ATSC 1.0 uses 8VSB for modulation. If OFDM is superior, why was 8VSB used?

TL;DR: 8VSB was the easiest to implement in the 1990s.

When creating the original ATSC standard, a choice had to be made on whether 8VSB could function as the modulation technique for ATSC television broadcasts. Many television broadcasters, including Sinclair Broadcast Group, were concerned about 8VSB’s multipath issues and preferred coded OFDM as the modulation technique.

Reasons to use 8VSB at the time:

• 8VSB required a lower minimum SNR compared to COFDM; more power was needed to match the same ‘range’ using COFDM

• 8VSB could carry 2% more data compared to COFDM

• 8VSB was cheaper for broadcasters and consumers

• 8VSB equipment weighed less on broadcast towers

It should be noted that Zenith, now owned by LG, had lobbied extensively to the Federal Government to ensure 8VSB was the modulation technique.

Reasons to use COFDM:

• COFDM is immune to multipath interference, specifically dynamic multipath

Even if ATSC 1.0 used OFDM, the update to ATSC 3.0 would still be worth it.