Abstract: In the transmit circuits of one terminal, a high frequency (HF) sinusoidal carrier signal of frequency f.sub.c is combined with a low frequency (LF) pulse signal having a PRF f.sub.p to produce a pulsed carrier signal having a plurality of component frequencies af.sub.c .+-. bf.sub.p. The pulsed carrier is modulated in each voice channel by an associated voice signal to produce sidebands of the HF component frequencies there. A different sideband is selected at HF for each channel by polylithic crystal bandpass filter. The selected HF sidebands are then combined with the carrier signal to translate them to low frequencies for subsequent transmission.

Abstract: The phase detector of this phase lock loop includes a transistor switch shaping the output of an Exclusive-OR gate which combines a data signal with a square wave local clock signal from a VCO for producing a digital error signal that is integrated to produce an error voltage that is applied to one side of a differential amplifier in an active lowpass filter. Other means integrates the local clock signal to produce a reference voltage that is applied to the other side of the amplifier, the output of the latter being a control voltage which drives the VCO. In a preferred embodiment, the reference voltage means and the path between the gate and the one side of the amplifier both include a switching transistor (the two being on a common substrate) and resistors of the same type and value for causing variations in the two input lines to the amplifier to track as a function of time and temperature.

Abstract: This chassis has side, top, bottom and rear plates which are made out of sheet stock and where are oriented at 90.degree. with respect to each other. Bifurcated tongues are formed in edges of plates. Elongated slots are also formed in plates at points spaced away from the edges thereof. The slots and tongues are dimensioned and oriented on the plates such that in an assembled shelf, the bifurcated tongues are located in associated slots so as to form square openings defined by walls of the associated slots and bifurcations-openings. Self-tapping screws threaded into the square openings and axially aligned bifurcations-openings cut threads in the walls defining these aligned openings over the full grip length of the screws to hold the plates together.

Abstract: A buffer amplifier, which prevents loading of the input signal, accepts at its input an amplified and equalized pseudo-ternary signal. The output of the buffer amplifier is a-c coupled to the input of a precision differential amplifier, from which two output signals are obtained. One said output signal is representative of the positive pulses and the other said output signal is representative of the negative pulses of the pseudo-ternary signal. These two output signals are both applied to the inputs of a peak detector and a slicer. The d-c output of the peak detector is also applied as one input to the slicer. Separate outputs are obtained from the slicer, one each for the positive and negative pulse inputs, and these two outputs are summed, and the summed output is then amplified to provide a clock driver output.

Abstract: Modified duobinary regenerative repeaters are tested in situ by means of a pulse pattern generator connected to the repeatered span line, a plurality of audio filters, one at each repeater site, a return transmission path and a measuring device for determining the character of the signal output from a selected repeater.

Abstract: The correlation properties of a 7-level correlative waveform permit detection of errors due to irregularities and impairments in the transmission facility, where these errors violate the correlation patterns of the waveform. The received 7-level correlative waveform is first decoded to obtain a pair of binary outputs which are representative of the original binary signal at the transmitter, except for errors that might have occurred during the transmission period. The pair of binary signals are operated on to obtain coded binary signals and their delayed counterparts. These coded binary signals are used to establish the effect of presence or absence of a top or bottom level that would result from the formation of a nonbinary correlative signal. If an error has occurred during transmission, the extreme levels of the locally generated signal will not normally coincide with those of the received signal.

Abstract: The embedding network of a microwave oscillator comprises three lengths of parallel conductors supported above a ground plane and having odd and even mode short circuits thereon. Two of the conductors are connected to different ones of the electrodes of a bipolar microwave transistor which has a third electrode connected to ground. A load is connected between the third conductor and ground. Physical and electrical characteristics of the network are varied to cause parameters thereof to be desired values which yield maximum output power and oscillation at desired frequencies.

