Tetsuo Kirimoto

Orthogonal periodic sequences derived from M-sequences on GF(q)

A novel construction is proposed to generate orthogonal periodic sequences whose elements consist of at most q complex numbers which are not expressed in the power of complex primitive roots of unity. The orthogonal periodic sequences are generated by mapping M-sequences on GF(q) into complex periodic sequences. >

A bandwidth extrapolation technique for improved range resolution of polarimetric radar data

Radar resolution is limited in range by its bandwidth. One of the various super-resolution techniques for improving resolution is bandwidth extrapolation (BWE). In this paper, the concept of BWE is extended, and a new algorithm called polarimetric bandwidth extrapolation (PBWE), applicable to polarimetric radar data, is proposed. It is shown through simulations that utilization of full polarization information allows PBWE to improve the resolution beyond the conventional BWE method.

A design method of clutter suppression filters with cascade connection using offset of zeros for staggered PRF

In search radar with staggered PRF (Pulse Repetition Frequency), a clutter suppression method to use time-varying filters with cascade connection has been presented. However, the suppression performance degrades in the case dig one frequency of zeros with filters coincides others at least. In order to overcome this problem in this report, we propose a design method of clutter suppression filters with cascade connection using offset frequency of zeros.

Target detection performance of PDI considering the change of the target distance

In radar systems, PDI (post-detection integration) techniques are widely used to improve the target detection performance. In a conventional PDI, targets are assumed to be stationary, that is the distance between a radar platform and a target is almost constant. Conversely, if the target distance changes, the target detection performance of PDI deteriorates. To resolve the above problem, we have proposed shift PDI method. In this method, we conduct the PDI processing, based on the various assumptions of target velocity, which results in the increase of PFA (probability of false alarm rate). In this paper, we conduct the numerical formula to calculate the PFA for shift PDI procedure. Moreover, we estimate the target detection probability of the shift PDI with considering the increase of PFA in the shift PDI procedure.

Extraction of the inphase and quadrature components from oversampled bandpass signals using multistage decimator with BPFs and its performance evaluation

We present a method of extracting the digital inphase (I) and quadrature (Q) components from oversampled bandpass signals using narrow-band bandpass Hilbert transformers. Down-conversion of the digitized IF signals to baseband and reduction of the quantization noise are accomplished by the multistage decimator with the complex coefficient bandpass digital filters (BPFs), of which the bandpass Hilbert transformers are composed. Most of the complex coefficient BPFs in the multistage decimator can be replaced with the lowpass filters (LPFs) under some conditions, which reduces computational burden. We evaluate the signal to quantization noise ratio of the I and Q components for the sinusoidal input by computer simulation. Simulation results show that the equivalent amplitude resolution of the I and Q components can be increased by 3 bits in comparison with non-oversampling case.<<ETX>>