generate questions: Early HDTV commercial experiments, such as NHK's MUSE, required over four times the bandwidth of a standard-definition broadcast. Despite efforts made to reduce analog HDTV to about twice the bandwidth of SDTV, these television formats were still distributable only by satellite.
How much more bandwith was required from early HDTV commercial experiments than an SD broadcast? {sep_token} Efforts were made to reduce analog HDTV to how much of the bandwith of SDTV? {sep_token} Despite the reduced bandwith, HDTV format still had to be distributed how? {sep_token} What kind of experiments required over four times the bandwith of a SDTV broadcast?