FireNetOnline

Anonymous writes "Portable 700-900 MHZ Digital Trunking Radios
Proving not to be the best choice on the Fire Ground

By Nick Markowitz Jr.
Fire Investigator

With the coming of the digital age the FCC is slowly running out of radio Bandwidth allocation and is strongly encouraging the use of Digital Trunked radio service for the emergency services to allow for less bandwidth usage and also allow for better communication between all agencies during an emergency.
And for the commercial 2 way radio market the systems work extremely well and are very dependable.

I field tested a professionally installed 800 MHZ system one of my customers was using for a small package bike messenger business and was extremely impressed by its coverage. But as they tried deploying it for the emergency services in my area they quickly found out there were many pitfalls to these systems including the fact 2 to 3 times the amount of repeaters are needed in an area to get equal coverage as analog. With analog, even if the signal is low and scratchy, a voice message can usually be understood. This is not the case with digital for it's either there or it is not.

There is also a delay when keying the radios up to allocate a channel to the radio. Plus coverage within buildings can be miserable ,then add in the problem of Nextel’s IDEN 2 way walkie talkie system interfering with Trunked systems which is costing millions to resolve and you have a real mess.

The state of Pa has found out the hard way when they started a state wide system which is now many millions of dollars over budget and years delayed, form 100% full coverage . despite the fact experts told the system would not worked as originally planned.

Trunked Radio systems definitely have a place and need but they are not ready for emergency services deployment until some very significant matters can be over come one of which is voice recognition over a channel a device called a Vocoder in a radio converts speech to digital and back and when there is back round noises such as a near by chain saw running or loud hose stream it does a lousy job allowing voice transmissions to be recognizable. This Vocoder component needs definite beef up in digital radios so they perform to there best level. Also there needs to be significant training of individuals using the radios when switching from an analog system to digital so they know how to properly use the radios with the slight delay.

In an emergency an analog radio you key it and start yelling for help but not with digital. With digital there is a 1-3 second delay which has to be taken into account. Yes digital is with us it is not perfect but as with all technologies bugs need worked out and now that the NFPA72 Fire code is recognizing and encouraging the installation of in building repeaters to help emergency personnel use the hand held radios
The systems will become another valuable tool in the firefighters arsenal.

Now that the problems have been identified and are being worked on to produce a product that will work flawlessly for the fire service.

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