USA As Represented by Secretary of the Navy

Alan Gordon

Gerald R Mackelburg

Stanley J Watson

Steven J Cowen

Jayson T Durham

Brett D Castile

A precision Doppler effect compensator provides Doppler compensation in astic transmission by simultaneously sending a known reference signal with an information signal. The information signal and reference signal undergo identical Doppler effects. The compensator uses the Doppler shifted reference signal to sample the analog Doppler affected information signal. The analog information signals are digitally converted and stored in a first in first out shift register. The samples are read out of the FIFO at a rate corresponding to the frequency of a non-Doppler shifted reference signal so as to precisely reconstruct the information signal as transmitted. The samples read from the FIFO are reconverted from digital to analog form to be presented to a receiving modem for further information processing.

Precision doppler effect compensator

An undersea communications system provides for improved data transmission pabilities. Two separate sources of information respectively modulate the upper and the lower sidebands of an acoustic carrier. The discretely modulated sidebands are simultaneously transmitted without the acoustic carrier or the acoustic carrier can be added to allow asynchronous or synchronous demodulation and use of the two modulating informations. Separation of the information in the two discretely modulated sidebands is assured by shifting the modulating information to ultrasonic regions and filtering out upper and lower sidebands of modulating information. Next, the shifted sidebands are modulated by an acoustic carrier which, optionally, is transmitted along with the discretely modulated upper and lower sidebands. A phase locked loop in the receiver portion assures synchronous demodulation or a crystal oscillator allows asynchronous demodulation of the discretely modulated upper and lower sidebands.

Synchronous/asynchronous independent single sideband acoustic telemetry

An apparatus and method of transmitting and receiving information underwa assure improved performance characteristics. Modulating a carrier and appropriately filtering it allows the transmission of only single sideband signals or a carrier along with single sideband signals to increase the range at reduced power consumption levels. Demodulating incoming signals can be done synchronously (when the carrier is present) or asynchronously (only single sideband signals) to extract the information. When a number of carriers are modulated and, simultaneously, are transmitted and received, the system's reliability is enhanced.

Single-sideband acoustic telemetry

The deleterious effects of backscattering on a video image received from a urbid environment is minimized by using a vertical raster scan combined with appropriate filtering between the camera and monitor.

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San Diego, CA, United States of America

Alan Gordon