Abstract: Cut-off malfunctions in a communication network are lcoated by establishing a connection through the network between a first terminal and a second terminal. At the first terminal, a prescribed sequence of first signals is generated and applied to the established network connection. At the second terminal, a second signal is generated responsive to receipt of a first signal over the established connection and the second signal is applied to the established network connection. A signal representing the difference between the number of first signals applied to the established connection and the number of second signals received from the established connection is formed at the first terminal. The established connection is maintained for testing when the difference signal exceeds a predetermined number.

Abstract: A differential pulse code arrangement reduces the bit rate of a composite color video signal by sampling the video signal at a predetermined rate of m times the color sub-carrier frequency, predicting the present video signal sample from reconstructed past samples and forming signal representative of the prediction error in a first predictive loop. The bit rate is further reduced in a second predictive loop embedded in the first predictive loop by generating a signal predictive of the error signal and forming a signal corresponding to the difference between the error signal and the signal predictive thereof. The difference signal is quantized and encoded for transmission. The error signal is reconstructed by summing the quantized difference signal and the predicted error signal and the prediction of the error signal is formed responsive to the sequence of past reconstructed error signals.

Abstract: An arrangement for retrieving information from a directory responsive to a sequence of spoken character signals in which a set of probable characters for each character signal is stored in a position ordered array. A candidate word is formed from the most probable characters of the array and the directory is repeatedly searched for words therein which match a candidate word. After each unsuccessful search, the candidate word is modified by selectively substituting array characters for mismatched position characters on the basis of the closest mismatched word found in the preceding search. If there are no more array characters for substitution after an unsuccessful search, a new candidate word is formed by placing an ignore character in the first mismatched position of the best candidate word of all preceding searches. The position of the ignore mismatch character is shifted left each time no further array characters are available for substitution.

Abstract: A predictive speech signal processor features an adaptive filter in a feedback network around the quantizer. The adaptive filter essentially combines the quantizing error signal, the formant related prediction parameter signals and the difference signal to concentrate the quantizing error noise in spectral peaks corresponding to the time-varying formant portions of the speech spectrum so that the quantizing noise is masked by the speech signal formants.

Abstract: A circuit for reducing reverberative interference utilizes a pair of spatially separated microphones to obtain speech signals from a common sound source. Each speech signal is transformed into an envelope representative signal having rapid increases responsive to direct path and echo energy bursts from the sound source and exponential decaying portions between energy bursts. A first pulse corresponding to a sound source direct path energy burst is generated responsive to the first speech signal exceeding its envelope representative signal, and further first pulses corresponding to echo bursts are inhibited for a predetermined time. A second pulse corresponding to said sound source direct path energy burst is generated responsive to the second speech signal exceeding its envelope representative signal, and further second pulses corresponding to echo bursts are inhibited for a predetermined time.

Abstract: A speech signal amplitude equalizer (compressor) circuit normalizes the amplitude variations of a real-time input speech signal s(t) to form the normalized output signal r(t) which may be either of two values: a constant amplitude (unilevel) speech signal or a zero-amplitude (squelched) signal. The normalized output signal r(t)=s(t)/a(t)+K where the envelope signal a(t)=s.sup.2 (t)+s.sup.2 (t) in which s.sup.2 (t) is the Hilbert transform and K is a control signal which can take one of two levels depending upon the amplitude of the envelope signal being above or below certain thresholds in a hysteresis type logic circuit.

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: An error reducing arrangement is provided for a signal receiver wherein a sequence of received signals is divided into groups and each group is partitioned into subgroups. A signal representative of the deviations among the signals of each group and a signal representative of the deviations among the signals of each subgroup of said group are generated. Responsive to a subgroup deviation signal exceeding its group deviation signal, the subgroup signals are altered to reduce the subgroup deviations. In this manner errors are reduced without affecting error free signals.

Abstract: A digital speech communication arrangement includes apparatus for partitioning a speech signal into a plurality of nonuniformly related, preassigned intelligibility contributing subbands, and quantized with an accuracy (bit allocation) based upon perceptual criteria. As a result, the quality of the coded signal is improved over that obtained from a single full-band coding of the total spectrum. "Integer-band" sampling may be employed to alias the signal in an advantageous way before coding. Each subband portion is digitally encoded after sampling at a rate related to the bandwidth of the subband. The digital codes of the subband are combined and applied to a common communication channel. A replica of each subband is formed by separating the digital codes, producing a sampled form of each digital coded signal and selecting the subband of the speech signal from said sampled form. The subbands are combined to reconstruct the speech signal. Other features include: aliasing for efficient frequency transposition.

Abstract: A method for applying lubricant to the surface of a cable in which the cable is inserted into a lubricant filled chamber through the deformably engaged aperture of a first flexible disc. Beads of lubricant from the chamber are applied to the cable surface through a plurality of radial slits cut through a second flexible disc as the cable exits from the chamber. The exited cable passes through the deformable aperture of a third disc having radial slits cut therethrough in rotatably displaced relationship to the radial slits of the second disc to uniformly spread the lubricant beads on the cable surface.

