Abstract: The subject invention is a precision controlled frequency synthesizer which is capable of precisely adjusting the frequency of an output signal to maintain a desired frequency difference between an input and output signal regardless of the stability of the frequency of an input signal. The synthesizer comprises the basic elements of a phase locked loop (PLL) type circuit. The PLL circuit portion detects the actual frequency difference, a value A, between the input and output signals. A reference source provides a desired frequency difference, a value D, which represents the frequency difference between a stable input frequency and a desired output frequency. The difference between the frequency difference values A and D serves as the amount of adjustment to the frequency of the output signal. This adjustment represents the amount of compensation necessary to maintain a specified frequency relationship between the input and output signals.

Abstract: A frequency and phase comparator circuit for determining the frequency difference between a reference signal of a known frequency and a variable signal of unknown frequency. The subject circuit monitors the two signals and detects the occurrence of phase shifts between the two signals. In particular, this circuit detects phase shifts of 180 degrees and 360 degrees and records a full slip indication with each occurrence of a 360 degree phase shift. These phase shifts indicate that at some point in time during transmission, the two signals were out of phase and not of exact frequency. In addition, the subject circuit provides a direction of drift indication with each 180 degree shift. These direction indications are output following a 360 degree phase shift or full slip and are determinative of the relative frequencies of the two signals by designating whether the frequency of the variable signal is higher or lower than that of the reference signal over the duration of the full slip.

Abstract: A man-machine interface is disclosed for translating discrete hand positions into electrical signals representing alpha-numeric characters. The interface comprises a glove having sensors positioned with respect to the hand for detecting the flex of finger joints and sensors for detecting the contact between various portions of the hand. Additional sensors detect the movement of the hand with respect to a gravitational vector and a horizontal plane of reference. Further additional sensors detect the twisting and flexing of the wrist. The additional sensors are associated with prescribed mode signals which determine whether subsequently formed or priorly formed character specifying hand positions are to be entered for transmission. The alpha-numeric characters associated with the formed character specifying hand positions are transmitted only when the appropriate mode signal results.

Abstract: A multimodule time division switching system is disclosed in which intermodule calls are served by transmitting call information words over a bus system interconnecting all modules. Each transmitted word contains information specifying the receiving module identification number, the time slot in which the call is to be served in the receiving module, as well as the message or intelligence representing the subject matter of the call. A FIFO memory in each module is used as an input buffer to temporarily store each received word and thereby reduce the need for short term time slot synchronization between modules.

Abstract: A multimodule time division switching system is disclosed having facilities for the serving of conference calls between port circuits in at least three different modules. Each module serving a conference call transmits a series of call data words to the other modules serving the same call over a special bus system interconnecting all modules. Each word contains information including a module ID number and a time slot number as well as the message or intelligence representing the subject matter of the call. The transmitted ID number specifies the identity of the other modules serving the same call and to which the word is directed. The transmitted time slot number specifies the time slot in which the call is to be served by only a first one of the specified receiving modules. This first module responds to the reception of the word and serves the call in the specified time slot.

Abstract: A PBX system is disclosed having a return answer supervisory circuit in a local PBX for automatically detecting and extending an answer indication from a called station located in a distant PBX to an attendant's console in the local PBX on tie trunk calls between the local and distant PBXs. The disclosed system is an improvement in the art in that it does not require major modification to existing equipment for returning the answer indication to the attendant's console.

Abstract: A microprogrammed processor which receives 16-bit words as input data from an I/O system, breaks down each received word into four 4-bit bytes, and performs all logical and arithmetic operations on a byte-by-byte basis. The processed bytes may either be stored for further use or reconstituted into 16-bit words and outputted to the I/O system. The processor includes two source buses for applying information to an arithmetic unit (AMU), a destination bus for receiving the AMU output, as well as circuits such as memories and registers for selectively applying AMU input information to the source buses and for receiving AMU output information from the destination bus. Certain ones of the memories can both apply information to source buses and receive information from the destination bus on the same machine operation. Microprogrammed controlled gating facilities specify the circuits that are to be connected to the buses on each machine operation.

Abstract: A PBX is disclosed having automatic number identification (ANI) equipment for generating signals which identify the calling station and trunk numbers of outgoing calls. A memory is interconnected with the ANI equipment for storing the identification signals prior to transmission to a central office. The memory can store up to five sets of identification signals and aids in preventing dial tone delay by decreasing the probability that the ANI system will become overloaded due to central office delay.