Class 375/337 - Separate mark and space channels

Subclass of Class 375 - Pulse or digital communications
Definition: Subject matter in which one frequency is received over one
No. of patents: 35
Last issue date: 07/10/2007

Number	Title	Issue Date
7243291	System and method for communicating image data using error correction coding A method for communicating video data is provided that includes generating a plurality of error correction code bits and positioning the error correction code bits in a stream of image data such that the stream of image data is encoded. The stream of image data may ...	07/10/2007
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 line level for a logical zero for a total of four logic levels. The e...	05/22/2007
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”) preamble. The present inventive system and method uses information from co...	01/02/2007
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 correctly carries out measurement of an error ratio or jitter or wander ...	08/24/2004
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 switch-on, the receiver is operated as a zero IF receiver in order to dete...	03/16/2004
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 respective slave stations to the master station, the master stat...	08/06/2002
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 to the two conditions of the binary signal. One of the osci...	09/27/1994
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 with a primary channel QAM modem at data rates up to 19.2 k...	05/25/1993
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 band and a lower side band; electric powers of the signal...	01/14/1992
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 response of duration comparable with the symbol period of...	11/12/1991
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 received is made by first comparing the energy on each mark and...	06/19/1990
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 less. The FSK demodulator includes a digital phase locked l...	04/25/1989
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 of a differential stage, a filter and a full-wave rectifi...	03/21/1989
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 an optical detector (31) carries out optical heterodyne or...	07/19/1988
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 character frequencies in a signal transmission. The outputs of the...	02/16/1988
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 signal frequency Wqt as one of the summed signal components ...	12/22/1987
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 signal causes the generation of two of three possible transmi...	03/18/1986
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 rectified separately and the result summed. The summed outp...	02/04/1986
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 Fa and Fb. On a piezoelectric crystal, is produced two surface wave filtering units, each comprisi...	09/24/1985
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 (fc &#b1;Ɗf), where Ɗf is the deviation and fc the carrier, and a second input for a local oscillator (20...	06/11/1985
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 passenger doors of a vehicle station. A sampling of the signal ...	02/05/1985
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 space or binary "0" frequency be present for a mark signal ...	08/07/1984
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 the user. The identifier transmits a plurality of radio fre...	07/10/1984
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 while the companion transmitter is transmitting digital d...	10/11/1983
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 the input ends and each having a band-pass filter, an ampli...	10/19/1982
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 are taken in relation to the known frequency of that sign...	06/01/1982
4291275	Frequency demodulation system A demodulator for demodulating an encoded signal comprising first and second predetermined patterns of contiguous signal segments of frequencies f1 and f2. A first signal processing means comprises first correlation means including a...	09/22/1981
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 of "δ" bits, also modulates the frequency of the carrier....	09/15/1981
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 signal as received clocks a flip-flop. The phase shifted sign...	03/03/1981
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 signals in phase-lock with the received signal, the system mi...	01/27/1981
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 translated mark and space tones. An additional set of cross co...	11/18/1980
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 between the two frequencies of the frequency-shift-keyed sig...	05/22/1979
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 predetermined bandwidth of the demodulation channel pair output...	10/18/1977
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. The method utilizes two synchronization channels, selecti...	03/08/1977
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 separated by corresponding band pass filters. After separation, ...	03/30/1976

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Class 375/337 - Separate mark and space channels