== Introduction and Overview Welcome to the Altus Metrum community! Our circuits and software reflect our passion for both hobby rocketry and Free Software. We hope their capabilities and performance will delight you in every way, but by releasing all of our hardware and software designs under open licenses, we also hope to empower you to take as active a role in our collective future as you wish! Our goal is to include in this document all of the information required to successfully configure and use Altus Metrum products. But documentation is a lot like software in that it can contain "bugs", and can probably always be improved! If you have questions that aren't answered in this manual, or just need a little help figuring things out, we strongly suggest joining the Altus Metrum user email list, which you can do by visiting https://lists.gag.com/mailman/listinfo/altusmetrum. There's a lot of useful information in the mailing list archives! The first device created for our community was TeleMetrum, a dual deploy altimeter with fully integrated GPS and radio telemetry as standard features, and a “companion interface” that will support optional capabilities in the future. The latest version of TeleMetrum, v2.0, has all of the same features but with improved sensors and radio to offer increased performance. Our second device was TeleMini, a dual deploy altimeter with radio telemetry and radio direction finding. The first version of this device was only 13mm by 38mm (½ inch by 1½ inches) and could fit easily in an 18mm air-frame. The latest version, v3.0, includes a beeper, higher power radio, extended on-board flight logging and an improved barometric sensor. TeleMega is our most sophisticated device, including six pyro channels (four of which are fully programmable), integrated GPS, integrated gyroscopes for staging/air-start inhibit and high performance telemetry. EasyMini is a dual-deploy altimeter with logging and built-in USB data download. EasyMega is essentially a TeleMega board with the GPS receiver and telemetry transmitter removed. It offers the same 6 pyro channels and integrated gyroscopes for staging/air-start inhibit. TeleDongle v0.2 was our first ground station, providing a USB to RF interfaces for communicating with the altimeters. Combined with your choice of antenna and notebook computer, TeleDongle and our associated user interface software form a complete ground station capable of logging and displaying in-flight telemetry, aiding rocket recovery, then processing and archiving flight data for analysis and review. The latest version, TeleDongle v3, has all new electronics with a higher performance radio for improved range. For a slightly more portable ground station experience that also provides direct rocket recovery support, TeleBT offers flight monitoring and data logging using a Bluetooth™ connection between the receiver and an Android device that has the AltosDroid application installed from the Google Play store. More products will be added to the Altus Metrum family over time, and we currently envision that this will be a single, comprehensive manual for the entire product family.