Local Talent Builds Radio System Too Expensive to have Engineered
The Tukwila, Wash., Fire Department is one of several serving a metropolitan area surrounding Seattle. It is adjacent to six other fire districts or departments—all on different radio frequencies except for two, a not uncommon problem in metropolitan areas.
The situation assumed importance when the Tukwila Fire Department began signing automatic and mutual aid agreements with adjacent departments. Often, Tukwila fire apparatus was dispatched beyond the city limits without ihe capability to communicate with the fireground commander. To receive information, the officer in command had to radio his dispatcher to contact the Tukwila dispatcher, who in turn, would relay instructions to the responding apparatus. This practice was timeconsuming and often involved a loss of accurate information.
The best solution was to form a single dispatching agency for the entire South King County area. For a variety of reasons, this was not an acceptable solution for many departments at that time.
Members of the Tukwila Fire Department began working on the problem to arrive at a theoretical solution that could be put into practical use.
The first logical step was to equip all fire apparatus with multifrequency radios. Since most Tukwila apparatus had such radios, this improvement could be made with the acquisition of two more mobile units.
The next step was to equip all apparatus with frequency-scanning devices. This was accomplished by the purchase of six four-frequency scanning devices that were mounted on the control heads of the mobile radios. The work was done by fire department personnel, many of whom could do limited work on two-way radio equipment.
Even at its best, this modification of radio equipment seemed to be inadequate for the operational efficiency the department was trying to reach. We still had two departments that had to work through dispatch centers for communications. An additional problem was created by the scanning units at fire operations. Often several fire departments would be active on different frequencies and would fill the air surrounding our fireground operations with considerable radio traffic that was not related to our operations. Our radio frequency is shared with 17 departments.
Fire Fighter Richard Francis had been working on the communications problem since it became apparent. Francis had a theory of combining an eight-frequency radio with a four-frequency scanning unit. This mating of equipment would eliminate the communications gap with the two departments that used frequencies we could not handle. After lengthy discussion, permission was obtained to build such a unit. It proved to be a mobile communication system complete with dispatching capacity.
The components of the system were:
- A 110-watt, eight-frequency mobile radio,
- A four-frequency scanning unit,
- A four-frequency portable radio,
- A Converta Com portable charger unit for the portable, and
- A four-tone mobile encoder.
The total cost for the equipment was a little less than $3200.
The first step was to modify the four-tone encoder to six-tone capacity. This provided tones for: Station 1, Station 2, general alarm, first alarm (call personnel), officers call (pagers) and paid personnel. A safety arming switch was installed to prevent accidental activation.
The scanning unit was then dismantled and rewired. This gave the radio the capacity to scan any four of eight frequencies instead of just the first four frequencies of the mobile radio.
Priority frequency indicator
During the rewiring, a lighted digital indicator was added to show the selected priority frequency during the scanning process. When a message on the priority frequency is being received, it overrides transmissions on all other frequencies.
To further build in safeguards, a loud tone was added to indicate when the priority was set for any frequency other than 154.250, the main Tukwila Fire Department frequency. This tone can be silenced by a lighted switch, which gives visual indication that the officer is operating on a different priority than 154.250. On fireground operations it is advantageous for the command vehicle to switch frequency priority.
The encoder was tied in with the mobile radio and the portable radio. This gives the capability to switch all functions performed by the mobile radio to the portable radio should the car radio be in for repairs or preventive maintenance. The portable Converta Com unit can handle the transmission of tones in addition to serving as the main communications radio. This allows the system to be dependable and have a certain amount of flexibility.
This new communications system has provided the following improvements in our two-way radio traffic and dispatching:
- Total communications capability between the officer in charge of an emergency and all surrounding communities.
- Communication between the Tukwila Fire Department and the Tukwila Public Works Department.
- A mobile command post from which all communications needs can be handled.
- Direct communications with the King County Office of Emergency Services.
- A mobile communications center to provide backup to the present fire department dispatching center.
- Capability for the officer in charge to call immediately for both off-duty and call personnel.
- Remote activation of outdoor sirens.
- Means for direct callback of all chiefs and other officers through a paging system.
- A dependable system for communications with built-in safeguards and backups.
The entire system was designed to fit into the front seat of a 1975 Dodge Dart. The 12 X 24-inch control panel contains a night light, Opticom control, PA-100 control, switches for the light bar and trunk, and breaker connections.
Easy access for repairs
A local truck manufacturing plant furnished the rolled and pleated finish to the control panel. The panel itself is hinged at the rear to provide fast access for repair or testing. The panel is connected to the floor by four bolts and can be removed in less than three minutes.
The system was centered around the modification of the control heads and not the radio chassis. Modifications to the radios would have voided Federal Communications Commission approval of the units.
Radio vendors had told us that we could not afford to have such a system engineered. However, by using personnel in the Tukwila Fire Department, the system was built. Any fire department that does not recognize the hidden talents of its personnel is overlooking a valuable source of expertise.