Abstract: An RF modem used with a host device for transmitting information to, and receiving information from, other host devices. Prior to a transmission, the information is Manchester encoded and transmitted by On/Off Keying. A superregenerative receiver circuit (which may also operate as the transmitter) operating at the transmitted frequency detects the transmitted information. The information is recovered in conjunction with a timing function which times the buildup of RF energy within the receiver circuit so that a transmitted binary 1 can be distinguished from a binary 0. For use in a system with a plurality of hosts, multiple channels of operation are provided. In order to conserve power, the apparatus is operated in a power saving, sleep or scanning mode, as well as a full power active mode.

Abstract: A superregenerative circuit which is operable in a transmit mode and a receive mode of operation. A superregenerative oscillator and a single antenna are functional in both modes. To minimize any undesired RF energy which may be radiated during the receive mode of operation, the circuitry includes decoupling means connected between the antenna and the oscillator. During reception, the oscillator is periodically quenched, and received signals are recovered by circuitry which obtains, during unquenched periods, time samples indicative of the time required for the RF energy to build up to a predetermined level in the oscillator circuit.

Abstract: A bandpass filter network having a first two pole filter and a second two pole filter provided in parallel to the first two pole filter. The first filter is optimally coupled while the second filter is extremely overcoupled. Moreover, the first filter and second filter are shifted 180.degree. out of phase with one another. This phase shift is preferably accomplished by a balun transformer. Alternatively, the 180.degree. phase shift may be accomplished by having the first and second filters utilizing different forms of coupling (i.e., one inductively coupled, the other capacitively coupled).

Abstract: A method for processing electrical signals includes the steps of: storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal in a memory; selecting one of the first data signals in response to a second input signal; combining the selected one of the first data signals with a second data signal representative of a subsequent instantaneous amplitude of the first input signal, to produce a difference signal; producing a first output signal in response to the difference signal; and combining the difference signal and the selected first data signal to produce a modified data signal and for replacing the selected one of the first data signals with the modified data signal in the memory. The method can be performed by an equalizer in a circuit for compensating for amplitude variations in a radio frequency signal or by a comb notch filter.

Abstract: This invention provides a method and circuit for separating a signal of interest from a composite signal including a signal of interest and an angle modulated interfering signal, in which an in-phase component of a reference signal representative of a composite signal is mixed with the composite signal to produce a first compound signal, selected components from the first compound signal are removed to produce a first filtered signal, and the in-phase component of the reference signal is mixed with the first filtered signal to produce a second compound signal. Similarly, a quadrature component of the reference signal is mixed with the composite signal to produce a third compound signal, selected components from the third compound signal are removed to produce a second filtered signal, and the quadrature component of the reference signal is mixed with the second filtered signal to produce a fourth compound signal.

Abstract: This invention provides a method and circuit for separating a signal of interest from an angle modulated interfering signal in which a composite signal, including the signal of interest and the interfering signal, is used to produce first and second signals, the first signal being representative of the composite signal and the second signal being representative of the envelope of the composite signal. Selected components are removed from the second signal to produce a filtered signal. The filtered signal is mixed with the first signal, to produce an output signal including a component representative of the signal of interest having a greater spectral power density than other components of the output signal.

Abstract: To leak test a cavity in a test item, a pressurizing gas, at a preselected pressure is applied to the test item and the flow rate of the pressurizing gas during pressurization is recorded. This recorded flow rate is compared with a threshold level based on gas flow signature data for a reference test item. If the recorded gas flow exceeds the threshold level, an excessive leak signal is produced. This leak testing method significantly reduces the time required to perform low flow rate leak detection in large volume test items.

Abstract: A binary capacitor consists of a piston having a metallized band on its periphery. The piston is movable between first and second positions within a cylinder which carries two spaced metallized bands. One of the positions of the piston defines a position of maximum capacitance, i.e. where the band on the piston overlaps both of the cylinder bands. The second position of the piston defines a position of minimum capacitance; i.e. where the piston band clears at least one of the cylinder bands. The piston is latched in its stable minimum and maximum states by fixed permanent magnets located at the ends of the piston in combination with soft iron slugs at the ends of the cylinder. The piston is moved by appropriately energizing electromagnetic coils wound over the soft iron slugs on the cylinder.

Abstract: The high power (10-1000 W) modulated carrier of a noisy transmitter is attenuated and amplitude limited and is used to control a power oscillator which regenerates the carrier and modulations without the loss of power. The power oscillator is slaved in frequency to the amplitude limited and attenuated signal, and it follows any phase or frequency modulation present thereon. Noise components appearing on the original carrier fall outside of the information passband of the power oscillator loop and therefore are not reproduced. The noise free output from the power oscillator is then A.M. modulated prior to power amplication and transmission. The oscillator operates at relatively high power (1 watt) and is automatically digitally coarse tuned and analog fine tuned.

Abstract: A radio frequency FM repeater system receives and retransmits at the same frequency, the retransmitted signal having the same deviation as the received signal. To accomplish this the IF filter is notched at its center frequency and the receiver feedback loop is inhibited when the received IF is within the notch, i.e., at the IF center frequency. In addition, the system is stabilized and the deviations of the received and retransmitted signals are kept equal by using positive feedback within the FM receiver, the feedback loop having a gain of 0.5.