The Thermal Imaging Training article in the March 2006 issue of Firehouse addressed the use of wireless transmitters, providing tips for more effective use of these systems at emergency scenes. The online article will address how to improve signal reception and performance.
Prior to trouble-shooting reception problems, you first need to have a realistic understanding of how the system should be operating. This is not a hardwire system. Static and transmission interruptions will occur. The transmitter strength is also limited, with most systems under 400 mW in strength, historically due to FCC restrictions. A normal fire department portable radio is a 5 W (or 5000 mW) transmitter. You cannot expect the same performance from these wireless video systems as you have come to expect from your handheld radios.
Performance in a standard, wood-frame, single-family dwelling should be consistent. However, your fire district will have unique buildings that vary from this simple standard. If at all possible, try to test your transmission system in these buildings as part of your incident planning process. Heavy construction, as well as multiple walls, will negatively impact signal strength. Significant variations in grade level can also dramatically impact the system's reception.
After you moderate your expectations with reality, you can work on improving the receiver's performance.
Firefighters are notorious for modifying equipment. For most equipment, this is a non-issue. However, certain modifications near the transmitter can cause poor signal reception. As much as possible, keep the area around the transmitter antenna clear. Your supplier can teach you where the antenna and transmitter are located within your thermal imager. Metal items hanging near the antenna will reduce the signal strength, as will layers of material (such as tape, handle grips, cloth, etc.).
Obstructions near the receiving antenna can cause similar problems, so try to give it a "clear view" of the operations area. Be sure to read the manufacturer's installation instructions and follow them carefully. Permanently mounted antennas should be properly grounded and mounted high on the exterior of the vehicle. Portable and mobile antennas should not be covered or modified.
Use fresh batteries with the transmitter, as well as with portable and mobile receiving systems. Old, partially discharged or weak batteries will not send as strong a signal as a fully-charged battery.
By avoiding modifications or obstructions to your transmitter antenna and receiver antenna, you can ensure the best possible reception. A strong, reliable power source for the transmitter and receiver will also improve the displayed image. While working to improve the signal, remember to have a realistic expectation of performance for these tiny transmitters.
Use your TI often, wisely and safely.
- March Issue of Firehouse Magazine: Getting the Most from Your Wireless Transmitter
Jonathan Bastian is a Thermal Imaging Specialist for Bullard. He is certified as a thermal imaging instructor by the Law Enforcement Thermographers' Association (LETA). He is also the author of the FD Training Network "FireNotes" book, Thermal Imaging for the Fire Service. Bastian served 12 years on the North Park, IL, Fire Department, including the last three as a captain. He has taught classes on thermal imaging, rapid intervention teams and search and rescue operations. He is currently a police officer in Lexington, Kentucky. If you have questions about thermal imaging, please send them to firstname.lastname@example.org.