What is a key difference between frequency modulation and amplitude modulation in microwave links?

What is a key difference between frequency modulation and amplitude modulation in microwave links?

• A. FM transmits a single channel; AM carries blocks of broadband channels between headends and hubs
• B. FM uses amplitude variation
• C. AM uses frequency variation
• D. FM and AM both carry multiple channels

Answer: (A)

In microwave links, how the signal is carried depends on the modulation type and how channels are multiplexed on the link. Frequency modulation encodes information in the instantaneous frequency of the carrier, keeping the carrier amplitude essentially constant. This makes it well-suited for a focused, single narrowband channel on a point-to-point path. Amplitude modulation, on the other hand, encodes information in the carrier’s amplitude, which allows the carrier to carry a broader payload—essentially blocks of broadband channels between headends and hubs. So the main distinction here is that FM is typically used for a single channel on the link, while AM is used to carry blocks of broadband channels across the link. The other statements mix up what each modulation type does (FM uses frequency variation, AM uses amplitude variation) and to carry multiple channels, which isn’t the defining difference in this context.

In microwave links, how the signal is carried depends on the modulation type and how channels are multiplexed on the link. Frequency modulation encodes information in the instantaneous frequency of the carrier, keeping the carrier amplitude essentially constant. This makes it well-suited for a focused, single narrowband channel on a point-to-point path. Amplitude modulation, on the other hand, encodes information in the carrier’s amplitude, which allows the carrier to carry a broader payload—essentially blocks of broadband channels between headends and hubs.

So the main distinction here is that FM is typically used for a single channel on the link, while AM is used to carry blocks of broadband channels across the link. The other statements mix up what each modulation type does (FM uses frequency variation, AM uses amplitude variation) and to carry multiple channels, which isn’t the defining difference in this context.