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January 21, 20155 min read

What’s happening with US Public Safety LMR monitoring?


Read about LMR monitoring for Public Safety in the Connection MagazineMonitoring practices for US Public Safety LMR systems vary greatly, from 24/7 live monitoring to simply relying on complaints from users. Darek Wieczorek looks at why this is, and how it needs to change.

When radio systems were relatively simple and isolated, system monitoring came down to the users reporting communications problems. While this may have been sufficient in the past, today’s systems are highly integrated, and depend on external computers, servers, routers, links, multiple software platforms, even people in different organizations. This is why even relatively-simple radio systems deserve active monitoring. But what should be monitored, why and how?

What’s happening now?

System monitoring practices among the US Public Safety radio systems vary greatly. At one end, there are organizations with fully-funded internal Network Operation Centers (NOC) providing 24/7 live monitoring. Of course, this is an expense that can be justified only for the largest networks. Consequently, it is not common. Unfortunately, the opposite end of the spectrum is much more common – agencies who rely solely on complaints from their users. The great majority fall in between. Networks are monitored, but not full time, or not by dedicated staff. Here are some common approaches:

Why more is needed?

The old radio systems were simple; not too many things could go wrong. They were all isolated, conventional hardware networks. Not only were they simpler, they were often less critical in nature – with a failure of a channel, users would be notified, or trained to temporarily move to another channel.

Perhaps some industry veterans are cringing reading these words. What about failing crystal oscillators? Burning transistors in power amplifiers? Dust de-tuning RF filters? With all due respect, let us look at what has changed… First came trunking. Suddenly a system failure meant loss of communications was no longer limited to one channel and one agency, but could affect hundreds – even thousands – of users (as shown recently in Detroit), and all agencies in the area.

Secondly, hardware-based platforms became heavily dependent on computers and software. A system based on “ones and zeros” – how hard could it be? Very hard! Unstable operating systems, bugs and glitches, improper parameter settings – the list goes on and on.

Thirdly, systems are no longer isolated. Despite the best efforts of Public Safety officials, it is becoming harder and harder to truly isolate a modern radio system. Every system is vulnerable to:

  • physical security (sharing premises),
  • IT security (sharing links and facilities)
  • user discipline (illegal/improper uses of computer terminals)
  • increasing dependence on connectivity with outside systems (PS databases, other data applications and peripherals).

LMR Monitoring - Public Safety Pros-cons Chart

Why more is not done

Why are the majority of Public Safety LMR systems under-monitored? Common explanations are cost and denial of the need. But neither one can be defended. Operators who deny the need for monitoring and rely on complaints from users are unnecessarily putting the safety of others at risk.

The majority of system operators cannot afford their own NOC, but there are businesses that will undertake the task at a fraction of the cost of a dedicated internal 24/7 set-up. Alternatively, there are many simple technical means that can provide at least high-level automatic alarm notifications via pager, cell phone, or email. For information about managed services you can visit the Tait website

Many malfunctions can be remedied or prevented if they are identified early. For example, power failure due to deteriorating transmission cables is often preceded by fluctuation of the mains voltage. Problems with antenna systems are preceded by increasing VSWR, misalignment of microwave link by increasing BER, etc. Don’t wait until your system fails to correct emerging issues.

“The most common explanations are cost and denial of the need. But neither one can be defended.”

What should be done

Technology is not the problem. The parameters for monitoring are well known and there are many available methods for each one. We know how to monitor for intrusion and theft, environmental factors, equipment malfunctions, antenna system problems, power problems and many more.

Where monitoring most often falls short is the human resource, the actual monitoring personnel. Very few agencies can afford the ideal – their own, dedicated, 24/7 Network Operations Center. But just because the ideal is not achievable doesn’t mean you must accept less than optimal means.

Large trunked systems with thousands of users should be monitored 24/7, which may require some ingenuity. For example:

  • you can add your system monitoring to an existing larger (state-wide or major urban area) NOC,
  • you can pool your resources with your neighbors – a regional NOC for a dozen county systems may be a worthwhile initiative,
  • you can work with your equipment vendor, your local service provider or search for a specialized service provider.

For smaller systems (less than a thousand users), your finances are likely to be more constrained and you may have to apply a combination of approaches. For example, you might rely on your own staff during working hours and dispatch personnel and/or third parties after-hours.

A word of caution; relying too much on non-technical dispatch personnel detracts from their core duties. If that is the only option available, it needs very clear operating procedures, easy-to-interpret alarms and regular training.

Even very small systems should still be monitored. Active 24/7 monitoring will likely be impossible to fund, even with the approaches above. Instead, install all the necessary alarms and bring them to a central terminal with logging and messaging capabilities. Determine which alarms warrant 24/7 immediate notification and which can be cleared the next working day. For example, you do not want to be woken every time a site’s voltage drops below 105 V, but you do not want to wait till the morning when your main repeater loses power altogether.

To summarize, even the simplest Public Safety communications systems are much more complex and vulnerable than their predecessors. While this is recognized by majority of the Public Safety community, it is not reflected in current system monitoring practices.

All modern radio systems should be monitored in some form. There are technical and logistical solutions to fit any size and any budget. So there is absolutely no reason to rely on complaints from the users to alert you when the system goes down. Just do it.


Tait Connection - Issue 5 This article is taken from Connection Magazine, Issue 5. Connection is a collection of educational and thought-leading articles focusing on critical communications, wireless and radio technology.

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