Kaon has a proven track record in providing leading edge and cost effective passive sonar processing systems to meet demanding customer requirements. Our breadth of experience covers many areas within this field and includes but is not limited too:

HADES - Both a broadband and narrowband passive processing unit, provided to the Royal Navy.

KRAKEN - KRAKEN was developed for FWG as part of their research, analysis and trails programme, providing real-time passive sonar tools within a flexible networked sensor environment.

RAT - RAT is a passive monitoring tool for a number of wideband analogue channels, providing displays, analysis functionality and real-time data recording.

Our systems are based on the building blocks provided by the Kaon Software Sonar library. Both Narrowband and Broadband techniques have been developed and used within Kaon systems:

• Beamforming - A core technique in sonar array processing to determine target direction. Kaon implements this technique in either the time domain or frequency domain. We also have experience in more advanced techniques such as triplet array beamforming, adaptive beamforming and synthetic aperture processing.
• Broadband Displays - both cross correlation and energy detection processes have been used within Kaon systems (HADES). Various normalisation techniques have been developed for the extraction of signal content in various acoustic conditions.
• Narrowband and Swath Displays - Kaon have used these within systems such as HADES, KRAKEN and RAT in order to allow for the visualisation and extraction of narrowband and swath signals. Various normalisation techniques have been employed, such as median, split window and robust mean estimators, set up appropriately for these signature types. These can be in the form of any of the standard passive sonar display types LOFAR, DEMON, Vernier.
• Transient and Active Intercept Analysis Displays - when short duration acoustic events occur, in order to identify what has happened operators need high resolution spectral displays of this type.
• Automatic Detection algorithms - Kaon have great experience implementing algorithms to automatically detect acoustic signals to provide operator prompts. The MMAD software for detecting marine mammals is a prime example.
• Increased Spatial Awareness Displays - that use various techniques to display multi-beam data in a way the human operator can manage effectively.

The standard passive analysis tools as provided by KRAKEN are:

• Lofargrams - a spectral display collected over time, showing the temporal evolution of the spectral content of a signal. They generally employ high levels of temporal integration with large FFT sizes in order to extract accurate spectral content and low signal levels. These are typically displayed as waterfall spectrograms.
• Vernier - These are similar to the lofargram, but are for selected frequency bands and employ a much higher frequency resolution. Vernier is typically used for fine frequency measurement and to spectrally separate signals. These are typically displayed as waterfall spectrograms.
• Demon - This is a demodulation technique which is used on broadband signals in order to measure their amplitude fluctuation rates. This is typically used to measure such things as the number of blades and blade rates of ship/boat propellers. These are typically presented as a waterfall display.

These displays commonly come with:

• Aural tools to allow the operator to listen to signals in a number of ways
• Various cursors to allow the operator to distinguish harmonic sets within a complex pattern of spectral lines, measure frequencies and times
• Ships speed from Doppler and "point of closest approach"