5 - Ultrasonic Flowmeters

Representing the channel varying rate and the mobile speed of a mobile terminal directly, Doppler shift is an important parameter in vehicular mobile communications and therefore is widely used in mobile target detection and adaptive applications. Hence, this paper puts forward an accurate Doppler shift estimator in mobile communications with high vehicle speeds, which can also be treated as a vehicular speed estimator due to the well-known relation between the Doppler shift and the mobile speed. Specifically, the proposed estimator is based on the channel level crossing rate, and an iterative process is presented to achieve signal-to-noise ratio SNR insensitive estimates in accordance with the level crossing rate estimation error analysis. Moreover, we prove the convergency of the iterative Doppler shift estimator in theory. Computer simulations conducted under a wide range of noise corruption clearly show that the proposed estimator substantially outperforms several existing estimators in terms of accuracy and achieves a good SNR-insensitive performance in a wide range of velocities and SNRs. Copyright © 2013 John Wiley & Sons, Ltd.

Accurate estimation of Doppler shift in mobile communications with high vehicle speed

A monostatic Doppler radar can yield accurate vehicle speed measurements over a very limited angular extent When applied to a multilane superhighway geometry, the area within which the vehicle must be confined for accurate measurement becomes quite small A much larger area yielding accurate measurement can be achieved by designing the radar system for bistatic operation In this geometry the transmitter and receiver are on opposite sides of the multilane highway and both transmitting and receiving antenna beams are oriented towards the vehicle A radiation leakage link is required between transmitter and receiver to provide a reference frequency signal Examples are given to show the conceptual advantage of a bistatic radar compared to a monostatic radar

Conceptual performance of bistatic Doppler radar for vehicle speed determination

Traffic volume information is widely used in all aspects of Intelligent Transportation Systems (ITS), such as transportation planning, traffic states identification, traffic management, safety analysis, and so on. In recent years, acoustic sensors are gradually applied to the detection of various traffic parameters. In this paper, acoustic data sets acquired from acoustic sensors are utilized to estimate the road traffic volume. The short-term energy (STE) algorithm and the energy to zero crossing rate (EZCR) algorithm are usually applied to acoustic analysis, and they both perform well under some simple circumstances, however, some urgent problems remain unresolved under certain complex conditions. One of such issues occurs when adjacent vehicle-pass signals (VPSs) intersect partially, seriously decreasing the accuracy of endpoint detection of VPSs, hampering the algorithm ability to maintain satisfactory traffic volume estimation. Another difficulty arises while multiple lanes are considered: some special VPSs cannot be detected. To solve these problems, a novel acoustic characteristic is defined, and an acoustic-based characteristic extraction algorithm for traffic volume estimation, entitled triangular wave analysis (TWA), is proposed. Comparing the TWA algorithm with the STE and EZCR algorithms, experimental results demonstrate the viability of the proposed algorithm in the case of intersectant VPSs.

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A Novel Acoustic Characteristic Extraction Algorithm for Traffic Volume Estimation

Information about a mobile user's velocity is important for efficient resource management and quality of service (QoS) provisioning in next generation (NG) wireless systems. A mobile receiver's velocity spreads the received signal envelope in the frequency domain. This spreading is directly proportional to its velocity. A novel algorithm called VEPSD (velocity estimation using the power spectral density of the received signal envelope) is introduced in this paper that uses the amount of Doppler spread in the received signal envelope to estimate the velocity of a mobile user. The Doppler spread is estimated using the slope of the power spectral density (PSD) of the received signal envelope. The performance of the proposed algorithm is evaluated in both Rayleigh and Rician fading environments. The sensitivity of the estimation error to additive white Gaussian noise (AWGN), the estimation interval (effect of finite sample size), the sampling period, Rice factor (K), and the angle of arrival of the line of sight (LOS) component is analyzed and compared with the level crossing rate (LCR) and co-variance based velocity estimators. Also, it is shown that the proposed algorithm, VEPSD, can be used for velocity estimation under non-isotropic scattering and frequency selective fading and is well suited for NG wireless systems.

An accurate velocity estimation algorithm for resource management in next generation wireless systems

An alternative method of speed detection is presented based on the Doppler effect in vehicular noise. A procedure is developed to correlate the noise frequency spectrum as the vehicle approaches an observer with the spectrum as it moves away. Limitations of the technique are evaluated using empirical data obtained under typical traffic conditions. These results demonstrate that the Doppler shift can be extracted from automotive noise and related to the vehicle's speed. Although sources of inaccuracy are significant at lower speeds, a resolution of ±5 percent was easily achieved at 60 mph. Such a technique may be found useful in large scale traffic speed and density monitoring systems.

D.S. Coe

Papers

Speed measurement through analysis of the Doppler effect in vehicular noise