Radio modems transfer data wirelessly across a range of up to tens of kilometres.

Using radio modems is a modern way to create Private Radio Networks (PRN). Private radio networks are used in industrial critical applications, when real-time data communication is needed. Also Radio Data Modem enables user to be independent of telecommunication or satellite network operators. In most cases users use licensed frequencies either in UHF or VHF band. Licensed frequency is reserved for given user in certain area thus ensuring that there is less likelihood to have radio interference from other RF transmitters. Also licence free frequencies are available in most countries, enabling easy implementation, but at the same time other users may use same frequency, thus making it possible that given frequency is blocked.
Typical users for Radio Data Modems are: Land survey

Surveying

See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

 differential GPS

Differential GPS

Differential Global Positioning System is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations....

, fleet management

Fleet management

Fleet management is the management of a company's vehicle fleet.Fleet management includes commercial motor vehicles such as cars, vans and trucks. Fleet management can include a range of functions, such as vehicle financing, vehicle maintenance, vehicle telematics , driver management, speed...

 applications, SCADA

SCADA

SCADA generally refers to industrial control systems : computer systems that monitor and control industrial, infrastructure, or facility-based processes, as described below:...

 applications (utility distribution networks), automated meter reading (AMR), telemetry

Telemetry

Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

 applications and many more. Since applications usually require high reliability of data transfer and very high uptime, radio performance plays a key role. Factors influencing radio performance are: antenna

Antenna (radio)

An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

 height and type, the sensitivity

Sensitivity (electronics)

The sensitivity of an electronic device, such as a communications system receiver, or detection device, such as a PIN diode, is the minimum magnitude of input signal required to produce a specified output signal having a specified signal-to-noise ratio, or other specified criteria.Sensitivity is...

of the radio, the output power of the radio and the complete system design.