Gadgets to help police communicate have advanced greatly since the 1970s. In the late 1970s most police officers used a radio with just three channels, that looked and felt "like a brick," according to Keith Hellwig, captain at the Wisconsin Department of Correction. Mobile communication devices, such as cell phones, were also unheard of. The cop on the street had to settle for a telephone box on the road.

Personal Data Assistants

Police often have to communicate with people whose first language is not English, so small PDA translator devices are becoming increasingly popular. Translators like Voxtec's Phraselator can enable police to communicate clearly in potentially dangerous situations such as large protests where many people in the crowd speak different languages. As well as crowd control, some police forces use them on patrols too.

Mobile Data Terminals

Gadgets in police cars are becoming more sophisticated. For example, mobile data terminals -- or MDTs -- allow police offers to check vehicle-registration records and exchange messages with central dispatching. Hands-free technology in cars also enable a police officer to "speak" a license plate number into the MDT so that he does not have to stop while driving.

Mobile Phones

Today, many police forces can use voice commands in their car to use a mobile phone. This includes answering the phone and using voice mail. Sophisticated technology, such as Bluetooth devices, enables the police to receive and send up-to-date communications about crimes.

Radios

A two-way radio is a police officer's staple communication device. Many U.S. counties are introducing radios capable of communicating with police in other jurisdictions. In January 2010, Maryland invested $1.5 million on a 700-megahertz radio. The move to upgrade radios followed the Sept. 11, 2001 terrorist attacks when emergency services were unable to communicate with each other.