Abstract: It is known to multiplex speech signals and nonspeech signals over a common communication path. One arrangement uses a portion of the frequency spectrum of the path for speech signals with the remainder for nonspeech signals. Another inserts data signals during gaps in the speech signals. Still another treats a speech signal as a carrier signal and modulates the speech signal with data signals. Unfortunately, users of such known arrangements experience excessive distortion or perceive others as encroaching on the path. These and other problems are mitigated by my improved signal processor (100, 200) for the spread spectrum (de)multiplexing of speech signals and nonspeech signals. In an illustrative embodiment, at a transmitter, a block (110) of speech signals may be converted (140) from a time domain to a frequency domain by a Fourier transformation. A Fourier component may be pseudo-randomly selected (130) from a subset of such components.

Abstract: Military organizations typically have exacting rules relating to the positioning of insignia on the uniforms of their personnel. Inasmuch as the rules are typically exacting, manual efforts to properly position the insignia are at best difficult. Aids have been developed to assist the personnel in the positioning of uniform insignia. However, known aids tend to be difficult to operate or tend to be expensive. My improved template for positioning insignia on a military uniform includes a center line marked thereon; none, one or more than one edge positioning guidelines marked thereon; one or more horizontal positioning lines marked thereon; and one or more longitudinal, horizontal slots therein. The center line and/or edge positioning guidelines are for aligning the template substantially parallel with respect to the uniform neckline.

Abstract: Bandwidth is a precious resource in a communication system. High frequency signals, for example, video signals, typically require a relatively large bandwidth. One means for reducing bandwidth is by way of time compression multiplexing wherein signals may be stored a short period of time, compressed in time and then transmitted over a communication path. The subject signal processor may time compress and time synchronize an input signal with a time multiplexed signal. In a first arrangement, responsive to a time delay difference between the signals (215), a first frequency signal (220) is used to modulate (230) the input signal (210). The modulated signal is extended through a dispersive filter (260) for introducing a delay to the input signal, the delay for synchronizing same with the time multiplexed signal. The synchronized output of the dispersive filter may be extracted by an envelope detector (270) for extension to an output terminal (280).

Abstract: Frequency and time division multiplexing arrangements are common for efficiently utilizing bandwidth in a communication system. Still another, lesser known arrangement is called time compression multiplexing. In time compression multiplexing, a signal from each input channel is stored for a short period of time. The signals from all channels are then read from the store, compressed in time and transmitted over a communication path to a receiver. Unfortunately, the art appears to be remiss in the time compression multiplexing of video signals. The subject signal processor includes a plurality of input terminals (111, . . . , 11N), each input terminal being adapted to receive a video signal, each video signal including a plurality of scan lines, each scan line having a time duration T seconds. The signal processor also includes an arrangement for compressing a video signal by a factor M (illustratively M=N). More specifically, the signal processor compressing arrangement includes apparatus (120, 131, . . .

Abstract: It is common that communications such as telephone calls between calling and called lines be made by sharing a single communications path on a time division basis. Each call is assigned to a shared path for a short time interval, also called a time slot. It is known to interchange an input time slot to a different output time slot. Unfortunately, known time slot interchange arrangements insert an input sample in a single output time slot. The instant time slot interchanger extends an input sample onto a plurality of output time slots for broadcasting a sample through a plurality of locations. Also, the instant time slot interchanger may selectively insert an alternate message, e.g., an error message, in an output time slot.

Abstract: The classification of a signal on a telephone line can be based on its short term average energy level; nonspeech (data or signalling) as high level; speech as medium level, and noise as low level. A common use for speech detectors occurs with a time assignment speech interpolation (TASI) system. A speech detector extends a trunk activity signal (TAS) for indicating whether energy or noise is detected on a trunk. Responsive to the TAS signal, a processor processes a signal on the trunk. On occasion, it may be desirable to process different energy signals according to different methodologies. For example, during overload, a TASI system may truncate bits of a speech signal and not truncate bits of a nonspeech signal. For classifying energy signals as between speech signals and nonspeech signals, the instant classifier includes an arrangement for extracting at least one feature, or property, such as the short term power of the signal to be classified.

Abstract: It is known for current meters to operate by sensing the magnetic field produced by the unknown current being measured. Such meters may include a core (200-1) of magnetic material which may be opened to receive a current carrying conductor (400-1) and which is adapted to be coupled to the magnetic fields surrounding the conductor. Winding (300-1), placed around the core, is excited at a fundamental frequency as supplied by an ac source (110). Responsive thereto, an output voltage of twice or higher even harmonics of the exciting frequency is produced. The output voltage is proportional to the magnetic flux produced by the current being measured and hence may be extended through a meter for indicating the unknown current. Such arrangements tend to be expensive. The instant current meter (100) includes an arrangement for providing a dc current (190) through the core winding to neutralize the nonsymmetry of the magnetic field created by the unknown current.

