A lidar including a laser having a first frequency-modulated laser radiation and a second frequency-modulated laser radiation, a first waveguide coupled to the laser, wherein the first frequency-modulated laser radiation and the second frequency-modulated laser radiation are transmitted by the laser into the first waveguide, a second waveguide, a filter coupled between the first waveguide and the second waveguide, wherein the filter is configured to couple and pass the first frequency-modulated laser radiation through the filter to the second waveguide, and is configured to not couple or pass the second frequency-modulated laser radiation through the filter to the second waveguide, and a photodetector coupled to the second waveguide.

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.

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.

The present disclosure provides a signal transmission method and apparatus, where the method includes: transmitting a first signal on subcarriers of a plurality of orthogonal frequency division multiplexing (OFDM) symbols, where a frequency offset of the subcarriers exists among the plurality of OFDM symbols. The present disclosure enables the first signal is no longer concentrated on the subcarriers at a specific frequency, but is dispersed more evenly. The interference of the first signal is more even for the signal being transmitted by the neighboring cell terminal device. On one hand, the influence on the data demodulation of the neighboring cell terminal device is reduced; and on the other hand, if the neighboring cell performs interference measurement, the difference in measurement results on different subcarriers is reduced and the accuracy of the interference measurement result is improved.

Methods, apparatus, systems and articles of manufacture for wideband and fast chirp generation for radar systems are disclosed herein. An example apparatus includes a phase digital-to-analog converter to convert a digital input that specifies at least one of a phase modulation or a frequency modulation into an analog output, and to generate a phase modulated output centered on an intermediate frequency. The example apparatus also includes a frequency multiplier to frequency multiply the phase modulated output centered on the intermediate frequency by a multiplication factor to generate a chirp signal.

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.

Signal transmission with symbol correction is disclosed. In one example, processing includes selection of one of known data and unknown data for each of symbols, as transmission data, while selecting a symbol of the known data for a reception side at one or both of timings of immediately before and immediately after selection of a symbol of unknown data for the reception side, modulation of each of the symbols of the selected transmission data, and transmission of a transmission signal obtained. Moreover, processing includes: reception of a transmission signal transmitted from a transmission side; and correction of a symbol of unknown data included in the received transmission signal on the basis of a symbol of known data included in the received transmission signal.

A signal may be generated by modulating a plurality of chirp signals with a set of input symbols. Chirp signals may be characterized by a second order bivariate polynomial and the coefficients of the quadratic terms of the polynomial may be selected to achieve desired frequency diversity. Furthermore, at least one of the coefficients may be adjusted based on channel state information to mitigate effective Doppler spread in a discrete affine Fourier transform domain virtual channel.

An apparatus for determining a suitability of a frequency band for data communication with a node by way of a communication channel may be provided. The apparatus may comprise a receiver configured to receive first and second signals from the node by way of the communication channel, the first and second signals having frequencies within the frequency band. The apparatus may comprise processing circuitry communicatively coupled to the receiver, the processing circuitry being configured to determine a calibration function depending on the first signal, process the second signal depending on the calibration function, determine the suitability of the frequency band for data communication with the node by way of the communication channel depending on the processed second signal and output an indication of the said suitability. The processing circuitry may be configured to determine the suitability of the frequency band for data communication with the node depending on the processed second signal by comparison of the processed second signal to predetermined reference data.

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.