Abstract: A solid state, band-pass filtered, RF power amplifier for equalizing the response of an amplified RF signal across the entire tuning range of a multi channel transmitter is disclosed. An RF signal is applied to the input of a low noise FET amplifier with a portion of the signal coupled off into a frequency counter which in conjunction with a digital switching logic selects a path through a band-pass filter having characteristics that reduce the broadband noise of the RF signal passed therethrough. Additionally, a dual directional coupler samples the output of the power amplifier with the forward sampled signal being used to control the amplifier output to a preselected level and the reverse sampled signal being used to reduce the amplifier output signal in proportion to an increase in the voltage standing wave ratio load between the amplifier and the transmit/receive switch.

Abstract: A radio frequency switch which has input and output diodes and a quarter length impedance inverter interconnecting the diodes. A switch drive signal is clamped to a predetermined voltage between drive signals so that the impedance with respect to the input source remains substantially constant during the entire switch operation.

Abstract: A segmented, transversal correlator for use in a spread spectrum communications system accurately synchronizes to an incoming spread signal by passively searching for a particular section of a known reference PN code sequence. To achieve correlator lengths of greater than one data bit long, the correlator may comprise a plurality of correlation subsections, each including a loading register for storing a different section of the overall reference PN code sequence. A section of the PN code sequence is transferred into a circulating register in each subsection through a parallel transfer. The dynamic, circulating PN code sequence is then correlated against statically stored analog samples of the incoming spread signal. When the dynamic PN reference code sequence is aligned with the corresponding PN sequence in the analog samples, a correlation signal is produced and magnitude detected to form a signal which is applied to a summation circuit.

Abstract: A transversal correlator is disclosed for demodulating a phase shift keyed (PSK) signal. The PSK signal is mixed with a local oscillator signal to produce quadrature I-channel and Q-channel signals. The I-channel and Q-channel signals are sampled at a periodic rate and the samples are propagated through a shift register for each channel. A preselected pseudo noise signal is stored in a local register which has an output tap for each stage. Each of the analog shift registers has a stage corresponding to one of the stages of the local register. Each of the I-channel and Q-channel samples is multiplied by the binary state in the corresponding stage of the local register. This multiplying operation produces a plurality of product signals. Product signals for alternate samples of the I-channel signal are summed with alternate but offset samples of the Q-channel signal to produce a first summation signal.

Abstract: A non-linear phase detector is disclosed which compensates for gains occuring during tuning a frequency generator of a known phase locked loop circuit which incorporates a Varactor tuned resonant circuit as a VCO. The phase detector is of the sample and hold type and incorporates a Varactor rather than a hold capacator to compensate for non-linear gains which occur when tuning the frequency generator across its band spread. Additionally, bias compensation is provided for the resonant circuit Varactor to offset its contact potential.

Abstract: A test in place poppet valve and fitting assembly having a minimal air volume internal configuration is provided for attaching a portable hydraulic test system to a snubber internal hydraulic line. The valve fitting includes structure for connection to the test system. After the valve fitting has been attached to the poppet valve, but before the poppet valve has been opened, a passageway and the interior of the poppet valve are evacuated and filled with hydraulic fluid. A remotely actuated, spring biased probe extends from the fitting through the passageway to engage a poppet for selectively opening the poppet valve. When actuated to an open position, a prong on the probe is inserted into a cavity, and the poppet is supported on the probe. Using the poppet valve and valve fitting, the test system may be attached to a snubber internal hydraulic line 12 without introducing an appreciable amount of air.

Abstract: A fast slew rate automatic gain control circuit (10) includes a variable gain amplifier (14) which is responsive to a gain control signal and an amplitude detector (18) which produces an amplitude signal corresponding to the amplitude of the received signal transmitted through amplifier (14). The amplitude signal is provided to the input node of a loop filter (24) and to the inputs of threshold detectors (30, 32). Positive and negative slew threshold circuits (34, 38) provide threshold signals respectively for the threshold detector circuits (30, 32). When the amplitude signal is within the range of the threshold signals the loop filter produces the gain control as the function of the amplitude signal. When the amplitude signal is less than the positive slew threshold signal the threshold detector (32) produces a drive signal which is provided to the loop filter (24) and causes the generation of the gain control signal to have an accelerated positive slew rate which increases the gain.

