Before revision: They are also used in many other communications circuits such as modems, cable television set top boxes, frequency division multiplexing systems used in telephone trunklines,microwave relay systems, telemetry systems, atomic clocks, radio telescopes, and military electronic countermeasure(antijamming ) systems.
After revision: They are also used in many other communications circuits such as modems, cable television set top boxes, frequency division multiplexing systems used in telephone ,countermeasure(anti-editing ) systems.