Keeping Firefighters Connected on the Fireground
When many of us see the acronym “DVRS” our first thoughts might be of the technology that lets us watch last night’s The Daily Show when we wake up in the morning, special episodes of Breaking Bad we can’t bear to part with, a few episodes of The Big Bang Theory we missed last season, or maybe some trashy reality shows that we’ll get to during the next rainy day. And while the DVR, or Digital Video Recorder, has transformed the way we watch television, “DVRS” here refers to “Digital Vehicular Repeater System,” and it is a technology that extends radio communications on the fireground. Indeed, DVRS have themselves transformed the way firefighters stay connected and safe when battling fires.
First, a bit of history.
Mobile repeaters have been around since Motorola developed the first ones in 1972. They were very low power (much less than 1W), operated in a different band than the mobile, and had some very basic logic to attempt to handle multiple units at a scene. The best known was the PAC-RT. The typical user was a State Trooper performing a traffic stop, somebody who was on their own, did not go far from their vehicle, and did not mind having a portable in a different band.
As you would imagine, these devices were unsuitable for most fire applications. In the late 1990’s this changed with the introduction of the Motorola/Futurecom VRS. It had the same power as a portable radio, was able to work “In-band” and had a sophisticated algorithm to handle multiple units at a scene. In 2005, it was replaced by the DVRS (Digital Vehicular Repeater System) which added P25 capability and a number of features of importance to the fire service.
So what is a DVRS, exactly?
At the most basic level the DVRS is a miniature conventional base station (that is the “DVR”) connected back to back to a mobile radio system (that’s the “S). It can work as a true repeater or as a base station, and can be programmed for either analog or P25, or even a couple of hybrid modes.
What makes the DVRS different from all previous generations of mobile repeaters is that, in P25, it extends the network not just the audio to and from the network. Portables IDs pass on both PTT and emergency, they affiliate with trunking networks, and they networks “see” them to be the same as a portable directly on the network.
Why Are They Used?
DVRS are deployed for a number of reasons, but the primary one is to extend radio communications, followed by allowing the use of conventional and/or analog on the fireground. While there is no such thing as 100% radio coverage, and that goal is certainly something we continue to work towards, the challenge faced by the Fire Service is that their areas of highest risk, like large structures, are also the most difficult to provide radio coverage. Additionally, firefighters may be crawling on the ground, making coverage even more difficult to obtain.
DVRS can frequently help with radio coverage inside buildings. There is no magic to how this works, it may just be easier for a portable radio to communicate with a DVRS parked outside the structure than with a tower site several miles away. As a rule of thumb, if you can talk portable to portable on a direct or simplex channel between somebody inside and somebody outside, then a DVRS will work for that structure. Additionally, due to the tactical nature of a DVRS, it can be positioned to provide optimal radio coverage. Many users report finding ‘sweet spots,’ and by positioning the DVRS in one of these locations, coverage is dramatically improved versus where a pumper might need to park. Additional steps can be taken if the required coverage isn’t achieved, but let’s save that for another discussion.
The significant advantage of the DVRS over just going to a simplex channel is that is keeps the users on the network so that their communications and emergency activations are monitored and recorded by dispatch as well as others on the network. There are many instances where something important is missed on a busy, noisy fireground but is picked up at dispatch or by others monitoring the radio traffic.
The advent of the dual band portable radio, like Motorola’s APX series, has meant that the DVRS is not used quite as often for interoperability. However, a cross band repeater is still a very effective tool, that can be referred to as “instant interoperability” that is very easy for users to set up quickly.
A unique application for fire can be using the DVR as a way to get VHF volunteer departments onto P25 700/800 networks. Users frequently have their own portables (which they may have purchased and may also double as pagers), so everybody purchasing their own P25 trunking portable is probably not feasible, but a VHF DVR connected to a 700/800 mobile would act as a gateway into the state network at a reasonable cost.
Over the past 15 years, improvements in technology have allowed over 300 fire departments to deploy mobile repeaters as key components in their radio networks. So while most of us will use a DVR to see what Jon Stewart had to say last night, remember that for firefighters, the DVRS is a valuable piece of communications equipment that keeps them connected on the fireground. You can see Motorola’s DVRS technology and speak with our experts this week at the International Association of Fire Chiefs’ (IAFC) Annual Conference and Expo, Fire Rescue International (FRI), from August 13 – 16.
Dhiren Chauhan is Manager, Fire & EMS for Motorola Solutions
Read other blogs by Dhiren Chauhan here.