Introduction
With the development of mobile devices, widely usage of device to device communication over audio is increasingly getting attention in the market. The D2D communication technology provides a sharing model that user can directly communicate to other devices with configuring WIFI or Bluetooth. For example, a mobile phone user can send a tone to a microphone depend on audio-based D2D. In this project, we will focus on certain tasks which enable implementing different audio communication and detect technology. By implementing this project, we can gain insight to audio-based data communication applicable to current mobile devices, master the access to speaker and microphone in mobile devices, and learn how to design and implement a basic audio-based data transmitter and receiver for personal mobile devices
Tasks
Task1. …show more content…
The laptop which is a sender run program to generate the tone signal and the microphone which is a receiver detect the signal playing the value of the frequency. This function I implemented using a simple method called the Goertzel algorithm, which can returns the squared magnitude value. The method can work for both lower frequencies and higher frequencies. The value of squared magnitude will change during loop through the audio bytes with specified frequency. The presence of a single tone can be detected when the magnitude reaches the highest level.
Task2. Extension of Single Tone Detection
In the task, I hardcode different frequencies to different digits. I tried to distance different frequencies from each other in my hardcode in order to keep the Goertzel algorithm work properly. When the receiver detects the highest level of magnitude in the audio signal, the frequency will be returned instantly. The frequency will be translated by comparing to the hardcode range table to the digits.
Task 3 Dual Tone