Abstract: A ringing signal generator is disclosed in which a low-level reference ringing signal, generated by a reference waveform generator (101), is amplified by a delta-modulation power amplifier (106, 108). The low-level reference signal is digitally encoded using delta-modulation techniques to generate a high-level digital signal. The high-level digital signal is filtered (421) to remove the high-frequency components therefrom and to decode the digital signal to form the high-level ringing signal that has the same shape and frequency as the reference signal. The delta-modulation power amplifier generates the ringing signal by comparing (401) the reference ringing signal (E.sub.i) with an analog feedback signal (E.sub.f) reconstructed from the high-level digital signal. The resultant binary error signal (E.sub..epsilon.

Abstract: Effects of multipath fading and Doppler frequency spread in a single sideband radio communication system are largely overcome by separating (17) from a received signal spectrum, a pilot frequency component including those effects and using that component to accomplish both phase (36) and gain (38) corrections on an information-containing frequency component. Signals essentially free of those effects are provided (10) for controlling necessary frequency translations in the receiver. One illustrative embodiment (FIG. 4) is conveniently arranged for facilitating diversity signal combining.

Abstract: Some cellular mobile radiotelephone systems use tones for certain call connection supervisory functions on radio links. The presence of the correct tone in a received radio channel call signal is determined by using the received signal for producing (32) a lower frequency tone that is readily selectable (36) from similar tones produced in response to incorrect supervisory tones. Circuits are also shown for separately processing received call signals to produce (41, 53) supervisory tone phase information that is indicative of range between communicating stations. Several circuits (72; 40 and 46; 59-62) are shown for enhancing the accuracy of the produced phase information of the correct tone.

Abstract: A switch (13) is provided with a common actuator (38) which is movable through successive discrete positions (47) for effecting successive circuit closures between a common circuit portion (21) and a selectable one of a plurality of conductors (20). In any selected position of the actuator, a deformation of the actuator, without changing its selected position, effects a further discrete circuit closure (58, 57) to indicate that an actuator position has been selected. These closures are advantageously utilized in a telephone station set environment to control a dialed digit display and to enable registration of a sequence of dialed digits for subsequent transmission.

Abstract: Linearly binary-coded digital control signals representing specific time segments of musical sounds are used in part to control stepped ramp signal generators in a digital synthesizer which runs continuously on a fixed program. The ramp signals are used to control amplitude and frequency parameters of multiple digital oscillators that produce respective constituent tones of the musical sound segments. The synthesizer is operable in response to time-multiplexed digital control signals for multiple musical voices, one voice portion of which is also being computed in real time for multiplexing with previously computed and stored digital control signals for other voices. The indicated computations are effected by known techniques on a commercially available computer to translate performer-actuated transducer output signals, designating notes of a composition, into the aforementioned binary-coded digital control signals.

Abstract: Improved current sources which provide n output units of current responsive to m input units of current are constructed by connecting (m+n).sup.2 transistors in a square array configuration, controlled by (m+n) control devices. The array contains (m+n) columns each of which conducts a current the magnitude of which is desired to equal the magnitude of the current flowing in every other column, and has a maximum deviation only in proportion to [1/(1+.beta.)].sup.4 where .beta. is the common emitter current gain of the transistors.

Abstract: Complementary outputs of a differential amplifier are individually peak detected and the resulting signals are applied to the amplifier differential input in a manner to cause the output peak excursions to have substantially the same direct current levels. This causes the crossover of the two outputs to occur at the midpoint of the signal swing regardless of the input signal peak-to-peak swing, at whatever level.

Abstract: Circuitry useful in PCM coders for effectively shifting the idle channel noise signal to a level midway between the code state boundaries thereby significantly reducing the likelihood that noise signals will cross a boundary and be encoded.

Abstract: The use of plural cell sizes in cellular high capacity mobile telecommunications systems is facilitated by providing dual service availability in an essentially geographically continuous large-cell grid and an overlaid and essentially geographically discontinuous small-cell grid. When using certain frequency channel set assignment plans, large-cell antenna sites employ their ordinary channel set assignments whether or not a small-cell antenna site is also present. When a large-cell site is operated in the vicinity of a co-channel small-cell site, the respective channels of the large-cell site are operated in a large-cell mode or a small-cell mode as required to cooperate with the overlaid small-cell site. When using frequency channel set assignment plans requiring departures from ordinary large-cell channel assignments, the departures are similarly effected on the large-cell site channels that are operated in the small-cell mode.

Abstract: A mobile radiotelephone station set base is provided with a pushbutton dialing pad in a first face and has a rectangular card-receiving slot in an adjacent face and opening into a card-receiving pocket extending into the base parallel to the first face. A flexible rectangular card for inscribing frequently used numbers is provided and suitably dimensioned so that when the card is in the base slot and pocket it is deformed for frictionally engaging the pocket walls. This engagement holds the card at any manually selectable degree of penetration into the pocket and such penetration is selected by a user so that a desired number inscribed on the card is indexed at the slot adjacent to the pushbutton dialing pad.

