SURTASS LFA

Active Sonar detects objects underwater by sending out a sound pulse or “ping” that bounces off the target and returns as an echo the system can detect. Some marine mammals use a natural echo-location system to navigate and find food prey.

Active sonar transmitter below a surface ship sends out pulses of sound that bounce off a submarine underwater and are detected as returning echoes.

SURTASS
The Surveillance Towed Array Sensor System (SURTASS) is a low frequency passive surveillance system that is deployed on surface ships with acoustic data collection and analysis capabilities. SURTASS provides passive detection of quiet nuclear and diesel submarines and real-time reporting of surveillance information to theater commanders.

The system consists of a long acoustic array, which is towed by a surface ship and carries environmental sensors, electronic components, and hydrophones that can detect underwater sound signals.

LFA
The Low Frequency Active (LFA) system will be used when a target is too quiet to be detected by the passive (SURTASS) system alone.

LFA is a set of acoustic transmitters suspended by cable beneath a surface ship. These “projectors” produce an underwater sound pulse or “ping,” much as a stereo speaker turns electrical impulses into audible sound waves in the air.

Compact LFA (CFLA)
As future undersea warfare requirements continue to transition to littoral ocean regions, the introduction of a compact active system deployable on SURTASS ships was needed. This system upgrade is known as Compact LFA, or CLFA. CLFA consists of smaller, lighter-weight source elements than the current LFA system, and is compact enough to be installed on the VICTORIOUS class platforms (T-AGOS 19). The operational characteristics of CLFA are comparable to the existing LFA system.The initial CLFA installation was completed on the USNS ABLE (T-AGOS 20) in 2008 and at-sea-testing commenced in August 2008. CLFA improvements include:

Operational frequency, within the 100 to 500 Hz range, matched to shallow water environments with little loss of detection performance in deep water environments
Improved reliability and ease of deployment.
Lighter-weight design with mission weight of 64,410 kilograms (kg) (142,000 pounds [lb]) vice 155,129 kg (324,000 lb) mission weight of LFA).

With the R/V Cory Chouest’s retirement in FY 2008, two systems are currently operational. At present, there is one SURTASS LFA sonar system onboard USNS IMPECCABLE (T-AGOS 23) and one SURTASS CLFA sonar system onboard the USNS ABLE (T-AGOS 20). Two additional CLFA systems are planned for the T-AGOS 19 Class. Late in FY 2011, the CLFA system onboard the USNS EFFECTIVE (T-AGOS 21) commenced at-sea testing and training. The CLFA system to be installed onboard the USNS VICTORIOUS (T-AGOS 19) is scheduled for at-sea testing and training in FY2012.