[catacon]

You have to convert the voltage to a distance value. The sensor should have a spec for mV/in or mV/m or something relating voltage and distance.

For example, the MaxBotics MB1010 LV-EZ1 has a spec of 9.8mV/in with a 5V supply. So, if you read 0.392V from the sensor, this would result in a distance of 40 inches. (0.392 / 0.0098)

Some simple code you could use.

AnalogInput ultrasonic(0);

float voltage(0);
float distance(0);
const float volts_to_inches(0.0098);

voltage = ultrasonic.GetVoltage();
distance = voltage / volts_to_inches;

These sensors tend to be pretty noisy, so I would suggest a simple low pass filter.

const float filter_alpha = 0.5;

voltage = ultrasonic.GetVoltage();
distance = distance + filter_alpha * ((voltage / volts_to_inches) - distance);

Hope that helps!


EDIT: Didn't realize this was in the Java forum and I wrote C++. Should still give you an idea of what to do.