Abstract: A data throttling arrangement is advantageously incorporated in a pulse width modulated (PWM) to pulse code modulated (PCM) signal converter for controlling the output rate of the PCM data stream. PWM data is converted to PCM data and stored in a memory. New PCM data is received and compared with the stored PCM data. The difference between the stored and the new PCM data is compared to a preselected threshold value. If the difference between the new and stored data is greater than the threshold value, the new PCM data is permitted to output; otherwise, the new data is disregarded as redundant or insignificant. Circuitry is provided to adjust the values of incoming PCM data by comparing it to predetermined zero offset values. Additional circuitry is provided to permit adjustment of the preselected threshold values in response to the rate of the PCM output data stream.

Abstract: A one-bit-out-of-n bit checking circuit is comprised of k serially connected detector levels. A first one of the detector levels accommodates n input signal lines and successively higher ones of the detector levels have one half the number of input signal lines as does the next lower detector level. Each detector level is comprised of a plurality of logic blocks with each logic block being connected to a separate pair of input signal lines. Each logic block in each level detects the presence of excitation signals on both input signal lines of the pair of input signal lines and generates an error signal in response thereto. Each logic block also detects the presence of an excitation signal on one input signal line of the pair of input signal lines and in response thereto propagates the excitation signal through successively higher detector levels to the k.sup.th detector level. The k.sup.

Abstract: A signal to be filtered is subjected to a known filter function a sufficient plurality of times and with appropriate processing to produce in a plot of the total filtering response versus the response of one such function at least one inflection in a portion of the plot corresponding to a transition band between a passband and a stopband of the filter function. Various embodiments of the overall filtering function are shown which are applicable to both recursive and nonrecursive filters and to filters having either single or multiple sets of passband and stopband combinations per filter function.

Abstract: A centrally located stage of a time division multiplex switching network is partitioned into blocks and a separate processor is provided to control each such block. The partition is extended to the edge of the network by having each partition processor control through the network both the network equipment in adjacent stages directly coupled to the controlled block, and a preassigned portion of the remainder of the network out to the edge thereof which can be reached either through such controlled equipment or through similar equipment of other partitions. In addition, translating, scanning, and service functions are advantageously separated out of the partitioned processors and performed by separate processors that communicate through the call switching network with the partition processors and/or the network-edge ports.

Abstract: A dual-speed, dual format full-duplex two-wire voiceband data transmission system provides automatic speed selection at the answering terminal responsive to a handshaking sequence which is compatible with existing systems operating at telegraph speeds. Existing systems provide asynchronous full-duplex serial data transmission in the speed range of zero to 300 bits per second using frequency-shift keying of tones in split frequency bands dedicated to the respective transmisson directions. Alternative full-duplex serial data transmission at 1200 bits per second using phase-shift keying of carrier waves in these same split frequency bands can now be provided from a common line protocol.

Abstract: A cable is passed through a lubricant filled chamber comprising an open housing and first and second flexible, annular discs each having radial slits along its inner circumference. A third flexible annular disc adjacent to said second disc includes radial slits on its inner circumference rotatably displaced from said second disc slits. The inner circumferences of the discs deformably engage the cable whereby lubricant beads are deposited at the second disc, which beads are uniformly spread by the deformably engaged sections of the third disc.

Abstract: A length of bar stock is screw-threaded at two different thread pitches along respective fractions of its total length. Two bodies are internally threaded at the different pitches. Each body engages the bar stock along the portion of its length which is threaded at the corresponding pitch, and the bodies move along the bar at different rates of travel from one another in response to rotation of the bar. The bodies are mechanically attached by means of pivot connections to an elongated member, the two pivotal connection points defining an axis on the member. Rotation of the bar stock drives the pivotal connection points on the elongated member in substantially the same direction transverse to the axis, but at different speeds, with the result that substantially pivotal motion is generated about an unattached point on the axis of the elongated member, on the other side of the slower moving pivotal attachment point from the faster.

Abstract: Subscriber-interface elements of a telephone station set are combined in and on a swivel panel. In one embodiment which is useful in automobile radiotelephone applications, the panel is a sun visor and includes arrangements to hold the handset in place even when the panel is upside down and to draw the handset up against the panel if the handset should be dropped during or after a call. Control buttons are arranged on the panel close to the user and, in the automobile embodiment, on a portion of the panel which is closest to the driver's line of vision. A cable connecting various station set elements to a control processor and radio extends through a swivel axle for the panel for convenient access to automobile body passageways from the visor to other locations of the automobile.

Abstract: This specification discloses a telephone conferencing arrangement employed with a plurality of conference interface ports in a time division multiplex (TDM), private branch exchange (PBX). Each port receives from the PBX the TDM conference signal of a respectively associated conferee and transmits an analog version of the conference signal to the conferencing system. Conferencing is achieved by combining the analog conference signals into a plurality of composite signals which are subsequently recombined via resistance-value related conductive paths with the uncombined analog conference signals in selectable transmission phases and amplitudes so as to provide at the receiving terminal of each conference interface port a composite signal comprised of the selectably phased conference signals transmitted by the other conference interface ports.

Abstract: A method and apparatus for sampling continuous wave signals to reduce aliasing distortion. The signal is sampled at n times the Nyquist rate, where n is an integer greater than 1; and the n most recently produced sequential samples are combined at the Nyquist rate to produce a sequence of composite samples. This sequence of composite samples exhibits reduced aliasing distortion compared with a conventional sampling or sample-and-hold gate.