Patents Assigned to International Mobile Machines
  • Patent number: 5212830
    Abstract: An RF communications system for providing wireless telecommunication service to sixteen contiguous geographic sectors or cells. The system includes an antenna array having a plurality of antenna sites located at the corners of contiguous geographic sectors. The central antenna site has four directional antennas. The four corner towers each have three directional antennas. Each directional antenna illuminates an entire sector. The location of the antenna sites and the allocation of a frequency group for each sector minimizes RF interference.
    Type: Grant
    Filed: May 31, 1991
    Date of Patent: May 18, 1993
    Assignee: International Mobile Machines Corporation
    Inventor: Craig Miller
  • Patent number: 5177741
    Abstract: In a wireless digital telephone system, a circuit for determining in a subscriber unit whether a particular RF channel is of the type designated by the base station to be either a control channel or a voice channel and for determining whether the channel is in the transmit or receive mode; the circuit utilizing the duration of an AM hole to determine the type of the channel and utilizing a unique word for determining the mode.
    Type: Grant
    Filed: October 12, 1988
    Date of Patent: January 5, 1993
    Assignee: International Mobile Machines Corporation
    Inventors: David N. Critchlow, Graham N. Avis, Sandra J. K. Earlam, Karle J. Johnson, Bruce A. Smetana, Gregory L. Westling, Eric Paneth, Moshe Yehushua
  • Patent number: 5168507
    Abstract: A digital wireless subscriber telephone unit for wireless communication with a base station. An IF is used within the subscriber unit and base station which is combined with a carrier signal generated by a synthesizer for RF transmission between stations. In intervals between actuation of the system, a training mode is used wherein a known training signal is compared with a known values to produce correction coefficients to compensate for undesirable variations in timing and/or frequency, these constants being stored for use in correcting actual received signals. During demodulation, the modulated digital signals are fed to the modem processor in the form of time multiplexed I and Q samples and are demultiplexed. The demultiplexed I and Q samples are fed to an equalizer and frequency correction circuit for minimization of errors for production of a frequency correction signal based upon the correction coefficients which is used to correct any errors in the timing and frequency of the system.
    Type: Grant
    Filed: November 9, 1989
    Date of Patent: December 1, 1992
    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, Eric Paneth, Moshe Yehushua
  • Patent number: 5159705
    Abstract: A frequency synthesizer that generates two output signals at a set frequency apart from each other and in synchronization with each other. The output frequency is selected by a microprocessor and the set frequency difference between the two output signals is determined by a frequency divider and a voltage controlled oscillator.
    Type: Grant
    Filed: March 13, 1992
    Date of Patent: October 27, 1992
    Assignee: International Mobile Machines Corporation
    Inventors: David N. Critchlow, Graham M. Avis, Sandra J. K. Earlam, Karle J. Johnson, Bruce A. Smetana
  • Patent number: 5146473
    Abstract: A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single processor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.
    Type: Grant
    Filed: February 20, 1991
    Date of Patent: September 8, 1992
    Assignee: International Mobile Machines Corporation
    Inventors: David N. Critchlow, Moshe Yehushua, Graham M. Avis, Wade L. Heimbigner, Karle J. Johnson
  • Patent number: 5121391
    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 analong 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 the signals and the power applied to the system are adjusted in accordance with the 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: November 20, 1989
    Date of Patent: June 9, 1992
    Assignee: International Mobile Machines
    Inventors: Eric Paneth, Mark J. Handzel, Steven A. Morley, Graham M. Avis
  • Patent number: 5119375
    Abstract: A system and method for the wireless transmission of information signals between a base station and a plurality of subscriber stations.
    Type: Grant
    Filed: December 27, 1990
    Date of Patent: June 2, 1992
    Assignee: International Mobile Machines Corp.
    Inventors: Eric Paneth, Mark J. Handzel, Steven A. Morley, Graham M. Avis
  • Patent number: 5101418
    Abstract: A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a baseband processor which is coupled to a storage 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 device 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 filted 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: October 12, 1988
    Date of Patent: March 31, 1992
    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, Eric Paneth, Moshe Yehushua
  • Patent number: 5072308
    Abstract: A telecommunication system and method for communicating communication signals between various stations over a selected carrier medium. An improved encoder and method is provided for compressing a communication signal into a selectively formatted encoded signal to facilitate its transmission over the selected carrier medium. The method is particularly useful for encoding fax and modem data signals which do not exhibit the harmonics of a voice signal. A decoder and method for reconstruction of the encoded signal are also provided.
    Type: Grant
    Filed: November 26, 1990
    Date of Patent: December 10, 1991
    Assignee: International Mobile Machines Corporation
    Inventors: Daniel Lin, Scott D. Kurtz, Brian M. McCarthy, James M. Kresse
  • Patent number: 5067141
    Abstract: An interpolator varies the sampling rate of a signal. The signal may comprise pairs of in-phase and quadrature components at a first rate which are serially input through a pair of memories connected in series. The serially connected memories operate at a second higher rate which is a multiple of the first rate. An output taps the signals being circulated by the serially connected memories which results in the output of a signal having the in-phase and quadrature components at the higher second rate.
