Abstract: A transmitter for generating a radio frequency, RF, transmit signal is provided. The transmitter includes signal generation circuitry configured to generate, based on a sequence of first control words each indicating a respective frequency shift with respect to a target frequency of the RF transmit signal, a RF carrier signal with sequentially varying frequency over time in order to frequency spread the RF transmit signal. Further, the transmitter includes modulation circuitry configured to generate the RF transmit signal by modulating the RF carrier signal with a modulation control signal. The transmitter additionally includes modification circuitry configured to generate the modulation control signal by modifying, based on the sequence of first control words, phase information of a baseband signal bearing information to be transmitted or phase information of a signal derived from the baseband signal in order to frequency de-spread the RF transmit signal.

Abstract: A configuration to determine a timing offset between a first wireless device and a second wireless device in order to synchronize timing between the first wireless device and the second wireless device. The apparatus determines a timing offset between a first wireless device and a second wireless device based on at least one transmission received from the second wireless device. The apparatus determines a location of a target device based at least on the at least one transmission from the second wireless device and the timing offset between the first wireless device and the second wireless device.

Abstract: A method of positioning using a shortest path based on a synthesized wideband channel estimate is described. In some embodiments, a method is disclosed, comprising: distributing an uplink schedule to a plurality of synchronized nodes; continuously capturing a reference signal across a plurality of carrier frequencies until frequency coverage for the synthetic wide band is achieved; removing frequency offset; calculating a plurality of channel estimates for the captured reference signal; aligning the plurality of channel estimates; combining the plurality of channel estimates to construct a single channel estimate of the synthetic wide band; deriving a shortest delay for the received reference signal; and using the derived shortest delay to estimate a time of arrival and thereby determine an estimated location.

Abstract: A method for providing digital communication over an acoustic channel is disclosed. The method includes dividing an operating frequency band of the acoustic channel into multiple adjacent non-overlapping subbands of an equal bandwidth, selecting subbands based on a symbol to be transmitted, generating a signal with linear frequency modulation in each of the selected subbands, combining the signals with linear frequency modulation, and transmitting the combined signals to the acoustic channel through an acoustic system, wherein slopes of linear frequency modulation for the signals with linear frequency modulation are equal.

Abstract: Communications method and apparatus include encoding information into a high-peakedness designed pulse train, converting the designed pulse train into a low-peakedness signal suitable for modulating a narrowband carrier to generate a physical communication signal with desired spectral and temporal properties, and generating and transmitting the physical communication signal. The communications method and apparatus also include receiving and demodulating the physical communication signal, and further converting the demodulated signal into a high-peakedness received pulse train corresponding to the designed pulse train, so that the encoded information may be extracted from the received pulse train.

Abstract: A radar system is disclosed that provides joint object detection and communication capabilities. The radar system includes a communication signal generator that provides a communication signal, a pre-distortion module that applies a pre-distortion to the communication signal to provide a pre-distorted communication signal, a linear frequency modulation (LFM) signal generator that provides a LFM signal, and a mixer that mixes the pre-distorted communication signal onto the LFM signal to provide a radar signal to be transmitted by the radar system. The radar system further includes an all-pass filter that filters a plurality of de-ramped reflected images of the radar signal to provide a filtered signal. Each de-ramped reflected image includes an associated image of the pre-distorted communication signal. The all-pass filter provides a linear group delay, and a non-linear phase response. The pre-distortion is an inverse of the non-linear phase response of the all-pass filter.

Abstract: A Global Navigation Satellite System (GNSS) receiver that includes a satellite signal generator generating signal data for a signal that is not being tracked by the receiver. The receiver includes a satellite signal generator running an algorithm to process first and second received signals to produce a software-synthesized satellite signal, and the generated signal data is used to correct bias or is communicated to a spaced-apart GNSS receiver or used for onboard positioning calculations. The satellite constellation may be the Galileo constellation, with the first and second signals being E5A and E5B signals tracked by the receiver and the generated third signal being an E5AltBOC signal. With a half-a-cycle bias resolution technique, the satellite signal generator generates synthetic E5AltBOC data of high quality. For a receiver, which physically tracks E5AltBOC, synthetic E5AltBOC may be used to monitor polarity of a physically tracked E5AltBOC and correct it if error is detected.

