Web-based dispatching for the bottom line
What do trucking companies, taxi companies, utilities, couriers, police departments, fire departments, ambulance services and parents with teenagers have in common? They want to know where their vehicles are.
Here’s the difference, though: The vehicle location service has to be configured and priced just right for each kind of user.
For example, many trucks travel interstate on lengthy journeys. Dispatchers need to know where they are, but not every minute. Private radio systems don’t have the necessary coverage, so satellite or cellular systems provide the mobile communications link.
Taxis, utilities and couriers often have their own radio networks or buy airtime from service providers that can supply or carry vehicle location information. These customers often need more frequent updates that can run up the cost.
Police, fire and emergency medical services need real-time location information, and they need the reliability of their own dedicated network or a data allocation on a public network.
And parents? Well, as much as they might like to know where their teenagers have driven the family car at any given moment, the cost may be too high. But it’s relatively economical to feed location information into a vehicle-mounted recorder for daily or weekly review to see where a car has been.
A combination of GPS, cellular and Internet products offers Web-based vehicle location service for over-the-road trucking. The three technologies come together to bring the cost down compared to the satellite services that trucking companies have used for many years.
In the vehicle, a black-box unit that combines a GPS receiver with a transceiver designed to communicate on cellular system control channels sends the truck’s position over cellular system control channels using an arrangement with cellular carriers fashioned by Atlanta-based Cellemetry, a subsidiary of Numerex.
Cellemetry’s technology transmits short messages via the control channels of the AMPS cellular network. The AMPS cellular network has 790 analog voice channels and 42 digital control channels. The control channels initiate cellphone calls. Once the call is initiated, the cellular system directs the telephone call to a voice channel.
The control channels are more robust than the voice channels for several reasons. First, the control channels are digital; the voice channels are analog. The control channels also operate at higher transmission power than the voice channels, giving better coverage. Finally, the cost of using the control channels is far less than the regular voice channels.
By using the cellular network, Cellemetry takes advantage of a proven technology used by millions of cellular users and available virtually everywhere. The analog cellular network is the biggest radio network in the world, and some 200 million packets of data are transmitted over the control channels every day in North America. This represents an average of only 10% of the maximum control channel capacity.
The Cellemetry service operates in the same manner that roaming telephones operate in the cellular system. A roaming telephone is defined as a cellphone operating in any system other than its home system. When a cellphone is turned on outside of its home system, it sends its mobile identification number (MIN) and its electronic serial number (ESN) to the cellular system via one of the control channels.
Based on the cellphone number, the local cellular switch communicates with the “home system” of the roaming telephone. It uses the SS7 network that interconnects all cellular switches in North America to confirm that the user is allowed to use the system and which phone-calling features are available to that customer.
The Cellemetry radio, like a roaming cellphone, sends an ESN and MIN number over the SS7 network, but the MINs are specifically assigned so the MIN and ESN are routed to a Cellemetry service gateway that is also connected to the SS7 cellular network. The MIN serves to identify the Cellemetry radio, and the ESN is the data field that contains vehicle location information.
The vehicle location information travels from the Cellemetry service gateway to a server at IDA, the black box supplier and vehicle location service provider in Fargo, ND. IDA makes the location information available to the customer via Internet protocol.
The system can be configured to send location information automatically every 15 minutes or every hour, and it can be polled or “pinged” at will to request location information. But it takes three to five minutes for the location information to travel from the vehicle through the cellular network, Cellemetry’s gateway, and IDA’s server and over the Internet to the customer. That’s adequate for trucking company purposes, but not for public safety agencies.
The black box hardware costs about $600 to $700 per vehicle installed. The software package for tracking vehicles with Web-based browser access is free. Cellemetry charges a $25 activation fee, and $20 per month pays for 12 location readings per day.
Service plans with more readings per day are available. Location readings every 15 minutes cost $50 per month, for example. Customers can “ping” a vehicle’s location for $1 per query.
The computer screen displays a map indicating the vehicle’s location during the periodic readings or queries.
IDA’s nationwide location system is fairly new, and is mostly being installed in over-the-road trucks. The company’s other AVL products are based on business-band radio or public safety radio applications that are more regional in nature.
For applications that do not require location information from vehicles as they move about, a GPS system can be placed in a vehicle, and its location recordings can be downloaded periodically to run in a program on a computer. Even more readings might be taken in this way because the buffer can hold 1,200 records.
For locating vehicles during their travel, the black box installed in the vehicle contains a GPS receiver and a cellular unit. A short “rubber duck” type antenna serves the cellular transceiver, and a magnetic-mount antenna serves the GPS receiver.
Although the GPS antenna has to have a good view of the sky, the box can often be mounted under the dash because the cellular antenna will receive through plastic and glass. If the box is mounted in the trunk or another inconspicuous position, the cellular antenna must be mounted outside the vehicle and connected to the box with a cable.
Public safety applications
A Web-based system of this type is not as popular with public safety users because location readings are delayed by a few minutes as the unit connects with the cellular network and the information travels across the Internet. When officers are involved in a high-speed chase, the dispatcher wants continuous and instantaneous position information. There is no way to provide that with Web-based software that has to route information through the Internet to IDA’s server and from there to the customer’s dispatching position.
Public safety agencies commonly use dedicated radio channels for mobile data. They purchase other equipment and software that allow them complete control of the AVL system.
But for delivery services that cover regional areas or a national footprint, no radio system other than cellular offers the necessary range. That’s where Web-based AVL fits the bill for low-cost GPS dispatching.
Bishop is editorial director. His email address is email@example.com.