereby identifying each device within the ultrasonic range. 3) The direction of the mobile coordinates to each detected device is obtained from the direction of arrival of the ultrasound signal or by combining the ultrasound signal with motion estimation based on the on-phone IMU. For example, this may be obtained using one of the following four alternatives: Direction is estimated by using two closely spaced microphones (<4 mm) and measuring the relative phase between the two microphones. 4) Orientation may be estimated using two separated microphones, both near the top of the phone. Ambiguities caused by microphone separation and wavelength may be resolved by comparing the relative phase shift with measurements made using an inertial measurement unit (IMU) to detect motion. 5) Orientation may be estimated by combining IMU data and microphones available on the moving object, for example by detecting the direction of movement and corresponding changes in the signal from the microphones by measuring corresponding phase or frequency changes during the movement. 6) If an acoustic transmitter is known to be stationary and the characteristics of the transmitted signal are known, it may be possible to ascertain the direction of movement towards the transmitter using only phase or frequency measurements with a single microphone.

[0038] Points 4), 5), and 6) require some movement of the phone, for example in a horizontal plane, and a continuous signal sent from the IoT device during this gesture, which may be a different signal (different frequency or chirp) than the initial signal discovered.

[0039] An example of a method according to the present invention is shown in Figure 2, where a first device, possibly after being activated as a function by a user, detects an acoustic signal having a known characteristic that indicates the possibility of providing a wireless connection to a second device that includes an acoustic source 21. An orientation or movement of the first device relative to the second device is detected 22, and if it is not within a certain range of direction or orientation, the device returns to an initial state 21.

[0040] If the orientation or translational movement is within specified limits, the device initiates wireless communication by returning a confirmation and identification code by acoustic or wireless communication 23. If accepted by the second device, communication is established 24.

[0041] After initiating the connection, the connection can be authenticated by the mobile sending an ultrasound code requested by the IoT device, for example: Over Bluetooth, the IoT device requests that the mobile device send a specified ultrasonic code to establish a connection. The code can be a series of pulses with a specified frequency, a series of chirps with a specified interval, or some other code. The mobile device responds if this is the IoT device the user wants to connect to (the device is pointing at).

[0042] In summary, the present invention relates to a system and a method for establishing a wireless connection between a mobile first device and a second device, both devices configured for wireless communication using known communication protocols, for example using WiFi, Bluetooth, etc., and the second device including an acoustic transmitter configured to transmit acoustic signals in the ultrasonic range.

[0043] The first device comprises two or more transducers, at least one of which is an acoustic receiver configured to receive signals within an ultrasonic range and based at least in part on the received acoustic signals, and the second and additional transducers, which may be second acoustic transducers, inertial measurement devices, compasses, etc., are configured to calculate movement of the first device relative to the second device. The first device is configured to initiate wireless communication when movement of the first device is within determined limits, e.g., direction and / or orientation, with respect to a direction towards the second device.

[0044] The first device preferably includes two acoustic receivers, the receivers being positioned at a known distance from each other, and is thus configured to detect a direction towards the second device and to initiate communication to the second device if the orientation is within predetermined limits relative to the direction towards the second device, e.g., pointed towards the second device.

[0045] At least one of the receivers may be configured to provide a 45 degree phase delay to increase the accuracy of the orientation measurement when the incoming acoustic signal propagates in a preferred direction between the first device and the second device to initiate communication. Alternatively, the receiver may be positioned at the first device along a line in a selected preferred direction to initiate communication, the distance being selected to provide the selected phase delay when aligned with the second device.

[0046] The acoustic signal may be encoded, for example, with information identifying the second transmitting device and / or the connectability of the transmitting device, which may then be readable by the first receiving device to enable the connection.

[0047] The present invention also relates to a mobile device suitable for establishing wireless communication with a fixed device. The mobile device includes a receiver unit for enabling wireless communication using a known protocol and at least two transducers, at least one of which is an acoustic receiver configured to receive signals within the ultrasonic range. The first device is configured to measure and calculate the movement of the first device relative to a second device transmitting the acoustic signal based at least in part on the acoustic signal received by the receiver. The second transducer may be configured to measure the movement or direction relative to the fixed device. The mobile device is configured to initiate wireless communication when the orientation or movement of the first device is within predetermined limits relative to a direction toward an acoustic source, for example, by being oriented within a few degrees relative to a direction toward the fixed, second device and / or being moved in a direction toward a known or measured location of the fixed device.

[0048] As described above, the mobile device may include two acoustic receivers, the receivers positioned a known distance from each other, and the mobile device is configured to detect a direction toward a second device and initiate communication to the second device when the orientation is within predetermined limits relative to the direction toward the second device.

[0049] Also, if the receivers are positioned along a line perpendicular to the preferred direction to the second, fixed device transmitting the acoustic signal, one of the receivers may be configured to provide a 45 degree phase delay to increase the accuracy of the orientation measurement. Alternatively, the receivers may be positioned on the first device along a line in the direction of the acoustic source chosen to initiate communication, the distance being chosen to provide the chosen phase delay when aligned with the second device.

[0050] The transmitted acoustic signal may be encoded and include information identifying the second, transmitting device and / or the connectivity of the transmitting device, the information being readable by the mobile device to enable the connection.