Abstract: Adaptive filters are commonly used in echo cancelers and automatic equalizers. Usually adaptive filters include a tapped delay line and apparatus coupled to the delay line for producing a tap coefficient signal, whose sign and magnitude indicate the appropriate correction in adjusting the filter. However, in the presence of input signals having a partial frequency band spectrum, known filters tend to become unstable, e.g., tap coefficient signals blow up. The instant arrangement includes apparatus for weakly driving the tap coefficient signals to optimal values. As illustrated in a deceptively simple embodiment, a tap coefficient updating component is extended through a one's complement converter to a first input of a binary adder. A two's complement output of the adder is fed back to a second input of the adder. The sign of the adder output is also provided to a CARRY-IN input terminal of the adder.

Abstract: Known adaptive differential pulse code modulation (ADPCM) coders typically convert a nonuniform input signal to a linearized representation thereof prior to processing the signal. Usually the linearized signal requires more bits than the nonuniform signal. To mitigate the expense of apparatus for manipulating signals having many bits as well as to dissipate a scale size mistrack between the coder and a decoder, the instant ADPCM coder, responsive to an improved adaptive control signal, converts (300, 600) the nonuniform input signal to special semiuniform representation thereof which representation is processed (400, 500, 600) by the ADPCM coder. The semiuniform signal permits use of fewer bits than the prior art linearized representation. Also, the adaptive control signal is provided by a scale index generator including rounding-up and rounding-down means, for dissipating scale size mistrack.

Abstract: In PCM systems, it is known to convert .mu.-law digital code words including a sign bit, m characteristic bits, and n mantissa bits representing respectively the polarity, segment value, and quantizing step of a quantized analog sample into a binary floating point representation thereof including a sign, exponent, and mantissa in order to process the digital signal. Known converters are of two relatively expensive types: (1) using a memory having 2.sup.m+n locations or (2) employing a .mu.-law to fixed point conversion followed by fixed point to floating point conversion. To mitigate such drawbacks, the present converter (100) employs a relatively inexpensive translator (200) for translating the segment value and a prefixed quantizing step into a reference mantissa. The code word quantizing step is then added (90, 95) to the reference mantissa to provide the floating point mantissa. The exponent is equal to the segment value; and the sign bit represents the sign.

Abstract: Circuit boards equipped with conductive paths are commonly adapted to fit into a suitable female connector. At times, protrusions of contact fingers within the female connector are bent to provide an electrical circuit closure, or short, between the bent fingers. As a male circuit board is plugged into the connector, the shorted fingers separate and electrically open. That common state of the prior art ignores the need for an arrangement for shorting pins in a male pin field. This problem is solved by a shorting contact (100) comprising an electrically conductive, folded cantilever spring. The contact, which is mounted on the board (10), mechanically touches predetermined ones (11-1, 11-2) of a plurality of male pins (11). Thereby, the predetermined pins are shorted together. Also, as the female connector (20), which may be lead connected to a printed wiring board, is fitted over the pins, an insulating housing (21) of the connector touches an arm (125) of the contact.

Abstract: A reference source of digital pulses of a first frequency f.sub.1 is coupled to the input of a frequency synthesizer which is capable of providing a second frequency f.sub.2 output signal. The second frequency is related to the first frequency by a predetermined, rational fraction (e.g., as f.sub.2 = (M/N)f.sub.1). The synthesizer includes a phase control unit comprising an adder by way of which a first number N is added each sample period to a remainder, the sum output of the adder being operated upon modulo a second number M, e.g., by dividing by M and discarding a resultant quotient to obtain a remainder. The remainder, having a value between zero and M-1, is compared to a prefixed signal, illustratively the largest integer in M/2. If the remainder is less than the prefixed signal, a first logic state control signal is provided to a control system; else a second logic state signal is so provided.

Abstract: The subject echo canceller includes a controller, which uses a feedback arrangement to improve speech detector performance, for providing an improved multistate control signal responsive to which adjustment of the estimate is inhibited or not inhibited. For example, a first state of the control signal is provided when the value of a first function of the error signal exceeds the value of a second function of the error signal, the second function being an average of first function values. One first function may be the algebraic square of the error signal as normalized with respect to the energy detected in a far end signal, while the second function is the average of the normalized signal where the averaging is done over a predetermined time interval. The predetermined time intervals may be those time intervals during which near end speech is absent.

