Az. Scanner,
The Phoenix Fire Department realized that they might have some coverage concerns during drive acceptance testing with Motorola. PFD and PPD had members involved in each of the drive tests doing talk back testing, and realized that the initial estimates of actual coverage may not be as could as projected.
Phoenix Fire then developed plans to do preliminary in-building testing to simulate units involved in an actual fire attack as per their SOPs. During these tests, it was apparent that the 800MHz, trunked, digital system couldn't perform in certain areas of buildings, i.e. sub grade areas, closed elevators, tunnels etc... PFD then developed a very comprehensive plan to test buildings in each of the varies DB coverage levels, using structures with each NFPA building type. The system in Phoenix and Mesa is designed with varying DB levels according to the type of structures and density involved. The system has levels of 12DB (outlying areas), 17DB (big-box and med. const.), and 23DB (central high rise district, ASU etc...) Each of these tests were done using a talk matrix developed as per their Vol. 2 SOP's and incident command structure. During this process, NIST (National Institute of Standards and Technology) sent a team of PHD's with equipment to measure frequency penetration into and out of these structures. The tests used VHF, UHF, 700 and 800MHz frequencies, both digital and analog. All tests were done with FD personnel and data was collected from each position within the building.
It was determined that the 800 trunked system had inherent, occasional problems maintaining communications inside various structures. PFD decided that depending on this type of system during hazard zone operations was not acceptable. A new project is in place to determine what the best possible alternative is for the system. Many options have been developed, and a final decision on what will be used is in the works. The 800 trunked system has many valuable options that work very well, however, 1 or 2 decks of simplex channels in either the 800 or 700 range would be beneficial for firefighting and in-building hazardous situations. PFD still plans to be on-line with the new system by August of '05, but obviously this time-line is variable due to the challenges involved in changes to the system.
If you have any other questions, please don't hesitate to ask.
