Mobile Data for Public Safety

Law enforcement agencies, fire and EMS agencies thrive on information—they need it to respond to emergencies, anticipate what they'll encounter when they arrive on-scene, and to help predict incident trends and patterns. In the pre-computer days, information was gathered by officers in the field, transmitted to others via paper notes, reports and other hand-written notations, and then filed in metal cabinets. Now the computer has taken over routine data collection, transmission and distribution at most of America’s law enforcement agencies, including transmitting data to mobile units in the field.

Along with the computerization that began in the 1980s, a few large agencies began installing specialized mobile data terminals (MDTs) in their patrol vehicles.Explore

At that point mobile data was defined by proprietary, small-screen (30 lines x 24 chars) terminals and agency-owned radio systems, supplied by just a handful of companies that specialized in mobile data. These turn-key, radio-and-terminal solutions did the trick, but were expensive, time-consuming to implement, and generally unreliable. The displays were also very limited in the type of data they could transmit—text-only on small screens, and using non-ergonomic keyboards.

The mobile data networks used radio systems built and maintained by the law enforcement agencies themselves. They required a dedicated radio channel and moved data at very slow speeds. But since the data usually consisted of very brief text information, the networks were generally sufficient for officers in the field who needed basic information access.

In the 1990s, commercial applications for mobile data began to appear, especially among package delivery and service companies that needed to efficiently manage their fleets. Consumer applications for mobile data began to appear in the form of alphanumeric pagers, personal digital assistants (PDA) and even cellular phones via text messaging. Suddenly, the proprietary nature of mobile data disappeared, replaced by a scores of companies offering both individual components of mobile data and entire end-to-end networks that could span the country.

Now, in the 21st century, mobile data is common among ordinary consumers and every size of American business—there are dozens of PDAs, cellular phones and laptops that can transmit data wirelessly from anywhere. Everyone from teens to corporate executives can check their e-mail, stock holdings, bank accounts and sports scores using wireless data applications.

But adoption of these advanced wireless data technologies has been slow to come for public safety agencies, including law enforcement. These agencies are necessarily limited by tight budgets, and constrained by the complexity of linking to records management and computer-aided dispatch (CAD) systems, and the requirement to deploy completely secure and reliable data links with criminal justice databases.

Large agencies have usually had the money and technical expertise to deploy mobile data systems to support their field forces. Sometimes these networks are implemented by large system integrators under a contract that includes a voice radio and computer data systems. Smaller agencies must usually depend upon outside experts to design and install mobile data systems, usually as part of a purchase of records management or CAD software.

Cellular telephone carriers offer a mobile data solution over networks that mirror their voice network coverage. Early networks used technology that offered no great speed advantage over private, agency-owned radio systems. However, the current cellular network eliminates the design, construction and maintenance of a private network, and in most regions provides improved and more reliable mobile coverage.

Early cellular data networks (CDPD) piggy-backed on the voice network, and sometimes suffered from congestion as network traffic increased. Today's third and fourth-generation (3G - 4G) technologies are operated separately from the cellular voice network, and have increased speeds as well.

As large and medium-size agencies have successfully implemented mobile data over the past five years, law enforcement officials recognized the advantages of having access to data from the field. This, in turn, as generated interest in so-called broadband applications for mobile data, including video, mug shots and other photos, fingerprints, in-field reporting, and sophisticated ad hoc networking and messaging at critical incident scenes. Just like consumer DSL and cable access to the Internet, law enforcement agencies wanted instant access to complex information anywhere within their jurisdiction.

In the wake of the September 11th terrorist attacks, the Federal Communications Commission (FCC) recognized the need for additional spectrum to allow broadband data communications. They allocated 50 MHz of spectrum in the 4.9 GHz band exclusively for public safety mobile or hotspot mobile data networks. The band is adjacent to the consumer Wi-Fi wireless data band, and the equipment operates using well-establish technical standards that allow broadband transmission speeds.

