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San Francisco / Oakland television station KTVU-TV2 recently aired an investigative report about concerns that some law enforcement officials have regarding the technology chosen for a proposed Bay Area regional police radio communication system. Jana Katsuyama from KTVU-TV2 provided the following report. Click the start arrow to watch the video.

Chief Louis Cobarruviaz of the Redwood City Police Department identified very important concerns shared by many police officers who use digital trunked radio systems.

  • Trunked radio systems allow only one user to transmit at a time. This is advertised as a trunked radio system feature, however it can be a severe liability during times of intense activity in critical police or fire situations. It’s commonplace with conventional analog radio systems for field units to occasionally talk at the same time, usually only for a brief instant. Other field units and the dispatcher will hear both units, albeit they will be less clear than if only one user had been transmitting at a time. The dispatcher can usually identify the user with priority traffic and ask he or she to repeat, and ask the other user to standby. In the case of digital conventional radio systems, it’s unlikely that either user would be heard. In the case of a trunked system, one user would probably get a channel assignment and the other user would hear a tone indicating that access to the radio system is denied. This is not simply a training issue. The ability for two units to occasionally transmit at the same time and both be heard is crucial to effective police and fire radio communication.
  • Police tactical situations and many firefighting scenarios often require rapid-fire exchanges of short messages. The keyup delay of a digital trunked radio system makes this impossible. This is not merely a training issue. Digital trunking technology is complex and it can take a few seconds for the system to prepare to convey a voice message. This is extremely frustrating, and potentially life-threating for police officers and firefighters why rely on their radios for critical communication.
  • The audio latency through a digital trunked radio system can be quite high. To put this in perspective, consider a law enforcement tactical operation where the operatives rely on hand signals as well as radio communication. A team member could raise his arm to touch his PTT button, speak a message, then put his arm down – all before the other team members hear the message. The audio and visual communication is incongruent, resulting in potentially critical error.

The KTVU report identified some very important concerns, however it contained some technical inaccuracies that should be clarified.

  • J.D. Nelson from the Alameda County Sheriff’s Department credited the County’s digital radio system with improved wide area coverage compared to its previous VHF analog radio system. The County of Alameda operates a Motorola 800 MHz analog Smartzone radio system and intends to replace it with a Motorola digital trunked radio system. The current system is analog. Coverage of the 800 MHz analog trunked system is better compared to the County’s former radio system because the County invested millions of dollars to develop new radio sites and purchase additional infrastructure, not because of the 800 MHz trunked radio technology. The County’s digital radio equipment has not been placed in service yet.
  • The reporter described analog radio systems as having only one channel while digital radios have as many as 45 channels. Perhaps she was alluding to the fact that trunked radio systems can have more talk groups than radio channels. Modern analog radios are capable of operation on hundreds of different radio channels.
  • Our research has determined that the proposed BayRICS radio system would cost more than $1 billion if it were to serve all 9 Bay Area counties plus Santa Cruz County. KTVU reports that it will cost each jurisdiction $8 to $10 million to convert to digital. Will it cost every city $8 million or more? What about the recurring costs? The total life-cycle cost for Bay Area cities is staggering. An in-depth study on the fiscal impact to local government would be an interesting topic for a follow-up story.

Even though the story contained some technical inaccuracies, it is important to note that the law enforcement executive who was interviewed felt strongly enough about the problems with digital trunked radio to take a controversial position against radio technology that is aggressively being sold to police and fire departments. Sometimes it’s best to call the baby ugly.


Click here to read a detailed report on the digital trunked radio problems experienced by the Redwood City Police Department.