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457 results about "Spread spectrum modulation" patented technology

Spread Spectrum Modulation. A collective class of signaling techniques are employed before transmitting a signal to provide a secure communication, known as the Spread Spectrum Modulation.

Marine asset security and tracking (MAST) system

Methods and apparatus are described for marine asset security and tracking (MAST). A method includes transmitting identification data, location data and environmental state sensor data from a radio frequency tag. An apparatus includes a radio frequency tag that transmits identification data, location data and environmental state sensor data. Another method includes transmitting identification data and location data from a radio frequency tag using hybrid spread-spectrum modulation. Another apparatus includes a radio frequency tag that transmits both identification data and location data using hybrid spread-spectrum modulation.
Owner:UT BATTELLE LLC +1

Signal detector employing a Doppler phase correction system

A spread spectrum detector employs a Doppler phase correction system that improves correlation of pseudo-noise (PN) codes to a received spread spectrum signal by combining phase shifts, in the time domain, to correlation values that compensate for the Doppler shift error that is inherent in the signal and that is imposed upon the signal by movement between the signal source and receiver. In architecture, the Doppler phase correction system includes a receiver to receive a spread spectrum modulated signal having the Doppler shift error, a multiplier to produce a plurality of complex first correlation values based upon the signal and a code. A phase shifter generates a plurality of complex second correlation values respectively from the first correlation values. The second correlation values being phase shifted by respective different amounts from corresponding first correlation values, so that the second correlation values exhibit less of the Doppler shift error than the first correlation values. The phase shifter can be implemented with a look-up table that stores a plurality of phase shift values, a counter that produces indices for the look-up table, and a multiplier that multiplies the phase shift values that are output from the look-up table with the first correlation values to produce the second correlation values. Finally, a combiner, such as an integrator, combines, or integrates, the second correlation values to derive a third correlation that indicates a degree of correspondence of the code with the signal.
Owner:CSR TECH INC

Apparatus for adaptive forward power control for spread-spectrum communications

A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units. The signals transmitted between the base station and subscriber unit use spread-spectrum modulation. The improvement apparatus for adaptive forward power control (APC) from a base station (BS) to a subscriber unit (SU), includes sending from the base station, using spread-spectrum modulation, a BS-spreading code on a forward channel. The subscriber unit despreads the BS-spreading code on the forward channel as a despread signal, determines a first power level Pd which includes power of the despread signal plus noise and a second power level PN, which includes despread-noise power. The subscriber unit determines a first error signal e1, from the first power level Pd, the second power level PN, and a required signal-to-noise ratio SNRREQ for service type, and a second error signal e2, from a measure of total received power Pr and an automatic gain control (AGC) set point Po. The subscriber unit forms a combined error signal from the first error signal e1, the second error signal e2, a first weight a1 and a second weight a2, and hard limits the combined error signal to form a single APC bit. The APC bit is transmitted to the base station. In response to the APC bit, the base station adjusts transmitter power to the subscriber unit.
Owner:INTERDIGITAL TECH CORP

Apparatus for adaptive reverse power control for spread-spectrum communications

A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units. The signals transmitted between the base station and subscriber unit use spread-spectrum modulation. The improvement method for adaptive reverse power control (APC) from a subscriber unit (SU) to a base station (BS), comprises the steps of sending from the subscriber unit, using spread-spectrum modulation, a SU-spreading code on a reverse channel. The base station despreads the SU-spreading code on the reverse channel as a despread signal, determines a first power level Pd which includes power of the despread signal plus noise and a second power level PN, which includes despread-noise power. The base station determines a first error signal e1, from the first power level Pd, the second power level PN, and a required signal-to-noise ratio SNRREQ for service type, and a second error signal e2, from a measure of total received power Prt at the base station, and an automatic gain control (AGC) set point Po. The base station forms a combined error signal from the first error signal e1, the second error signal e2, a first weight a1, and a second weight a2, and hard limits the combined error signal to form a single APC bit. The APC bit is transmitted to the subscriber unit. In response to the APC bit, the subscriber adjusts transmitter power to the base station.
Owner:INTERDIGITAL TECH CORP

Demodulation of multiple signals

A demodulation system for receiving and demodulating multiple modulated signals, including a first modulated signal having a first bit rate and / or a first modulation format and a second modulated signal having a second bit rate and / or a second modulation format. The demodulator demodulating the first modulation format modulated signal provides a cross-correlated demodulated in-phase and quadrature-phase baseband signal and the demodulator demodulating the second modulation format modulated signal provides a second demodulated baseband signal. A selector selects either the first or the second or both bit rate and / or modulation format demodulated baseband signals. In an alternative embodiment two demodulators are implemented for the demodulation of multiple signals. In certain embodiments the demodulator demodulating the first bit rate modulated signal or the second bit rate modulated signal is comprised of bit rate switchable filters and / or mis-matched filters which are mismatched to that of the filters of the modulator of the first or the second bit rate modulated signal. In some of the applications the first or the second modulated signal is an Orthogonal Frequency Division Multiplexed (OFDM) modulated signal and / or a spread spectrum modulated signal and / or Phase Shift Keying (PSK) modulation, or a Quadrature Modulation (QM), or a Frequency Modulation (FM) modulated signal. In certain implementations and applications the demodulator is used for demodulation of Gaussian Minimum Shift Keying (GMSK) modulated signals and spread spectrum modulated signals.
Owner:WI LAN INC

