By Bob Daigle
David Clark Company Incorporated
Communication is critical for firefighters during all phases of fire service response, whether the call is for an actual fire or is medical-/EMS-related. Not surprisingly, during the past two decades we have witnessed unprecedented growth and acceptance of wired headset/intercom communication systems by thousands of fire departments. Headset communication systems are no longer considered a luxury but a necessity for a fast-growing number of fire/EMS first responders. There is no question that wired intercom systems using noise-attenuating headsets have dramatically improved communications both en route and at the scene. The success of wired headset/intercom systems in the fire industry has now given way to a new, more effective technology-wireless headset communication systems.
The advent of wireless technology picks up on the advantages offered by wired systems and adds the benefits of enhanced freedom and mobility. With wireless systems, firefighters are no longer tethered to fire equipment and apparatus as in wired system configurations. The added freedom and mobility dramatically improve safety, response time, and situational awareness-both en route to an incident and at the scene.
With wireless communication systems, firefighting personnel can maintain constant communication with the intercom and radio while exiting the apparatus and while maneuvering to and operating the pump panel or turntable. Wireless systems are especially useful for aerial applications because bucket crews can communicate freely and operate the aerial bucket. Wireless systems also help maintain communications for dozens of other operations, including retrieving extrication tools and rescue equipment, setting vehicle stabilizer bars, and enhancing communications while walking the perimeter of the scene. Because fire personnel are untethered to equipment and apparatus during these operations, freedom and mobility are increased while communicating clearly at a normal voice level over roaring engines, blaring sirens, and other ambient noise at the scene.
Wireless and Cordless Systems
There are a variety of wireless systems available on the market today. But, purchasers should note that there are marked differences between “wireless” systems and “cordless” systems. Many cordless wireless communication systems feature headsets that contain all electronics within the domes of the headset. Although this type of system provides freedom and mobility, the self-contained design means that the headsets may be inherently heavier and bulkier. Some firefighters began to complain that the heavier headsets became uncomfortable during long hours of use, and the bulkier domes were viewed as cumbersome during various operations at the scene. Because the electronics are built into the dome, the normal wear and tear headsets must endure in the firefighting environment may adversely affect performance and reliability.
In response to the drawbacks of the self-contained wireless headsets, some manufacturers have introduced a new design that features a headset with a short cord that connects directly to a small belt station worn by the firefighter or first responder. The belt station is synched to a wireless gateway, which may be linked to a host intercom system. Although these systems are not technically cordless, they provide the same freedom of movement and all of the additional benefits of a wireless system without the excess weight and bulk of self-contained wireless headsets. Headsets are lighter and more compact, providing firefighters a more comfortable wireless system alternative. Some of these systems provide added benefits such as a more rugged and reliable design with features such as weather-tight, marine-grade construction.
Systems that use self-contained wireless headsets may also include permanently built-in batteries. Although this feature may be perceived as a convenience, these installed batteries can also add to the weight and subsequent discomfort of the headsets. In addition, when battery power runs low or the headset dies, the entire headset becomes inoperable during recharging, which can take several hours. This can only be remedied by purchasing additional headsets that charge in the background and must be available on-scene. In some cases, a self-contained headset with a battery that has expended its useful life cycle must either be returned to the manufacturer for factory replacement-at a premium, in many cases -or discarded entirely. With belt station-type systems, accessible batteries that are dead or low on charge can be replaced quickly and easily so that the headset remains in operation with no downtime and with redundancies only requiring spare batteries from the department’s budget.
Can’t Lose the Signal
Another important facet of wireless systems pertains to antennae because the systems’ reliable range is only as effective as their antennae implementation. The antenna from the gateway that drives the wireless system is most important in this regard. Some gateways rely on internal or fixed antennae to provide the wireless signal, where others provide mechanisms for installing external, remote antennae, which can greatly enhance a system’s reliable working range where line-of-sight to and from the gateway is an issue. There are also gateways available that provide two connections for antennae, thus implementing an antenna diversity that allows the best signal received from both antennae to be used to both transmit and receive signals, with antennae selection being evaluated up to 10 times a second, which further enhances wireless system reliability and user safety.
Communication can be the most critical component of firefighter safety. Many wireless systems will simply shut down automatically when users are out of range or if the signal is lost. To provide added safety, several systems using belt stations will provide a series of beeps when the user is approaching the extent of the system’s wireless range, followed by a voice warning automatically notifying firefighters that communication connectivity has been lost, allowing them to return within range if possible or react accordingly if not. An additional voice prompt will then indicate to firefighters when they are within the system’s wireless range and connectivity has been restored. This voice prompt feature is crucial to first responder safety, giving clear warning of communications or lack thereof.
Bluetooth vs. DECT
There are also important differences from system to system that relate to critical communication itself. Many wireless systems on the market use Bluetooth® technology; others feature DECT-based technology.
Bluetooth originated as a wireless data protocol, and voice was added as the specification matured. DECT was developed intentionally for wireless audio, initially for cordless telephone handsets. Bluetooth frequencies are in the ISM band where industrial and consumer products operate. Wi-Fi, baby monitors, and microwave ovens are just a few examples of devices operating within the same frequency allocation. DECT, however, operates at frequencies reserved exclusively for voice communication using the DECT protocol. DECT gateways support four wireless users; Bluetooth can handle three maximum, and implementing Bluetooth is complex and problematic.
Selecting a Wireless System
Along with the differences already mentioned, other considerations when specifying and purchasing a wireless communication system include the following:
• Does the manufacturer of the system show demonstrable experience in the development of headset communications for high-noise environments in general and systems for critical operations in particular?
• Does the system use hands-free, full-duplex intercom technology?
• How durable are system components? Will they stand up to the rigors of the fire/EMS environment?
• Will the system be compatible and interface with most HF, VHF, and UHF radios?
• Are batteries easily replaceable? What is the battery life?
• How are the system’s antennae implemented?
• Are the headsets comfortable for personnel to wear during long periods of use?
• How simple is the system to use, and how easy is it to link multiple users through the wireless technology?
There is no question that the wireless communication systems on the market today will greatly enhance critical communications and safety. The question of which system to purchase will depend on many factors-not the least of which is the ultimate safety of firefighters and first responders.
BOB DAIGLE is product manager for fire and marine communication systems at David Clark Company in Worcester, Massachusetts. Since joining David Clark Company in 1995, he has been responsible for wired and wireless headset communication system product development and marketing for OEM and Special Markets divisions (railroad, pro-audio, auto racing), as well as aviation ground support and government contracting.