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Radar, Sonar and Navigation, IEE Proceedings -

Issue 4 • Date August 2002

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Displaying Results 1 - 6 of 6
  • Near-field source localisation using bottom-mounted linear sensor array in multipath environment

    Publication Year: 2002 , Page(s): 202 - 206
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (489 KB)  

    The paper presents a 3-D near-field source localisation algorithm using a bottom mounted linear sensor array for a multipath environment. The proposed algorithm utilises the signals from different paths plus a simple linear sensor array to estimate the 3-D location of a source, whereas conventional 3-D localisation algorithms require a 2-D array of sensors. The conic angles of the source signal are different for each path and each path signal has a different arrival time. As such, equations are derived for the source location, time difference of arrivals, and conic angles, then the location of the source is estimated by simultaneously solving these equations View full abstract»

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  • PFA algorithm for airborne spotlight SAR imaging with nonideal motions

    Publication Year: 2002 , Page(s): 174 - 182
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (839 KB)  

    The nonuniform-interpolation polar format algorithm is developed for processing spotlight SAR data with nonideal platform motions. Instead of two uniform interpolations for the conventional polar format algorithm (PFA), this algorithm employs a one-dimensional uniform interpolation in the range direction and a one-dimensional nonuniform interpolation in the azimuth direction to remove effects of nonideal motion. For azimuth-nonuniform interpolation, the output sample spacing depends on the pulse number, range and motion data, and can be easily computed. The output sample spacing can also be precomputed and stored in RAM. The computational load of azimuth-nonuniform interpolation is almost the same as azimuth-uniform interpolation, if the output sample spacing is precomputed and stored. The computational load is the same for both algorithms. Theoretically, for scatterers in the focus target plane (FTP), this algorithm can produce a SAR image with the same quality for the nonideal motion case as for the ideal motion case. Like conventional PFA, it is compatible with autofocus. Computer simulation results validate the algorithm View full abstract»

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  • Multiple GPS receiver multipath mitigation technique

    Publication Year: 2002 , Page(s): 195 - 201
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    The applications using differential GPS (DGPS) have grown over the years, and the dominant error source for many DGPS techniques is reference receiver multipath. As a result, there is great interest in reducing reference receiver multipath, especially for safety-critical applications such as DGPS-based precision landing. A new method for reducing code and carrier phase multipath is presented which uses measurements from multiple receivers in order to obtain accurate estimates of code or carrier phase multipath. Using this method, a least-squares condition adjustment is performed to generate a multipath estimate for each individual receiver/satellite pair. It does so on an epoch by epoch basis, so no filtering over time is required, and no initialisation period is necessary. Static and dynamic test results using this method are presented. For these tests, code differential positioning is performed with and without the adjustment, and it is shown that the adjustment significantly improves positioning accuracy. It is also demonstrated that the condition adjustment can enhance carrier-phase integer ambiguity resolution View full abstract»

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  • Continuous pavement profiling with ground-penetrating radar

    Publication Year: 2002 , Page(s): 183 - 193
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1231 KB)  

    Ultra-wideband (UWB) monostatic ground-penetrating radar (GPR) has been proven to be very useful in road and highway pavement profiling. Pavement profiling involves estimating the thickness and permittivity of each underground layer, which can be done through layer stripping inversion, using efficient time-delay-estimation algorithms. In monostatic GPR applications, time delay estimation is routinely performed on a scan-by-scan basis. The authors first propose a multiscan data model for the continuous survey, by taking into account the vertical motion of moving vehicles as well as the lateral continuity of echoes arising from a multilayered media along the scan direction. Then a new algorithm, referred to as MCPEG (motion compensation and parameter estimation for GPR), is presented for simultaneous motion compensation and time-delay estimation. MCPEG outperforms the conventional scan-by-scan estimation approach in terms of both computational efficiency and estimation accuracy. Numerical and experimental examples are provided to demonstrate the performance of the new algorithm View full abstract»

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  • Joint estimation of Doppler and time-difference-of-arrival exploiting cyclostationary property

    Publication Year: 2002 , Page(s): 161 - 165
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (583 KB)  

    For the problem of estimating the time-difference-of-arrival (TDOA) of radio waves impinging on one or a pair of antennas for the purpose of actively or passively locating the source of a communications or telemetry signal in the presence of interfering signals and noise, W A. Gardner has developed some effective methods, such as CCCC and SPECCOA etc. However, it is shown that CCCC, SPECCOA and related methods do not apply to moving targets because the Doppler shift changes the cycle frequencies of the signal of interest. Two new methods based on the cyclic cross-ambiguity (CCA) function and the spectrally cyclic cross-ambiguity (SCCA) function are introduced in the paper for the joint TDOA and Doppler estimation, and their consistency in estimating the TDOA and Doppler is also discussed. Practical experiments, utilising FM radio signals emitting from a remote FM transmitter to detect the planes and estimate the values of TDOA and Doppler, have been carried out. Experimental results demonstrate the efficiency of the CCA and SCCA methods in the estimation of TDOA and Doppler View full abstract»

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  • Spotlight MUSIC: super-resolution with subarrays with low calibration effort

    Publication Year: 2002 , Page(s): 166 - 173
    Cited by:  Papers (15)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1055 KB)  

    A central problem in applying super-resolution to phased arrays is the knowledge of the 'array manifold', i.e. the complete knowledge of the array outputs for a plane wave impinging on the array from all considered directions. This becomes a problem for large arrays where only subarray outputs are digitised. In the paper methods for determining an array manifold model with minimum knowledge of the subarray channels are investigated. The basic idea is to treat the subarray centres as phase centres of omni-directional 'super-array' elements. Only the location of the centres and the gains have to be determined by calibration. The drawback of the simple model is that only a local super-resolution property is achieved. By steering the look direction of the array, local super-resolution can be applied like a spotlight mode for any direction of interest. The local super-resolution property has the advantage of suppressing uninteresting sidelobe sources and thus simplifying the super-resolution procedure due to the lower target number. Optimised subarray configurations which are determined by post-processing the subarray outputs are investigated. Using the MUSIC method as an example it is shown that no significant advantage can be gained with the optimised approach View full abstract»

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Aims & Scope

IEE Proceedings Radar, Sonar and Navigation covers the theory and practice of systems involving the processing of signals for radar, radio location, radio navigation and surveillance purposes.

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