Abstract: An active R bandpass filter network (10) is formed by four operational amplifier stages interconnected by discrete resistances. One pair of stages (12, 14) synthesizes an equivalent input impedance of an inductance (L.sub.eq) in parallel with a discrete resistance (R.sub.0) while the second pair of stages (16, 18) synthesizes an equivalent input impedance of a capacitance (C.sub.eq) serially coupled to another discrete resistance (R.sub.i) coupled in parallel with the first two stages. The equivalent input impedances aggregately define a tuned resonant bandpass filter in the roll-off regions of the operational amplifiers.

Abstract: A binary coded input signal is converted to a binary coded decimal signal having N decades by employing N four bit shift registers. The bits of the input signal are sequentially supplied, in order, to the least significant position of the register for the units decade, with the most significant bit of the input signal being applied to the units register first. Each of the registers includes a right shift-parallel load mode control input terminal. In response to the sum of the values stored in each register and the binary value 0011 being less than the binary value 1000, the mode control input terminal is activated to shift the register contents one bit to the right. In response to the sum being greater than 1000, the mode control input terminal is activated to load the sum into the register. A binary one is loaded into the least significant bit position of the register for the adjacent higher decade in response to the sum being greater than 1000.

Abstract: A method of determining vegetation height and water content of vegetation from the intensity and state of elliptical polarization of a reflected train of microwaves. The method comprises the steps of reflecting a circularly polarized train of microwaves from vegetation at a predetermined angle of incidence, detecting the reflected train of microwaves, determining the ratio of the intensities of the electric field vector components, measuring the phase difference of the components, and computing the refractive index and thickness of the layer of vegetation from a formula, wherein the refractive index is given essentially by the water content of the vegetation.

Abstract: Memory device for two-dimensional radiant energy array computers in which the memory device stores digital information in an input array of radiant energy digital signals that are characterized by ordered rows and columns. The memory device includes a radiant energy logic storing device having a pair of input surface locations for receiving a pair of separate radiant energy digital signal arrays and an output surface location adapted to transmit a radiant energy digital signal array and a regenerative feedback device that couples one of the input surface locations to the output surface location in a manner for causing regenerative feedback.

Abstract: A method and apparatus for the automatic, remote measurement of the internal delay time of a transponder at the time of operation is provided. A small portion of the transmitted signal of the transponder is converted to the receive signal frequency of the transponder and supplied to the input of the transponder. The elapsed time between the receive signal locally generated and the receive signal causing the transmission of the transmitted signal is measured, said time being representative of or equal to the internal delay time of the transponder at the time of operation.

Abstract: The contrast produced from a photographic transparency is controlled by placing the transparency between a pair of partially reflecting mirrors forming walls of an optical cavity. Mirrors are used to trap a collimated laser beam illuminating the transparency so that at least a portion of the beam energy is passed through the transparency plural times. The distance that the light beam travels between the mirrors is controlled as a function of the wavelength of the beam energy to control the phase of light interference in the beam passing through the transparency, thereby controlling the intensity of the beam derived from the mirror downstream of the transparency. The contrast of the transparency is increased or decreased, depending upon whether constructive or destructive interference for the beam energy is provided by the mirror spacing. For a negative input transparency a low to high contrast projected negative or positive image can be obtained.

Abstract: A phase modulated wave that may have no carrier power is demodulated by a phase locked loop including a phase detector for deriving an A.C. data output signal having a magnitude and a phase indicative of the phase of the modulated wave. A feedback loop responsive to the data output signal restores power to the carrier frequency component to the loop. In one embodiment, the feedback loop includes a phase modulator responsive to the phase modulated wave and the data output signal. In a second embodiment, carrier frequency power is restored by differentiating the data output signal and supplying the differentiated signal to an input of a voltage controlled oscillator included in the phase locked loop. Preferably, the phase modulator is linear and includes a series inductance-capacitance network, wherein the capacitor is a voltage controlled varactor. To compensate for nonlinearities in the varactor reactance vs. voltage characteristic, the series circuit is shunted by a properly selected inductance.

Abstract: A braking apparatus for a tape transport device including first and second, stacked coaxial reels includes first and second feelers respectively mounted in proximity to the first and second reels for respectively sensing the tape being fully wound on the first and second reels. A brake means is mounted in proximity to adjacent, central hubs of the first and second reels. The brake means simultaneously, frictionally engages both hubs to brake both reels by virtue of a mechanical actuator being mechanically coupled to both feelers and the brake means. The brake means comprises a pair of rubber shoulders that extend in opposite directions relative to a common axis. The brake means turns about the axis in response to either of the feelers, which are eccentrically mounted relative to the axis, being turned about the axis.