Abstract: A peak detector circuit (10) is disclosed wherein an input signal is full-wave rectified by a circuit (14) and the rectified signal is provided simultaneously to peak detect, hold and dump circuits (18), (20). Each of the peak detect, hold and dump circuits is discharged at the start of periodic intervals with a phase offset between the intervals for the two circuits. The peak signals are discharged at essentially the start of the interval followed by rapid charging of the peak signal to the peak amplitude of the rectified input signal. The later portions of each of the intervals of the peak signals produced by the peak detect, hold and dump circuits (18) and (20) are transmitted alternately through a multiplexer circuit (24). The resulting output signal is transmitted through a high impedance buffer amplifier (30) to an output terminal (32) of peak detector circuit (10).

Abstract: An item identified by a location code is tracked through a transport image in a process controller (48). The transport image is characterized by input data to the specific construction of tracker units (32, 34). Location codes for each item are received by the process controller 48 and tracked by a service routine (152) to set a divert flag or an inject flag (172). Each location code is advanced through sections of the transport image by an INCH routine (200). When the location code matches a pocket identification a divert gate is actuated to remove an item from the distribution system.

Abstract: A recovery loop includes an analog circuit that mixes a fixed frequency signal from a temperature controlled oscillator (20) with an IF input to produce product signals corresponding to the quadrature components of data signals with frequency offset. A digital complex multiplier (32) is responsive to the product signals and to the output of a number controlled oscillator (34) to produce a digital output corresponding to the data signals. The output of the number controlled oscillator (34) is controlled by a digital phase lock loop.

Abstract: A processing circuit (50) in a communication system performs multi-channel adaptive array processing using a summed reference technique. A plurality of adaptive modules (56 and 58) modify the magnitude and phase of antenna element signals from a plurality of antenna elements. The outputs of the adaptive modules are combined by a combiner (60) to produce a summation signal. A modem (64) processes and divides the summation signal into a plurality of reference channel signals on channels 1 through K. A summer (70) adds the reference channel signals together to produce a composite reference signal that is subtracted by a subtractor (74) from the summation signal to produce an error signal. The error signal is applied to the adaptive modules (56 and 58) which respond to nullify interfering and noise signals and to enhance the signal-to-interference ratio for the summation signal.

Abstract: A radio receiver is disclosed in which a received signal is amplified, filtered, and then sampled at a rate determined by a clock signal produced by a selectable-rate, digital oscillator. In sampling the received signal, a family of harmonics are generated which are distributed in a pattern determined by the sampling rate. One harmonic is selected as an intermediate frequency signal and, like the received signal, it is amplified, filtered, and sampled. The second sampling process is driven by a second clock signal produced by a variable-rate, digital oscillator. This produces a second family of harmonics which are derived from the intermediate frequency signal. The second clock signal rate is selected to produce one harmonic which has a carrier component centered on zero frequency. This harmonic, which is the desired baseband signal, is separated from the other harmonics by means of a low-pass filter.

Abstract: A frequency agile phase detector includes a digital frequency detector section connected to a hold-sample-hold phase detector section. The digital frequency detector develops control signals related to frequency differences between a reference periodic signal and a variable periodic signal. The control signal determines the amplitude of a voltage signal impressed across a first hold circuit. A sample signal acts to sample and transfer the sample voltage signal from the first to a second hold circuit so as to reduce phase differences between the reference and variable periodic signals. The detector is incorporated into a phase locked loop using the VCO output as the variable periodic signal so that acquisition and lockup of the loop is obtained even when the two periodic signals are decades apart. Additionally, the hold-sample-hold section aids in reducing the reference and sampling energy required which results in a spectrally pure output signal.

Abstract: A surface acoustic wave variable time delay includes a surface acoustic wave device (10) which is secured within a housing (30). The device (10) is provided with an input transducer (12) and an output transducer (16) which are respectfully connected to input lines (14) and output lines (18). An electrostrictive element (20) is secured within housing (30) between an end of device (10) and an interior wall (34) of housing (30). A control signal is applied to electrodes (22, 24) connected to element (20) to vary the size thereof. Element (20) applies a mechanical force to the surface acoustic wave device (10) to alter the distance between the input transducer (12) and output transducer (16) to thereby control the delay time between the signal supplied to the input lines (14) and the output signal at the output lines (18).

