Tham khảo tài liệu 'advances in vehicular networking technologies part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 112 Advances in Vehicular Networking Technologies Fig. 8. Power spectrum of transmit signal with spectrum-hole of Fig. 9. Range spectra with and without hole. A point target is placed at Effect of spectrum-hole The effect of spectrum-hole on the range spectrum is presented where the measurement specification is shown in Table 1. Two sphere targets with -9dBsm and -15dBsm are measured in an RF anechoic chamber Skolnik 2001 Nakamura et al. 2011 . The measurement was conducted in an RF absorber where theses targets on turn table were placed at and 3m from the antenna. shows the range spectrum with spectrumhole of s which is compared with that without hole. Please note that the other echoes at and are from the turn table. shows the range spectrum as a function of rotation angle where the distane from thsese targets to the antenna are almost equal at the rotation angle of 90 degree. These targets are found to be discriminated because of the range resolution of approximately 15cm. The measurements were conducted for Af and N 30. Consider Af and N 133 however the maximum detectable range dmax is 20m and the range-resolution is approximately 15cm which is applicable to the shortrange automotive radar. From the measurement results it can be concluded that the stepped-FM radar without high speed A D devices can be coexistent with other narrowband wireless applications. Ultra-Wideband Automotive Radar 113 Frequency 3 4GHz Stepped width Af Number of step N 30 Stepped cycle 10msec A D 10kS sec IDFT point 1024 Table 1. Measurement specifications Fig. 10. Range spectra for two targets when the spectrum-holes is Range mJ Fig. 11. Range spectrum as a function of for two sphere targets 4. Detection using trajectory estimation Short-range automotive radar with high range-resolution should suffer from clutter because of its very broad lateral coverage. It is therefore an important issue to detect moving .
