Design of double ring lock ring in extensible frequency clock generator chip

With the continuous development of computer technology and the continuous improvement of interface data rate, the clock frequency has reached the demand of several gigahertz, which makes the electromagnetic interference problem very serious. Spread spectrum clock is an effective method to reduce electromagnetic interference of digital chips. Therefore, this paper designs a double-loop phase-locked loop that can spread spectrum and has strong anti-electromagnetic noise interference ability. The designed dual-loop phase-locked loop can be used in the clock generator chip. The overall structure of the circuit consists of a main loop and a secondary loop. The main loop is an adjustable phase-locked loop circuit that can provide an output with a center frequency of 500MHz. The secondary loop can realize the spread spectrum function by charging and discharging the filter capacitor of the main loop loop, and at the same time, the spreading depth can be set by the feedback based on the frequency division. The dual-loop phase-locked loop designed in this paper has a good effect in spread spectrum and anti-electromagnetic interference noise.

Sistem Visualisasi Polaradiasi Antena Memanfaatkan Mikrokontroller Sebagai Pengendali Antena Penerima (Rx)

ola radiasi merupakan salah satu parameter antena yang sangat penting untuk diketahui dan difahami oleh mahasiswa jurusan teknik telekomunikasi pada khususnya dan mahasiswa politeknik pada umumnya. Oleh karena itu pada mata kuliah praktek antena, pengukuran pola radiasi sangat diutamakan. Proses pengukuran pola radiasi antena selama ini dilakukan secara manual, dimana resolusi pengambilan data yang dapat dilakukan minimum 10o sehingga hasil penggambaran pola radiasi kurang akurat. