For a low-power wireless system, radio interference must initiate a trouble signal if interference lasts longer than how many seconds?

• A. 10 seconds
• B. 15 seconds
• C. 20 seconds
• D. 30 seconds

Answer: (C)

In a low-power wireless alarm system, the radio link is continuously watched for interference. If that interference keeps the channel from reliably carrying signals, the panel flags a trouble condition to alert the user and the monitoring station that the wireless link may be down. Twenty seconds is used because it’s long enough to filter out brief blips, yet short enough to warn promptly about a persistent problem. Shorter durations like ten or fifteen seconds risk false alarms from temporary noise, while waiting thirty seconds would delay recognizing a real issue.