A test system is disclosed for facilitating analysis and evaluation of medical performance of ultrasonic examination equipment, including ultrasonic imaging systems, Doppler ultrasonic systems and ultrasonic color flow mapping systems. The test system is employed while the ultrasonic examination system is operating. A test transducer apparatus is positioned at a location at which it receives incident ultrasonic energy from the examination system. Receiver and analyzer circuitry senses and identifies characteristics of the incident ultrasonic energy being produced by the examination system, and electronically produces signals representing these sensed characteristics. A storage device is provided to preserve representations of these characteristics. Synthesizer apparatus and circuitry utilizes the stored characteristic information to actuate the test transducer apparatus to propagate back to the transducer of the examination system apparent return echoes resembling ultrasonic echoes which would have been produced by the incidence of incident ultrasonic energy upon an acoustic image, had such an acoustic image been located within the examination system's field of view. The monitored characteristics of the incident ultrasound include wave shape, frequency, phase, signal duration, pulse duration and pulse rate. The location of the apparent acoustic interface represented by the false echoes returned can be adjusted by varying the time delay of the apparent return echoes relative to the occurrence of the corresponding incident ultrasonic energy. A moving acoustic image or point thereof can be simulated by changing the frequency of the apparent echoes relative to the frequency of the incident ultrasonic energy.

Performance evaluation of ultrasonic examination equipment

Dynamic characteristics of a liquid surface (160) are measured by sending acoustic signals (140) to or more target areas (162a-162c) on the liquid surface and receiving said acoustic signals (150a-150c) after reflection from the target area. The detected signals are processed to measure phase shift between the sent and received acoustic signals, the measured phase shift varying over time. The varying phase shift is used to indicate fluctuations over time in the local height of the liquid surface in the target area. The liquid may be water, effluent etc. flowing in a channel or conduit. With suitable calibration, the measured height fluctuations can be used to infer flow characteristics such as surface roughness, wave height, flow depth, flow velocity, volumetric flow rate, shear stress, sediment transport. Using an array of receivers and target areas, additional spatial and temporal characteristics of the surface and the flow can be measured.

Methods and apparatus for detection of fluid interface fluctuations

The decoy comprises a hydrophone 10 followed by a receiving amplifier and a memory 12 for the incident signal. The latter is applied to programmable delay circuits 31 to 33 to which are connected in parallel the programmable amplifiers 41 to 44 ending up with an adder 50. A circuit 40 controls the delays of the units 31 to 33 and the gains of the units 41 to 44, as well as the level of a white noise generator 49, the output from which is also applied to the adder 50. The result is applied to the frequency shift circuit 51 and to the transmitter amplifier 52 followed by the sonar transducer 53.

Method for deceiving a sonar or radar detector, and a decoy for implementing the method

A target simulator which shifts the frequency of a received signal and retransmits it to the sending station to simulate doppler shift having a first converter transducer which mixes the received signal with the output of a first oscillator and passes the signal to a bandpass filter which filters out all signals except the one having a frequency equal to the sum of the received signal and the first oscillator and passes the signal to a second converter transducer which mixes the signal with the output of a second oscillator the frequency of which is removed from the first oscillator by the desired doppler shift. The output is transmitted through a low pass filter which filters out all signals except the one having a frequency equal to that of the initially received signal plus that of the first oscillator minus that of the second oscillator.

Edward W Early

Papers

Torpedo target simulator