Abstract: A substrate carrying electrical circuit patterns and elements is supported in an upright position on a printed circuit board by a clip so as to restrict rotational movement of the substrate from that position when pins and plated through holes on the substrate and board are engaged. The clip comprises a body having a flat bottom for contacting one side of the board and a first-cylindrical peg depending from the bottom. Spaced-apart sections on one side of the body are in a common plane perpendicular to the bottom with a protrusion near the top of the body extending beyond this plane. A second-rectangular peg also extends from the one side of the body past the common plane, with the base of the second peg being in line with the flat bottom. A trough in the protrusion receives one edge of the substrate, with one side of the latter contacting the side sections in the common plane, and the opposing edge of the substrate being proximate the bottom of the body.

Abstract: A modified duobinary signal is separated into two (odd and even) pulse trains, each of which is representative of a bipolar pulse train. Each representative bipolar pulse train has a bit rate one-half that of the modified duobinary signal. Violations of the modified duobinary coding rules appear as violation of the bipolar coding rules. The bipolar violations which occur are detected separately for the odd and even pulse trains. The detected errors are read into an error combiner and are read out serially at the original modified duobinary bit rate.

Abstract: Apparatus and method for generating a multilevel correlative signal wherein the multiple levels are digitally generated. A serial binary bit stream is first converted into two parallel binary bit streams each at half the bit rate of the original serial binary bit stream. The parallel bit streams are encoded in accordance with the relation B = C - .DELTA..sup.2 C MOD 4; where B is the original waveform, C is the resultant waveform, and .DELTA..sup.2 indicates two units delay or 2T seconds where 1/T is the parallel speed in digits per second. Next the binary encoded bit streams are digitally converted to a 7-level waveform; and, finally the 7-level waveform is transformed into an analog signal which retains the 7-levels and provides a band limited 7-level signal related on a one-to-one basis to the binary input signal.

Abstract: An initial error indicated by a pulse at the binary input is applied through a gating circuit to trigger a monostable multivibrator (one-shot) to start a timing interval. The output of the one-shot is applied to a second gating circuit which inhibits the first gating circuit to prevent retriggering of the one-shot. Subsequent error pulses are then applied directly to a counting mechanism which counts the errors which occur during the predetermined time interval established by the one-shot. An acceptable error density is established by the predetermined time interval for the one-shot in relation to the number of errors that would occur during this predetermined time interval. If the number of errors which occur exceeds the acceptable error density, the counting circuit puts out a signal which may be applied to an alarm (or framing) circuit. Once the error counter produces an output, i.e.

Abstract: In PCM transmission, it is well known to transmit 24 voice-grade channels at a bit rate of 1.544 Megabits per second (Mb/s). The number of channels which may be transmitted in about the same bandwidth is doubled by the use of correlative level coding, such as the modified duobinary technique. Because of the degradation experienced by the modified duobinary signal in passing over cable pairs, periodic regeneration of the signals is required for effective transmission. The present invention is directed to a regenerative repeater which equalizes, amplifies, reshapes, and retimes the received modified duobinary signal so as to provide a regenerated signal which is nearly identical with that originally transmitted.

Abstract: An end-office repeater accepts a high-speed bipolar signal, converts the bipolar signal into a unipolar signal, scrambles the unipolar signal, and encodes the scrambled unipolar signal into a modified duobinary signal for transmission over a cable pair. Before cable loss would severely degrade the duobinary signal, line repeaters and/or inter-office repeaters are installed at predetermined intervals so as to equalize and regenerate the modified duobinary signal. By so doing, the signal is recovered with acceptable phase jitter, which permits recovery of the original high-speed bipolar signal at the distant end of a repeatered span line. The receiving-end office repeater equalizes and regenerates the modified duobinary signal, decodes the signal to obtain a unipolar signal, descrambles the unipolar signal, and converts the unipolar signal into a bipolar signal.Detection of errors in the modified duobinary signal may be obtained without adding redundant digits.

Abstract: The dies here comprise opposed sets of parallel-elongated members which are arranged for engagement to form component leads. Members at opposite ends of the dies cooperate in pairs to cut axial leads of a component positioned between the dies to prescribed lengths when the dies are engaged. A third member of one die has a slot through one of a pair of opposite sides thereof that are adjacent one end thereof and the component. A second pair of elongated members of the other die are positioned to move adjacent the opposite sides of the third member. When one lead of a component is held against the one end of the third member, with one ends of the second pair of members being proximate the component body and the free end of the one lead, engagement of the dies causes the second pair of members to force a portion of the component body into the slot and the one lead adjacent to the other opposite side of the third member to form the component leads into a hairpin pattern.