Abstract: In the electrodeposition of metals, the position and shape of the anode with respect to the cathode is critical for uniform deposition of the metal on the cathode. A bipolar electrode comprising a pair of electrically interconnected porous electrodes having surfaces of the metal to be deposited is interposed between the anode and the cathode. The bipolar porous electrode facing the cathode provides metal ions for deposition on the cathode and the bipolar porous electrode facing the anode is plated with metal ions formed at the anode. The position of the bipolar electrode may be periodically reversed, and uniform deposition on the cathode is obtained independent of the shape, size, and position of the anode.

Abstract: This speaker recognition system offers improved recognition by comparing the mean and variance of an unknown (test) speaker's Orthogonal Parameter signals versus those of previously-stored known (reference) speakers. The unknown speaker's Orthogonal Parameters represent his hypothesized identity because his original speech linear prediction coefficients are transformed into his set of Orthogonal Parameters using the stored (reference) transformation coefficients of each of the previously-recorded known speakers.

Abstract: A real-time predictive speech synthesizer produces an artificial speech signal from pitch period segmented codes. Responsive to the predictive parameters of the currently occurring pitch period, preceding speech samples, and the adjusted excitation signal of the current pitch period, a prescribed set of current pitch period speech samples are generated in regularly spaced time periods. In the intervals between spaced time periods, prescribed components of the excitation level adjustment signal of the next successive pitch period are formed from the prediction parameters of the next successive pitch period, the preceding speech samples, and the next successive pitch period excitation signal. After the current pitch period final spaced time period, the formed components are combined with the next successive pitch period energy signal to produce the next successive pitch period excitation level adjustment signal.

Abstract: A general purpose interpolator-decimator circuit for increasing or decreasing the sampling rate of a digital signal by a factor L/M, where L and M are integers, is disclosed. The circuit includes means for determining each output sample by multiplying a sequence of previous input samples by a set of coefficients and accumulating the resulting products. L sets of coefficients, in which each coefficient is a function of the factors L and M, are stored in a specific sequence which permits sequential addressing of both the coefficients and input signal samples. A multistage decimator cascaded with a multistage interpolator to effect a narrow-band FIR filter is also disclosed.

Abstract: In a luminous indicator circuit, a plurality of luminous elements are connected in series relation to form a series circuit which is supplied through a constant current device. A solid state switching device is placed in parallel with each luminous element (e.g., LED). A control circuit including switches connected to a D.C. source determines the conduction of each solid state switch, so that the associated luminous element is controlled independently of the other luminous elements in the series circuit. The control circuit includes switching means which supplies voltage to the indicator circuit only when at least one luminous element is activated. Circuit protection against unwanted transient voltages is provided.

Abstract: Disclosed is apparatus for generating carrier signals modulated by baseband symbol signals. The disclosed apparatus includes samplers for sampling input symbol signals, multipliers for multiplying the sampled signals by a precessing phase that is a function of the carrier signal's frequency, and modified filters for convolving the multiplied signals with a complex (real and imaginary) low pass impulse response and for selecting the real part of the convolved signals.

Abstract: Apparatus for the real-time analysis of speech signals in which a digital signal representative of the speech signal is adaptive threshold center-clipped and infinite peak-clipped to form a signal comprising three logic states (+1,0,-1). The autocorrelation function of this signal is determined by a circuit which employs simple combinational logic and an updown counter circuit. Pitch period and voiced-unvoiced indication are determined from the location and magnitude of the peak value of the autocorrelation function. Additionally, a signal representative of the speech energy is provided by summing the digital speech signals over a predetermined time interval and intervals of silence are detected by comparing the speech energy in an interval of time with a predetermined or adaptively determined threshold energy.

Abstract: Disclosed is a discrete-time filter configuration employing a shift register having output taps at only preselected stages for developing an output signal that is responsive to the signal of each stage of a shift register. The desired output signal is computed in a filter processing network by multiplying each of the output taps signals by a plurality of filter coefficients, by appropriately delaying the multiplied signals and by summing the delayed signals to produce the desired output signal.

Abstract: A loudspeaking teleconferencing circuit serving a plurality of remote conference room locations includes a plurality of speakerphone sets at each conference room location and a communication network connected to an incoming and an outgoing terminal at each location. The transmit channel of each set couples a microphone to the outgoing terminal; the receive channel of each set couples the incoming terminal to a loudspeaking device; and a control circuit selectively activates one of the set transmit and receive channels at a time responsive to speech energy present on the transmit and receive channels. Each set control circuit is operative independently of the control circuits of the other sets; and the outputs of all active transmit channels are combined and applied through the location outgoing terminal to the communication network.

Abstract: A component card assembly includes a grooved guide adapted to interengage a component card edge between the card receiving and base ends of a support frame. The guide is fixedly attached to the frame base end and comprises an elastically elongatable section. A lever pivotally mounted on the card engages the guide at the frame card receiving end. The pivoting of the lever into a locked position on the frame elastically elongates the guide whereby the component card is controllably restrained in a home position on the frame.