Wataru Tsujita

Cramér–Rao Bounds for a Coupled Mixture of Polynomial Phase and Sinusoidal FM Signals

This letter introduces a new coupled mixture of polynomial phase signal (PPS) and sinusoidal frequency modulated (FM) signal, motivated by real-world applications, for example, contactless linear encoders. Specifically, the coupling is introduced to express the sinusoidal FM frequency as a function of the PPS-related parameters. Given the coupling mixture, it generalizes two existing models: the pure PPS model and the independent mixture model. Performance bounds of parameter estimation for the coupled mixture model are established in terms of the Cramér–Rao bound (CRB). Unlike the pure PPS case, the derived CRB shows its dependence on the PPS-related and sinusoidal FM-related parameters due to the coupling mixture. On the other hand, the derived CRBs for the PPS-related parameters are lower than their counterparts of the independent mixture model, as the sinusoidal FM frequency provides additional information on the PPS parameters.

2 in 1 leakey coaxial cable for intrusion detection sensor

Novel leaky coaxial cable (LCX) is developed. It contains both transmitting and receiving LCX for intrusion detection sensor. While the suppression of coupling between transmitter and receiver is major theme in microwave technology, we give a solution of transmitter and receiver antenna combination. We have developed a prototype of 2 in 1 LCX and then evaluated its performance for intrusion detection sensor in field experimentation.

Metamaterial absorber for THz polarimetric sensing

THz encoders have distinct advantages for position sensing compared with other types of encoders, such as those based on optical and inductive sensors. A polarization-dependent metamaterial absorber reflects one polarization while absorbs the other, which makes it an ideal building block for the barcode of a THz encoder system. In this paper, we present the design, fabrication, and experiments of a THz polarization-dependent metamaterial absorber, and its application to a polarimetric sensing system.

Integrity monitoring of train positioning with GNSS

This paper discusses the integrity monitoring of train positioning with GNSS. It is shown that the number of samples needed to approximate the probability distribution of errors caused by interference with a sufficiently small risk is astronomically large. As an alternative, a geometrical upper bound for these errors is proposed. This bound is calculated from an observed clock bias in each epoch regardless of the interference. Experiments with a commercial rubidium oscillator show promising results in terms of the accuracy of the clock bias observation as well as the realistic upper bounding of positioning errors.