Book Image

Raspberry Pi for Secret Agents - Third Edition

Book Image

Raspberry Pi for Secret Agents - Third Edition

Overview of this book

This book is for all mischievous Raspberry Pi owners who’d like to see their computer transform into a neat spy gadget to be used in a series of practical pranks and projects. No previous skills are required to follow along, and if you’re completely new to Linux, you’ll pick up much of the basics for free. We’ll help you set up your Raspberry Pi Zero, Raspberry Pi 2 and Raspberry Pi 3 and guide you through a number of pranks and secret agent techniques that are so inconspicuous yet high on mischief. You’ll learn how to configure your operating system for maximum mischief and start exploring audio, video, or Wi-Fi techniques. We’ll show you how to record, listen, or talk to people from a distance and how to set up your own phone network. Then, you’ll plug in your webcam and set up a motion detector with an alarm and find out what the other computers on your Wi-Fi network are up to. Once you’ve mastered the techniques, we’ll combine them with a battery pack and GPS for the ultimate off-road spy kit.
Table of Contents (7 chapters)

Recording conversations for later retrieval


So we have our audio gear all configured and ready to record-let's get sneaky with it!

Picture the following scenario: you know that something fishy is about to go down and you'd like to record whatever sound that fishy thing makes. Your first challenge will be to hide the Pi out of sight with as few cables running to it as possible. Unless you're working with a battery, the Pi will have to be hidden somewhere within a few meters of a power outlet.

Next, you'll want to connect your USB microphone and keep it hidden, yet uncovered if possible, to avoid a muffled recording. Unless you expect the action to take place right in front of the microphone, you should set the capture signal to the max with alsamixer for the microphone to be able to pick up as much of the room as possible.

Now, all we need to worry about is how to trigger the recording.

Writing to a WAV file

The Waveform Audio File (WAV) is the most common file format used for recording audio...