Last Friday the FCC issued a News Release announcing the Office of Engineering and Technology had released an updated to OET Bulletin 69 -- "Longley-Rice Methodology for Evaluating TV Coverage and Interference." Bulletin OET-69 describes the procedures, program parameters and ratios to be used when calculating TV coverage and interference based on the NTIA Irregular Terrain Model (Longley-Rice). Although OET-69 was created in 1997 to assist engineers analyzing proposed DTV facilities, it is also being used when calculating interference between analog stations. Since its publication in July 1997, the FCC has clarified the guidelines for processing DTV applications and in the case of adjacent channel interference, the interference ratios in the FCC rules do not match those in the July 1997 Bulletin OET-69.
According to the FCC's news release, with the exception of the adjacent channel desired to undesired interference ratios, "the changes are of an editorial nature, and the program parameters given in the new release are exactly those used by the Media Bureau in processing applications for new or modified stations."
As of Sunday, the FCC had not posted the updated Bulletin OET-69 on the OET Bulletins On Line web page. When it is released, if I find any interesting differences between the updated and the July 1997 version I'll report on them here.
