Abstract: A frequency agile signal generator provided for emulating a communication signal of predetermined frequency and modulation characteristics including frequency hopping. The signal generator includes a digital controller such as a microprocessor or microcomputer for generating digital command signals specifying the desired characteristics of the output signal. In response to the digital command signals, a base digital frequency signal representing the desired base or center frequency of the output signal is generated by a number controlled oscillator in response to a digital frequency control signal. The digital command signals also control the generation of an analog modulation signal having desired modulation characteristics.

Abstract: The invention is directed to an apparatus for gripping and holding a plurality of relatively small flat chips, such as electron microscope grids, by the edges thereof. An elevated support member is provided, the support member having a top surface which defines a table and having an aperture therein. A support flange extends inwardly from the aperture a predetermined distance below the table surface. A gripping assembly is removably mountable in the aperture in the support member. The gripping assembly includes a first gripping member having a periphery corresponding to the contour of the aperture and having a thickness at its periphery which corresponds to the predetermined distance. A second gripping member opposes the first gripping member. At least a portion of the periphery of the second gripping member has a contour that corresponds to the periphery of the first gripping member.