Timex running watches

Timex fitness system uses digital FM technology.  This increases accuracy with its superior resistance to interference from external sources like treadmills and electrical power lines.  Other heart rate monitors use an analog signal to send signals from the transmitter worn around the chest to a monitor worn on the wrist.

Test results show that the digital heart rate monitoring system to be within 3 beats-per-minute of EKG precision!  Digital technology also allows Timex's heart rate monitor to synchronize the signal from the chest strap to the watch without experiencing crossed signals from other nearby heart rate monitors.  Crossed signals present problem with many other current monitors that pick-up signals from other analog heart rate monitors being used in the same general vicinity like the start of a race or in a crowded gym.

Timex heart rate monitors send a signal for every heart beat and then rely on the monitor to calculate the actual rate using an exclusive "smart sensor" technology.  The Timex calculates the heart rate from the transmitter and then sends the signal to the wrist watch.  This increases the accuracy and lengthens battery life (both watch and transmitter batteries are easily replaceable).