Abstract: A continuously variable delay line (10) includes a piezoelectric crystal (12) having an input transducer (14) and an output transducer (16). An input signal is transmitted through input lines (18) to the input transducer (14) and received through output lines (20) from the output transducer (16). The input signal is converted to a surface acoustic wave for transmission across the surface of crystal (12). Control electrodes (22 and 24) are applied to surfaces of the crystal (12) and are connected to control lines (26). A control signal is applied to the control lines (26) to apply an electric field to the crystal (12). The electric field thus applied alters the longitudinal dimensional characteristic of the crystal (12) and thereby controls the propagation distance between the input transducer (14) and the output transducer (16).

Abstract: A communications management system includes a central processor (10) which is connected via an order wire subsystem (12) to various remote terminals (14, 16, 18). The central processor (10) maintains tables (42, 44) which relate remote terminals (14, 16, 18) to communication operating frequencies and assign jammers to selected operating frequencies. Further tables are maintained to list adversary frequencies (40), remote terminal locations (46) and remote terminal channel monitor assignments (48). Processor (10) develops the communications assignment table based on a preselected set of operating channels minus the channels being jammed or used by adversary parties. The channel assignments are changed on a recurring basis to reduce the probability of intercept and jamming. An operator console (24) is provided for displaying the data in the tables and for entering commands to update the tables.

Abstract: Three sample and hold circuits (26, 30 and 34) sample a received pulse amplitude modulated signal at twice the data bit frequency or timing of the received signal. The clock to the sample and hold circuits is timed so that three consecutive samples, two mid-bit samples and a transition sample are held in the circuits (26, 30 and 34) once every two sample periods. The mid-bit samples are added together by an adder (32) and divided by two in a divider (38) to provide an average. The transition sample is subtracted from this average in a subtractor (36) to produce an error signal. The error signal is normalized in a multiplier (44) using the reciprocal of the difference in magnitude between the two mid-bit samples to produce a normalized signal. A clock signal is generated by a voltage controlled oscillator (52) in response to the normalized signal at twice the bit frequency or bit timing and in synchronism therewith.

Abstract: A pressure-tight, rotary pipe coupling joins rotating, high temperature fluid transmission lines. Pressure seals of the coupling are maintained at a temperature lower than that of the high temperature or primary transmitted fluid by thermally insulating the seals from the high temperature fluid and by pumping a fluid coolant through annular cavities located adjacent the seals. A balanced pressure structure substantially eliminates thrust forces between the coupling members and reduces rotating friction.

Abstract: A portable coaxial cable trimmer (10) for trimming coaxial cable (12) with shielding (36), insulation (38), and a conductor (40) comprises a hollow, elongated housing (18) with a laterally disposed port (44). A first bushing (22) is attached to the end of the housing (18) for centering the cable (12). A first cutter (30) is secured in the housing (18) for trimming the insulation (38) and shielding (36) to produce a shaving (42) which is discharged from the housing (18) through a port (44). A second bushing (46), secured in the housing (18), centers the exposed conductor (40) of the trimmed cable (12). A second cutter (48) disposed in the housing (18) rounds and cuts the end of the exposed conductor (40). A device for rotating the housing, such as an air drill or an electric drill (14) can be attached to the cable trimmer (10) for rotating the housing (18) with respect to the cable (12).

Abstract: A device for transporting and buffering a flow of small articles, such as mail pieces, includes a conveyor belt that moves the articles onto a linearly displaceable carriage which delivers the articles into a buffer stack at a constant entrance angle regardless of buffer stack size. Articles in the buffer stack are supported and agitated by a plurality of rotating beater bars. Agitation causes skewed articles to level while the rotation of the beater bars transports the articles toward a moving edging belt that propels them into a feeder output. One of the plurality of beater bars includes screw thread sections for advancing the articles toward the feeder output.