Abstract: A multi-user system to simultaneously perform operations such as communication, RADAR, Light Detection and Ranging (LIDAR) and Relative Navigation (RELNAV). The techniques according to an embodiment includes generating a Fourier based orthogonal chirp sequence of length P, a prime number greater than the number of users targeted for communication. The orthogonal chirp sequence is based on an identifier, in the range of one to P?1, associated with one of the targeted users. The method further includes using the orthogonal chirp sequence to generate a spread user signal based on a message directed to the one targeted users. The method further includes generating a sequence of training pulses for insertion into the spread user signal to facilitate reception of the signal. The method further includes transmitting and receiving a reflection of the spread user signal from one of the targeted users, the reflection used to detect and range the user.

Abstract: Described herein is a system that overcomes challenges pertaining to density and range of urban LP-WANs despite the limited capabilities of base station and client hardware. The invention proposes a novel technique that aims to disentangle and decode large numbers of interfering transmissions at a simple, single-antenna LP-WAN base station by exploiting the hardware imperfections of low-cost LP-WAN clients to its advantage Second, the present invention exploits the correlation of sensed data collected by LP-WAN nodes to collaboratively reach a far-away base station, even if individual clients are beyond its range.

Abstract: The invention concerns a method for receiving and a receiver configured to receive a radio signal carrying information, the radio signal including an overall frequency band having a first frequency sub band and a second frequency sub band. The receiver is further configured to receive during a first time period a first portion of the information carried by the radio signal in the first frequency sub band, and to receive during a second time period a second portion of the information carried by the radio signal in the second frequency sub band. The receiver is further configured to perform channel estimation of the first frequency sub band in order to determine a first phase and to perform channel estimation of the second frequency sub band in order to determine a second phase. The receiver is further configured to determine an overall phase basis of the radio signal using the first and second phases.

Abstract: A system and method for generating communications waveforms that can operate in congested frequency spaces and in applications in which the receiver is moving with respect to the transmitter is provided. In one or more examples, each symbol to be encoded and transmitted is converted into a sequence of frequency chirps. The sequence of frequencies used by the sequence of chirps is based on the symbol that is to be encoded. Each chirp can have a center frequency, and the frequency can be swept over the duration of the chirp. In this way each chirp can have a varying frequency over the duration of the chirp, but the phase of the chirp can be continuous throughout the duration of the chirp. The bandwidth and sweep rate of the chirp can be based on the expected maximum velocity of the receiver and the transmitter relative to one another.

Abstract: Method and apparatus for nonlinear signal processing include mitigation of outlier noise in the process of analog-to-digital conversion and adaptive real-time signal conditioning, processing, analysis, quantification, comparison, and control. Methods, processes and apparatus for real-time measuring and analysis of variables include statistical analysis and generic measurement systems and processes which are not specially adapted for any specific variables, or to one particular environment. Methods and corresponding apparatus for mitigation of electromagnetic interference, for improving properties of electronic devices, and for improving and/or enabling coexistence of a plurality of electronic devices include post-processing analysis of measured variables and post-processing statistical analysis. Methods, processes and apparatus for secure communications include low-power communications and physical-layer steganography.

Abstract: An active canceller includes a magnitude estimator, a phase estimator, a tone generator, and a suppressor. The magnitude estimator estimates the magnitude of spurious signals on a channel. The phase estimator estimates the phase of the spurious signals on the channel. The tone generator generates a tone signal based on the estimated magnitude and phase. The suppressor subtracts the tone signal from a channel signal to suppress the spurious signals. The magnitude and phase estimators and the suppressor may operate in the time domain.

