Abstract: An art work stretcher assembly is disclosed having any desired arcuate, e.g., elliptical, shape. The stretcher assembly includes a plurality of plastic tubes that are flexed and arranged with their ends in abutment so as to provide a closed loop. A separate wooden dowel is inserted into each pair of abutting tube ends, to hold the tube ends together and to provide increased rigidity, and thus reduced curvature, in those regions of the closed loop. An elongated wooden strip is secured to the inwardly facing side of the closed loop of tubes, to provide a surface onto which can be fastened a planar art work substrate such as canvas.

Abstract: A chirp signal generator circuit includes a pulse generator PG for generating a single impulse for application to first surface acoustic wave device SAW. This device produces an output signal comprising several cycles of energy at a predetermined frequency. A threshold circuit TH passes only that part of the output signal which second surface acoustic wave device EXP having the predetermined frequency as its center frequency, and this output signal is then amplified. The second device EXP generates a frequency modulated chirp signal.

Abstract: A gating arrangement for a pulse compression circuit includes a surface acoustic wave delay line SAW responsive to an input pulse to generate a frequency-modulated radio-frequency output signal which is applied to an output gate OG. The output signal is also applied to circuit means DC operable to product a digital pulse corresponding to each cycle of the output signal. The pulses are counted by a counter CT and applied to control means CM. This responds to first and second predetermined counter states to control the operation of the output gate OG.