Echo Repeater Acoustics Source
|Echo Repeater Acoustics Source (ERAS) is a compact and versatile system for the performance evaluation of a wide range of active and passive sonar. It has been designed to be hand-deployed from small vessels with few facilities - the transducer assembly is a small lightweight unit containing both projector and hydrophone. At the surface, the system includes a rugged, portable, power amplifier unit and a controlling computer.|
- Applications and Features
- Sonar test and calibration
- Underwater target detection
- Sonar operator training
- Noise signature simulation
- At sea, acceptance trials
- Broadband operation
- Operator control via computer
- Self contained and transportable
- Small and lightweight
- Easily deployed from a range of ocean going vessels
- Advanced, acoustic source and echo repeat functions
The initial function of ERAS was to act as a very low frequency acoustic source with an echo repeating capability for at sea, customer acceptance of a shipborne, active and passive sonar suite. Whilst its frequency range of operation is specific to these target sonars it can easily be tailored to the specific needs of any user. Please contact our sales department with your requirements. When compared to alternative systems, ERAS is extremely attractive to a user due to its relatively low cost, small size and light weight. It can be deployed easily from a small boat, if required, but still offers a very sophisticated suite of signal source and echo repeating capabilities.
ERAS has been designed to be hand-deployed from small vessels with few facilities - the transducer assembly is a small lightweight unit containing both projector and hydrophone. At the surface, the system includes a rugged, portable, power amplifier unit and a controlling computer. ERAS retains many of the powerful features of the Chelsea Technologies Group Versatile Acoustic Source System (VASS) but without the complexity of a towed format obviating the need for larger vessels. ERAS is controlled by an easy-to-use Graphical User Interface commanding the Digital Signal Processor which is used to Echo Repeat, Transpond, and produce calibrated transmissions with up to 24 tones simultaneously. ERAS provides a highly versatile and flexible sonar test system that is configured by simple mouse or keyboard selections. In addition to instant configuration changes, via its Graphical User Interface run from Windows XP Professional, ERAS allows desktop set-up of complete trials’ programs in advance hence avoiding potential errors in signal definition during calibration trials.
- Complex Signal Source
- Echo Repeater
- Received Signal Monitor
- Slant Range Measurement
Typical Source Level
Specification for a typical ERAS system used for test and calibration of a surface ship sonar suite. General Specification Modes: Source, Echo Repeat, Transponder Transmit Bandwidth: 280Hz to 2600Hz (user definable) Horizontal Beam Pattern: Omni-directional Vertical Beam Pattern ±30° Source Mode Pulse Lengths: 3ms to 10s or CW Number of Pulses: Up to 1000 Pulse Intervals: Up to 60s Variable Step Levels: -10 to +10dB Tones: Up to 24 (each with definable source levels and frequencies - CW or pulsed) Sweeps: LFM or LPM Noise: Either broadband or up to 5 user definable bands Noise types: White, Pink or Pseudo-Random Modulated Signal: AM or FM, user definable carrier and modulating signal Mechanical Computer: 405 x 225 x 205mm, 10kg Power Amplifier: 445 x 220 x 538mm, 15kg (splashproof) Transducer: 260 outer diameter x 608mm length, 8.3kg Cable length: 50m Computer Power Requirement: 90 to 250V AC auto switching 50/60 Hz PA Power Requirement: 95 to 130V or 185 to 260VAC auto switching 50/60 Hz Transponder Mode Frequency Range: 280Hz to 2600Hz Pulse Length: 10ms to 10s Variable Step Levels: -10 to +10 dB Trigger Types: Acoustic, TTL pulse or manual Trigger Level & Averaging: Fully user definable Transpond types: LFM or LPM sweep, Monotone or Source Mode (see above) Echo Repeat Mode Echo Frequency: 2000Hz to 2600Hz Trigger Types: Acoustic, TTL pulse or manual Trigger Level and Averaging: Fully user definable Echo Length: 10ms to 5s Added Doppler: -40 to +40 knots Added Echo Strength: - 30 to +40dB Echo Delay: Up to 60s Highlights: Up to 5 Highlight Strength: -30 to +30dB Highlight Offset: Up to 200ms Moving Track Target : Velocity –40 to +40 knots Tag on Transponder: User configurable
The ERAS system operates in three modes: Echo Repeat Mode Source & Sequence Mode Transpond mode In Echo Repeat mode, ERAS can repeat signals (between 2000Hz and 2600Hz) received from a hydrophone contained in the hand-deployable, transducer head. It does this in response to a trigger event, based either on the incoming acoustic signal, an external input, or under operator control. The repeated signal can have a highlight structure imposed upon it to mimic the reflections from a target. The many configurable parameters are controlled via an easily operated Graphical User Interface. Within this interface, the user can add Doppler, target strength and signal highlights to the echo repeated acoustic signal. A programmed sequence of echo repeated signals can be configured to simulate a moving target by appropriate addition of Doppler frequency shift and monotonically changing time delay. As a calibrated acoustic test, signal transmitter (source mode) ERAS can generate complex acoustic test signals (between 280Hz to 2600Hz). It is capable of concurrently generating up to 24 tones. The system also allows up to five noise bands (selectable from white, pink or PRN (Pseudo Random Noise)) and 5 bands of Band Limited noise (White, Pink or PRN) to be generated with the tones. The frequency & source level of each tone (&noise band) may be controlled independently &each selected as CW (Continuous Wave) or pulsed. ERAS can also generate LFM (Linear Frequency Modulation) or LPM (Linear Period Modulation) sweeps and complex modulated transmissions. The system allows pulse trains up to 1,000 pulses with stepped source level.
In Transpond mode, ERAS can transmit a user defined acoustic signal (between 280Hz and 2600Hz) in response to a trigger event which can be either acoustic, from an external input or under operator control. The transpond signal can be defined as a single pulse, or a ramp of pulses, either of a monotone or LFM or LPM sweeps, with selectable frequency and source level. In addition, any selection within the Source Mode can be transponded.