Abstract: Channel estimation using a chirp signal and the Fractional Fourier Transform (FrFT) is disclosed. A relatively short chirp may be transmitted, and its received components may be converted to tones using the FrFT, from which the channel tap magnitudes and delays can readily be computed. This may involve measuring peaks in the rotated spectrum, measuring the time between the peaks, and mapping the time in the rotated plane back to the original time. Such a technique has various advantages over conventional channel estimation techniques, such as providing high accuracy even in very poor multipath environments and requiring relatively few samples of a chirp, which hence can reduce pilot overhead.

Abstract: A method of providing wireless communications in a wireless network can include wirelessly receiving a chirp spread-spectrum modulated signal at a first gateway device, the chirp spread-spectrum modulated signal being transmitted by a remote client device. The chirp spread-spectrum modulated signal can be demodulated at the first gateway device to provide demodulated data at the first gateway device. The demodulated data can be processed to provide an indication that a decode of a packet including the demodulated data failed. Time adjacent chirps included in the demodulated data can be combined to provide combined data at the first gateway device. A message can be transmitted from the first gateway device to a remote server responsive to an amplitude of the combined data exceeding a threshold value and the indication that the decode of the packet including the demodulated data failed.

Abstract: A method of providing wireless communications in a wireless network can include wirelessly receiving a chirp spread-spectrum modulated signal at a first gateway device, the chirp spread-spectrum modulated signal being transmitted by a remote client device. The chirp spread-spectrum modulated signal can be demodulated at the first gateway device to provide demodulated data at the first gateway device. The demodulated data can be processed to provide an indication that a decode of a packet including the demodulated data failed. Time adjacent chirps included in the demodulated data can be combined to provide combined data at the first gateway device. A message can be transmitted from the first gateway device to a remote server responsive to an amplitude of the combined data exceeding a threshold value and the indication that the decode of the packet including the demodulated data failed.

Abstract: A Long Range (LoRa) communication system with an improved data rate and method thereof are provided. When a packet to be transmitted is received, a transmission device determines a transmission scheme. When the determined transmission scheme is an enhanced transmission scheme, the transmission device transmits a preamble signal indicating that a packet is to be transmitted using the enhanced transmission scheme, converts n-th data of the packet to an up-chirp signal, converts (n+1)-th data of the packet to a down-chirp signal, generates a transmission signal by adding the n-th data converted to the up-chirp signal and the (n+1)-th data converted to the down-chirp signal, and transmits the transmission signal to a reception device.

Abstract: An information processing device and method, a transmitting device and method, and a receiving device and method are disclosed for multiplexing transmission signals in the same channel. In one example, transmission signals are generated by performing chirp modulation on data to be transmitted, and the transmission signals are multiplexed by shifting transmission timings of a plurality of transmission signals in a time direction and transmitting the transmission signals. Further, a plurality of chirp-modulated transmission signals which are multiplexed by shifting the transmission timing in the time direction and transmitted from a transmission side are received, and the plurality of received transmission signals are dechirped at timings according to the transmission timings.

Abstract: Generated chirp pulses are modified so that they have an increased time bandwidth product to compensate for noise and/or attenuation in a communication channel. In certain circumstances, the modification alone may be inefficient so a counterbalancing modification may be applied at the receiver.

Abstract: A method for calibrating a radiofrequency multichannel subsystem of a telecommunications payload includes a step of generating and injecting a calibration signal at one or more input access channel injection points; a step of tapping off the injected and propagated calibration signal at tapping-off points of an access channel at output; and then a step of estimating the amplitude and/or phase differences between the internal channels of the multichannel subsystem on the basis of the calibration signal injected at input, serving as a reference, and of the extracted calibration signal or signals; and then a step of correcting the amplitude and/or phase differences by way of correction means. The injected calibration signal is a chirp signal, formed of a chirp or of a sequence of at least two identical chirps. A calibration system implements the calibration method.