Some agencies have created hot-spot mobile data networks using this new band or the standard Wi-Fi band. They have placed base stations at strategic locations around the jurisdiction (headquarters, gas pumps, parks, etc.) to allow officers access to the network when they’re within range so they can upload reports from the field and download reference information. Some jurisdictions are small enough that they have been able to create city-wide Wi-Fi networks to allow broadband communications from anywhere within the city or town.

More recent developments allow the creation of a so-called mesh network using Wi-Fi access points scattered around the jurisdiction. A receiving base station relays data from a field unit on to another base station, and the process repeats until it’s received at the main base station. Out-going data is transmitted to the field unit the same way. The method has the advantage of broadband speeds and lower network deployment costs.

Most recently, several companies are offering computer-to-computer messaging applications that use the Wi-Fi and 4.9 GHz band. The programs allow instant messaging, multiple streams of and audio video between several computers, and unit management features to handle a critical incident.

Several companies offer multi-path networks that select the best network among those available and route the field unit’s data appropriately. The software’s intelligence can locate and use the agency’s own radio network, a cellular network or a nearby Wi-Fi access point to create a constant data link for the field officer.

By 2011, the number of companies deploying wide-area Wi-Fi technologies (tens of square miles) has dwindled to one—Clearwire. That company has about 77 cities operational now, offering 3-6 Mbps service over about 30 square-miles. Several companies (Panasonic Toughbook, Dell, etc.) offer 30 different laptop models with built-in Wi-Max features, while add-on wireless modem cards are available for about $140.

Staring in 2007, several U.S. cities considered offers from commercial companies to deploy free, city-wide Wi-Fi networks that would be used both by the public (some free, some fee) and public safety agencies. Some contracts were signed and some systems were deployed. However, starting in mid-2008, the companies began pulling back from their offers, cancelling contracts and even turning off systems.

Cellular companies have mapped out ever-faster data networks for the future, with some companies promising speeds up to 6 Mbps within the next two years, faster than traditional wired DSL service.

For now, the nation’s law enforcement agencies generally use one of these mobile data solutions:

  • slower-speed networks which the agency must build, operate and maintain. The trend towards regional radio networks, including 800 MHz trunked systems, has made this option feasible, particularly for smaller agencies.
  • higher-speed cellular data networks operated and maintained by cellular carriers. This option is excellent for small agencies in well-covered cellular regions, since there is little up-front cost and there are typically fewer units for which to pay a monthly access fee.
  • self-built Wi-Fi networks for computer-to-computer or computer-to-base networks, all installed and maintained by the agency. This option provides full broadband data speeds, but with very limited range unless the jurisdiction is very small.

Within each option the challenges remain basically the same as the 1980s: initial and on-going cost, reliability and speed of transmission.

Here are the basic questions to ask when considering mobile data:

  • What information do you need to access from the field: basic text (vehicle registrations, etc.), high-volume text (in-field reporting, records management, CAD, etc.), or broadband (photos and other graphics, video, fingerprints, etc.)?
  • Can you depend upon a cellular carrier for network service, or should you build your own mobile data radio system, either standard radio or Wi-Fi / 4.9 GHz?
  • Do you need a proprietary data terminal for only mobile data, or do you need to use a ruggedized laptop for other applications such as word processing?
  • How and where will the network terminate: at the your agency’s local server, through the Internet to a server, at the county/state interface to NCIC, etc.?
  • What applications will be available on the network: records management, CAD, links to warrants and vehicle registration databases, automatic vehicle location (AVL)?
  • Do you need mobile data access only in vehicles, or also portable, hand-held access?













Agency-Owned Radio


Wi-Fi / Wi-Max / 4.9 MHz

Data rate
Note: the actual downstream speeds are much lower than the theoretical speeds often quoted by cellular companies

up to 96 kbps now, although
vendors say 230 kpbs is
possible using
future wide-band transmission

2 Mbps to 14 Mbps down,
0.8 Mbps to 2 Mbps up

Carriers are moving from 2.5/3G systems with progressively higher data speeds. Check Wiki-pedia for techno-explanation, and this April 2010 article on the current state of cellular data.

