FM: TV6 Interference Study
The FM/TV6 Interference study is designed to calculate the predicted area of interference to the reception of TV channel 6 caused by an FM station operating in the reserved band (channels 201-220). Calculations are based on FCC Rules section 73.525 (e). The section below, Report Details, details how the report is run.
View Study Sample
The customer must provide the following information to run this study:
- Job title
- Metric or English
- Channel
- Coordinates
- c/r AMSL (center of radiation above mean sea level)
- ERP
- Directional antenna (make, model, orientation)
- Polarization (vertical=no to 6 dB television receiving antenna directivity per Section 73.525 (e)(iii) of the FCC Rules)
- Maximized ERP (study calculates maximum ERP for population compliance
Price: $150.00. (Maximizer option - $250.00, Interference Popcount - $100.00,
Plot - $100.00.
To purchase, please call (800) 331-5086 or e-mail info@bia.com.
Report Development Details
First, if necessary, interpolation of ERP values is done to fill in any portions of the pattern not supplied by the user.
Next, FM HAAT figures are generated for the eight (8) cardinal radials. Linear interpolation is used for HAAT figures between the cardinal radials.
Relative HAAT figures are then generated for the TV channel 6 station selected. Since the official HAAT figure for the TV station was probably not generated using computerized topographic data, the eight computed HAAT figures are adjusted so that their average agrees with the HAAT figure in the database.
The extent of the TV 6 grade B (47 dBu) is then calculated using the FCC F(50,50) curves. If the FM transmitter site is within the TV grade B contour, an interference area is assumed to exist and the boundaries of the interference area will be referenced to the FM transmitter site. The interference site will be the FM transmitter site.
If the proposed FM site is outside the TV 6 grade B contour, other tactics are used. First, an FM interfering F950,10) contour, the value of which is 47 + 6 plus the appropriate U/D ratio from the charts, is computed in the direction of the TV 6 station. If this contour does not overlap the TV grade B contour, it is assumed that no interference area exists. If it does overlap, an interference site is selected from which the boundaries of the interference area will be referenced.
Once it is determined that interference exists and an interference site has been determined, the program computes the boundaries of the interference area. Radials are computed every degree of azimuth from the interference site to the point at which interference stops occurring. These calculations are based on the appropriate F(50,50), F(50,10) and FM/TV6 protection ratio curves. If enabled the field strength for distances less than one mile, free space calculations are used. Where appropriate, the FM/TV 6 protection ratio (U/D) figures are adjusted by 6 dB to account for receiving antenna directivity. These radials are denoted by * on the detailed printout.
To purchase, please call (800) 331-5086 or e-mail info@bia.com.
