Final answer:
VDSL uses 3 FDM channels like ADSL and is designed for local loops of 4500 ft or less, offering higher data rates over shorter distances.
Step-by-step explanation:
The type of DSL that is designed for local loops of 4500 ft or less and also uses 3 FDM channels as in ADSL is VDSL (Very-high-bit-rate Digital Subscriber Line).
VDSL is an advancement over ADSL (Asymmetric Digital Subscriber Line), designed to support higher bandwidths over shorter distances. While ADSL is more common and used for longer distances, VDSL provides much higher data rates but works best within limited range, typically up to 4500 ft from the distribution point. This makes VDSL a suitable option for areas that require higher bandwidth capabilities and are closer to the network's central office.
Just like ADSL, VDSL also employs Frequency Division Multiplexing (FDM) to create multiple channels for data transmission. However, it manages to achieve higher speeds by using a wider frequency band compared to ADSL, which is why it's optimal for short distances.