Abstract: Disclosed herein is a design, simulation, and hardware build of a photonic compressed sensing Nyquist folding receiver that is able to directly undersample wideband RF signals and detect the original Nyquist zone and frequency information. According to an exemplary embodiment, this is achieved by generating a frequency modulated optical impulse train for directly undersampling the RF environment at the antenna. The impulse train undersamples the signals using an optical modulator configuration at 1550 nm and collects the detected samples in a low pass interpolation filter which is subsequently processed to extract the undersampled signals.

Abstract: A Long Range (LoRa) communication system with an improved data rate and method thereof are provided. When a packet to be transmitted is received, a transmission device determines a transmission scheme. When the determined transmission scheme is an enhanced transmission scheme, the transmission device transmits a preamble signal indicating that a packet is to be transmitted using the enhanced transmission scheme, converts n-th data of the packet to an up-chirp signal, converts (n+1)-th data of the packet to a down-chirp signal, generates a transmission signal by adding the n-th data converted to the up-chirp signal and the (n+1)-th data converted to the down-chirp signal, and transmits the transmission signal to a reception device.

Abstract: A synthesizer comprises a first two-point modulation phase locked loop, TPM PLL, circuit that receives a first reference clock signal at a first reference frequency and a feedback signal at a feedback frequency and generates a first chirp signal by applying a two-point modulation PLL on the first reference clock signal, a second integer-n TPM PLL circuit that receives a second reference clock signal at a second reference frequency lower than the first reference frequency and generates a second chirp signal by applying a TPM PLL on the second reference clock signal, a mixer that downconverts the first chirp signal by the second chirp signal to obtain the feedback signal at the feedback frequency corresponding to the difference of the frequency of the first chirp signal and the second chirp signal, and a feedback path that feeds back the feedback signal to the first TPM PLL circuit.

Abstract: Interference is a common problem in wireless communication networks. This disclosure provides a method and system that detect and locate interference sources based on various data describing or captured from an operational network during normal mobile wireless service times.

Abstract: A UE may be operating in a wireless communication network having a UE-centric medium access control layer, and the UE may detect presence of a trigger event to signal a base station of the wireless communication network. The UE may identify one of a plurality of functionalities corresponding to the trigger event, and may generate a chirp signal that includes chirp purpose indicator and a chirp message, wherein the chirp purpose indicator and a format of the chirp message correspond to the identified one of the plurality of functionalities. Accordingly, the UE may transmit the chirp signal having the chirp purpose indicator to the base station, which may provide a chirp response message that includes message contents that relate to the chirp purpose indicator.

Abstract: A non-linear spread spectrum clock generator using a linear combination may include a phase locked loop configured to receive a reference signal and generate an output signal according to the reference signal and a feedback signal that compensates for the output signal. The phase locked loop may include a divider configured to generate the feedback signal by dividing the output signal by a divisional ratio. The non-linear spread spectrum clock generator may include a non-linear profile generator configured to generate a non-linear signal by selectively outputting selected ones of a plurality of signals according to the absolute magnitudes of the signals and a delta-sigma modulator configured to receive the outputted linear ramp function and to change the divisional ratio. The signals may vary according to different linear ramp functions. The different ramp functions may include different slopes and initiation time values.

Abstract: The communication process for high-sensitivity and synchronous demodulation signals between a transmitter (2) and a receiver (3) comprises a first synchronisation phase followed by a modulation and demodulation phase of the data. To achieve this, the transmitter transmits a pseudo-periodic chirp signal to the receiver, where a frequency conversion of the chirp signal is performed in a mixer (33) by an oscillating signal (So) at constant frequency of a local oscillator (34) to supply an intermediate signal, which is filtered and sampled for a logic unit (37). An assembly (38) of m pairs DFT blocks phase-shifted in relation to one another and operating in parallel is provided in the logic unit. A processing unit (39) receives the result of the pairs of the assembly to determine frequency and phase errors between the transmitter and the receiver on the basis of two peaks detected by one of the pairs above a threshold to synchronise the receiver.