    Type: Grant
    Filed: October 10, 1989
    Date of Patent: November 19, 1991
    Assignee: International Mobile Machine Corporation
    Inventors: David N. Critchlow, Graham M. Avis, Sandra J. K. Earlam, Karle J. Johnson, Bruce A. Smetana, Gregory L. Westling, Eric Paneth, Moshe Yehushua
  • Patent number: 5022024
    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: May 8, 1989
    Date of Patent: June 4, 1991
    Assignee: International Mobile Machines Corporation
    Inventors: Eric Paneth, Mark J. Handzel, Steven A. Morley, Graham M. Avis
  • Patent number: 5008900
    Abstract: A subscriber unit for wireless communication with a base station in a wireless subscriber communication system includes a FIR chip, a DIF (digital intermediate frequency) chip, a single processor chip and a radio. The processor chip transcodes a digital voice input signal to provide digital input symbols; demodulates an output signal received from the base station to provide digital output symbols; and synthesizes a digital voice output signal from the digital output symbols. The FIR chip FIR filters the digital input symbols and generates timing signals for timing the transcoding and synthesizing operations in the processor chip. The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. The radio further processes the modulated input signal for transmission to the base station.
    Type: Grant
    Filed: August 14, 1989
    Date of Patent: April 16, 1991
    Assignee: International Mobile Machines Corporation
    Inventors: David N. Critchlow, Moshe Yehushua, Graham M. Avis, Wade L. Heimbigner, Karle J. Johnson, George A. Wiley
  • Patent number: 4996697
    Abstract: In a digital wireless subscriber telephone unit for wireless connection with a base station which includes a modem processor whose signal is converted to an analog signal which is then upconverted and filtered to form an IF signal, a deglitching circuit for removing glitch spikes occurring during the transition periods from digital signals to analog signals comprising a timing system, a detector for detecting the transistion periods in order to control the timing system, and a mixer coupled to the output of a D/A converter to mix a blanking signal from the timing system with the analog signal received from the D/A converter during the transistion periods, whereby the output of the mixer is returned to an intermediate reference level.
    Type: Grant
    Filed: October 12, 1988
    Date of Patent: February 26, 1991
    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, Eric Paneth, Moshe Yehushua
  • Patent number: 4994802
    Abstract: An analog to digital converter system utilizable in a wireless digital telephone network, the system comprising a circuit to produce an analog signal, and a circuit for amplifying this signal, mixing the amplified signal with a signal from a timing circuit and applying the output of the mixer to a sample and hold circuit; the output of the sample and hold circuit being then applied to an analog to digital converter, the output of which is applied to a FIFO, whose output is then available for further processing.
    Type: Grant
    Filed: October 12, 1988
    Date of Patent: February 19, 1991
    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, Eric Paneth, Moshe Yehushua
  • Patent number: 4974099
    Abstract: A telecommunication system and method for communicating communication signals between various stations over a selected carrier medium. An improved encoder and method is provided for compressing a communication signal into a selectively formatted encoded signal to facilitate its transmission over the selected carrier medium. The method is particularly useful for encoding fax and modem data signals which do not exhibit the harmonics of a voice signal. A decoder and method for reconstruction of the encoded signal are also provided.
    Type: Grant
    Filed: June 21, 1989
    Date of Patent: November 27, 1990
    Assignee: International Mobile Machines Corporation
    Inventors: Daniel Lin, Scott D. Kurtz, Brian M. McCarthy, James M. Kresse
  • Patent number: 4953197
    Abstract: A spatial diversity system for digital mobile telephone networks which comprises at least two antennas, one antenna being part of a primary (or master) unit and the other being part of a diversity (or slave) unit, each unit having processing means to detect the "quality" of digital audio signals received by their respective antennas, the "quality" comprising link quality, AGC level and parity errors; the primary unit being capable of comparing the "quality" of the audio signals received by each antenna, selecting the higher "quality" signal and transmitting the higher "quality" signal to the telephone network.
    Type: Grant
    Filed: December 8, 1988
    Date of Patent: August 28, 1990
    Assignee: International Mobile Machines Corporation
    Inventors: John D. Kaewell, Jr., Nicholas C. Schreier, James J. Roller
  • Patent number: 4943983
    Abstract: A digital wireless subscriber telephone unit for wireless connection with a base station. The subscriber unit has a 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 determines whether the subscriber unit will be in the transmit mode or the receive mode.
    Type: Grant
    Filed: October 12, 1988
    Date of Patent: July 24, 1990
    Assignee: International Mobile Machines Corporation
    Inventor: David N. Critchlow
  • Patent number: 4940956
    Abstract: A band pass-band reject filter in which the filter housing which comprises the resonant cavity is contained within an annular wall that is supported at each end by an end plate. The filter is connected to an instrument rack or the like by the distal ends of bolts which extend between the end plates and which lie closely along side the annular wall. The end plates are soldered to the annular housing. The bolt heads are soldered to the end plate and their shafts are soldered to the side wall.
    Type: Grant
    Filed: September 21, 1988
    Date of Patent: July 10, 1990
    Assignee: International Mobile Machines Corporation
    Inventor: William J. Garner
  • Patent number: 4935927
    Abstract: A wireless digital telephone system containing at least one emulated base station plus one or more subscriber stations, the emulated base station comprising a station similar to the subscriber station but having the capability of initiating a synchronization process whereby it is enabled to assign time slots to the subscriber station within the frame pattern of an amplitude signal by means of monitoring for positive edges in the signal.
    Type: Grant
    Filed: November 20, 1987
    Date of Patent: June 19, 1990
    Assignee: International Mobile Machines Corporation
    Inventors: John D. Kaewell, Jr., Scott D. Kurtz
  • Patent number: 4912705
    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 16, 1989
    Date of Patent: March 27, 1990
    Assignee: International Mobile Machines Corporation
    Inventors: Eric Paneth, Mark J. Handzel, Steven A. Morley, Graham M. Avis