Physically secure digital signal processing for wireless M2M networks

A method and apparatus for physically secure communication over machine-to-machine (M2M) networks is claimed, through the use of frequency-hop and random access spread spectrum modulation formats employing using truly random spreading codes and time / frequency hopping and receiver selection strategies at the transmitters in the M2M network, blind signal detection and linear signal separation techniques at the receivers in the M2M network, completely eliminating the ability for an adversary to predict and override M2M transmissions. Additional physical security protocols are also introduced that allow the network to easily detect and identify spoofing transmissions on uplinks and downlinks, and to automatically excise those transmissions as part of the despreading procedure, even if those transmissions are received at a much higher power level than the intended transmissions. Extensions to weakly and strongly macrodiverse networks are also described, which provide additional efficiency and security improvements by exploiting the route diversity of the network.
Owner:AGEE BRIAN G

Transponder Satellite Communication Navigation and Positioning System

A transponder satellite communication navigation positioning system relates to the field of space technology. The system is equipped with a high-precision atomic clock at a ground communication navigation reference station, and the satellite orbit data is given by the satellite orbit determination system; the satellite integrity is given by the monitoring system The data forms the navigation message, and the ranging code composed of pseudo-random codes forms an integrated baseband signal, which is modulated by spread spectrum to form a navigation signal carrier, which is transmitted through the antenna and forwarded by 3 to 9 satellites in a certain geometric distribution in space The device converts the frequency and forwards the downlink, and broadcasts the signal to the coverage area; the ground user terminal receiving device receives the navigation signal carrier, and despreads and demodulates it to obtain the navigation data, thereby determining the position, speed and time of the user terminal receiving device. The invention has the advantages of low investment, guaranteed accuracy, convenient and flexible system maintenance and management, and dual functions of navigation and communication, so that the navigation and positioning accuracy can reach meter-level precision or be better than meter-level precision.
Owner:NAT ASTRONOMICAL OBSERVATORIES CHINESE ACAD OF SCI +1

Non-filter D type audio amplifier based on chaotic spread-spectrum modulation technique

The invention discloses a no-filter D-class audio amplifier based on the chaos frequency spreading modulating technology, mainly comprising a chaos frequency spreading triangle-wave generator, a comparator and a full-bridge output-stage circuit, wherein the chaos frequency spreading triangle-wave generator is used for generating chaos frequency spreading triangle-wave signals. When an audio signal is sent, the comparator is used for comparing voltage values of the audio signal and the chaos frequency spreading triangle-wave signal to output a square wave signal with changeable dutyfactor. After the power of the square signal is amplified by the full-bridge output-stage circuit, the square signal is outputted to a loudspeaker and recovered to the audio signal above the loudspeaker. The invention has the following advantages that the electromagnetic interference of the output signal of the D-class amplifier is effectively inhibited under the condition of no filter, the integration is easy, the chip area is saved, and the linearity of the chaos frequency spreading triangle wave used as the PWM carrier wave is not influenced by the modulation signal (chaos sequence) is guaranteed, thus, the distortion factor of the output audio signal is not influenced.
Owner:BEIHANG UNIV

Watermark Embedding

According to an inventive scheme for introducing a watermark into an information signal, the information signal is at first transferred from a time representation to a spectral / modulation spectral representation). The information signal is then manipulated in the spectral / modulation spectral representation in dependence on the watermark to be introduced to obtain a modified spectral / modulation spectral representation, and subsequently an information signal provided with a watermark is formed based on the modified spectral / modulation spectral representation. An advantage is that, due to the fact that the watermark is embedded and / or derived in the spectral / modulation spectral representation or range, traditional correlation attacks as are used in watermark methods based on a spread-band modulation cannot succeed easily.
Owner:FRAUNHOFER GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG EV

Method and system for controlling radio controlled devices

The present invention is a method and system for controlling a RC device via a secure radio link. In one embodiment of the invention, spread spectrum modulation may be employed which may provide a digital radio frequency (RF) link between a controller and a RC device. A controller may be coupled with a transmitter module and a radio controlled device may be coupled with a receiver module in accordance with the present invention to provide an add-on upgrade capability. The method and system for controlling a RC device may also include error detection and correction, interpolation of lost packets, failsafe technology and force-feedback telemetric technology to further enhance the user experience with radio controlled devices.
Owner:HORIZON HOBBY
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