How to Block RF Interference

By Adam Benks

Radio frequency interference (RFI) is common in urban areas.
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Radio frequency interference (RFI) is a common phenomenon in urban areas where wireless is widespread. It is neither easy to avoid or difficult to find. Interference stems from an outside source that is external to the signal path and creates unwanted artifacts in the signal. Radio Frequnecy (RF) is part of that electromagnetic spectrum that is above audio (roughly 20 KHz) and below infrared (roughly 30 THz).

In audio systems, RFI decreases the quality of signal by remodifying the audio to undesired noises. In video systems, RFI causes different types of herringbone patterns. In data connections, RFI causes non-intended behavior such as system crashes.

Step 1

Keep cables as short as possible and pay attention to routing. Generally, the longer the cable, the better it will make an antenna. Route the cables close to metal racks or concrete floor. This will reduce the probability of antenna effects.

Step 2

Use cables with heavy-gauge shields. Braided copper shields offer more protection against common-impedance coupling than foil and drain wire shields.

Step 3

Double-check your connectors to verify quality signal. Interference that changes when the cable is wiggled signifies a poor contact.

Step 4

Install RFI filters in the signal path. RFI filters block high-frequency electrical noise and block interference. The filters do not require much panel space.