VLF Underwater Transducers for Through-water Communication

Elbit Systems’ Canadian subsidiary, GeoSpectrum Technologies, is set to deliver its first through-water communications system to a military customer – in this case, an undisclosed NATO member.

The system, featuring the company’s C-BASS range of compact VLF (1-200Hz) underwater transducers, is due for delivery by the end of August, the company revealed earlier in the month. Originally developed for marine seismic applications, these transducers are now being offered for a variety of military missions, including shore- or vessel-to-submarine or UUV communications, diver alert and communications, acoustic influence sweeping and submarine signature augmentation/emulation.

According to GeoSpectrum, many existing high-power underwater VLF sources are large, costly and require a crew of at least a dozen people to operate. The C-BASS family has been engineered for small size and weight, while maintaining high power output and wide bandwidth, thereby making possible applications that were previously considered impractical.

Generating high power at low frequencies from a small source represents a technical breakthrough, explained GeoSpectrum’s president Paul Yeatman. “The standard technology that we use is piezo-electrics, but they didn’t cut it for these really low frequencies […] We also looked at moving coil projectors, but these are horrendously inefficient, which means you need a lot more power, and they also generate a lot of heat which becomes problematic.”