A panel advising the Federal Communications Commission on selecting a single U.S. standard for high definition TV has rejected the Japanese firm NHK’s analog system.That leaves only four systems in the hunt for the lucrative HDTV system standard, and all transmit digitally. Two of the systems have been developed jointly by General Instrument and MIT, another is from Zenith and AT&T, and the fourth was developed jointly by Thomson , Philips, NBC and Sarnoff Labs. The FCC’s Advanced TV Advisory Committee met last week to review HDTV testing , and decided at week’s end that NHK’s Narrow MUSE did not cut the mustard. The advisory committee agreed to several more months of testing of the four finalists before submitting a final recommendation to the FCC around August. The FCC is expected to then select a single HDTV by year end.