Matches 101 - 150 out of 213 < 1 2 3 4 5 >
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5612650 Transmitting device for a frequency modulated digital transmission signal  
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...
5602875 Method and apparatus for encoding and decoding information in a digtial communication system  
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....
5598435 Digital modulation using QAM with multiple signal point constellations not equal to a power of two  
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...
5553099 FSK detector for determining an increasing time period between adjacent pulses of an FSK modulated square wave pulse train  
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...
5539355 Frequency-shift-keying detector using digital circuits  
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...
5532654 FSK modulator using saw resonator with switchable capacitors  
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...
5533062 Method and apparatus for carrier tracking and demodulation  
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...
5513219 Apparatus and method for transmitting information with a subminimally modulated transmission signal  
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...
5499270 Spectral encoding-decoding system and method thereof  
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...
5457708 Method and apparatus for signal modulation and detection  
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...
5446421 Local oscillator phase noise cancelling modulation technique  
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...
5414736 FSK data receiving system  
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...
5406584 Time shift keying digital communications system  
A digital modulation technique is disclosed which is unique in that it does not utilize fixed time slots for varying the characteristics of an electromagnetic carrier signal, but actually uses...
5398031 DTMF signal generating circuit  
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...
5386202 Data communication modulation with managed intersymbol interference  
A communication system (10) includes a modulation section (12) and a demodulation section (14). The modulation section (12) performs frequency modulation in accordance with a frequency trajectory...
5382924 Continuous phase frequency shift keying modulator  
A modulator is adapted for use in a transmitter of an information transmission signal in which the information is in the form of a frequency shift keyed code. The signal is centered on a fictional...
5377229 Multi-modulation scheme compatible radio  
A transceiver compatible with both wide channel constant envelope 4 level FSK FM modulation and narrow channel π/4 differential QPSK linear modulation allows compatible interaction between...
5365548 Digital FSK transmitter  
A digital FSK transmitter utilizing a clock feedback signal driving an accumulator to operate a pair of registers having a pair of preset numbers stored therein to selectively add said numbers...
5363409 Method and system for multiplexed data transmission from hazardous environments  
A three frequency system employs frequency shift keying (FSK) to transmit digital data from a plurality of non-stationary objects such as fuel trucks connectable to a plurality of transmit...
5361046 Modulator having fractional sample/symbol time  
A modulator capable of providing a fractional sample or symbol 995486 time employs a decimation counter (23) responsive to a clock having a frequency equal to M/N×(data symbol clock), where M is...
5321729 Method for transmitting a signal  
In a method of transmitting a signal wherein the signal is partitioned into windows comprised of overlapping blocks with each block containing a partial signal. The partial signal in each block is...
5295160 Apparatus for FM-modulation of digital signals  
One of a reference phase signal and an orthogonal phase signal is inverted to provide an inverted phase signal. when an arrangement of a local frequency is the same between transmitting and...
5289141 Method and apparatus for digital modulation using concurrent pulse addition and subtraction  
A method and apparatus for generating an output signal (616) having a pre-determined frequency shift relative to the frequency of a reference signal from a reference frequency generator (202)...
5265126 Voice recording and reproducing apparatus having perpendicular carrier modulation  
A voice signal is modulated using two carriers which are perpendicular to each other. The modulated signal is supplied to a low-pass filter, and then sampled. The sampled data are encoded, and then...
5222076 Data communication apparatus and method with low power standby mode  
An apparatus and method for communication of data, the apparatus including a transmitter operable to transmit a first signal at a first frequency and a second signal at a second frequency. The...
5208835 Automatic frequency control system and method for frequency-shift-key data transmission systems  
The present invention provides a system and method of automatic frequency control (AFC) in a frequency-shift-key (FSK) data transmission system that allows a receiver to be used that has a...
5073903 Information transmission arrangement using frequency modulation  
A control circuit (10) controls a voltage controlled oscillator (15) to cause the signal at the output of the oscillator to have slopes of frequency variation in accordance with biphase encoded...
5057796 Digital frequency modulation system in which high and low frequency portions are processed separately  
In a frequency modulation system, a modulating signal is split into its low-frequency and high-frequency components. The low frequency component is used to modulate a carrier signal by conventional...