[0051] The present invention also relates to a method for establishing a wireless connection between a first device and a second device using a wireless communication protocol, the method comprising the steps of transmitting, from a second device, an acoustic signal within a near ultrasonic range, wherein the first device is configured to receive the transmitted signal at at least one location at the first device, to calculate an orientation and / or movement of the device relative to a source of the acoustic signal, and to initiate wireless communication when the orientation and / or movement is within determined limits relative to a direction towards the acoustic source.

[0052] When the first device includes two acoustic receivers and the receivers are positioned at a known distance from each other, the device is configured to detect a direction toward the second device based on a phase or time difference between the received signals and initiate communication to the second device when the calculated orientation is within predetermined limits relative to the direction toward the second device. To increase the sensitivity of the phase measurement, one of the receivers may provide a 45-degree phase delay to increase the accuracy of the orientation measurement. When the receiver is positioned on the first device along a line in the direction of the second device selected to initiate communication, the distance is selected to provide the selected phase delay when aligned with the second device. [Explanation of symbols]

[0053] 1 First Fixation Device 2 ultrasonic transmitters 2a acoustic signal 3. Portable Devices 4a microphone 4b Microphone 5 processors 6 Inertial Measurement Unit (IMU) 6a Movement 11 Secondary Fixation Device 12 speakers 31 Primary Device Unit 32 speakers 33a Secondary unit, telephone 33b Secondary unit, telephone 34 Microphone 36a IMU sensor 36b IMU sensor

Claims

1. 1. A system for establishing a wireless connection between a mobile first device and a second device, wherein the devices are configured for wireless communication using a known communication protocol, the second device includes an acoustic transmitter configured to transmit acoustic signals in an ultrasonic range, the first device has at least two transducers, at least one of which is an acoustic receiver configured to receive signals in the ultrasonic range, the first device is configured to measure and calculate movement of the first device relative to the second device based at least in part on the acoustic signals received at the receiver, and the first device is configured to initiate the wireless communication when the movement of the first device is within determined limits relative to a direction towards the second device.

2. 2. The system of claim 1, wherein the first device includes two acoustic receivers, the receivers positioned at a known distance from each other, and the device is configured to detect the direction toward the second device and initiate communication to the second device when the orientation is within predetermined limits relative to the direction toward the second device.

3. The system of claim 2 , wherein at least one of the acoustic receivers is configured to provide a 45 degree phase delay to increase accuracy of the orientation measurement.

4. 3. The system of claim 2, wherein the acoustic receiver is positioned on the first device along a line in the direction of the second device selected to initiate the communication, and the distance is selected to provide a selected phase delay when aligned with the second device.

5. 2. The system of claim 1, wherein the acoustic signal is encoded and includes information identifying the second transmitting device and / or the connectivity of the transmitting device, the information being readable by the first receiving device to enable a connection.

6. 1. A mobile device for establishing wireless communication with a fixed device, the mobile device including a receiver unit enabling wireless communication using a known protocol, the mobile device having at least two transducers, at least one of which is an acoustic receiver configured to receive signals within the ultrasonic range, a first device configured to measure and calculate movement of the first device relative to a second device based at least in part on the acoustic signals received at the receiver, and the first device configured to initiate the wireless communication when an orientation or the movement of the first device is within determined limits relative to a direction towards an acoustic source.

7. 7. The mobile device of claim 6, wherein the mobile device includes two acoustic receivers, the receivers positioned at a known distance from each other, and the device is configured to detect a direction toward the second device and initiate communication to the second device when the orientation is within predetermined limits relative to the direction toward the second device.

8. 8. The mobile device of claim 7, wherein at least one of the receivers is configured to provide a 45 degree phase delay to increase accuracy of the orientation measurement.

9. 8. The mobile device of claim 7, wherein the receiver is positioned to the first device along a line in the direction of the acoustic source selected to initiate the communication, and the distance is selected to provide a selected phase delay when aligned with the second device.

10. 7. The mobile device of claim 6, wherein the acoustic signal is encoded and includes information identifying the second transmitting device and / or the connectivity of the transmitting device, the information being readable by the mobile device to enable a connection.

11. 1. A method for establishing a wireless connection between a first device and a second device using a wireless communication protocol, the method comprising: transmitting an acoustic signal within a near ultrasonic range from the second device; wherein the first device is configured to receive the transmitted signal at at least one location at the first device; calculate an orientation and / or movement of the device relative to a source of the acoustic signal; and initiate the wireless communication when the orientation and / or movement is within determined limits relative to a direction towards the acoustic source.

12. 12. The method of claim 11, wherein the first device includes two acoustic receivers positioned at a known distance from each other, and the first device is configured to detect a direction toward the second device and initiate communication to the second device when the orientation is within predetermined limits relative to the direction toward the second device.

13. The method of claim 12 , wherein at least one of the receivers provides a 45 degree phase delay to increase accuracy of the orientation measurement.

14. 13. The method of claim 12, wherein the receiver is positioned on the first device along a line in the direction of the second device selected to initiate the communication, and the distance is selected to provide a selected phase delay when aligned with the second device.

15. 12. The method of claim 11, wherein the acoustic signal is encoded and includes information identifying the second transmitting device and / or the connectivity of the transmitting device, the information being readable by the mobile device to enable connectivity.

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