| The transmitter changes the frequency of the variable signal by 30 Hz either side of the allocated frequency each time it rotates |
| The transmitter varies the amplitude of the variable signal by 30 Hz each time it rotates |
| The receiver adds 30 Hz to the variable signal before combining it with the reference signal |
| The rotation of the variable signal at a rate of 30 times per second gives it the characteristics of a 30 Hz amplitude modulation |
EN 