Application of low-frequency ultrasonic communication to audio marker for augmented reality

User-Aware Audio Marker Using Low Frequency Ultrasonic Object Detection and Communication for Augmented Reality

“…Instead, our previous work proposed an audio marker based on low frequency ultrasound (LFU) [14]. There were many benefits to this approach.…”

“…This was because the LFU spread across all directions within the room, regardless of the user's visual focus or line-of-sight with the marker. However, the conventional LFU-based audio marker in [14] simply broadcast a rendering queue to anonymous devices inside the room, making it difficult to provide specific virtual objects of interest to a given user. Thus, an object detection method from the reflected LFU signal is required to provide user-awareness on the LFU-based AR marker, in order to overcome this limitation without relying on other types of additional sensors such as cameras [16] or PIR sensors [17].…”

“…In detail, the binary text message is broadcast near the audio marker using a differential phase shift keying (DPSK) scheme, and consequently an AR device capable of demodulating DPSK can correctly receive the message when located near the audio marker. While the conventional audio marker system in [14] broadcasts the marker information to all the users inside the room, the proposed audio marker system first only utilizes low-frequency ultrasound to recognize users around the marker, and then sends the marker information to the detected user. In particular, when the visual sight is considerably distracted by ill-visual conditions affected by illumination or occlusion, the conventional image-based or location-based markers suffer greatly; however, the proposed system can still generate virtual objects and an environmental effect.…”

“…The remainder of this paper is organized as follows. Section 2 reviews the conventional LFU communication-based audio marker system [14,15], after which Section 3 proposes a user-aware audio marker system based on object detection using reflected LFU images and LFU communication for sending audio maker information. Section 4 evaluates the objective performance of the proposed The proposed audio marker system consists of an object detection module using received LFU images as well as an LFU communication module providing the audio marker.…”

“…Finally, Section 5 summarizes and concludes this paper. Figure 2 shows a block diagram of a conventional LFU communication-based audio marker system [14]. As shown in the figure, a binary text data message as an audio marker is encoded in the audio marker transmitter using a forward error correction (FEC) coding algorithm, followed by DPSK modulation and gain normalization.…”