Abstract: This invention relates to automatic direction finding methods and systems for an electromagnetic or acoustic signal source by utilizing the concept of adaptive nulling of a narrow or wideband signal received by one sensor from the same signal received by the other, along with appropriate adjustments, in a two-sensors-interferometer. Plurality of sensors can be used to measure two orthogonal angles of arrival of a signal. Inventive methods and devices permit singling out a particular signal of interest among others by allowing a frequency tuning and selective amplification of the particular signal of interest without destroying the differential phase or time delay between the signals received by the sensors that determine the angle measurement. A high degree of signal cancellation during the adaptive nulling process permits a correspondingly high degree of accuracy and resolution for the angle measurement and also permits a relatively short baseline for the interferometer.

Abstract: Devices and methods for selectively reducing an electromagnetic or acoustic interference present in a transmission line by an active adaptive means, are described. For the electromagnetic interference, the transmission line may include a waveguide carrying a desired signal along with an undesired interference, the objective of the invention being to reduce the interference selectively at the output of the transmission line without affecting the desired signal substantially. Similarly, for an acoustic interference, the transmission line may include an exhaust pipe of an auto or Diesel engine carrying an undesired acoustic interference or noise, the objective of the invention being to reduce this noise at the output of the pipe.

Abstract: Apparatus and methods for combining incoherent signals having different carrier frequencies but a common modulation to obtain a coherent summation of the modulations of such signals are described. The apparatus comprises adaptive means of changing the carrier frequencies and corresponding phases of various signals to a common carrier frequency and a common phase, thus enabling the coherent summation of the common modulation and enhancing, thereby, the level of received information content. When the incoherent signals are transponder-signals, radiated from an object or platform in response to a modulated interrogating signal, and are obtained by different frequency offsets from the interrogating signal carrier frequency, the particular offset frequencies being unique to that object or platform, the ability combining of modulations coherently provides a means of unique identification of the object or platform.

Abstract: Devices and methods for minimizing multifrequency acoustic or electromagnetic noise that is propagated from its source to a remote region where the noise is to be abated by adaptive means are described herein. The noise minimization is achieved by sampling a noise, synthesizing from this sample a counternoise, the source of which is close to the noise source, and allowing the counternoise to propagate toward said region such that the noise and counternoise cancel each other as they arrive at said region. A closed-loop control is used to adjust the amplitude and time delay, or phase in case of monochromatic noise, of the counternoise during the synthesis, until the residual noise at said region becomes zero. For closed-loop control, the residual noise is transmitted back to the counternoise source by a communication link so that it can be used for said synthesis of the counternoise.

Abstract: Apparatus and methods for selective removal of specific biological cells or specific antigens or antibodies, from fluid containing their mixture with other biological cells and particulates are described. Filtration by this biochemical filter system is effected in a continuous closed-loop fluid flow path. The apparatus described herein comprises a source of fluid containing specific biological cells, antigens or antibodies to be removed; a source of complementary cells or complementary antibodies for the antigens and complementary antigens for the antibodies which can form large agglutinates following a biochemical reaction a reaction chamber providing conditions favorable for fast clump formation following the reaction; a filter for trapping large agglutinates; one or more pumps to regulate various flow rates; and necessary connecting links to form a closed-loop fluid flow path that includes the sources of biological cells, antigens or antibodies and complementary cells, reaction chamber, and filter chamber.