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Wireless microphones are essential tools in business, education, entertainment, and other domains. However, most existing designs rely on batteries, leading to the inconvenience of frequent recharging and the risk of unexpected power failure during use. In this paper, we present TagMic, a battery-free wireless microphone enabled by a novel radio frequency (RF) backscatter technology. TagMic is built on two key innovations.(i) Parametric backscatter tag design:This design enables the RF tag to operate at separate excitation and reflection frequencies, fundamentally mitigating the self-interference problem inherent in conventional RFID systems. Unlike harmonic backscatter approaches, it also requires a significantly lower activation voltage, resulting in a longer communication range.(ii) Voice modulation via RF coupling:A passive piezoelectric sensor is integrated with the RF tag through RF coupling to enable analog-domain frequency modulation (FM), directly encoding voice signals onto the backscattered signal. This eliminates the need for digital signal processing, allowing for truly continuous voice streaming. We have built a prototype of TagMic and evaluated it under realistic conditions. Extensive experiments demonstrate its effectiveness in achieving battery-free, continuous, and seamless wireless voice streaming in realistic applications.
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This content will become publicly available on December 1, 2026
Underwater Optical Backscatter Communication using Acousto-Optic Beam Steering
We present a high-speed underwater optical backscatter communication technique based on acousto-optic light steering. Our approach enables underwater assets to transmit data at rates potentially reaching hundreds of Mbps, vastly outperforming current state-of-the-art optical and underwater backscatter systems, which typically operate at only a few kbps. In our system, a base station illuminates the backscatter device with a pulsed laser and captures the retroreflected signal using an ultrafast photodetector. The backscatter device comprises a retroreflector and a 2 MHz ultrasound transducer. The transducer generates pressure waves that dynamically modulate the refractive index of the surrounding medium, steering the light either toward the photodetector (encodingbit1) or away from it (encodingbit0). Using a 3-bit redundancy scheme, our prototype achieves a communication rate of approximately 0.66 Mbps with an energy consumption of ≤ 1 μJ/bit, representing a 60× improvement over prior techniques. We validate its performance through extensive laboratory experiments in which remote underwater assets wirelessly transmit multimedia data to the base station under various environmental conditions.
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- Award ID(s):
- 2326904
- PAR ID:
- 10655820
- Publisher / Repository:
- ACM
- Date Published:
- Journal Name:
- ACM Transactions on Graphics
- Edition / Version:
- -
- Volume:
- 44
- Issue:
- 6
- ISSN:
- 0730-0301
- Page Range / eLocation ID:
- 1 to 14
- Format(s):
- Medium: X Size: - Other: -
- Size(s):
- -
- Sponsoring Org:
- National Science Foundation
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