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)

Configuring your audio gadgets


Before you go jamming all your microphones and noisemakers into the Pi, let's take a minute to get to know the underlying sound system and the audio capabilities of the Raspberry Pi board itself.

Sound variations

Across the range of Raspberry Pi versions, there are significant differences in how we can get sound out of our Pi. The earlier models featured a standard 3.5 mm stereo output, while from the Model B+ onwards, the output is a 3.5 mm four-pole jack, which is also shared with the composite video out.

However, on the Pi Zero there is no dedicated audio output port, in order to keep the board as small and as low-cost as possible, but you can get sound from the audio channels on the HDMI connection, as with all versions.

There are no native audio input capabilities on the Raspberry Pi, so if we want to put sound into the Raspberry Pi for processing and recording, we will need to connect an external audio device to one of the USB ports.

Introducing the ALSA sound...