Difference between revisions of "Radio transceiver interference and noise"

Revision as of 22:23, 22 July 2016

A discussion of various sources of noise and interference, things that degrade your ability to listen to other stations on your radio transceiver.

Ham radio codes for noise fall into two categories, that which is man made "QRM" and that which is natural "QRN." Lightning is an example of QRN.

The FCC no longer investigates RFI complaints to telephone, TV or entertainment systems. You can call their 800 number (888-CALL-FCC) and listen to the FCC's RFI message.

intermod

Intermod is short for intermodulation. Intermodulation is a source of interference that arises from the combination of two or more signals at different frequencies in some kind of non-linear system. For example, you could hear strong interference at 14.0 MHz if there are two strong signals at 86.0 and 100.0 MHz that combine in a rectifying circuit, such as an oxidized fence connection or a gutter.

power line noise

Power-lines or associated hardware improperly generate unwanted radio signals that override or compete with desired radio signals. Disruption of radio communications, such as amateur radio, can occur. Loss of critical communications, such as police, fire, military and other similar users of the radio spectrum can result in even more serious consequences.

Power line noise is typically due to a spark or arcing across some power-line related hardware. A breakdown and ionization of air occurs, and current flows between two conductors in a gap. Alternatively, although possible, Corona discharge is rarely the source of power line noise. Corona discharge has to do with the breakdown of air near a conductor and is very limited in range.

see: http://www.arrl.org/power-line-noise

spurious emission

LED traffic lights are a major source of RFI in the VHF range.