FM: Detailed Interference Study

The FM Detailed Interference study tests a proposed educational FM channel or FM translator site with the interference criteria specified in Section 73.509 of the FCC Rules. It allows the user to apply directional antenna parameters to the proposed facility. For more information, see Full Report Details below.     View Program Sample

Customers must provide the following information to run this report:

• Job title
• Metric or English
• Exclude/Include translators
• Class (A, B, 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
• HAMSL (height above mean sea level for proposed transmitting antenna)
• ERP (effective radiated power of the proposed antenna)
• Directional Antenna (make, model, orientation)

Price: $500.00. Detailed Interference Plot $100.00.
To purchase, please call 800.331.5086 or email info@bia.com.

Report Details

The Detailed Interference study performs the most rigorous test available for compliance with FCC interference criteria. The study calculates coverage and interference contours for 360 radials around the study site and any pertinent existing stations or proposals. Calculations are performed to determine interference received and generated, thus determining both compliance with FCC Rules and feasibility as a broadcast facility. The study lists, for each station listed, the extent of the protected contour (usually 1 mV/m or 60 dBu), the undesired to desired (U/D) ratio (dB) specified by the FCC Rules, and the appropriate interfering contour from the proposed facility.

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.

When the study finds interference it prints a line item (for each radial that has interference) of the allowed db.  This enables the user to modify erp/antenna etc in order to remove the interference to the existing facility.

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.

The calculations are also performed in reverse; that is, interference to the station under study is determined from existing stations and proposals. For the case of IF problems (+ or - 53 & 54 channels), the FCC spacing table is employed. A summary of the ERP limitations for each of 360 radials concludes the report. As an option, a map of the pertinent interfering and service contours can be provided.

Price: $500.00. Detailed Interference Plot $100.00.
To purchase, please call 800.331.5086 or email info@bia.com.