Abstract: A wireless communication method in a network comprising a plurality of nodes including ranging masters, broadcasting a chirp-modulated ranging requests, and ranging slaves slave, replying with thereto with chirp-modulated ranging responses, whereby mobile nodes can locate themselves passively by listening to the request/reply exchanges, based on the respective time differences of arrival.

Abstract: A radio frequency (RF) receiver comprises a passive impedance transforming voltage amplifier and a resonant, latching micromechanical switch having a deflectable bridge, an RF actuation electrode receivingly connected to the amplifier, and a DC bias electrode positioned to latch the switch in a closed position by electrostatic attraction when energized by a suitable voltage. The bridge is configured with a mechanical mode of vibration that periodically urges the switch toward the closed position.

Abstract: In one embodiment, a network interface broadcasts an audible message from a first computing device to a plurality of second computing devices over a first channel. The audible message comprises an audible noise broadcasted using a plurality of frequencies and a first unique identifier indicative of the first computing device. The network interface receives an acknowledgment message from each of the plurality of second computing devices over a second channel. A processor identifies each of the plurality of second computing devices based on the second unique identifier in the acknowledgment message and initiates a collaboration session between the first computing device and the plurality of second computing devices by sending a collaboration message from the first computing device to the plurality of second computing devices. The collaboration message automatically causes the plurality of second computing devices to enter the collaboration session.

Abstract: A ranging and positioning system comprising transmitters and receiver nodes communicating together by chirp-modulated radio signals, that have a ranging mode in which ranging exchange of signals takes place between a master device and a slave device that leads to the evaluation of the range between them. The slave is arranged for recognizing a ranging request and transmit back a ranging response containing chirps that precisely aligned in time and frequency with the chirps in the ranging requests, whereupon the master can receive the ranging response, analyze the time and frequency the chirps contained therein with respect to his own time reference, and estimate a range to the slave.

Abstract: Generated chirp pulses are modified so that they have an increased time bandwidth product to compensate for noise and/or attenuation in a communication channel. In certain circumstances, the modification alone may be inefficient so a counterbalancing modification may be applied at the receiver.

Abstract: A wireless communication method in a network comprising one or several beacons and a plurality of end-points, comprising: sending by a beacon a timing message modulated according to a chirp spread spectrum format, receiving said timing message in one or several end-nodes a receiver, detecting said timing message aligning a local frequency reference and/or time reference of the end-node to the time reference of the transmitter by means of said timing message.

Abstract: A radio frequency locator system and method. First, second and third reference devices are operable to transmit a plurality of spread spectrum chirp signals frequency offset from one another. An object device is operable to receive the plurality of spread spectrum chirp signals, the object device is further operable to evaluate the received plurality of spread spectrum chirp signals for relative phase shifts between the plurality of spread spectrum chirp signals and derive a fine propagation time between the reference devices and the object device using the phase shifts between the spread spectrum chirp signals. The reference devices determine their location independent of the object device and determine the location of the object device as a function of each of their locations and of their range to the object device.

Abstract: A system and method to produce an electric network from estimated line impedance and physical line length among smart meter devices is provided using communication between the smart meters. The smart meters: (1) synchronize time using GPS pps signals, which provide an accurate time stamp; (2) send/receive an identifiable signal through the same phase of electric networks; (3) identify other smart meters on the same phase lines by listening to the information signal on the same phase lines; and (4) calculate time-of-arrival of an identifiable signal from other smart meters. The time of arrival information is used to calculate the line length, which is then used to calculate impedance of a line and topology of the electric network. The system then constructs an electric network by combining geo-spatial information and tree-like usual connection information.

