10.12.2004 12:00 AM
DTV Table of Station Assignment and Service Information Now Available
The FCC has released its first version of the DTV Table of Station Assignment and Service Information. The table lists facilities authorized by a construction permit (CP), if the station has one, or the facilities authorized by a license, if the station doesn't have a CP. For stations without either a license or CP, the table lists the facilities authorized by its DTV allotment, either in the initial Table of Allotments or as authorized in an individual rule making proceeding. The facilities' description includes the effective radiated power (ERP) in kilowatts, the antenna height above average terrain (HAAT) in meters, and the location in latitude and longitude. DTV population and service areas are also listed. According to the explanation in the table, "DTV pop. and area columns are the population and area (people and square kilometers) within the DTV service contour where service is predicted based on consideration of intervening terrain and interference from other DTV and NTSC stations." While not mentioned in the Table, the DTV Second Periodic Review Report and Order stated, "All analyses of service and reduction of service due to interference will be based on population only. We will use population data from the year 2000 census in determining the populations served by stations and the impact of interference on stations' service."

A quick review of the listings showed that some recent grants are not reflected in the Table. The FCC noted that "some changes will continue to be made to reflect data base error corrections that have been submitted to the Video Division. In addition, changes will be made to reflect grant of applications for construction permits or modification of construction permits, including applications to implement DTV channel changes approved in rule making proceedings. A limited number of proposed data changes are not fully reflected in this Table."

I compared some of the Table's entries for DTV population served with those I'd calculated using Longley Rice 1.2.2 coverage inside the noise-limited threshold contour. I found the Table's counts tended to be somewhat higher, even though I hadn't accounted for interference in my calculations. However, I did not use the FCC software, so differences in treatment of "Error Code 3" cells, the method of depression angle calculation, and the population databases likely explain this. Consulting engineering firm Hammett and Edison will be filing a Petition for Reconsideration of the DTV Second Periodic Review Report and Order outlining problems with the FCC's methods of calculating DTV coverage and interference. Look for a full report on this in my RF Technology column in the Nov. 10 issue of TV Technology.

I noticed the FCC has revised its DTV software. A check of the files at the FCC's Office of Engineering and Technology (OET) DTV Television Channel Allotment Web page showed a new version of tv_process.zip with files dated 9/22/2004 and a population_2000.zip file dated 9/24/2004. Don't plan on downloading these files and running them right away on your PC. The Web site has Fortran source code files only, which means they will have to be compiled before they can be used.


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