Abstract: A controlled simulation of an underwater target for testing and evaluating a sonar system. The target simulation system receives an acoustic test signal and generates a simulated reflected signal emulating the test signal reflected from a target of known target strength. The system includes hydrophones and projectors located underwater and a signal processing system located out of the water. The signal processing system detects the test signal received by the hydrophone and converts the test signal to digital format. A computer modulates or weights the digital signal using a target strength value representing the target strength to produce a digital representation of a simulated reflected signal. This simulated reflected signal is converted to an analog format and is retransmitted as a simulated reflected acoustic signal using the projector. The level of the simulated reflected acoustic signal can be increased or decreased to simulate various sizes of the same target.

Abstract: A target simulation provides a controlled simulation of an underwater target for testing and evaluating a sonar system. The target simulation system receives an acoustic test signal and generates a simulated reflected signal emulating the test signal reflected from a target of known target strength. The target simulation system includes hydrophones and projectors located underwater and a signal processing system located out of the water. The signal processing system detects the test signal received by the hydrophone and converts the test signal to digital format. A computer system modulates or weights the digital test signal using a target strength value representing the target strength to produce a digital representation of a simulated reflected signal. This digital simulated reflected signal is converted to an analog format and is retransmitted as a simulated reflected acoustic signal using the projector.

Abstract: A system, or applique apparatus, for recording and reproducing large numb of electrical signals on input channel limited recording devices is described. It is accomplished by time sequencing groups of pluralities of separate input signals to a plurality of recording units within a recorder, wherein each recording unit handles a separate group of input signals. The time sequence is provided by a multiplexer controller and is common to each group. The plurality of recording units after recording the signals provide them in the groups in which they were received to respective demultiplexers. A demultiplex controller that receives 2 timing signals from the multiplex controller via the recorder supplies timing signals to the plurality of demultiplexers for reconstruction of the original input signals.

Abstract: The Smart Programmable Amplifier System provides a microprocessor based aification system which uses programmable gain amplifier (PGA) techniques. It is used in remote data acquisition systems where it must cover a wide signal range, but the actual measurement range is much smaller during a given time interval. The system interfaces to a host computer to provide complete operator control and to relay continuous status information. The system provides automatic and programmable gain control to meet individual test requirements.

Abstract: An apparatus is provided for simulating a planar wavefront propagating at a nown frequency and incident upon an imaginary linear array of receiving elements at a known angle of incidence. A master clock generates a clock signal at a selected frequency. A frequency divisor and time delay divisor are generated based upon the master clock's frequency, spacing between the receiving elements, frequency of propagation, angle of incidence, and wavefront propagation speed. Frequency generation counters are provided such that each is connected to receive the master clock signal and the frequency divisor. A time delay counter is connected to receive the master clock signal and the time delay divisor to generate a pulse every T seconds where T is the time difference associated with receiving the planar wavefront at any two adjacent receiving elements. A delay enable shift register is connected to the time delay counter to receive the generated pulse every T seconds.