Abstract: A method and system for encoding ancillary information at a transmitter in a high-speed communications network, the method comprising: generating an electromagnetic interference (EMI) reduction signal; receiving an ancillary data symbol; generating an EMI reduction signal variation based on the ancillary data symbol; and varying a characteristic of the EMI reduction signal based on the generated EMI reduction signal variation to encode the ancillary data symbol in the varied EMI reduction signal.

Abstract: A ranging and positioning system comprising transmitters and receiver nodes communicating together by chirp-modulated radio signals, that have a ranging mode in which ranging exchange of signals takes place between a master device and a slave device that leads to the evaluation of the range between them. The slave is arranged for recognizing a ranging request and transmit back a ranging response containing chirps that precisely aligned in time and frequency with the chirps in the ranging requests, whereupon the master can receive the ranging response, analyze the time and frequency the chirps contained therein with respect to his own time reference, and estimate a range to the slave.

Abstract: A system includes a driver circuit, a modulator circuit, and a reset circuit. The driver circuit drives a plurality of light emitting diodes via a switch. The switch is controlled by a first signal having a first frequency. The driver circuit controls brightness of the light emitting diodes based on a second signal including a plurality of pulses. The modulator circuit modulates the first signal using a direct sequence spread spectrum modulation. The direct sequence spread spectrum modulation uses a sequence generated based on the first signal. The reset circuit resets the modulator circuit at each of the plurality of pulses of the second signal. The modulator circuit repeats the sequence at each of the plurality of pulses of the second signal.

Abstract: A method for adaptive Radio Frequency (RF) jamming according to one embodiment includes dynamically monitoring a RF spectrum; detecting any undesired signals in real time from the RF spectrum; and sending a directional countermeasure signal to jam the undesired signals. A method for adaptive Radio Frequency (RF) communications according to another embodiment includes transmitting a data pulse in a RF spectrum; and transmitting a reference pulse separated by a predetermined period of time from the data pulse; wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated. A method for adaptive Radio Frequency (RF) communications according to yet another embodiment includes receiving a data pulse in a RF spectrum; and receiving a reference pulse separated in time from the data pulse, wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated; and demodulating the pulses.

Abstract: Spread spectrum clocking circuitry may be configured to produce a spread spectrum clock signal that coordinates the actions of functional circuitry. Spread spectrum clocking circuitry may be configured to include delay circuitry configured to generate a random delay signal based on a random input value and generate the spread spectrum clock signal based on the random delay signal. By introducing true randomness into the delay signal, spread spectrum clocking signal may be able to generate a truly random, as opposed to a merely pseudo random, clock signal.

Abstract: A method detects symbols in a signal received via a wireless channel by generating a statistical model for each symbol, and determining contribution from all other symbols in the signal as an expected interference. The expected interference is subtracted from the signal to obtain an interference-free signal. Then, the symbol is inferred based on the statistical model and the interference-free signal.

Abstract: An electromagnetic transmission system is provided, comprising: M chirp generators, each operating at a first frequency, each of the M chirp generators being configured to generate an ith digital chirp portion comprising (1/M)th of a digital chirp signal having a set ramp rate; a parallel-in serial-out register configured to receive the M digital chip portions in parallel at the first frequency, and configured to output the M digital chip portions in series as the digital chirp signal at a second frequency; and a digital-to-analog converter operating at the second frequency and configured to convert the digital chirp signal into an analog chirp signal, wherein i is an index that goes from 1 to M, and wherein the second frequency is M times the first frequency.

Abstract: This document discusses, among other things, a system and method of measuring and correcting for frequency offset in wideband signals of bandwidth X within a communications system. A synchronization signal is generated and transmitted, wherein generating a synchronization signal includes generating a first chirp signal that sweeps a portion of bandwidth X and generating a second chirp signal to sweep approximately the same portion of bandwidth X but in the opposite direction. The synchronization signal is received at a receiver. The receiver then detects a first offset as a function of the first chirp signal and a second offset as a function of the second chirp signal and calculates the frequency offset as a function of the first and second offsets.

