Update: The cause of this particular instance of interference was effectively prevented, but interference from new sources will always be a potential continuing issue. Contact BRICS with a support ticket if you have an occurrence with specific date, time and talkgroup affected.
Users have reported hearing radio traffic across many talkgroups that doesn’t belong – that is, the radio traffic doesn’t sound to be coming from our area, or from users who should be on that talkgroup.
Initial investigation by BRICS Support staff points toward “co-channel interference.” Since there are a finite number of radio frequencies available, the FCC reuses the frequencies it licenses with enough geographic separation to prevent interference under normal conditions. A frequency like 851.5125MHz, for example, might be licensed in Cincinnati and Columbus. Normally, that’s far enough apart and there are no problems.
That’s all great, until:
- If an otherwise properly licensed user for the system in Columbus wanders outside their service area and closer to Cincinnati, they could interfere with those using the same frequency.
- If specific atmospheric conditions occur, you get what is often referred to as “skip” – radio signals, for a brief period, are heard far (and sometimes very far) away. You might suddenly hear a dispatcher in Texas.
We’re currently working on identifying which specific frequency or frequencies are getting the interference, and where it might be coming from. Once we know that, we’ll be able to figure out the next steps to reduce the occurrences.