The first pedometers were mechanical models that worked much like a pendulum clock. They featured tiny moving parts that would move back and forth along with the motion of the body as you walked. Each time your body moved with a step, the tiny parts would trigger a switch that would add one to your step count.
Modern pedometers work in a very similar way but are partly electronic. Open one up and you'll find a metal pendulum (a hammer with a weight on one end) wired into an electronic counting circuit by a thin spring. Normally the circuit is open and no electric current flows through it. As you take a step, the hammer swings across and touches a metal contact in the center, completing the circuit and allowing current to flow. The flow of current energizes the circuit and adds one to your step count. As you complete the step, the hammer swings back again (helped by the spring) and the circuit is broken, effectively resetting the pedometer ready for the next step. The pedometer shows a count of your steps on an LCD display; most will convert the step count to an approximate distance in miles or kilometers (or the number of calories you've burned off) at the push of a button. Note that in some pedometers, the hammer-pendulum circuit works the opposite way: it's normally closed and each step makes it open temporarily.
More modern pedometers take advantage of the many technological advances that have been made in the last decade. Rather than moving mechanical parts, these newer pedometers keep track of steps with internal gyroscopes, accelerometers, and Global Positioning System (GPS) signals.
Modern pedometers can also interact with smartphones via Bluetooth technology. This allows your pedometer to communicate with your smartphone to let it know your current step count. Software applications on your smartphone can then display this information so it's easier to see. These applications can also use that data to calculate other variables, such as distance walked and the number of calories burned.
If you've ever used a pedometer, you know they're not always 100% accurate. A pedometer might not always recognize a step if your body doesn't move enough. On the other hand, it might also count steps when you're not walking if you're otherwise moving your body or shaking the pedometer.
Passometer is an electromechanical and portable instrument, which count the number of paces or velocity of the body movement. It automatically records the number of paces. Its mechanism is being operated by the movement of the body. It is similar to the speed meter of any mechanical transport. But the speed meter counts the speed per a unit distance. And Passometer counts the pace of the body which is a circular or periodic measurement.
The pedometer is also an electromechanical and also a portable instrument, which count each step a person takes by detecting the motion of the person's hands or hips. Mainly it counts the distance how much the user passes. Or how much distance he crossed by. It is adjusted according to the length of the pace of the person carrying it. It is important to use it vertically for better measurement.