5055659 High speed system for reading and writing data from and into remote tags  
A system for reading from and for writing data into electronic tags which may be associated with objects which are moving with respect to an interrogator, or may be located in fixed positions in...
4962496 Transmission of data via power lines  
A method for transmitting data in the form of a sequence of data words according to PLBus communications protocol in a channel (20) carrying data transmitted, according to a different protocol, in...
4935940 Interference-proof reception of radio signals using frequency hopping techniques  
Two interference-proof techniques are shown for detecting binary radio sils transmitted by frequency hopping techniques. In the first, the decision as to which type of binary signal is being...
4866771 Signaling system  
Periodic components of a data signal are generated from a periodic original signal in a manner to cause the periodic components to represent not only the data but also information about...
4748640 Digital circuit with band limiting characteristics for modem  
The input digital signal is applied to a transition detector which causes an up/down counter to increment or decrement each time a transition is detected. The output of the counter is utilized to...
4745628 Symbol generator for phase modulated system  
A symbol generator is provided for generating a filtered analog waveform for use in phase modulating a carrier. A memory (30) is provided for storing predetermined waveform segments. The waveform...
4694471 Digital data communicating  
A digital data communications system transmits digital data over a telephone line using frequency multiplexing for the different channels. Each channel includes a receiver and a transmitter coupled...
4682344 Rf fsk transmitter  
An improved transmitter circuit for rf modems usable for communication in local area computer networks is provided. The transmitter circuit includes a digital/analog conversion circuit for...
4635278 Autoregressive digital telecommunications system  
In a digital communications system, one of two tones is selected for each bit, a first tone for a "0" and a second tone for a "1"; the tones are unique for each bit. The tones for all of the bits...
4627078 Data communication system  
A system for communicating digital data over a limited bandwidth transmission link, including a transition detector for detecting transitions in the binary logic state of an input digital signal...
4625318 Frequency modulated message transmission  
A data signal is encoded as frequency modulation by selecting carrier sources of different phases in response to data signals and filtering the resultant wave to produce an output deviating from...
4606049 Remote transmitter control system  
A remote transmitter system including a control station and a remote trantter station. The control station includes a variable frequency oscillator, a modulator, a parallel to series digital data...
4599583 Mixed dual frequency generating system  
A mixed dual frequency generating system for generating a digital FSK signal or a signal including two mixed frequencies includes a ROM which stores in consecutive addresses sampled data obtained...
4596022 FSK data communication system  
A system for communicating digital data over a limited bandwidth transmission link, including a transition detector for detecting transitions in the binary logic state of an input digital signal...
4583090 Data communication system  
A data communication system for general purposes having a new ternary carrier frequency shift keying (TCSK) signal. The system is applied to a utility load control by transmission of a sub-carrier...
4580276 System and method for transporting data  
A private local area network (LAN) is created for use with a variety of transmission media for the purpose of exchanging data preassigned addresses, and control signals according to simplified...
4578798 Method for communicating binary data using modified frequency shift keying techniques  
A method for communicating binary data using modified frequency shift keying techniques generally includes the steps of selecting a first bit count representative of a first untranslated frequency...
4578796 Programmable multiple type data set  
A digital processor based voiceband modem that provides computers and terminals access to telephone lines and performs line control functions to originate, answer and terminate data calls in...
4577333 Composite shift keying communication system  
A Composite Shift Keying (CSK) modulation technique is described which provides enhanced error detection capability in a noisy transmission medium, such as an AC power line. A modulating binary...
4556866 Power line carrier FSK data system  
A frequency shift keyed (FSK) data transmission system utilizes existing power lines to transmit data by superimposing a high frequency FSK signal on the power line carrier. A transmitter includes...
4543547 Demodulation filter for a signal modulated in binary frequency manner  
The invention relates to a filter for demodulating signals modulated in frequency in binary manner by the switching of two frequencies F a and F b . On a piezoelectric crystal, is produced two...
4528675 FSK modem for bidirectional loop communications system  
A modem which utilizes a method and means for coding a data signal for transmission and reception which includes the steps of generating a prefix signal which is a train of pulses at a multiple or...
Matches 101 - 150 out of 213 < 1 2 3 4 5 >