Abstract: At a channel bank, such as a D-type channel bank used in the Bell System, a steady visual alarm is exhibited if the source of a detected failure is at a location either within the channel bank or in the digital hierarchy of a digital transmission network. Unfortunately, a craftsperson is unable to distinguish between the two failure locations. To distinguish between the locations, apparatus for indicating the failure location to be in the hierarchy is situated between the hierarchy and the channel bank and, responsive to an alarm failure signal from the hierarchy, extends a predetermined cyclic code signal to the channel bank. Without modification of the channel bank and responsive to the code signal, a cyclic visual alarm in lieu of the prior art steady alarm is provided thereat.

Abstract: In a digital communication system, synchronization of a plurality of asynchronous digital signals is usually achieved by stuffing one or more pulses in a pulse stream. Thereby, stuffing equalizes the input signal bit rate with the usually fixed bit rate of a signal on a transmission link. For example, in pulse stuffing, single pulses are added at certain allowed times to equalize the input bit rate with the transmission link bit rate. On the other hand, in block stuffing, a block of pulses is added. However, conventional block stuffing usually requires a narrowband phase-locked loop for removing jitter in the received signal. As a result, slower acquisition of synchronization occurs.

Abstract: In a digital speech interpolation system, speech inactivity time is utilized to reduce the bit rate on a link between transmitter and receiver by compressing digital characters from a plurality of trunks onto a lesser plurality of channels. If the number of trunks having active speech samples exceeds the number of channels, an overload may exist. To mitigate overload, it is common to truncate one or more bits from a transmitted character. However, bit truncation leads to signal degradation. Of course, it is desirable to abate the degradation consistent with mitigating the overload. Unfortunately, the number of bits truncated from a character on a first trunk is typically more or less than the number of bits truncated from a character on a second trunk. As a result, the signal degradation may not be uniform. To obtain a more uniform signal degradation, the instant priority rotation arrangement rotates the starting point for assigning bits to a digital frame responsive to the activity status of the trunks.

Abstract: A facsimile scene typically includes a plurality of lines, each line having a plurality of picture elements (pels). Often, pel signals are adaptable for run-length coding, a run being one or more successive pels having the same brightness level. To increase the length of a run and hence to permit a more efficient use of a transmission link, a processor is disclosed for permuting a measure of the pel signals responsive to a reference signal. Illustratively, the reference signal is the pel signal from a previous line. In one exemplary bi-level pel signal embodiment, the measure is the current pel signal. Specifically, if the reference pel signal is a logic one, the current pel signal is loaded beginning at one end of a memory; if the reference pel signal is a logic zero, the current pel signal is loaded beginning at the other end of the memory. In a second embodiment, the measure is an error signal for indicating a difference between the reference signal and the current pel signal.

Abstract: A facsimile scene typically includes a plurality of lines, each line having a plurality of picture elements (pels). Often, pel signals are adaptable for run-length coding, a run being one or more successive pels having the same brightness level. To increase the length of a run and hence to permit more efficient use of a transmission link between transmitter and receiver, a processor arrangement is disclosed for permuting a measure of the pel signals responsive to a reference signal. The reference signal is a calibration signal. The measure is an error signal for indicating a difference between the current pel signal and a prediction thereof. In an illustrative bi-level facsimile system embodiment, if the calibration signal is a logic one, the error signal is loaded beginning at one end of a memory; if the calibration pel signal is a logic zero, the error signal is loaded beginning at the other end of the memory.

Abstract: In a communications system such as a time assignment speech interpolation (TASI) system for concentrating signals from N trunks onto C channels (C < N), and for expanding same, it is common for a speech signal to pass through a plurality of transmitter/receiver terminals, perhaps connected for tandem operation. Unfortunately, transmitter speech detector clipping of the speech signal leads to a distortion accumulation problem. Also, while a calling trunk is inactive, an inserted noise signal is commonly furnished by a receiver to the called trunk to avoid an aural "too quiet" condition. Unfortunately, actual calling trunk noise and the called trunk inserted noise may differ, leading to a noise signal contrast problem. To mitigate the signal contrast problem, communications apparatus including an improved noise signal inserting arrangement, responsive to a measure of calling trunk noise, supplies an adaptively adjusted, deterministic, pseudorandom noise signal to the called trunk.

Abstract: In a PCM system, character compression using nearly instantaneous companding (NIC) is known to obtain a reduction in the number of bits transmitted. Unfortunately, in tandem digital PCM-to-NIC-to-PCM conversions, a signal delay results because a maximum segment value is usually unknown until a block of PCM characters, which are to be converted to make up a block of NIC characters, has been received. Further, if the PCM block is received out-of-phase, a signal degradation may result because the incorrect maximum sgement value may be used during a subsequent conversion. To mitigate delay, the disclosed processor discards certain least significant bits of a PCM character and substitutes therefor a predetermined bit pattern corresponding to the difference between the maximum segment value and the segment value of the first character of the block.