802.11b = 11 Mbps
802.11a = 54 Mbps
802.11g/n = 11 & 54 Mbps
Wi-Max = 3-6 Mbps (wide area)
Coverage depends upon design, but usually limited to a single jurisdiction and a small surrounding area 2G nearly global; 3G in most developed regions; 4G still being developed relatively limited: within 300 feet of a fixed antenna site; newer Wi-Fi Max technology extends to about 31 miles, but few installations or vendors (Clearwire)
Hardware base station, antenna, optional remote receivers, data modem for each vehicle data modem for each vehicle, linked to laptop; can also be used other mobile devices (smartphones, etc.). fixed base stations; Wi-Fi receiver built into laptop/tablet or installed in PC/PCMCIA slot; other mobile device (PDA)
Links to user must configure and link receiver to route data to Internet or private network any IP address IP network, either internal to organization or linked to the Internet
Security as configured by the agency varies by carrier, but add-ons may be necessary to conform to NCIC encryption requirements encryption and user authentication are available, supplied by user
Cost all the radio & network gear (tower, transmitter, etc.); cost of modem, laptop and installation in vehicle; no monthly usage fee unless connected to outside networks cost of modem or PC card, laptop and installation in vehicle; flat monthly fee per unit, estimated to be $35 to $80 per month ~$99 for Wi-Fi PC cards and base stations; possible cost of installing network lines to remote access points; monthly cost of IP network access (varies greatly based on speed, other factors).
Applications CAD interface, DOJ/DMV inquiries, short messaging CAD interface, DOJ/DMV inquiries, short messaging, e-mail, chat CAD interface, DOJ/DMV inquiries, e-mail, peer-to-peer messaging, broadband downloads
Major vendor


Sprint-Nextel / AT&T,
Verizon, T-Mobile


Once you have a wireless network, it must connect to something in the field: a laptop, tablet PC, PDA, or other specialized device. Here are some examples:

St. Paul (Minn.) patrol car with old model MDSI, proprietary mobile data terminal (MDT). This unit was in use in 1999, but it's becoming more rare to see these one-purpose devices.   Minnesota State Patrol car, in use in 1999. Another one-use, proprietary mobile terminal

A newer model, laptop-type mobile data device in a Minneapolis (Minn.) PD patrol car.

A Minnesota DOT Commercial Inspection patrol unit with both a proprietary terminal and a typical laptop. The laptop was connected to a portable printer, allowing the enforcement officer to generate a forms-based citation for offending truckers, and to print out the citation on-scene.

Las Vegas Metro Police with newer style mobile terminal that features a separate screen and keyboard.

Las Vegas Metro Police patrol unit with an old-style mobile terminal. When this photo was taken, the unit was in the radio shop for conversion of the MDT to the newer design (left).

 Typical mobile data set-up in a law enforcement vehicle, in this case the Travis County (Tex.) Sheriff's Office, using a ruggedized Panasonic laptop running a TriTech Software Systems application. Notice the other gear: on-dash radar, in-car video camera just above the right sideview mirror, and radio/overhead light console below the laptop.

mobile data Limestone County (Ala.) Sheriff's mobile laptop using a Rugged Notebooks Blackhawk Duo model notebook.

Fujitsu ST5000 tablet PC   Panasonic Toughbook laptop computers
Palm Tungsten PDA, with Wi-Fi capability
Blackberry's latest handheld device, the 7100g.
REDFLY smartphone terminal    

Vintage Mobile Terminals

Well, we wish these were vintage terminals. These items were listed on eBay for sale, but there are hundreds of these terminals still in use by public safety agencies.

Motorola KDT-480 and keyboard, and very early
proprietary terminal.

Motorola KDT-480 keyboard - note the upper row of function keys (some labeled with 10 Codes)
and green-colored keys that also perform special functions. The keyboard is illuminated from a
back-lit panel (reddish at top in photo). The upper-left function key is designed as an emergency
button, and has a collar around it to protect against accidental activation.

Motorola 9100-11, display unit and keyboard. Many of the
keyboard keys have special functions, as do the grey
buttons to the right of the small video screen.

Motorola 9100-11, with screen showing "Log On/Off" screen.
The display appears to be 8 lines x 40 characters.

Wireless Data Resources

Hardware / Software


RAM/Bell South

Other Resources