Frequency Shift Keying Patents (Class 375/272)
  • Patent number: 5974092
    Abstract: A method and system for alerting a mobile terminal in a high-attenuation propagation environment within a mobile satellite communication network are disclosed herein. The method comprises receiving an incoming call directed to the mobile terminal, generating a paging signal in response to the incoming call, determining whether the mobile terminal has failed to receive the paging signal, and generating an alerting signal in response to the determination that the mobile terminal has failed to receive the paging signal.
    Type: Grant
    Filed: July 26, 1995
    Date of Patent: October 26, 1999
    Assignee: Hughes Electronics Corporation
    Inventors: David Roos, Seok Ho Kim, Enrique Laborde, Neeraj Tewari, Adrian Morris
  • Patent number: 5940436
    Abstract: The present invention relates to a circuit for allocating a channel to a transmission between at least two modems that use an electric network as a medium for the transmission of a binary data flow. The circuit includes, on the receive side, a device for selecting a channel that is selected for having the best transmission level according to the energy received on several transmission channels. The transmission of the binary data flow occurs, at least at the beginning of each communication on the several channels.
    Type: Grant
    Filed: July 9, 1996
    Date of Patent: August 17, 1999
    Assignee: SGS-Thomson Microelectronics S.A.
    Inventor: Joel Huloux
  • Patent number: 5898733
    Abstract: Packets of data are transmitted over a distributed communications network formed by a number of transceivers. To minimize interference by other signals, the carrier frequency of each transmission is varied compared with the last transmission by that transceiver, for example by using a linearly sliding carrier frequency which varies continuously during periods of inactivity and while transmitting. The receivers scan the band at a rate sufficient to detect a preamble carrier burst preceding each data packet. The transceivers operate asynchronously with low data rate FSK signals, using carrier frequencies between 900 and 950 MHz.
    Type: Grant
    Filed: June 30, 1995
    Date of Patent: April 27, 1999
    Assignee: Philips Electronics North America Corporation
    Inventor: Srinagesh Satyanarayana
  • Patent number: 5864585
    Abstract: A digital communication system is disclosed which is unique in that it modulates a sinusoidal carrier with a discrete cosine segment, a zero slope level segment, and combinations thereof. The discrete cosine segments may contain different time and amplitude values. The discrete cosine segments may be combined with each other or with zero slope level segments in order to effectively modulate the sinusoidal carrier. Rather than employing the use of filters for controlling instantaneous voltage changes, the present communication system forces the bit edges of the discrete cosine segments to occur at the zero slope points of a cosine wave, where no voltage changes occur. The communication system utilizes direct digital synthesis in order to create a carrier signal which closely represents sinusoidal carrier signal. The present communication system may be used in conjunction with various conventional methods such as phase-shift keying and amplitude-shift keying.
    Type: Grant
    Filed: October 7, 1996
    Date of Patent: January 26, 1999
    Inventor: David Erisman
  • Patent number: 5862456
    Abstract: A device of a vehicle for data transmission to a stationary beacon 91), which has a transceiver, comprising an on-board unit (2) with an antenna (6) for receiving a continuous signal (5), broadcast by the beacon (1), and for transmitting the received signal (5) back after modulation with a data signal (i(t)), is characterized in that the signal (7) transmitted back by the on-board unit (2) is a double-sideband signal. In that case, the on-board unit (2) can be designed as extremely simply and in the simplest case comprises a diode (9) connected to the base of the antenna (6).
    Type: Grant
    Filed: March 27, 1997
    Date of Patent: January 19, 1999
    Assignee: Robert Bosch GmbH
    Inventors: Friedrich-Wilhelm Bode, Hans-Juergen Fischer, Hans-Ulrich Rossius, Andreas Vahle
  • Patent number: 5852636
    Abstract: A method and a transmitter system is provided for modulating binary information on a frequency shift keying carrier in a very narrow band. Phase reversal keying is initially used to create a carrier. The transmitter of the present invention generates a carrier signal by modulating a reference signal and a control signal having two frequencies representing the binary data to be transmitted. The resulting phase reversal carrier signal is processed by high order filtering such that the output of the transmitter provides a frequency shift keyed carrier at very close frequencies. The resulting carrier signal may, at the receiver, be processed by very narrow band filtering so as to create a communication system which will use only a small part of the available spectrum.
