WDSO INTERFERENCE INFORMATION
Steps you can take to help reduce interference. We have listed a number of possible steps that you can take to help reduce interference on your TV.
Engineering Report of WDSO -- This report summarizes the results of spurious and harmonic radiation measurements for WDSO.
Excerpts from the FCC Interference Handbook -- We have included parts of this book on our site since the FCC no longer publishes it. This publication has a number of pictures and descriptions of Interference to Television (TVI).
If you believe WDSO is causing interference to your TV, please look over the information below.
Below is a diagram of the proper order of your TV hookup.
- Is your TV more than 15 years old? Older TV's cannot reject unwanted signals (interference) as well as a newer TV can.
- Is the affected TV a portable unit? Filtering cannot be done to TV's with built in antennas.
- Are you having problems with your cable TV or an outside receiving antenna? If you are having problems with your cable TV you will need to call the cable company.
- What is the condition of the antenna? Is it more than 7 years old? Due to all of the industry in this area, antennas will only last around 7 years. After this period of time your antenna may not perform properly. Are any radials broken or bent? If so, you will need to replace the antenna.
- Are you using twin lead (flat) antenna wire? If so, you will need to replace it with coaxial cable.
- How are all of your connections? Are they loose? Are they screwed on all of the way?
- Are you using a high gain antenna? High gain antennas are not needed in our area since the Chicago TV stations are only 36 mile away. These antennas can amplify and actually manufacture there own interference.
- Do you have a grounding block installed before the amplifier? Is it properly hooked up to an 8 foot copper grounding rod? (Most insurance companies require this, and some even require 2 or more grounding rods.)
- If you have a filter, is it installed before the amplifier? If you have a two-piece amplifier, the filter needs to be installed before both pieces
- Is the amplifier turned up all of the way? If it is, you will need to turn it down.
What the FCC (Federal Communications Commission) says about interference:
Title 47 Code of Federal Regulations Section 73.317 - FM transmission system requirements.
...(d) Any emission appearing on a frequency removed from the carrier by more than 600 kHz must be attenuated at least 43 + 10 Log10 (Power, in watts) dB below the level of the unmodulated carrier, or 80 dB, whichever is the lesser attenuation.
Title 47 Code of Federal Regulations Section 73.318 - FM blanketing interference.
Areas adjacent to the transmitting antenna that receive a signal with a strength of 115 dBu (562 mV/m) or greater will be assumed to be blanketed [approximately Chesterton Middle School and Chesterton Park property]. In determining the blanketed area, the 115 dBu contour is determined by calculating the inverse distance field using the effective radiated power of the maximum radiated lobe of the antenna without considering its vertical radiation pattern or height...
...(b) After January 1, 1985, permittees or licensees who either (1) commence program tests, or (2) replace their antennas, or (3) request facilities modifications and are issued a new construction permit must satisfy all complaints of blanketing interference which are received by the station during a one year period. The period begins with the commencement of program tests, or commencement of programming utilizing the new antenna. Resolution of complaints shall be at no cost to the complainant. These requirements specifically do not include interference complaints resulting from malfunctioning or mistuned receivers, improperly installed antenna systems, or the use of high gain antennas or antenna booster amplifiers. Mobile receivers and non-RF devices such as tape recorders or hi-fi amplifiers (phonographs) are also excluded...
...(d) Following the one year period of full financial obligation to satisfy blanketing complaints, licensees shall provide technical information or assistance to complainants on remedies for blanketing interference. [Emphasis added]