V۰I Chip Solves a Noise Problem Underwater
Sonar is an acronym for sound navigation and ranging and allows one to “see” through the water using acoustics. Sonar has many uses in navigation, communication and detection. Active sonar can be used to detect submarines too quiet to be located with passive sonar. Other active sonar systems are used to detect large marine mammals in commercial shipping lanes or in high sound pressure zones such as those used for military exercises.
One of Vicor’s customers specializes in rapid prototyping of harsh environment instrumentation and ocean-acoustic research. Their expertise in quantifying noise and vibration measurement has been applied in diverse commercial and government programs. A recent project involved the development of an enhanced active sonar system for harbor defense.
The sonar system is an underwater cylinder with attached hydrophone transducers. The system transmits a signal and waits to receive a reflected signal in response. The incoming signals are interpreted to identify the object or intruder, i.e. a swimmer, whale or underwater vehicle. This underwater detection system has to be as small and unobtrusive and function at a low internal temperature. Most importantly, the system must operate with high reliability.
The customer chose a V•I Chip solution for the high efficiency, low noise and small size attributes that are critical to this application.
The power requirement for the sonar system is 1 kW. The small, low profile PRMs and VTMs are connected in a high-power parallel array that provides control of isolated Point of Load voltages of 48, ±15, ±12, and 5 V. Another requirement of the design is to control the internal temperature in the system. The compact structure of the system does not allow for significant internal air circulation. Moving heat out of the system and into water was a priority. The very low heat dissipation of the V•I Chip modules is an advantage.
In this sonar application, signals are transmitted at a very low frequency. Received signals are amplified, so any noise interference is also amplified. During the process of transmit and receive, conventional switching power supplies operate at no load and switch in the same frequency band as the system, making noise an issue. The PRM and VTM modules array operate on a fixed higher frequency that switches above the target band, so there is no noise interference.
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