    Type: Grant
    Filed: August 8, 1997
    Date of Patent: December 22, 1998
    Assignee: Serge Mathieu
    Inventors: Serge Mathieu, Dominic Tremblay
  • Patent number: 5838730
    Abstract: A wireless local area network includes a radio transmitter/receiver for transmitting and receiving in accordance with the FCC rules for the ISM band. The receiver/transmitter supports spread spectrum frequency hopping in the 2.4 GHz ISM band and can be tuned to one of e.g. 82 different frequencies spaced at 1 MHz intervals. The radio transmitter/receiver is a low cost, low power, small size unit located on a printed circuit board in a PCMCIA form factor. Third order mixers are used in combination with a switched prescaler for a low cost and compact frequency control system capable of rapid switching of the radio between transmitting and receiving functions. No special shielding is needed between the frequency control circuitry and the receiver IF circuitry.
    Type: Grant
    Filed: May 11, 1995
    Date of Patent: November 17, 1998
    Assignee: Netwave Technologies Limited
    Inventor: Peter K. Cripps
  • Patent number: 5812612
    Abstract: A transmitter which can easily suppress diffusion of a spurious signal with a simple constitution, wherein the on/off operations of the transmitting circuit and the carrier signal generating circuit are controlled by the first control signal which rises at the predetermined timing and falls at the predetermined timing, and the on/off operation of the modulator is controlled by the second control signal which gently rises at the same or later timing than the rise timing of the first control signal and gently falls at the same or earlier timing than the fall timing of the first control signal, so that a phenomenon which is similar to pulse modulation of the leaked carrier signal fc becomes hard to be generated, therefore diffusion of the spurious signal can be suppressed.
    Type: Grant
    Filed: November 17, 1995
    Date of Patent: September 22, 1998
    Assignee: Sony Corporation
    Inventor: Shin Saito
  • Patent number: 5809067
    Abstract: A computing device (100) including a wireless packet data communications modem (101) used in conjunction with a computer (103) to provide untethered access to data bases and other computer users. A method is provided for controlling data transmission and reception using the wireless packet data communications modem (101) in tandem with the computer (103). Two-way communications is achieved using a small, low-cost, light-weight wireless packet data communications modem contained in a housing, integral to a computing device, or a removable housing conforming to a PCMCIA industry standard.
    Type: Grant
    Filed: June 15, 1994
    Date of Patent: September 15, 1998
    Assignee: Motorola, Inc.
    Inventors: Gregory Funk, Ronald J. Vanderhelm
  • Patent number: 5793261
    Abstract: A digitally-controlled SAW stabilized FSK oscillator circuit having an oscillator and a single-port SAW resonator with a predetermined circuit resonant frequency and being coupled to the oscillator for establishing a first oscillator output frequency, F.sub.SAW. A bipolar transistor has at least one predetermined shunt capacitance value, C, that is placed in electrical series with the single-port SAW resonator when the transistor is in the OFF state and a closed switch that replaces the capacitance when the transistor is in the ON state to cause the first frequency, F.sub.SAW, to be generated by the oscillator when the transistor is ON and to cause a second frequency, F.sub.2, to be generated by the oscillator when the transistor is in the OFF state.
    Type: Grant
    Filed: April 10, 1997
    Date of Patent: August 11, 1998
    Assignee: RF Monolithics, Inc.
    Inventor: Harry O. Boling, III
  • Patent number: 5789991
    Abstract: A signal FSK-modulated with a binary data signal has first signal portions representing first logical level data contained in the binary data signal and second signal portions representing second logical level data contained in the binary data signal. Each of the first signal portions has a first frequency and lasts for a first time period and each of the second signal portions has a second frequency and lasts for a second time period. These first and second time periods are determined such that a number of cycles of the FSK-modulated signal appearing in each of the first time periods is equal to a number of cycles of the FSK-modulated signal appearing in each of the second time periods.
