In many cases the range of frequencies used are also very different.

Soon after the war began, he heard a radio message on a frequency used by the Americans.

Since then, police have been listening in to the frequency used by the gang.

Many bats improve their sound picture by using different frequencies.

The system used low frequencies from 70 to 129 kHz.

The increased range is due to the frequencies used and the power of the transmitter.

People on the frequency used by the Cubans rarely identify themselves.

There was no signal on any frequency commonly used for communication.

Note: The frequency currently being used varies on a daily schedule.

Regional systems are cheaper and can carry more message traffic because they use different frequencies.