Temperature is significant for many applications such as weather forecasting, precision agriculture, and building management. Though measuring ambient temperature is often deemed as an easy job, collecting large-scale temperature readings in real-time is still a formidable task. Recent blooming of network ready (mobile) devices and the subsequent mobile crowdsourcing applications do offer an opportunity to accomplish this task, yet equipping commodity devices with ambient temperature sensing capability is highly non-trivial and hence has never been achieved. In this paper, we propose Acoustic Thermometer (AcuTe) as the first ambient temperature sensor empowered by a single commodity smartphone. AcuTe utilizes on-board dual microphones to estimate air-borne sound propagation speed, thereby deriving ambient temperature. To accurately estimate sound propagation speed, we leverage the phase of chirp signals, circumventing the low sample rate on commodity hardware. In addition, to prevent disruptive audible transmissions, we convert chirp signals into white noises and propose a pipeline of signal processing algorithms to denoise received samples. Furthermore, we propose to use both structure-borne and air-borne propagations to address the multipath problem. As a mobile, economical, highly accurate sensor, AcuTe may potentially enable many relevant applications, in particular large-scale indoor/outdoor temperature monitoring in real-time. We conduct extensive experiments on AcuTe; the results demonstrate a robust performance, a median accuracy of 0.3 degree even at a varying humidity level, and the ability to conduct distributed temperature sensing in real-time.

The files under android are for Android-side application, written purely in Java. The files under server are for server-side display, using node.js. Below is a short video demo for this project.

For android app, the minimum required os version is Android KitKat 4.4.0. The following pictures shown some snapshots of this application.

The following is the menu for setting:

The first thing to do is to configure the parameters for sensing. The speaker to microphone distance difference should be calibrated at known temperature. This app provoides only one-point application. More points are preferable and can improve accuracy. The higher the sampling rate, the better the stability of the sensing system.

The calibration page only needs to input current temperature.

Real-Time temperature data over time.

Real-time frequency spectrum for debug.

Extracted peak value for debug.

If you find this useful, please cite our paper

@inproceedings{AcuTe,
author = {Chao, Cai and Zhe, Chen and Hengling, Pu and Liyuan, Ye and Menglan, Hu and Jun, Luo},
title = "{AcuTe: Acoustic Thermometer Empowered by a Single Smartphone}",
year = {2020},
booktitle = {Proc. of ACM SenSys}, 
pages = {1-14}
}

Our updated version - AcuTe+ that allows temperature sensing under severe interference can be found in the follow paper.

@article{AcuTePlus,
author = {Chao, Cai and Hengling, Pu and Peng, Wang and Jun, Luo},
title = "{Active Acoustic Sensing for Hearing Temperature under Acoustic Interference}",
year = {2021},
journal = {IEEE Transactions on Mobile Computing}, 
pages = {1-14}
}

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