Beamforming when the sound velocity is not precisely known

Beamforming when the sound velocity is not precisely known

Beamforming is an integral part of most signal processing systems in active or passive sonars. The delays used to generate a beam are functions of the sound velocity, which depends on temperature, salinity, and pressure. There is a loss in array gain if the delays are incorrectly set. This will occur when the sound velocity in the water surrounding the hydrophones is different from the velocity...

Cross-Language Phone Recognition when the Target Language Phoneme Inventory is not Known

Cross-language speech recognition often assumes a certain amount of knowledge about the target language. However, there are hundreds of languages where not even the phoneme inventory is known. In the work reported here, phone recognisers are evaluated on a cross-language task with minimum target knowledge. A phonetic distance measure is introduced for the evaluation, allowing a distance to be c...

When is Digital Evidence Forensically Sound?

Forensically sound” is a term used extensively in the digital forensics community to qualify and, in some cases, to justify the use of a particular forensic technology or methodology. Indeed, many practitioners use the term when describing the capabilities of a particular piece of software or when describing a particular forensic analysis approach. Such a wide application of the term can only l...

When is Limited Feedback for Transmit Beamforming Useful?

Multi-antenna systems have been shown to offer tremendous capacity increase in ideal rich scattering conditions. Transmit beamforming and receive combining are low complexity techniques that help in achieving the full diversity afforded by the multiantenna channel. Even if complete channel knowledge at the receiver maybe a realistic assumption in these systems, the same may not be true at the t...

When the ICU is not the answer.