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7221711 Multilevel data encoding and modulation technique  
The multilevel data encoding and modulation technique uses a pair of complementary logic sets. In its most basic form, the sets are binary sets each containing a line level for a logical one and a...
7158588 System and method for obtaining accurate symbol rate and carrier phase, frequency, and timing acquisition for minimum shift keyed waveform  
The present invention relates generally to communication systems, both wired and wireless, employing a continuous phase modulation (“CPM”) waveform with a minimum shift keying (“MSK”)...
6782353 Instrument for measuring characteristic of data transmission system with high accuracy and clock reproducing circuit used therefor  
The present invention provides a measuring device which extracts, from an inputted data signal, a clock signal in which there is little internal occurrence of absence or phase fluctuations, and...
6707858 Low IF receiver  
A low IF receiver frequency translates an input signal in quadrature related mixers, filters in respective low pass channel filters, and derotates to produce a wanted signal and its image. At...
6430218 Communication control apparatus  
In a communication control apparatus in which the master station transmits a batch transmission frame to a plurality of slave stations and individual response frames are transmitted from the...
5351273 Process and system for the transmission of a signal  
A system for the transmission of a signal having at least two conditions includes a device for emitting signals that has two oscillators whose signal amplitudes are alternately switched according...
5214641 Mixed analog digital secondary channel FSK modem  
A secondary channel FSK modem for use with primary channel QAM modems is described. The present invention is a fully integrated 75 bps narrowband secondary channel FSK modem which may be utilized...
5081644 Spread spectrum receiving device  
A spread spectrum communication (SSC) receiving device is disclosed, in which a received signal consisting of an SSC signal in the SSC signal band and disturbance wave is divided into an upper side...
5065409 FSK discriminator  
The outputs of two filter channels for accepting two keying frequencies are compared to produce the output. Each channel uses finite impulse response transversal filters; preferably with an impulse...
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...
4825452 Digital FSK demodulator  
The present invention provides a digital frequency shift keying (FSK) demodulator circuit which receives a hard-limited FSK input signal and recovers the modulating baseband signal at 300 baud or...
4814717 FSK frequency discriminator for a coherent optical transmission system  
A frequency discriminator for an optical coherent transmission system, wherein FSK signals having the frequencies F(1) and F(2) are processed. The discriminator comprises a first series arrangement...
4759080 Coherent optical communication system with FSK heterodyne or homodyne detection and little influence by distortion of a modulated optical signal  
A laser (21) is frequency modulated by an electrical modulating signal of a bit rate into a modulated signal of a first and a second modulated frequency. A combination of an optical mixer (27) and...
4726041 Digital filter switch for data receiver  
A digital filter switch for use with a data receiver incorporates first and second squaring units connected to the outputs of first and second band-pass filters tuned to the separation and...
4715045 System protocol for composite shift keying communication system  
A system protocol for the composite shift key communication of binary signals in which a transmitting transceiver transmits a first summed signal having a first qualifying signal at a qualifying...
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...
4568882 Digital FSK demodulator circuit  
An FSK demodulator is disclosed suitable for use in a CMOS IC using switched capacitor circuits. The mark and space filters are each modified to produce sine and cosine outputs. These outputs are...
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...
4523324 Direct modulation FM data receiver  
A direct modulation FM data receiver including a mixer (14) having a first input for receiving a directly modulated FM signal (f c ±Δf), where Δf is the deviation and f c the carrier, and a...
4498198 Binary signal decoding apparatus and method  
An apparatus and method is provided for decoding a transmitted comma free coded signal, having a plurality of bits and two message frequencies, and suitable for application in controlling the...
4464756 System for error detection in frequency shift keyed signals  
An improved binary signal discrimination system for demodulating FSK transmitted signals is disclosed which requires that both the mark or binary "1" signal frequency and the complementary of the...
4459474 Identification system with separation and direction capability and improved noise rejection  
An electronic identification system having a portable identifier with the ability to transmit by radio or audio signal the contents of an included memory upon interrogation or command to identify...
4409593 Threshold-less collision detection and bit arbitration in a CFSK data system  
In a chirped-frequency-shift-keyed data system, in which a plurality of stations each contain a data transmitter and a data receiver constantly monitoring a common system communications medium even...
