51
Alexander Feiner, Dennis Bryan James, James Royce McEowen: Telephone line visual status indication circuit. Bell Telephone Laboratories Incorporated, David H Tannenbaum, April 20, 1976: US03951248 (17 worldwide citation)

In telephone installations it is often necessary to know, without actually physically going off-hook, the status of the line. A solution to this problem is presented by the design of a low drain line status indicator circuit. Advantage is taken of the fact that the idle line voltage available from t ...


52
Bryan S Moffitt, Alexander R Ross: Digital conference time slot interchanger. Bell Telephone Laboratories Incorporated, David H Tannenbaum, May 3, 1983: US04382295 (16 worldwide citation)

A time slot interchanger is disclosed for selecting and buffering digital signals between buses. The arrangement is particularly useful in forming conferences in a distributed digital time division system. In one embodiment, a clock is used to generate time signals corresponding to time slots of the ...


53
Christopher Lanzafame, Bryan S Moffitt: Synchronization detection circuit. American Telephone and Telegraph Company, AT&T Information Systems, David H Tannenbaum, David R Padnes, April 12, 1988: US04737971 (15 worldwide citation)

There is disclosed an asynchronous pulse catching circuit that, for each edge of the variable frequency input, regardless of duty cycle, will provide a pulse, synchronized to a high speed clock. There is also disclosed a pulse comparison circuit consisting of a state machine that provides slip detec ...


54
Robert H Astmann: Communication system distributed processing message delivery system. American Telephone and Telegraph Company, AT&T Information Systems, David H Tannenbaum, David P Padnes, August 1, 1989: US04853956 (14 worldwide citation)

There is disclosed a message formatting arrangement which allows messages from a central processor to be distributed over a bus to a plurality of remote processors using a single address presentation for any message without regard to the byte length of the message. Each message consists of a variabl ...


55
Alexander Feiner, Chao Kai Liu, Sigurd G Waaben: Variable loop length compensated barrier circuit. Bell Telephone Laboratories Incorporated, David H Tannenbaum, October 14, 1980: US04228323 (14 worldwide citation)

A gain and frequency compensated barrier circuit is disclosed for use with a telephone transmission line having variable loop lengths. A DC component of the input signal is provided to the input side of the barrier circuit. Loop length losses, as well as barrier gain variations, are adjusted on the ...


56
William J Gartner: Automatic synchronous/asynchronous modem. American Telephone & Telegraph Company, AT&T Information Systems, David H Tannenbaum, December 22, 1987: US04715044 (14 worldwide citation)

There is disclosed an arrangement which enables a single modem port to be used for either synchronous or asynchronous data transmission, with no manual changes required. The modem determines whether the incoming call is synchronous or asynchronous by detecting the presence (or absence) of SYNC chara ...


57
Douglas C Smith: Automatic gain and return loss compensating line circuit. Bell Telephone Laboratories Incorporated, David H Tannenbaum, January 2, 1979: US04132863 (14 worldwide citation)

The disclosed T-type line compensation circuit reduces the gain and return loss variations when customer equipment is connected to a central office or PBX over telephone lines of various lengths. A linear resistor of a first series leg is thermally coupled, as a heat source, to a positive temperatur ...


58
Richard Henry Bidlack, Wayne Jay Egan, Steven Gary Miller: Key telephone system intercom arrangement. Bell Telephone Laboratories Incorporated, David H Tannenbaum, August 24, 1976: US03976847 (14 worldwide citation)

A key telephone system is disclosed in which intercom calls may be answered "hands-free" at the called station. Intercom calls are originated in the standard manner, with the subscriber picking up the handset at the calling station and dialing the number of the called station. A voice communication ...


59
Leslie A Baxter: Digital communication system fault isolation circuit. Bell Telephone Laboratories Incorporated, David H Tannenbaum, July 14, 1981: US04279034 (14 worldwide citation)

There is disclosed, for use in a digital communication system, a fault detector circuit operable for removing faulty stations from the system. The disclosed circuit uses a distributed bypass isolation technique and may be used with individual stations or with groups of stations. A multi-bit delay re ...


60
Milton L Embree, William G Garrett: Voltage to current converter. Bell Telephone Laboratories Incorporated, David H Tannenbaum, October 12, 1982: US04354122 (13 worldwide citation)

In situations where it is desired to provide an extremely accurate output current generated from an input voltage, errors occur in the conversion. Conventional solutions depend upon operational amplifiers and rely upon the availability of both positive and negative reference voltages. When attemptin ...