    Type: Grant
    Filed: December 20, 1996
    Date of Patent: August 4, 1998
    Assignee: Nippon Steel Corporation
    Inventor: Eiichi Ishii
  • Patent number: 5764700
    Abstract: A radio link system in which a fixed radio connection is established between two radio link terminals. The radio link terminals transmit alternately at the same radio frequency. Each of the radio link terminals includes (a) a baseband modulator in the transmitting branch for generating baseband modulation signals from a digital data stream; (b) a demodulator in the receiving branch for generating a baseband data stream by demodulating baseband signals to be received; (c) a common quadrature mixer and a local oscillator for forming an RF transmitting signal directly from the baseband modulation signals to be received directly from the RF signal to be received; and (d) a timer for connecting the radio link terminal alternately to a transmitting and receiving mode. The transmitting and receiving branches are separated at the baseband.
    Type: Grant
    Filed: June 28, 1996
    Date of Patent: June 9, 1998
    Assignee: Nokia Telecommunications Oy
    Inventor: Jarmo Makinen
  • Patent number: 5712878
    Abstract: A FSK modulator which uses the combination of a state machine and a toggle flip-flop to generate the FSK signals. The state machine has a loop having a predetermined number of states. The number of clock cycles that the state machine takes to traverse the loop depends on the state or level of the signal at the input to the modulator. The flip-flop converts the state machine output signal to a signal having a rectangular waveform.
    Type: Grant
    Filed: August 19, 1996
    Date of Patent: January 27, 1998
    Assignee: Elsag International N.V.
    Inventor: Joseph C. Nemer
  • Patent number: 5642380
    Abstract: A system for the transmission of data, and a modem for use in such a system, utilize variable shift keying (VSK), in which a data signal is modulated to form a continuous phase signal in which successive symbols are represented by successive signal segments of constant phase angle, typically or one half cycle, different symbols being distinguished by the segments being of different duration, i.e. at different frequencies. The ratios of the frequencies may be chosen to facilitate signal modulation and demodulation, and to control the frequency spectrum of the transmitted signal. Each symbol may represent one or more bits of the data signal. The lengths of half cycles used to represent different symbols may be adjusted by introducing flat peaks into the half cycles whilst maintaining uniform the profile of their flanks so as to facilitate generation and reduce zero crossing detection jitter during reception.
    Type: Grant
    Filed: June 3, 1992
    Date of Patent: June 24, 1997
    Assignee: Data Radio Inc.
    Inventor: Claude Lambert
  • Patent number: 5633898
    Abstract: A first AFC apparatus receives and detects I and Q signals from a received first FSK signal with a local osc signal; demodulates the I and Q signals; F/V-converts I or/and Q signals into a voltage; compares it with a reference; and detects a frequency deviation direction of the local osc signal from the carrier signal according to the results of comparing and the demodulating. The local osc frequency is controlled by a given amount according to the result of the frequency deviation direction detection. A second AFC apparatus receives and detects I and Q signals using a first osc signal; FSK-modulates the I and Q signals with a second local osc signal having a lower frequency than the first local osc signal; and compares the frequency of the second FSK signal and the second local osc signal to supply a demodulation result. A frequency control for the first local osc signal is obtained by an averaging circuit averaging the modulation result.
    Type: Grant
    Filed: December 21, 1994
    Date of Patent: May 27, 1997
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takaaki Kishigami, Katsuaki Abe, Masahiro Mimura, Makoto Hasegawa, Katsushi Yokozaki
  • Patent number: 5633893
    Abstract: Continuous phase modulated (CPM) signals, such as quaternary CPFSK signals, are filtered to limit their bandwidth while simultaneously minimizing the amount of amplitude modulation and intersymbol interference introduced by this filtering process. By designing a modulation filter such as a finite impulse response (FIR) filter to add only a nominal, controlled amount of amplitude modulation, high efficiency, nonlinear power amplifiers may be employed to transmit the filtered CPFSK signals. Although the filter adds a small amount of amplitude modulation and intersymbol interference, digital signal processor-based receivers satisfactorily demodulate this type of signal using sequence estimation algorithms such as the Viterbi algorithm. Thus, the filtering of CPM signals permits narrowing of the transmitted signal spectrum while managing the intersymbol interference resulting from the controlled amount of amplitude modulation added by filtering.
