Question: In accordance with 3GPP electromagnetic compatibility (EMC) standards for Base Stations (BS), what is the specified amplitude modulation depth for the 1 kHz sinusoidal audio signal used in testing transmitters, receivers, and transceivers?
Option 1: 40% amplitude modulation depth
Option 2: 60% amplitude modulation depth
Option 3: 80% amplitude modulation depth
Option 4: 100% amplitude modulation depth
Explanation: The correct answer is Option 3 because, as per the specified test method for EMC (in accordance with IEC 61000-4-3), the test level for transmitters, receivers, and transceivers should be amplitude modulated to a depth of 80% by a sinusoidal audio signal of 1 kHz. This specific modulation depth is crucial for accurately assessing the immunity of these devices to electromagnetic interference across the defined frequency range (80 MHz - 6000 MHz).