FM: Interference Study
The FM Interference study is designed to test a proposed educational FM channel or FM translator site with the interference criteria specified in Section 73.509 of the FCC Rules. Details of how this study is run is described in Report Details below.
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Customers must provide the following information to run this report:
- Job title
- Metric or English
- Exclude/Include translators
- Class (A, B, C, C0, C1, B1, C2, C3 or FT)
- Safety zone (distance beyond required separations)
- Safety dB (if over default)
- Channel (s) (Educational band 201-220)
- Transmitter coordinates
- HAAT (height above average terrain for proposed transmitting antenna)
- ERP (effective radiated power of the proposed antenna)
Price: $150.00 (first channel, multiple channel pricing same site/same day available)
To purchase, please call (800) 331-5086 or email info@bia.com.
Report Details
An FM Interference Study first searches the database and retrieves all records pertinent to the particular study. For each channel studied, the program retrieves all records pertinent to the study. These consist of all geographically close records on the same channel (co-channel), 1, 2 or 3 channels removed (1st, 2nd and 3rd adjacent) and 53 or 54 channels removed (Intermediate Frequency). Records are retained which fall within the distances specified in the commercial spacing table from the FCC Rules with the addition of the safety zone. If no records are found within this distance for a given channel, the nearest record for that channel is retrieved.
The records are then sorted by channel, and within each channel, by distance to the user-supplied site. The facility record entry on the report is accompanied by a required separation distance, if pertinent. This value is computed differently for the Interference study than the Spacing study.
For the Interference mode, the program calculates the required separations using the appropriate protected F(50,50) and interfering F(50,10) contours. These contours are calculated in both directions; that is, the proposal is tested for interference to the facility record and the facility record is tested for interference to the proposal. The required separation is the maximum of these two distances. Detail of the contour calculations is supplied on the printout to inform the user whether the F(50,50) or F(50,10) curves were used. If the F(50,10) curves are determined to be out of range (approx. 16 km or 10 mi.), the F(50,50) curves are used.
To purchase, please call (800) 331-5086 or e-mail info@bia.com
