Abstract: A system for voice distribution amongst a plurality of telephone subscriber locations operating on a broadband cable network wherein RF transmitting and RF receiving channels for carrying voice and signalling information are established at the subscriber locations and coupled with the broad band network and a central switch is also coupled with the broadband network and enables each RF transmitting channel to be selectively coupled to any of the RF receiving channels. Phase correction pilot tones having a known phase relationship are generated at the telephone subscriber locations and transmitted in one or more phase correction pilot tone channels separate from the RF transmitting channels to the central switch. At the switch, the phase correction pilot tones are recovered and the phases of the pilot tones are used to correct the phases of the transmitting channels.

Abstract: A fault detection system for a broadband network having a central switch for switched telecommunications connections among subscribers each provided with subscriber interface equipment. The subscriber interface equipment has a received voice path and generates baseband signals for voice telephony which are carried at a carrier frequency on the broadband network. The fault detection system is provided with a tone generator for providing a constant, continuous pilot throughout the network. A pilot tone detector at the subscriber interface equipment detects the absence of pilot tone. The central switch is responsive to each pilot tone detection to recognize the absence of pilot tone at the corresponding subscriber location.

Abstract: The present invention which is an interactive communication system includes a specialized software or programming system to function in a general field known as intelligent tutoring, which is a promising means of delivering instructions on procedural skills relating to programming and like subjects. What has been developed is integrated distance learning tutor (IDLT) techniques involving the specialized programming, and which inexpensively integrates the concepts of "shared work space" and distance learning technology for a PC based intelligent tutoring systems.

Abstract: To train a speech recognizer, a new voice message (one or a few isolated words), after being spoken by a user, is converted into a token. The token is then compared with a plurality of templates stored in the recognizer and a recognition score is obtained each time. The templates previously stored in the recognizer include templates for previously trained voice messages and one or more previously formed templates of the new voice message. Three tests are applied to the recognition scores to determine if the token and one of the previously formed templates of the new voice message can become paradigm templates, if the new voice message is too close in pronunciation to a voice message the recognizer has been previously trained to recognize, or if the user should repeat the new voice message to form another token. This training procedure provides a certain level of automatic control over the training process of a speaker dependent speech recognizer in an otherwise unsupervised environment.

Abstract: A system for performing optical pattern recognition includes a first detector neural network for detecting the presence of a particular optical pattern in an input image and a second locator neural network for locating and/or removing the particular optical pattern from the input image. The detector network and the locator network both comprise nodes which can take on the -1, +1, or undefined states. The nodes are arranged in layers and each node in a layer has a location corresponding to a pixel in the input image. A particular application of this neural network is in finding the amount field on a check and removing the line which borders the amount field.

Abstract: An improved digital parallel correlator is disclosed. Illustratively, the inventive correlator utilizes a shift register which receives a signal comprising data bits encoded as chips. At each cycle of the signal, the chips in the shift register are compared to a reference sequence and the number of matches is obtained. Whenever the number of matches exceeds a fixed high threshold or falls below a fixed low threshold, indicating the presence of a binary 1 or binary 0 data bit, the chips in the shift register are set to a predetermined sequence such as the reference sequence or its complement. This amounts to correcting any chips of a bit that are received in error as soon as it is determined that the bit is a binary 1 or binary 0. This enables the high and low thresholds to be located as far as possible from the peak correlation values thereby increasing the number of chips that can be received in error.

Abstract: A dual mode LMS channel equalizer is disclosed. The inventive channel equalizer utilizes an LMS algorithm to both identify channel parameters and to smooth the received data signal to mitigate the effects of channel additive noise. In real time operation, the inventive equalizer first identifies the channel parameters in a training period. Thereafter, the same LMS algorithm is switched to smooth the received data signal, while intermittently, the LMS algorithm is switched back to track the slowly changing channel parameters. In comparison with the conventional LMS adaptive channel equalizer, the inventive dual mode channel equalizer achieves a significant performance improvement at little additional cost.

Abstract: A circuit and method is disclosed for recovering the transmitter clock at a receiver in a direct sequence spread spectrum communication system where a transmitter and receiver run independent clocks of nominally the same frequency. At the receiver, to select the phase of the local clock that yields the strongest signal, a clock recovery circuitry cycles through M phases of the locally generated receiver clock. The cycling is halted and the phase is locked soon as an indication is obtained that a phase is valid. Alternatively, all M phases of the local clock are tested for validity or invalidity, and depending on the resulting pattern of valid and invalid phases, a particular phase is selected for the local clock. A phase is valid or invalid depending on whether there is a second correlation crossing at the expected instant one data bit period after a first correlation crossing.

Abstract: A method and apparatus for transmitting a stream of data bits in a spread spectrum format is disclosed. The inventive method comprises providing 2.sup.N predetermined spreading sequences, where N is equal to or larger than 2. The predetermined spreading sequences have suitable autocorrelation and cross-correlation properties. For each group of N bits in a stream of data bits to be transmitted, a particular one from the 2.sup.N predetermined spreading sequences is selected and transmitted. In this manner, each transmitted spreading sequence corresponds to a particular arrangement of N bits. The invention achieves an N-fold increase in data rate for a particular symbol rate by encoding N bits in a spreading sequence.

Abstract: A system and method are disclosed for testing a switched telecommunications network by utilizing a terminating transponder unit 410 to respond with a unique identification code over switched network 300 following the receipt of a test signal from an originating micro logic terminal unit 210 over switched network 300, both units operating under the control of a central general purpose mini-computer 100.

Abstract: A method for controlling audiotex services which is analogous to the method by which users operate conventional commercial radios is disclosed. In accordance with the inventive method, upon dialing a general audiotex telephone number, the user hears what sounds like the slow changing of stations on a radio. The effect is produced by successively transmitting to the caller a short excerpt from each of a plurality of available audiotex services. The caller may stop the scanning of the audiotex services at any particular audiotex service by pressing a particular key on the telephone keypad. Other keys may be used to resume the scanning of the audiotex services in the forward or reverse directions and at a slow or fast speed. Some of the keys on the user's telephone keypad may be used as memory keys. When a user presses one of these memory keys, access to a particular audiotex service is immediately provided.