Fade Dynamics Investigation applying Statistics of Fade Duration and Level Crossing Rate
Abstract — The impact of rain attenuation on wireless communication signals is predominant because of the used high frequency (above 10 GHz). The knowledge of statistics of attenuation is very important for planning point-to-point microwave links operating in high frequency band. Describing the statistics of attenuation is possible for instance with fade duration or level crossing rate. In our examination we determine these statistics from one year measured data for a given microwave link, and we are going to make an attempt to transform the level crossing rate statistic to fade duration statistic. Keywords — Rain Attenuation Measurement, Fade duration, Level Crossing Rate. I. I NTRODUCTION O investigate wave propagation phenomena a rain attenuation and weather data measurement system was established. Currently in Hungary a number of point-to-point millimetre wave links operating in the frequency bands of 13, 15, 23 and 38 GHz. The received IF signal powers are collected with the meteorological data together using weather stations at different locations for data collection. This paper investigates the dynamics of rain attenuation. Different statistics such as fade duration, number of events and level crossing rate are important for analysis of wave propagation phenomena, because they are indicating important information about the dynamics of the received signal. These statistics can be derived from our available measured data. To prepare these second-order statistics a one year period data measured on one 38 GHz link in Hungary in 2004 is considered. Fade duration and level crossing rate statistics will be compiled for attenuation exceeding different attenuation levels (fade thresholds) from 3 up to 8 dB. The parameters of the investigated link are described in Table I. The paper is organized as follows: Section 2 presents the fade duration and level crossing rate, Section 3 describes our data processing method while Section 4 shows our fade duration estimation from LCR, concluding remarks are given in Section 5.
Radiowave Propagation Modelling for SatCom Services at Ku-Band and Above
This paper gives an overview of the activities of COST Action 255. It outlines the structure of the Action and gives some indication as to the expected outcome.
Actuating Principle of Online Automatic Balancer with Counter Weight Driven by Magnetic Force
Kinematic precept of mass block in automatic balancer is proposed following the principle of online automatic dynamic balancing.By combination of electromagnet and permanent magnet,the magnetic circuit of the balancer with ring coil and rare earth permanent magnet is designed.Actuating process of the balancer is discussed and then a step drive voltage waveform is defined.For the high-speed grinding motorized spindle 170MD12Y16,the mechanical structure and dimensions of the balancer are schemed out.The electromagnetic simulations for the designed balancer are conducted and the better coil ampere-turns and reluctance adjusting ring thickness are then determined.The validity of simulation results is verified by a balancer driving experiment and the desired voltage value and its duration time are also determined.the designed balancer has a stable operation process without out-of-step and fluctuation around balanced position when the ampere-turns are considered as 1 kA,the reluctance adjusting ring thickness 0.2 mm,the driving voltage 12.4 V and the voltage duration time 120 ms.