Abstract: In a broadcast telephone system for communicating information signals over an assigned frequency channel, the combination of a synthesizer for generating a signal at the assigned frequency and a PROM storing a plurality of sets of first and second signals associated with different predetermined assignable frequencies.
Type:
Grant
Filed:
June 27, 1988
Date of Patent:
August 29, 1989
Assignee:
International Mobile Machines Corporation
Abstract: A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has baseband processor which is coupled to storage means for the baseband functions. The baseband processor is direct access coupled to a modem processor whereby the two processors may communicate with each other. The modem processor generally acts as the master in the system, although lock-out means may be used in certain circumstances. The signal from the modem processor is converted to an analog signal, which is subjected to deglitching, and the deglitched signal is then upconverted and filtered to form an IF signal which is thereafter amplified. The amplified IF signal is combined with a signal generated by a synthesizer to provide an RF signal. On the basis of certain signals received from the base station, the baseband processor produces initiating signals which determine whether the subscriber unit will be in the transmit mode or the receive mode.
Type:
Grant
Filed:
August 7, 1986
Date of Patent:
April 25, 1989
Assignee:
International Mobile Machines Corporation
Inventors:
David N. Critchlow, Graham M. Avis, Sandra J. K. Earlam, Karle J. Johnson, Bruce A. Smetana, Gregory L. Westling
Abstract: A system for the wireless transmission of multiple information signals utilizing digital time division circuits between a base station and a plurality of subscriber stations. The subscriber stations may be fixed or movable. The number of time division circuits is determined by the transmission quality of the signals. The base station is interconnected with an external information network, which may be analog and/or digital. The information signals are selected from the group consisting of voice, data, facsimile, video, computer and instrumentation signals. The modulation level of the signals and the power applied to the system are adjusted in accordance with signal error detection in the system. The system is provided with spatial diversity by using a plurality of antennas selectively spaced from each other to provide relatively high signal reception despite signal fading. The base station operates over a plurality of RF channel pairs.
Type:
Grant
Filed:
March 27, 1987
Date of Patent:
March 28, 1989
Assignee:
International Mobile Machines Corporation
Inventors:
Eric Paneth, Mark J. Handzel, Steven A. Morley, Graham M. Avis
Abstract: A subscriber communication system includes a base station in a network with a plurality of subscriber stations, wherein control information is communicated between the base station and the subscriber stations over a radio control channel (RCC) at a frequency selected by the base station from a plurality of predetermined frequencies. The a base station transmits control messages including a unique network number over the RCC. Each subscriber station processes the network number in the control message received over the RCC to enable the subscriber station to process the control message in accordance with whether the subscriber station is in the same network as the base station. The timing of communications transmitted by a subscriber station over a given communication channel between a base station and the subscriber station is refined upon initial establishment of the communication channel.
Type:
Grant
Filed:
July 8, 1987
Date of Patent:
March 7, 1989
Assignee:
International Mobile Machines Corporation
Inventors:
Graham M. Avis, Thomas E. Fletcher, Gregory T. Saffee
Abstract: In a communication system that comprises a plurality of subscriber stations in RF communication with a base station having multiple sequentially repetitive time slots, each time slot being assigned to a particular subscriber station, means to change either the frequency or the time slot configurations, or both, in the event of a deterioration of transmission quality caused by modulation change, frequency channel interference, equipment failure, or the like, or by the entrance of additional subscriber stations going on line.
Type:
Grant
Filed:
August 6, 1987
Date of Patent:
November 15, 1988
Assignee:
International Mobile Machines Corporation
Inventors:
Duane R. Bolgiano, Chumlong Deangdeelert
Abstract: In a broadcast telephone system for communicating information signals over an assigned frequency channel, the combination of a synthesizer for generating a signal at the assigned frequency and a PROM storing a plurality of sets of first and second signals associated with different predetermined assignable frequencies.
Type:
Grant
Filed:
March 18, 1986
Date of Patent:
November 15, 1988
Assignee:
International Mobile Machines Corporation
Abstract: A modulator for a modem, said modulator being adapted to convert a bit stream, wherein each given number of successive bits defines a symbol, into a phase modulated intermediate frequency (IF) signal, the symbols in the modulator section being phase modulated DPSK conversion. The phase modulated symbols are then digitally filtered to provide a filtered signal comprising time shared, digital in-phase and quadrature phase components that, when converted into an analog signal, provides a modulation signal of a frequency that is centered about a predetermined frequency and deviates therefrom in accordance with the value of the phase modulated symbol. The filtered signal, after being converted to an analog signal is then filtered and passed to a mixer for up conversion to an IF signal.
Type:
Grant
Filed:
November 24, 1986
Date of Patent:
August 16, 1988
Assignee:
International Mobile Machines Corporation
Inventors:
Eric Paneth, David N. Critchlow, Moshe Yehushua
Abstract: A telephone system for actuating a function-generating device such as ringing a telephone bell, lighting a lamp, reading a meter, and the like, the system being adapted to be directly operated by a pulse-generating means such as a rotary telephone dial.
Type:
Grant
Filed:
April 26, 1982
Date of Patent:
May 1, 1984
Assignee:
International Mobile Machines Corporation
Abstract: A filter-type pulse counter system which separates pulses of desired frequencies from pulses of undesired frequencies, filters out the pulses of undesired frequencies, and then accepts and counts only those pulses of the desired frequencies.
Type:
Grant
Filed:
August 17, 1976
Date of Patent:
March 28, 1978
Assignee:
International Mobile Machines Corporation
Abstract: A system for screening out undesired signals from desired signals, the system being selectively programmed to effect this screening through programmed codes, the system also having means to utilize the desired signals to effect the performance of a selected function such as the sounding of a signalling means to indicate the transmission of the desired signals, the activation or deactivation of electrically controlled devices, or the actuation of a reprogramming means, the system being especially adapted to utilization in a telephone system for screening out undesirable calls and permitting desirable calls to effect activation of the selected functions.
Type:
Grant
Filed:
October 28, 1975
Date of Patent:
February 1, 1977
Assignee:
International Mobile Machines Corporation
Abstract: A system for selectively deactivating a telephone bell on a telephone instrument whereby when a telephone number is called, an auxiliary system automatically cuts in to prevent ringing of the bell until a predetermined code is dialed or touch-toned, at which time the telephone bell is actuated.
Type:
Grant
Filed:
September 4, 1975
Date of Patent:
January 4, 1977
Assignee:
International Mobile Machines Corporation
Abstract: A system for selectively deactivating a telephone bell on a telephone instrument whereby when a telephone number is called, an auxiliary system automatically cuts in to prevent ringing of the bell until a predetermined code is initiated by the calling station, at which time the telephone bell is actuated.
Type:
Grant
Filed:
August 12, 1974
Date of Patent:
February 3, 1976
Assignee:
International Mobile Machines Corporation