What is kAccelerometerMinStep?

I have been looking at the Accelerome开发者_如何学Cter Graph example in the iOS Developer library and I have a question about one of the variables that is used...

#define kAccelerometerMinStep               0.02

What is the Accelerometer Min Step? and what role does it have?

Here is how it is being used in the Low Pass Filter...

-(void)addAcceleration:(UIAcceleration*)accel
{
    double alpha = filterConstant;

    if(adaptive)
    {
        double d = Clamp(fabs(Norm(x, y, z) - Norm(accel.x, accel.y, accel.z)) / kAccelerometerMinStep - 1.0, 0.0, 1.0);
        alpha = (1.0 - d) * filterConstant / kAccelerometerNoiseAttenuation + d * filterConstant;
    }

    x = accel.x * alpha + x * (1.0 - alpha);
    y = accel.y * alpha + y * (1.0 - alpha);
    z = accel.z * alpha + z * (1.0 - alpha);
}

And here is how it is being used in the High Pass Filter...

-(void)addAcceleration:(UIAcceleration*)accel
{
    double alpha = filterConstant;

    if(adaptive)
    {
        double d = Clamp(fabs(Norm(x, y, z) - Norm(accel.x, accel.y, accel.z)) / kAccelerometerMinStep - 1.0, 0.0, 1.0);
        alpha = d * filterConstant / kAccelerometerNoiseAttenuation + (1.0 - d) * filterConstant;
    }

    x = alpha * (x + accel.x - lastX);
    y = alpha * (y + accel.y - lastY);
    z = alpha * (z + accel.z - lastZ);

    lastX = accel.x;
    lastY = accel.y;
    lastZ = accel.z;
}

If someone could tell me what the min step is responsible for I would be very grateful...

I would like to capture accelerations ranging in magnitude from 0.05 to 2.00 g force with a frequency response of 0.25-2.50 Hz

Thanks.!