Abstract: A method includes generating multiple copies of a signal that comprises a plurality of time division multiple access frames. The multiple copies of the signal includes a first copy and one or more other copies of the signal. Each of the one or more other copies of the signal having a respective fixed delay and a respective phase relative to the first copy of the signal. The method also includes transmitting the multiple copies of the signal using hopping carrier frequencies. The hopping carrier frequencies associated with a consecutive pair of the plurality of time division multiple access frames are separated by an odd multiple of a separation value representing a frequency separation between two adjacent carrier signals. The respective fixed delay is proportional to the separation value for each of the one or more other copies of the signal.

Abstract: An apparatus and method for signal emitters determining and using a reduced number of discrete frequency transmitters based on frequency segmentation and degradation analysis of a candidate filter configuration compared to an original waveform input signal for acceptability determination in view of desired system parameters. A method that configures a device to produce a complex waveform over a desired range of frequencies is provided. Configuring a device can include filtering to reduce a number of frequencies which in turn is used to reduce signal emitters and configuring resulting reduced signal emitters includes producing a desired complex waveform over a desired range of frequencies.

Abstract: Apparatus for generating and encoding data onto chirp signals, said apparatus including a chirp generator configured to generate a chirp; a cyclic frequency offset modulator configured to set the cyclic frequency offset of the chirp to a cyclic frequency offset selected from a plurality of predetermined cyclic frequency offsets; and a phase modulator configured to modulate the chirp onto a signal to form a chirp signal symbol at a phase offset selected from a plurality of predetermined phase offsets.

Abstract: A system, method and apparatus for digital communication that is insensitive to a sampling clock error. In one embodiment, a digital communication system that is insensitive to a sampling clock error is provided. The digital communication system includes a transmitting communication unit and a receiving communication unit. The transmitting communication unit is configured to generate a digital data communication signal and includes a modulator configured to modulate digital data such that the modulated digital data communication signal is invariant to a stretched frequency scale resulting from a lack of synchronization with a receiving communication unit. The receiving communication unit is configured to receive the digital data communication signal and includes a demodulator configured to demodulate the digital data.

Abstract: Apparatus for generating and encoding data onto chirp signals, said apparatus including a chirp generator configured to generate a chirp; a cyclic frequency offset modulator configured to set the cyclic frequency offset of the chirp to a cyclic frequency offset selected from a plurality of predetermined cyclic frequency offsets; and a phase modulator configured to modulate the chirp onto a signal to form a chirp signal symbol at a phase offset selected from a plurality of predetermined phase offsets.

Abstract: An aspect of the invention is directed to a method for maintaining the synchronization of a receiver with a chirp signal sent over a link from a transmitter. The chirp signal comprises at least a first chirp having a gradient greater than one. The transmitter may encode data on to the signal by varying the properties of the chirps it transmits. The receiver correlates the received first chirp with an expected reference chirp to produce a set of correlation results. Should the gradient of the received chirp match the gradient of the expected reference chirp, then a distinct large “prompt” peak will be present having a greater magnitude than any other correlation peaks present in the correlation results. Transmitted data symbols may be inferred from properties of this prompt peak, for example its position in samples in the correlation results.

Abstract: A chirp receiver processes broadcast chirp signals in the frequency domain to distinguish direct path signals from multipath signals. The receiver processes received chirp signals consisting of respective pulsed frequency sweeps by combining the signals with a synchronized local chirp signal and phase adjusting and concatenating the results over multiple sweeps based on estimated clock phase errors and expected phase rotations of the direct path signals, and produces a sine wave. The phase adjustment and concatenation allows the use of longer Fast Fourier Transforms, which provide increased accuracy of frequency estimation and separate component signals that are very close in frequency. The frequency corresponding to the direct path signal is identified by the lowest frequency bin in which power is above a predetermined noise threshold. The receiver then determines a time delay based on the identified frequency and uses the time delay to calculate accurate clock phase error and position.