    Type: Grant
    Filed: September 29, 1994
    Date of Patent: May 27, 1997
    Assignee: Ericsson Inc.
    Inventors: Ross W. Lampe, Jyun-chen Chen
  • Patent number: 5623518
    Abstract: A method and apparatus for transmitting binary data trains of 0 and 1 data bits, or combinations of these data bits over a communications network. The data bits are converted into pulses whose polarity changes from pulse to pulse, so as to enable an optimal exploitation of the transmission channel with a low error rate. The pulses generated by an apparatus of the present invention have a signal shape that produces a minimum inter-symbol interference. Processing and evaluation of the transmitted pulses are performed by a processor, so that a minimal error rate is attainable even under unfavorable transmission conditions.
    Type: Grant
    Filed: April 16, 1993
    Date of Patent: April 22, 1997
    Assignee: Hani Prolectron AG
    Inventor: Peter Pfiffner
  • Patent number: 5612650
    Abstract: A microcomputer includes therein an operation control part which can be operated when a clock signal is applied thereto by an oscillation circuit. If the operation control part reads out an identification code from an EEPROM, then it switches a control signal to be given to a switching element in accordance with the levels of the respective bits. When the control signal is off, the oscillation frequency of the oscillation circuit is F1. On the other hand, if the control signal is turned on, then one terminal of a capacitor is grounded to thereby switch the oscillation frequency over to F2. The clock signal is divided by a frequency dividing circuit before it is output. The frequency of the output signal after being divided becomes f1 or f2 in accordance with the above switching and the output signal is transmitted in the form of a frequency modulation signal.
    Type: Grant
    Filed: September 13, 1995
    Date of Patent: March 18, 1997
    Assignee: Kabushiki Kaisha Tokai Rika Denki Seisakusho
    Inventors: Takashi Mizuno, Sadao Kokubu, Hisashi Aoki, Yoshiyuki Mizuno, Shinichi Koga
  • Patent number: 5602875
    Abstract: A communication system (100) encodes and decodes information utilizing at least four modulation levels for transmitting the information as symbols representing symbol bits in symbol bit positions. At least one of the symbol bit positions exhibits an error rate higher than that of another of the positions. A processor (204) encodes (702) the information into an even number of code words and transmits the code words as an interleaved data stream. The processor (204) rearranges (706, 708) the transmission order of the code word bits in a predetermined way to form a modified transmission order such that the code words are transmitted (710) with substantially equal error rates. A receiver (110) receives and demodulates (712) the interleaved data stream to derive the code word bits, and then reorders (714, 716) the code word bits to undo bit modifications resulting from the modified transmission order, thereby restoring the code words. The receiver then decodes the code words to recover the information.
    Type: Grant
    Filed: January 13, 1995
    Date of Patent: February 11, 1997
    Assignee: Motorola, Inc.
    Inventors: G. David Mantel, Gregory L. Cannon, R. Louis Breeden
  • Patent number: 5598435
    Abstract: Data are transmitted using multiple carriers modulated by quadrature amplitude modulation. In general, the carriers carry different numbers of bits, to exploit the fact that the properties of a transmission path are more favorable to carriers at some frequencies than to those at others. The bit allocation process is made closer to optimum by permitting allocation of a non-integer number of bits to a carrier. Input bits are grouped for several carriers and this binary representation is converted to a number representation in which the base of each digit corresponds to the number of points in the QAM constellation for a respective carrier (or to this number divided by a power of two).
