The Difference Between Active and Passive Alarm Monitoring

June 21, 2022 | By: mm-admin

We are often asked, “How are signals sent and received in your alarm monitoring station?”. Because our monitoring station is ULC compliant, we utilize active and passive forms of communication, which are recognized within the CAN-ULC standard referenced within the Fire Code and the Building Code. By using the recognized forms of communication, FMC is equipped to monitor your alarm system in a variety of ways, which allows us to adapt to any possible scenario your site may present. Below we will explain the difference between active and passive fire and security alarm monitoring.

Active Alarm Monitoring

Active alarm monitoring means that the communication channel between your building and our Signals Receiving Centre (SRC) is actively supervised by the SRC. This supervision is done every 180 seconds with an acknowledgement between the monitoring transmitter in your building and the monitoring receiver in the SRC. This means that if there is a communication failure between your building and the SRC, our dispatch will be notified about it within 180 seconds. The ULC-S561 standard requires FMC to notify you of this communication failure if has not been restored within 5 minutes. If the communication failure continues, your system will be placed on “manual watch”, which means that if an alarm is triggered, someone on site must call 9-1-1. Systems that utilize active monitoring include:

  • Cellular
  • IP – provided that a 24-hour battery back up is present

Systems that utilize active alarm monitoring are typically very stable, and have very little service downtime.

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Passive Alarm Monitoring

Passive alarm monitoring is simply less regular supervision of the communication channel between your building and the SRC. In a passive monitoring scenario, the check in is done once daily at a predetermined time. Forms of passive monitoring can include:

  • Phone line
  • Cellular
  • IP

If this sounds like a less secure option than active alarm monitoring, you’re correct. A passive system that receives an acknowledgement and then experiences a disruption would not be identified until they miss their next scheduled check-in. Testing times can be daily, weekly, or sometimes even monthly.

For this reason, in passive monitoring scenarios where fire or security alarm monitoring require (or desire) higher-level security, dual path monitoring is required. CAN/ULC-S561 states that when passive forms of communication are used, two non-redundant forms of communication need to be present. In this set up, each line of communication monitors each other, this way, if one goes down, the other advises the monitoring station and confirms its activity. For example, where a phone line is disrupted and cellular communication is used as the second path, the cellular line would send a signal to the monitoring station advising that the phone line has gone missing. Any signals from that building could still be sent through the cellular line, and vice-versa if the cellular channel went offline.

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