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A reaction to computer aided dispatching and mobile data terminals

CAD systems may be interconnected with automatic vehicle location systems, mobile data terminalsoffice telephones, and selective calling and push-to-talk ID. There are a multitude of CAD programs that suit different department needs, but the fundamentals of each system are the same. Simply, location, reporting party and incident are the main fields that have to be populated by type-codes.

If the location was at the 1400 block of Madison, the type-code could be "14MAD. A typical CAD printout looks something like this based on the example above: The dispatcher then receives the call from the call-taker and is able dispatch the call to those available. The dispatcher's screen would show the available personnel that are dispatchable. A typical setting can be exemplified by this: Inc 554121 747 - Avail.

Inc 554122 ----------------------------------- Everything that is gathered, dispatched and disposed is usually stored in a central server in which the type codes reside, or possibly another server.

All of these calls which have incident numbers attached to them can be recalled by an internal search engine. For example, a request for a printout of all calls to Madison in the past hour could be gathered by querying the CAD program by location: Now filled in Search by: Left picture is dispatcher console position.

Right picture is supervisor's console.

At right is a drawing showing basic controls for a single channel. Communications consoles are mounted in desk-style electronics racks. Features include multi-line telephones. Modern facilities usually include a variety of computing systems for operational and administrative purposes.

Consoles serve as a human interface and connect to push-to-talk dispatch radio systems. Audio from all channels is processed through audio level compression circuits and is routed to two separate speakers identified as select and unselect. Each has a volume control. The select channel or channels carry the highest priority communications. To prevent missed messages on critical channels, the select volume may be configured so it cannot be set to an inaudible level.

Unselect channels may be used for special events, other agencies, or purposes that do not involve dispatch and may be inaudible. By pressing a button, any channel on the console can be toggled between select and unselect status. Each channel has an independent push-to-talk button, allowing the dispatcher to talk over one channel at a time.

For broadcast messages, a single button transmits over all selected channels at the same time. Each channel has a label identifying it and indicator lights and buttons to control settings. A typical channel has a busy light, a call light, select light, select button, and a transmit button.

The steady, red busy light indicates another dispatch position is transmitting on the channel. The flashing yellow call light indicates a field unit is talking on the channel.

The call light usually blinks for several seconds after a transmission ends allowing a busy dispatcher to look up from a telephone call and determine which channel the last message came from.

Some console dispatch panels are actually a PC-based application. Such is the case of Zetron's Acom system and Avtec's Scout system. This allows for easy customization and modification of the dispatch key layout. Service levels and geographic information[ edit ] Computerized mappingautomatic vehicle locationautomatic number identification and caller-identification technology are often used to enhance the service by pinpointing the locations of both the client and the most suitable vehicle for serving the client.

  • SOS or systems of systems is a methodology and a set of technology for linking distributed independent applications into one meta-system or system of systems;
  • Unselect channels may be used for special events, other agencies, or purposes that do not involve dispatch and may be inaudible;
  • There are a multitude of CAD programs that suit different department needs, but the fundamentals of each system are the same;
  • Communications consoles are mounted in desk-style electronics racks.

Some CAD systems allow several sources of information to be combined. For example, adding automatic vehicle location AVL and geographic information GIS could improve service by getting units to a service call location faster.

This information is used to suggest the closest vehicle to an event. How is the closest unit determined? Basic zone system[ edit ] The simplest system is a beat or zone map system. For example, in a community with four fire stations, a grid is overlaid on a community map. Each zone of the grid is identified with a progression of police beats, ambulance zones, transit zones, or fire stations.

This means fire station 2, then 4, then 1, then 3 would respond to a fire call occurring inside this zone. The predefined order is created by persons with expertise in the service being provided, local geography, traffic, and patterns in calls for service. Since only basic GIS information is included, if AVL was available, it would simply display service vehicle locations on a map. The closest unit would a reaction to computer aided dispatching and mobile data terminals interpreted by the dispatcher looking at vehicle locations projected on the map.

To make the computing problem easier, the CAD system may use centroids to evaluate service vehicle locations. The system calculates a distance from a fire station or AVL location to a centroid point. The closest fire station, according to CAD system rules, would be assigned. Staff based at a fire station that is physically closer by drawing a straight line on the map may be slower to reach a zone.

This can occur because responding units must drive around freeways, lakes, or terrain obstructions in order to reach a zone. A centroid may be moved because 200-car freight trains often block a railroad crossing used to access a particular zone.

