Operation Gold Star
Resourceful interconnection of law enforcement radio resources can support communications for coordinated tactical operations. Delays in vox detection for cross-channel rebroadcast can be circumvented.
With “Operation Gold Star,” the idea is simple. Ask for volunteers from police, deputy sheriff, highway patrol and numerous state and federal agencies to participate in an evening exercise. Then ask the respective departments to commit their officers for one or two evenings a month to make up a task force to sweep through communities looking for gang activity, drunk drivers, parole and curfew violations. These officers would also check on suspicious vehicles, expired vehicle registrations and unlicensed drivers. Do you think there would be any takers?
You bet there would be! Not only has there been a tremendous acceptance on the part of the communities within Fresno County, CA, but there is actually a waiting list of officers wanting to participate in the Gold Star operation, which is conducted monthly within Fresno County.
With so many agencies involved, how does one retain control of this massive influx of law enforcement resources? Operationally, the Fresno County sheriff assumes control of the task force, providing dispatching, computer resources and radio support.
But what about the radio resources? Each agency must furnish its officers with communications equipment. Unfortunately, not all radio communications equipment is directly compatible. Although many agencies operate on VHF highband, the larger cities of Fresno and Clovis, CA, operate on UHF. So how do all of these officers communicate with each other?
Certain common radio frequencies exist to allow law enforcement mutual aid communications to occur. Within California, the state has licensed both VHF and UHF frequencies as the California Law Enforcement Mutual Aid Radio System (CLEMARS). These channels allow agencies to cross-communicate with each other within a single frequency band; however, no provision is made to cross-communicate between bands. The problem of how to “link” VHF and UHF channels still exists.
Both Fresno County and the city of Fresno use systems of repeaters with auxiliary receivers connected to them. These receivers are electrically selected by a receiver comparator, sometimes called a voting comparator. A simple block diagram is illustrated in Figure 1 on page 32.
New-generation dispatch consoles contain electronics known as “cross-channel rebroadcast.” Receive audio is detected and assigned, by the dispatcher, to another channel. The console provides the audio detection and transmitting protocol, such as direct current or tone keying. The biggest drawback to cross-channel rebroadcast is that all detection is done by voice activation vox. The audio must be present before it can be detected. Because of the time required for the console to activate the selected transmitter, the first or second word of the transmission is usually lost. With soft-spoken officers, or an officer that pauses significantly while talking, the system drops off and must be reactivated, repeating the cycle. Law enforcement radio transmissions are brief. Channel rebroadcast using this system of vox circuits has proved unacceptable for the Fresno County Sheriff.
Rather than having the voting comparator look at an individual receiver, and then select it into a system, what would happen if an entirely separate radio system were connected as though it were merely an individual receiver? That receiver could then be connected into the existing channel, with both system audios being routed to the repeater output. The voting comparator would act as an audio mixer, routing the respective channels back to the dispatcher and then allowing audio to be connected back to the respective repeater, as shown in Figure 2 on page 32.
The voting receiver is receiver-activated, as opposed to voice-activated, so as soon as the officer transmits, the patch is activated and remains online until the transmission is completed. The previous problems of transmission dropout and loss of first or second words of the transmission are eliminated.
The Fresno County Sheriff and the city of Fresno committed support to Operation Gold Star, and each agency made one radio channel available. The city committed a UHF channel, and the county committed a VHF channel. All highband users were granted operational authority by the sheriff to operate on the county-wide VHF tactical channel, while the cities of Fresno and Clovis operated on the city of Fresno UHF CLEMARS system under the California state license.
A simple interface, dubbed a “receiver simulator,” was built, allowing the city’s entire UHF radio channel to look like an individual receiver on the county’s VHF radio system.
Fortunately, Fresno County and the city of Fresno had dispatch centers located across the street from each other. For preliminary testing, a short length of telephone cable was suspended between the two buildings that housed the telephone cable for each agency. Audio from the city’s system was connected to appear to the system as if it were a county receiver, while audio containing the county’s repeated car-to-car and dispatcher audio was returned to the city and connected to the city’s transmitter. Only two pairs of wires were needed to complete the patch. Audio levels were set, and the system was up and online.
The Operation Gold Star patch has been so successful that permanent cable is now being run to replace the temporary cable. While current connection and disconnection of the patch is made both at the city and county communications centers, provisions are now being made to allow the dispatchers of each agency to turn the patch on or off at will.
This system could allow for additional inputs from other agencies to be accommodated. Theoretically, the number of agencies would only be limited by the number of receiver voting modules available and the number of receiver simulators constructed on the system. Using a voting comparator as an automatic mixer results in a simple, yet effective, way of combining multiple systems into a single, multifrequency system allowing cross patching of users from one frequency band to another.
Operation Gold Star represents an example of how separate government agencies and multiple jurisdictions can join to achieve a common goal. While the radio staff of the city and county accomplished a technically difficult project with excellent results, the real winners are the citizens of the city and county of Fresno who now benefit from the increased law enforcement presence and resultant reduction in crime.
Earlier this year, California’s 10 largest public safety agencies adopted the California Public Safety Radio Communications Strategic Plan. After problems with the current radio systems such as aging equipment, channel congestion, limited functionality and lack of interoperability, the public agencies decided to frame a common vision in which modern mobile communications technology would enhance the delivery of public safety services into the 21st century. The goals included:
* universal statewide access. Basic radio communication capabilities must be available to all public safety service providers as they travel throughout the state.
* improved interoperability. Agencies must be able to communicate with one another.
* enhanced functionality. By 2010, data and image transmission will account for the majority of all public safety communications.
* channel availability. Additional spectrum, greater spectrum efficiencies and system expansion are required to ensure that public safety personnel have immediate access to communication channels.
The Warner Group, a consulting firm in Woodland Hills, CA, wrote the strategic plan in cooperation with the agencies. In committing to a partnership, saving money and using new technology, the public safety agencies’ main goal is to secure the safety of California’s residents and visitors.