A method for measuring, using a radar or sonar, the velocity with respect to the ground of a carrier moving parallel to the ground, includes the following steps: a) orienting the line of sight of the radar or sonar toward the ground; b) emitting a plurality of radar or sonar signals (P.sub.1-P.sub.N) that are directed toward the ground, and acquiring respective echo signals (E.sub.1-E.sub.N); c) processing the acquired echo signals so as to obtain, for one or more echo delay values, a corresponding Doppler spectrum; d) for the or at least one the echo delay value, determining a high cut-off frequency of the corresponding Doppler spectrum; and e) computing the velocity of the carrier with respect to the ground on the basis of the one or more high cut-off frequencies. A system allowing such a method to be implemented.

The present disclosure belongs to technical field of indoor positioning, and discloses a method and system for wide-area acoustic indoor positioning based on RF enhancement, comprising: design of an acoustic signal, using Blackman window function to control the amplitude of acoustic signal entering and leaving channel; a mixed multiple access transmission of the acoustic signal, combining three multiple access schemes of time, space and frequency, assisting a small amount of BLE signals, and constructing a wide-area coverage capability of the acoustic positioning signal; acoustic measurement based on RF enhancement, including TOA estimation of an acoustic signal and area identification based on low-power Bluetooth RSS; robust fusion positioning of an inertial sensor and multi-source measurement, including pedestrian walking speed estimation, multi-source heterogeneous measurement, acoustic measurement compensation and correction, measurement quality evaluation and control.

A measurement configuration of a remote sensing device for use in implementing a remote sensing measurement campaign is improved. One method includes adjusting a scan geometry configuration of the remote sensing device during the measurement campaign based on measurement data acquired in a previous scan geometry configuration. In another method, the remote sensing device is configured in a scan geometry configuration having a plurality of scan geometries, and following acquisition of a measurement data set by the remote sensing device at a first time interval, one of the scan geometries indicative of an improved or optimal scan geometry at the first time interval is selected. The remote sensing device forms part of a remote sensing system and includes an optical source emitting a probe as a light beam along different lines of sight. The remote sensing device includes or is operatively associated with a receiver for detecting the reflected probe.

Methods and apparatus to measure and analyze vibration signatures are disclosed. In some examples, a meter is provided comprising a waveform generator to generate a waveform based on first distance measurements of an object. In some examples, the meter includes a waveform generator to determine a first vibration characteristic of the object based on the waveform. In some examples, the meter includes a comparator to compare the first vibration characteristic to a signature vibration characteristic of the object, the signature vibration characteristic of the object indicative of normal characteristics of the object. In some examples, the meter includes a reporter to, in response to determining the first vibration characteristic does not match the signature vibration characteristic, generate an alert.

A wideband sonar receiver is provided that includes: a selectable bandpass filter adapted to filter a received sonar signal to produce a filtered signal and a correlator adapted to correlate the baseband samples with baseband replica samples to provide a correlated signal. In addition, the wideband sonar receiver may include a shaping filter to shape unshaped received pulses. Finally, a variety of sonar processing algorithms are described with regard to reducing clutter and interference, target detection, and bottom detection.

An ultrasound detect circuit includes a decimator that decimates a transmit signal to be transmitted through an ultrasonic transducer. The transmit signal is decimated to generate first and second template signals. The decimator uses a different decimation ratio to generate the first template signal than the second template signal. The circuit also includes a first correlator to correlate a signal derived from the ultrasonic transducer with the first template signal, aa second correlator to correlate the signal derived from the ultrasonic transducer with the second template signal, and a Doppler shift determination circuit to determine a Doppler frequency shift based on an output from the first correlator and an output from the second correlator.

This disclosure describes presence-detection devices that detect movement of a person by emitting ultrasonic signals into an environment, and characterizing the change in the frequency, or the Doppler shift, of the reflections of the ultrasonic signals off the person caused by the movement of the person. The techniques include downsampling the audio signals from the carrier frequency range down to a frequency range with a center frequency around 0 Hz. A filter is applied to attenuate signals around 0 Hz and below (or above), such as the emitted signals. In addition to removing the emitted signals, the negative side (or positive side) of the audio signals are removed, but the Doppler shift is still represented in the remaining portion of the audio signals. By removing a portion of the audio signals, the amount of processing required to detect the Doppler shift in the reflections of the ultrasonic signals is reduced.

A practically implementable robust direction-of-arrival (DoA) estimation approach that is resistant to localization errors due to mobility, multipath reflections, impulsive noise, and multiple-access interference. As part of the disclosed invention the inventors consider infrastructure-less 3D localization of autonomous underwater vehicles (AUVs) with no GPS assistance and no availability of global clock synchronization. The proposed method can be extended to challenging communication environments and applied for the localization of assets/objects in space, underground, intrabody, underwater and other complex, challenging, congested and sometimes contested environments. Each AUV leverages known-location beacon signals to self-localize and can simultaneously report its sensor data and measurement location. The approach uses two known location beacon nodes, where the beacons are single-hydrophone acoustic nodes that are deployed at known locations and transmit time-domain coded signals in a spread-spectrum fashion.

A survey system including a multibeam echo sounder having a projector array and a hydrophone array in a Mills Cross arrangement uses a multi-component message to ensonify one or more fans to estimate a Doppler velocity.

An object detection apparatus includes a transmitting portion configured to transmit a transmission wave, a receiving portion configured to receive a reception wave based on the transmission wave which returned, an estimation portion configured to estimate an amount of frequency transition between the transmission wave and the reception wave on the basis of a result of a frequency analysis, a correction portion configured to correct the reception wave to obtain consistency of frequencies with the transmission wave on the basis of an estimation result of the estimation portion, and a detection portion configured to detect information related to the object on the basis of a relation between the transmission wave and the corrected reception wave corrected by the correction portion.