This is the cheapest system to develop because it requires the least detailed geographic information and the simplest calculations. Another problem occurs where several services use the same system. Police and transit, for example, may have different ideas about what boundaries define the ideal zone or how centroids should be weighted. CAD using geocoding[ edit ] Geocoding is a translation system allowing addresses to be converted to X- and Y-coordinates.

Someone placing a call for service has an address attached to a wired phone number or tells the dispatcher their address. For example, suppose the caller's address is 123 Main Street. The table may identify odd-numbered addresses in the community as being on the north and east sides of streets. This estimate produces a latitude and longitudeor a set of Universal Transverse Mercator coordinates.

The coordinates are close enough to identify the closest service vehicle. This system may automatically append the name of the nearest cross-street or intersecting street. Again, the system uses a straight-line distance to determine which service vehicle is closest to a call for service. Next, the positions are compared to the service vehicle status. The CAD system may identify several of the closest units that have a status of available. The dispatcher makes an ideal choice from the CAD system shortlist.

This type of system is significantly more expensive than a zone system. The basic system may start with maps from the US Census Bureau or a county assessor's office. The quality of these maps may be good but will not be ideal for dispatching. There would normally be one or more persons on staff who would deal with data changes from new development, new streets, or data quality problems. Geocoding varies in accuracy depending on data sources and vendors. It normally takes years of work and planning before a system is implemented.

Modern geocoded systems will often display service vehicle locations, the location of service calls, and the locations of callers on a map. This helps to disambiguate calls for service and reduces the likelihood of dispatching two reports of a single call for service as two separate calls. Another problem comes from technologies using differing datums or coordinate systems. For example, suppose your AVL system uses degrees-decimal degrees format.

The CAD system uses degrees-minutes-seconds format data and shows the same location as 481700N, 1125009W. How do you translate? This is sometimes a problem with neighboring CAD systems.

  1. It normally takes years of work and planning before a system is implemented. The steady, red busy light indicates another dispatch position is transmitting on the channel.
  2. Modern geocoded systems will often display service vehicle locations, the location of service calls, and the locations of callers on a map. Each channel has a label identifying it and indicator lights and buttons to control settings.
  3. The CAD system uses degrees-minutes-seconds format data and shows the same location as 481700N, 1125009W.
  4. The basic system may start with maps from the US Census Bureau or a county assessor's office.

Ideally, you should be able to send and receive calls to and from CAD systems in neighboring areas. What if the state or provincial government has standardized on a different coordinate system?

Computer-aided dispatch

Can a service vehicle turn left from eastbound Carnegie Street onto northbound Hooligan Boulevard? A scoring system is used to assess the difficulty of making the turn. At one end of the scoring system there might be an interchange where service vehicles had unrestricted access in making the turn. Perhaps both streets are one-way, making it relatively easy to turn from one onto another.

In the middle scores, a left turn might be blocked occasionally by heavy traffic, a draw bridgeor street cars.

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At the most difficult score, the two streets may cross but the lack of any interchange does not allow service vehicles to get from one to the other. It assesses the path from the service call to the AVL location of available vehicles. The system recommends the service vehicles with the shortest path. For example, to reach a point in the southbound lanes of a turnpike, service vehicles may need to drive north to the next exit then return on the southbound side.

The analysis of a routable street network takes this into account so long as the event location is accurately reported. Routable systems account for barriers like lakes by calculating the distance of the driven route rather than a straight-line distance. It is assumed the service vehicle driver knows the shortest path or that all drivers make similar numbers of wrong turns.

Concentration[ edit ] CAD systems require support staff with special skills.

  1. Inc 554121 747 - Avail. The closest fire station, according to CAD system rules, would be assigned.
  2. Some entities have arrangements that already support data exchange between systems, but standards aim to make these interconnections more common. This system may automatically append the name of the nearest cross-street or intersecting street.
  3. It assesses the path from the service call to the AVL location of available vehicles.
  4. Simply, location, reporting party and incident are the main fields that have to be populated by type-codes. This system may automatically append the name of the nearest cross-street or intersecting street.
  5. Some console dispatch panels are actually a PC-based application.

This can lead to concentration of dispatch facilities, particularly where there is population growth or where automation is required to meet defined service objectives. In any system, concentration of facilities increases risks of outages or massive failures. In a system where the call traffic is so high that advanced technology is needed to handle routine levels of day-to-day calls, relatively minor failures can have major effects on service levels.