Much of our consulting work involves tracking down interference sources and resolving interference problems. We perform this work for public safety agencies, but also for the three national wireless operators (AT&T Wireless, Verizon Wireless and T-Mobile).

The interference problem is multifaceted. Sometimes the cell site is causing interference to public safety handheld radios and is known as strong signal interference.   Other times, there is interference to the receivers at the cell site.  Most of this interference originates from unintentional emitters. This interference comes from a variety of sources, including the following:

• Passive intermodulation (PIM) at the cell site, caused by unintentional non-linear mixing of transmit frequencies in corroded joints, loose connectors, etc. This is sometimes the easiest to identify provided one has the proper test equipment.
• Booster amplifiers (sometimes called BDAs) that sometimes oscillate when there is inadequate isolation between input and output. Some of these are found in residences and inside vehicles and are designed to boost cell phone coverage for the user.
• Utility power transformers (occasionally)
• Fluorescent light ballasts (occasionally)
• Cable TV set top boxes, especially those used in hotel rooms
• Cordless phones and any devices operating in the 902-928 MHz license-free band
• More recently, LED light fixtures (from the LED DC power supply).  This is a common and growing problem.

Pericle uses sophisticated software and test equipment to identify and track down interferers, but experience is often the most valuable tool. The work is inherently labor intensive, but one can get to the root of the problem quickly by recognizing potential interference sources by sight. Direction finding is an important first step, but it does not solve the problem completely. One must still track the interference down and correct it.

We do this work across the western U.S., including Colorado, New Mexico, Wyoming, Utah, Idaho, Montana, Nevada, southern California, Washington State, Oregon, Alaska and Hawaii.