4355407 Device for disconnecting the receiver in case of a small signal-to-noise ratio for a digital-modulated radio system  
Rapid disconnection of a receiver in response to a small signal-to-noise ratio is provided in that in the receiver there is arranged a FSK demodulator having two channels connected in parallel at...
4333150 Signal receiving apparatus and method  
A signal receiving apparatus and method are provided to decode an input signal to determine the presence of at least one desired frequency component in that input signal. A number of signal samples...
4291275 Frequency demodulation system  
A demodulator for demodulating an encoded signal comprising first and second predetermined patterns of contiguous signal segments of frequencies f 1 and f 2 . A first signal processing means...
4290140 Combined coherent frequency and phase shift keying modulation system  
A system of modulation and demodulation for the transmission of binary data in the presence of multipath. The binary data modulates the phase of the carrier and the same binary data, after a delay...
4254503 Radio receiver for tone modulated signals  
A radio receiver for frequency modulated (FM) tones. Received signals are split and one split portion of the signal is phase shifted relative to the other and mixed with a local oscillator. The...
4247943 Piecewise coherent, combined frequency and phase-shift-keyed signal demodulator  
A system for demodulating piecewise coherent, combined frequency and phase-shift-keyed signals that are modulateed by orthogonal or biorthogonal code words. Rather than maintain local reference...
4234852 Coherent frequency shift key demodulator  
Disclosed is a frequency shift key demodulator for the coherent detection of both mark and space tones. Cross coupled phase locked loops lock onto and track the difference in frequency between...
4156194 Frequency-shift-keyed receiver  
Frequency-shift-keyed signals are detected by a receiver having an input which supplies the received signals to first and second mixers. A local oscillator produces signals at a frequency midway...
4054842 Channel gain imbalance compensation for FSK demodulator  
Channel gain imbalance in a FSK demodulator for receiving binary data is ameliorated by developing D. C. compensating signals indicative of the imbalance through the energy contained within a...
4011511 Frequency-shift digital data link and digital frequency detection system  
In a digital data link system which transmits and receives frequency-shift keyed digital data over mark/space frequency channels, the invention enhances system performance in the presence of noise....
3947769 Threshold correction system in FSK transmissions  
A demodulator produces mark and space signals in response to mark and tone signals received from a radio receiver. The signals after detection are in the form of characteristic tones and are...
3921075 Radio teletype detector circuit  
Apparatus for detecting the output signals of a frequency-shift-keying receiver wherein identical filters are used for discriminating each of the two frequency signals to reduce the susceptibility...
3858117 RADIO TELETYPE DETECTOR CIRCUIT  
Apparatus for detecting the output signals of a frequency-shift-keying receiver wherein identical filters are used for discriminating each of the two frequency signals to reduce the susceptibility...
3832637 FSK MODEM  
A low-speed FSK data modem. A crystal-controlled oscillator drives a ripple-carry binary-counter. The intermediate outputs of the counter are selectively connected to four NAND-gates which decode...
3737778 DEVICE FOR THE TRANSMISSION OF SYNCHRONOUS PULSE SIGNALS  
A receiver for a synchronous pulse signal formed with the clock, carrier, and shift frequencies having mutual ratios of integers. The receiver has two channels controlled by a clock pulse generator...
RE27595 Title is not available  
3636257 DIGITAL PULSE IDENTIFICATION SYSTEM  
A frequency shift digital communications system has two band-pass filters for passing mark-space signals in two different channels with means for selectively switching either filter to pass one of...
3614639 FSK DIGITAL DEMODULATOR WITH MAJORITY DECISION FILTERING  
A digital FSK demodulator including frequency detecting circuits, temporary storage, and a majority detector. A plurality of the most recent data bits from the frequency detecting circuits are...
3551889 REMOTE SIGNALING OF CONTROL SIGNALS  
3519847 CIRCUIT ARRANGEMENT FOR DEMODULATING FREQUENCY SHIFT KEYED BINARY SIGNALS  
3507997 FREQUENCY-SHIFT TELETYPEWRITER  
3474341 FREQUENCY SHIFT DETECTION SYSTEM  
3470536 FREQUENCY SENSITIVE APPARATUS  
3383600 Binary radio receiving system  
3349371 Quaternary decision logic  
3348153 Frequency-shift receiver insensitive to distortion and selective fading  
3339143 Selective receiver for communication by phase shift  
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