    Type: Grant
    Filed: February 4, 1994
    Date of Patent: January 28, 1997
    Assignee: British Telecommunications public limited company
    Inventor: Richard G. C. Williams
  • Patent number: 5565745
    Abstract: A protocol for communication between devices connected via a bus having three handshake lines and at least one data line. A first device controls two of the three handshake lines, and a second device controls the third. The first device mixes toggling of the first and second handshake lines in a pattern which identifies a type of information packet. The second device polls the first and second handshake lines, and from the toggling pattern identifies the packet type. Once identified, the packet is transmitted according to a predefined format for the type. Typically, transmission of information is completed asynchronously using the handshake lines to carry request and acknowledge signals. In one embodiment, the protocol is implemented in a virtual reality system having a video game console as a first device and a head mounted display as the second device.
    Type: Grant
    Filed: January 4, 1994
    Date of Patent: October 15, 1996
    Inventors: James L. Huether, Unnikrishnan Pillai, Daniel L. Yee
  • Patent number: 5553099
    Abstract: An FSK detector circuit and method which may be utilized for the demodulation of a digital data signal from a modulated sine wave carrier signal. A simple, low parts count FSK detector is disclosed which is readily implemented as an integrated circuit for the detection of a digital data signal in wireless applications without the use of an associated phase locked loop or other frequency detection circuitry.
    Type: Grant
    Filed: February 10, 1994
    Date of Patent: September 3, 1996
    Assignee: Racom Systems, Inc.
    Inventors: Gary T. Carroll, J. Donald Pauley
  • Patent number: 5539355
    Abstract: A signal modulated by frequency-shift keying is input to a detector consisting of an instantaneous phase detection circuit that detects the instantaneous phase of the input signal, a differentiating circuit that differentiates the instantaneous phase to obtain the instantaneous frequency, and a baseband processing circuit that recovers clock and data signals from the instantaneous frequency. To detect the instantaneous phase, the instantaneous phase detection circuit compares the logic levels of the input signal and a clock signal, and filters the resulting bit stream with a digital low-pass filter. The detector consists entirely of digital circuits that are well suited for large-scale integration.
    Type: Grant
    Filed: June 2, 1995
    Date of Patent: July 23, 1996
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Seizo Nakamura
  • Patent number: 5533062
    Abstract: A frequency shift keyed receiver (214, 220, 218) estimates a carrier frequency and demodulates (1020) a symbol value associated with the carrier frequency. During symbol intervals, the receiver (214, 220, 218) receives a radio signal including symbol values (502-518) corresponding to predetermined frequency offsets (604, 606) from a carrier frequency. The radio signal is digitized (1008) during a symbol interval, and then converted (1010) into a frequency domain signal. The frequency domain signal is stored (1012), and additional symbol intervals are converted to obtain a plurality of frequency domain signals, which are processed to generate (1016) a composite frequency domain signal (702, 704). A windowing function (706) of predetermined shape is convolved (1018) with the composite frequency domain signal (702, 704) to locate a frequency distribution therein that corresponds to the predetermined frequency offsets (604, 606).
    Type: Grant
    Filed: October 3, 1994
    Date of Patent: July 2, 1996
    Assignee: Motorola, Inc.
    Inventors: Joseph C. Liberti, Jr., Douglas I. Averst, Tony R. Branch, Stephen R. Carsello
  • Patent number: 5532654
    Abstract: An FSK modulator including an amplifier for oscillation has a surface acoustic wave resonator connected in series with a switching circuit formed without a variable-capacity diode but including a semiconductor switch and one or more fixed-capacity capacitors. When an input signal is received, the switch causes a capacitor or combination of capacitors to become connected in series with the surface acoustic wave resonator, providing oscillations with two frequencies to effect FSK modulation.
    Type: Grant
    Filed: June 1, 1995
    Date of Patent: July 2, 1996
    Assignee: Murata Manufacturing Co., Ltd.
    Inventors: Tsutomu Ieki, Yasuhiko Hirano
  • Patent number: 5513219
    Abstract: Applicant's invention includes an apparatus and associated method for transmitting information at a high rate using an undermodulated frequency shift keyed signal. The transmission rate is independent of the data content and the system requires no zero crossing detectors. The demodulator combines non-linear processing circuitry with a conventional demodulator.
