Inside the MOTOACTV

Basically, the MOTOACTV is a computer. If you were to crack one open, you'd find a circuit board with several chips soldered to it. These chips give the MOTOACTV its functionality.

The brain of the gadget is a 600-megahertz processor. That processor speed would look pretty puny on a desktop computer label. But the MOTOACTV has a limited set of functions that the processor can handle just fine. Whether it's playing a music track to get your heart pumping or recording each time your heart pumps, the processor takes care of business.

There are two models of the MOTOACTV, but the only difference is the amount of memory each one has. The base model has 8 gigabytes of memory. The premium model doubles that to 16 gigabytes. In both models, the memory comes in the form of a flash memory solid-state chip.

Also inside the MOTOACTV is a GPS receiver. It can detect the presence of GPS signals and use that information to pinpoint your location. It does this by using trilateration. The receiver compares data from different satellites -- each satellite broadcasts its location with a time stamp. The receiver calculates how far away you are from the satellite based on how long it took the signal to get to you. By combining that data with the information sent from at least two other satellites, the receiver can determine where on the surface of the Earth you are within a few feet.

The MOTOACTV has an accelerometer inside it. The accelerometer's job is to detect changes in velocity. Velocity is speed and direction. If either speed or direction changes, the accelerometer detects it. While Motorola hasn't released information on the specific type of accelerometer used in the MOTOACTV, it's a good bet that it's a micro-electromechanical systems (MEMS) sensor.

While that sounds like the sort of technobabble you'd get on an episode of "Star Trek," breaking down the word makes it relatively easy to understand. Micro is easy -- it means small. Electro means that there's an electrical component to the sensor. And the mechanical part means there's a part inside the sensor that actually moves. This moving part is small -- sometimes only a few hundred microns long and less than a dozen microns wide.

When you apply a force on a MEMS sensor, the mechanical element moves. It either moves closer to or further from a capacitor plate -- or more likely a pair of capacitor plates arranged in layers above and below the mechanical element. As the mechanical element gets closer to a capacitor, the capacitance -- the ability for the capacitor to store energy -- increases. If the mechanical element moves further away from the capacitor, its capacitance decreases.

The MOTOACTV processor takes the information from the MEMS sensor and interprets the changes in capacitance as motion. After calibrating the MOTOACTV to your personal stride, it can keep track of how many steps you take.