Single Channel Ground and Airborne Radio System
The Single Channel Ground and Airborne Radio System (SINCGARS) is the name of a family of military radios and associated communications security equipment, principally used for ground-based, short-range communications for the U.S. Army. The family operates in the very high frequency (VHF) part of the electromagnetic spectrum, which, while requiring a longer antenna than UHF on aircraft, is less strictly line-of-sight, so it can reach to the patrol behind the next hill. Their capabilities will be included in the Joint Tactical Radio System, replacing SINCGARS-only radios.
As the name implies, SINCGARS was originally intended to be able to tune to a single frequency, but, like the HAVE QUICK II UHF system optimized for aircraft communications, is has been adapted to function properly in an environment with active electronic warfare. Both systems use frequency-hopping as a means to interfere with jamming and interception for electronic intelligence, as they rapidly change the frequency they use, so that the jammer will find itself on the wrong frequency, or the interception receiver will not be hearing the signal until it determines the new frequency. In like manner, direction finding systems may not be able to follow the changing frequency long enough to get an accurate position.
While frequency hopping is not encryption, it increases security, and most SINCGARS radios can be equipped with an encryption device. The sequence and order of frequency hops is determined by a pseudo-random number generator in each radio, with the hopping being time-synchronized using a Global Positioning System (GPS) time reference.
Depending on the particular device, the radio may be capable of linking to other military systems, such as the Joint Tactical Information Distribution System (JTIDS). JTIDS would allow information to be shared among an infantry unit, radar that tracks artillery fire back to its source, and M109 howitzers in artillery units that can shoot back at the enemy cannon site while its shells are still in flight.
SINCGARS radios come in manpack, vehicle, aircraft and other mounts.
Radios designated as "short-range" transmit, over level terrain, between 4-8 km (i.e., squad tactical radio range); long-range radios have 35 km range. Many units have low-power switches to reduce the transmitting power and range, which can be desirable to increase battery life, to decrease the possibility of interception, or to avoid interference with other units.
Basic units provide some communications privacy, and, more importantly, resistance to electronic attack from their frequency agility. For more serious security, many units can connect to a National Security Agency approved encryption device.
SINCGARS is one of the first waveforms that will be spoken by the Joint Tactical Radio System, along with Have Quick II , so only a single physical radio will be needed to communicate in both modes.