Using a math channel allows data to be manipulated into an easier-to-read form. It may be something as simple as inverting a channel (so that positive values are negative and negative values are positive) to make it more represent what we consider “more” or “less”. And it may be something incorporating several channels and a multitude of functions. It’s easy to get carried away and create multiple channels simply because they are available, but the downside is that you’ve got even more channels to clutter up a graph and your computer’s memory. For a math channel to be considered useful, it should display data in such a way that you can quickly and easily see an important characteristic. For example, we look at longitudinal acceleration in braking zones to see how hard the rider is braking, rather than trying to judge how steep the speed graph declines.
The software package with your data acquisition system should offer the capability to create math channels. The various companies each offer different methods of generating the channel, but essentially you want to make a formula using one or more channels, various operators and functions. The possibilities include, but are not limited to:
The basic operators of addition, subtraction, multiplication and division allow you to add two channels together, find the difference or ratio between two channels, or convert a particular channel’s units of measurement.
Square, square root and exponentials
Combining channels as vectors requires using squares and square roots, and we can also use these operators to exaggerate certain characteristics.
Manipulating the acceleration channels to find various traits – again using vectors – requires using trigonometric functions such as sine, cosine and tangent, and these functions can also be used to split a channel into various components.
Derivatives and integrals
The derivative of a channel allows us to monitor how it changes over time – for example, we can see how quickly the rider is opening or closing the throttle by differentiating the TPS channel. Integration is the opposite of differentiation; for example, if we have a chassis gyro to show how quickly the motorcycle rolls, we can integrate that channel to find lean angle.
Difference or delta
This operator shows the change in a single channel over two laps. For example, a delta-speed math channel shows the difference in speed between two laps as a separate graph.