    Type: Grant
    Filed: August 26, 1994
    Date of Patent: April 30, 1996
    Assignees: Compaq Computer Corporation, Ronald E. Ham
    Inventor: Ronald E. Ham
  • Patent number: 5499270
    Abstract: The spectral encoding-decoding system and method are for encoding a sequence of N data bits where N is a predetermined integer, into an information signal to be transmitted on a communication medium, and for decoding the information signal transmitted on the communication signal into an estimated sequence of N data bits. The system comprises an encoder and a decoder. The encoder receives the sequence of N data bits, encodes the sequence into the information signal, and emits the information on the communication medium. The decoder receives the information signal transmitted on the communication medium, decodes the information signal and transmits the estimated sequence of N data bits. The method corresponds to the operations performed by the system.
    Type: Grant
    Filed: August 1, 1994
    Date of Patent: March 12, 1996
    Assignee: Pierre Charrier
    Inventors: Lascar B. Popovici, Daniel Vliegen
  • Patent number: 5457708
    Abstract: The disclosure relates to methods and apparatus for separating radio signals arriving from different directions and for multiplexing signals intended for receivers dispersed in different directions. The methods and apparatus employ a plurality of antennas with spacing and individual feedline characteristics designed so that a modulation is imparted to each of a plurality of incident signals, for receiving antennas, and radiated signals for transmitting antennas, the modulation level of each signal being determined by the direction of propagation of the signal and by the spacing between antenna pairs. Accordingly, the orientation of lines connecting pairs of antennas as well as the spacing between antennas are set to inhibit the modulation in a particular direction, or to strip a particular modulation off a signal incident from a selected direction.
    Type: Grant
    Filed: July 19, 1993
    Date of Patent: October 10, 1995
    Inventor: Elie J. Baghdady
  • Patent number: 5446421
    Abstract: A data transmission system includes a source of a data signal and a modulator, responsive to the data signal, producing a first modulated signal representing the data signal and a second modulated signal representing a signal 180 out-of-phase with the data signal. The first and second modulated signals are transported via a transmission channel. A first demodulator demodulates the transported first modulated signal and a second demodulator demodulates the transported second modulated signal. A subtractor, responsive to the first and second demodulators, produces a signal representative of the data signal.
    Type: Grant
    Filed: February 2, 1994
    Date of Patent: August 29, 1995
    Assignee: Thomson Consumer Electronics, Inc.
    Inventor: David L. Kechkaylo
  • Patent number: 5414736
    Abstract: An FSK data receiving system is provided which is capable of constituting a direct-conversion receiver suitable for realizing an integrated circuit, is capable of decoding in a wide receiving band width, and is capable of realizing a small-sized and less-electric power consumption data receiving. An FSK-modulated local oscillator signal 3 is applied to a local oscillator 2, and there is provided a decode circuit 15 which obtains the decode signal 14 by judging whether the FSK-modulated frequency deviation of the carrier wave signal 1 is a positive deviation or a negative deviation on the basis of a comparison result of a voltage change in a frequency-voltage conversion circuit 16 for a base-band signal 8; i.e. the output signal of a frequency mixer 6.
    Type: Grant
    Filed: August 7, 1992
    Date of Patent: May 9, 1995
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Makoto Hasegawa, Kazuaki Takahashi, Masahiro Mimura, Kazunori Watanabe, Katsushi Yokozaki, Hiroyuki Harada
  • Patent number: 5398031
    Abstract: A DTMF signal generating circuit for producing output of a selection signal having a frequency corresponding to a signal entered from push buttons. A high frequency oscillation signal output from an oscillatory circuit are delivered to both a first frequency dividing circuit for dividing high frequency signals by a first dividing ratio and a second frequency dividing circuit for dividing high frequency signals by a second dividing ratio, thereby producing two kinds of divided signals each of which has its own predetermined frequency. A fractional frequency division is then accomplished by switching from an output of a first frequency dividing circuit to an output of a second frequency dividing circuit at a predetermined timing. The signals output form the switch are then counted by a ROM address counter, producing an output of an address value signal.
    Type: Grant
    Filed: August 18, 1992
    Date of Patent: March 14, 1995
    Assignee: Rohm Co., Ltd.
    Inventor: Mitsuro Saji