Abstract: Apparatus for reducing interference in a first signal caused by a second signal. Before the signals are transmitted, the first signal is tested to determine how much interference can be tolerated. During portions of the first signal which can tolerate a large amount of interference, the amplitude of the second signal is increased. During portions of the first signal that can only tolerate a small amount of interference, the amplitude of the second signal is decreased. The average amplitude of the second signal is large enough to provide an acceptable bit error rate or signal to noise ratio, yet small enough not to substantially corrupt the first signal. In one embodiment, the technique is employed to allow transmission of additional data on a television channel.

Abstract: A graphic arts image comprising a plurality of regions, each region having a characteristic multilevel intensity, hue, texture or the like, is sampled and coded using samples along two consecutive scan lines. Individual code words are generated for the beginning, or head, of each run defining the start of a vein or boundary of a region of contiguous like-valued samples along each line and other code words are used for connecting information relating to samples on adjacent lines defining continuations of the boundary for the same region. Other code words identify the characteristic intensity or the like of the region, and a final type of code word identifies the end of the vein. Because the present method and apparatus advantageously codes each internal boundary between adjacent regions only once, an increase of efficiency by a factor approaching two is realized over techniques previously used.

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 multitone pushbutton dial array each switch in the array has a variable impedance coupling between a fixedly mounted conductive plate and a movable conductive plate spaced apart from the fixedly mounted plate. Digitally synthesized signals having a predetermined phase and frequency are sequentially and recurrently used to scan interconnected columns of movable plates in the pushbutton dial array. Signals having an opposite phase from the scanning signals are continuously applied to the fixedly mounted plates. When a pushbutton is depressed variable impedance coupled summation signals are produced and these signals have a phase which is opposite to that of signals coupled to the detector from an unoperated switch. The detected digital signals are used to generate digital multitone row and column frequency signals. These digital row and column signals are converted to analog form and are transmitted to a telephone central office as a dialed digit code.

Abstract: A self latching and unlatching connector assembly includes first and second connectors having mating electrical contacts. The first connector has affixed thereto a pair of latch members. The second connector is mounted in an assembly which includes upper and lower shell halves, each of which has a groove therein for engaging a mounting flange on the connector. A pair of levers, each having first and second arms, are mounted on a pair of pivots which are integral with the lower shell half. One arm of each of these levers engages one of a pair of spring latches, each of which has provision at one end thereof for latching the second connector assembly to the first connector latch members. A sleeve having a pair of locking pins affixed thereto fits over the two mated shell halves. To effect disconnection the sleeve is grasped at any position on its periphery and pulled.

Abstract: In many digital processing systems it is necessary to delay an applied signal by a time interval which is not an integer multiple of the system sampling period. Disclosed herein is a digital phase shifter which utilizes a particular digital filtering scheme for supplying virtually any predetermined delay. Although conceptually related to the digital concepts of phase shift by interpolation and decimation in which the sampling rate is first increased and then restored to the original sampling rate after effecting the desired phase shift, the disclosed phase shifter operates entirely at the system sampling rate. This is accomplished by establishing a specific predetermined subset of digital filter coefficients and combining the coefficients with the input signal samples in a multiplier and accumulator circuit.

Abstract: A binaural sound recording and reproduction system which utilizes a recording mannequin equipped with an electroacoustic model of the human auditory tract to thereby record the sound pressure which would be incident on a listener's eardrum and also utilizes a headset with in-ear transducers or receivers which exhibit a flat frequency response as measured at the listener's eardrums is described. The receiver units utilize acoustic impedance matching to the listener's ear canal to effect the flat frequency response characteristic. An electrical equalizer circuit to facilitate the use of the subject in-ear receivers with conventionally recorded sound is also disclosed.

Abstract: 1. In a privacy system in which the signals are divided into fragments on a time basis and the different fragments are delayed in transmission by different amounts to afford privacy, a timing means having a timing cycle divided into several periods, a relay individual to each period and individually operated during its respective period by said timing means, a plurality of delay devices to introduce delay into said signals, means controlled by said timing means to select a delay device for each timing period, and means jointly controlled by said relays and selecting means to operate the selected devices.