Sonar calibration, test and training made easy with ERAS

Building on a rich heritage of acoustic transducer development spanning over four decades, our technology partner Chelsea Technologies develops the echo repeater acoustic source system (ERAS). This compact and flexible sonar test system is a low-logistic alternative to support the calibration of both low and high frequency sonars. Mobilised from small vessels and vessels of opportunity, the collocated projector and hydrophone can also be used for test and evaluation as well as training sonar operators.

The ERAS is the culmination of several decades of experience. This experience has seen Chelsea Technologies design and develop both sophisticated and simple echo repeater systems. These have been used extensively by the UK MoD and have also been supplied to the US Navy.

The result is a commercial-off-the-shelf instrument used to echo repeat, transpond, monitor and produce complex calibrated transmissions. An instrument you can trust, the calibration of ERAS has been conducted at the UK’s National Physical Laboratory.

How does ERAS improve testing and evaluation of your anti-submarine warfare capability?

ERAS packs a lot of functionality in a compact form factor. The main features are summarised as follows:

• ERAS transmits custom signals over a wide frequency range.
• ERAS replies at a calibrated source level and range.
• ERAS monitors incoming signals, records and repeats them. The echo repeat mode is triggered in response to an acoustic signal or an operator request.
• ERAS is compact and can be mobilised from a small RHIB.

What do these features mean for you? They mean that you can plan a test and evaluation exercise at a significantly lower price point with smaller teams and smaller budgets. You can calibrate your passive and active sonars for range and detection. You can test your equipment for different concepts of operations. You can simulate different noise signatures including sonar pings and even ship noise. In addition, the system can be used to send a programmed sequence of acoustic signals to simulate movement or Doppler.

What is its specification?

ERAS operates across a broad range of Low to High Frequencies. Using the following two bands:

• Band 1 Low Frequency (LF) – 3 kHz to 23 kHz
• Band 2 High Frequency (HF) – 23 kHz to 50 kHz

In addition, ERAS can transmit at up to 171 dB re 1 µPa@1m with a flat transmit response to within ±1.5 dB across these two frequencies bands. The LF source level can be increased to 180 dB re 1µPa@1m between 7 kHz and 19 kHz.

As new offboard platforms are being considered to conduct anti-submarine warfare operations, testing and evaluation demands are likely to increase. ERAS will support higher volume of experimentation at a lower price point.

Forcys, working with its technology partners, has extensive experience in multi-aspect underwater sensor technologies, with a proven capability in underwater acoustic transducer design and manufacture, optical/magnetic/electric and biological sensors, electronics and software, signal processing and the packaging of sensors and electronics, including battery power packs, into small volume, underwater pressure housings.