Seed Measurement by Radio Wave Spatial Filter

由于多程衰落现象，广播电台产生和传播的无线电波的电场强度呈现随机周期性的空间分布模式。本研究的目的是将空间滤波技术应用于电场强度的变化，研制一种新型的车速计。此外，我们还考虑利用卫星无线电波进行GPS以及GPS信号与车载本地传感器的融合。研究项目计划研究以下4个方面：(1)研究多程衰落现象作为空间滤波的空间测量；(2)开发快速响应调谐器；(3)利用卫星无线电波进行GPS；以及(4)GPS信号与本地车辆传感器信号的融合。主要研究结果如下：(1)作为空间滤波的空间量度，无线电波电场强度的低频变化会产生误差。通过两个天线电场强度的空间差异，减少了低频变化，实现了准确的速度测量。当检测到车辆行驶时，需要使用快速响应调谐器来检测电场强度。利用对数放大器研制了一种Q值较小的调谐器。该调谐器可以检测行驶速度超过100 km/h的车辆的电场强度。(3)我们尝试将卫星无线电波强度的变化用于GPS，但由于接收机的采样间隔太慢，本质上是卫星在运动，因此无法确定它是否适用。(4)利用卡尔曼滤波技术对定位信息和车载本地传感器(速度计和速率陀螺仪)的定位信息进行融合和融合。定位精度非常好，不需要地图信息。

The electric field intensity of radio waves generated and propagated from a broadcasting station show stochastically periodic spatial pattern due to the multi-pass fading phenomenon. This research aims at developing a new type of speedometer by applying the spatial filtering technique to the change in the electric filed intensity. Further here we consider use of radio waves from satellite for GPS and the fusion of GPS signal with local sensors in the vehicle.The research project was scheduled to investigate the following 4 items, i.e.,(1) investigation of multi-pass fading phenomenon as a spatial measure for spatial filter, (2) development of quick response tuner, (3) use of radio waves from satellite for GPS,and (4) fusion of GPS signal and signals from local vehicle sensors. We have the following results ;(1) As a spatial measure for the spatial filter, the low frequency change in the electric field intensity of radio wave causes error. Spatial difference by 2 antennae of the electric field intensities reduces the low frequency change and yields accurate speed measurement. More antennae than 2 leads to more accurate measurement.(2) Quick response tuner is required to detect the electric field intensity when detected driving vehicle. A tuner with less Q-value was newly developed by using log-amplifier. The tuner can detect the electric field intensity from a vehicle driving faster than 100km/h.(3) We tried to use the change in the intensity of radio waves from satellites for GPS.But we could not find if or if not it can be used, because the sampling interval of the receivers was too slow and essentially, the satellites are moving.(4) The positioning information and those from vehicle local sensors (speedometer and rate gyro) are fused and integrated by applying Kalman filtering technique. The accuracy of positioning is so good that no map information is required.