Abstract: Printed circuit boards are moved in a conveyor with the underside of flat boards spaced a prescribed distance above the top surface of a rotating cutting disk. In order to protect the circuit patterns on the underside of the board and the board itself, a V-shaped wheel is loosely rotatably supported on a shaft with the wheel being in front of and orthogonal to the cutting disk. The height of the wheel is adjusted such that the uppermost point on the circumference thereof is in the line of travel of the boards. Movement of a board that is bowed downward in the direction of the disk causes the wheel to roll on the underside of the board and to raise the board above the top of the cutting disk. In this manner, the underside of warped circuit boards is maintained at least a prescribed distance above the top surface of the cutting disk as the board moves over the leading - cutting edge of the latter and component leads are trimmed thereby.

Abstract: This protector holder includes a plurality of double ended spring terminals which are arranged in a row in a housing that is made up of mating body halves. Each spring terminal includes a folded ribbon contact and adjacent-facing folded finger contacts formed on opposite ends thereof which are connected together by a shank. Each body half has a plurality of openings arranged in a row in one side thereof, each opening having a slot extending through the top wall and one side of the body half and having a trough in the one side of the latter body half which extends through the bottom wall thereof. The finger contacts and shanks of spring terminals are located in associated openings and slots, respectively, with the folded ribbon contacts extending above the top wall of a body half in pairs which face each other. A pair of body halves mate such that the slots and openings form slotted compartments in a housing which hold the shanks and finger contacts of the terminals in place.

Abstract: This article protects the toe-end portion of the shoe upper of a drummer playing a trap set. It is formed from a single sheet of leather and has a flat sole portion that is the same general shape as the sole of the drummer's shoe has a pair of sides and a toe panel extending up at right angles to the sole portion, and has a tongue extending from the toe panel. The forward parts of the sides are cut away from the sole portion, turned in behind the toe panel and attached to the latter. A first pair of straps extend over the tongue to hold it securely against the arch of the drummer's foot. A second pair of straps extends around the heel of the drummer's foot to hold the formed leather piece in place over the forward part of the shoe.

Abstract: The frequency of a microwave oscillator is stabilized by coupling a portion of the RF signal therefrom to an HF oscillator operating at a sub-multiple of the microwave frequency and producing a strong harmonic at the microwave frequency in order to cause the operation of the microwave and HF oscillators to be locked together. The HF signal frequency, which includes any drift in the microwave oscillator frequency, is divided down a specified amount and compared with the frequency of a stable crystal reference oscillator in a comparator. The output of the comparator is a DC error voltage which is proportional to any drift in the frequency of the microwave oscillator. This error voltage is applied to the microwave oscillator to cause the operating frequency thereof to be more nearly constant.

Abstract: In this converter, a common transistor Q2 is one of the two transistors Q1 and Q2 of a multivibrator and is also one of a pair of power switching transistors Q2 and Q3 that are connected in series across an input port receiving an input voltage-V of one polarity. The other transistor Q1 of the multivibrator is also connected across the input port. The multivibrator causes the switching transistors Q2 and Q3 to be alternately conducting and nonconducting. A pair of capacitors C3 and C4 and unidirectional diodes D4, D5, and D6 are connected to the switching transistors Q2 and Q3 in such a manner that only one capacitor C3 is charged in one direction during conduction of the common transistor Q2, and that this one capacitor C3 discharges through the other capacitor C4 to charge the latter and produce an output voltage of the other polarity across it and an output port only during conduction of the other switching transistor Q3.

Abstract: A Bode equalizer which has as one active element thereof a high-gain, differential-input amplifier and which has as a second active element a variable negative resistance, the equalizer circuit being controlled by a resistance arrangement which effectively comprises a series-connected, fixed resistor and the variable negative resistance.