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SCIENCE CHINA Information Sciences, Volume 62, Issue 4: 040302(2019) https://doi.org/10.1007/s11432-018-9735-6

Diversity considerations in wideband radar detection of migratingtargets in clutter

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  • ReceivedNov 2, 2018
  • AcceptedJan 5, 2019
  • PublishedFeb 20, 2019

Abstract

Wideband radars have been proposed for detection of moving targets, with unique capability of non-ambiguous detection due to range migration. Moreover, frequency diversity has long been used for mitigating the fading effects caused by target and clutter fluctuations. The real benefits of wideband radars are difficult to analyze, since they derive from the combined effects of target resolution in range, migration over successive cells of clutter, Doppler resolution and instantaneous bandwidth, and residual ambiguities in Doppler. In order to contribute to a better understanding of the benefits of agile transmissions for detection of moving targets, clutter cancelling performances of wideband radars are examined, demonstrating clear benefits from diversity on clutter and target, primarily – but not only – obtained through target migration effects. Special attention is given to long-range surveillance and tracking, and new results on detection of moving targets in clutter will be provided to demonstrate the effectiveness of these new architectures for small targets detection at long range, in difficult environments. Finally, recommendations for system designs that improve the discrimination of moving targets against fixed and diffuse clutter are presented.


Acknowledgment

This work was partially supported by STW (now Toegepaste en Technische Wetenschappen (TTW)) (Grant No. 12219).


References

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  • Figure 1

    Detection and false alarm probabilities after imposing a threshold $T$ on the detected quantity $X$ [1].

  • Figure 2

    (Color online) The diversity gain for fluctuating target detection. The traces show noncoherent versus coherent integration for a $P_{\rm~fa}=10^{~-~6}$. The vertical scale is linear (not in dB).

  • Figure 3

    (Color online) Range migrating extended target in spiky clutter.

  • Figure 4

    (Color online) Detection probability of a range migrating point target in compound Gaussian clutter with: $~v~=~0$ m/s and $v~=~15$ m/s, SCR is the power of clutter after whitening, exponential correlation in range with $\gamma~=~1$ and $\gamma~$ $=~+\infty~$; PFA = 10$^{~- 5}$. Radar parameters: $f_{c}=~10$ GHz, $B~=~1$ GHz, $\delta_{R}=~0.15$ m, $T_{r}=~1$ ms, $M$ (number of pulses) = 32.

  • Figure 5

    (Color online) Exponential model for diffuse clutter$^{3)}$.

  • Figure 6

    (Color online) Residual clutter after adaptive filtering (diffuse clutter only).

  • Figure 7

    (Color online) Loss of SCNR for WB (a) and NB (b) radars in the presence of purely diffuse clutter. $\beta$ is the clutter shape parameter and $\omega$ is the wind speed.

  • Figure 8

    (Color online) Loss of SCNR of WB radar in the presence of both stationary and diffuse clutter, after adaptive filtering.

  • Figure 9

    (Color online) Residual clutter after adaptive filtering of stationary (a) and moving (b) targets in the $K$-distributed model of clutter.

  • Table 1   Characteristics of wideband and narrowband radars
    ParameterWB radarNB radar
    $f_{c}$10 GHz10 GHz
    $B$1 GHz10 MHz
    $T_{r}$1 ms1 ms
    $M$ (pulses)6416
    $V_{a}$15 m/s15 m/s
  • Table 2   Four different target extent situations; in each case, the targetextent is assumed to be 4 range cells for signal processing (non-coherentsummation along the target extent profile)
    Model numberCell number
    1234
    11/41/41/41/4
    21/21/41/40
    33/41/400
    41000

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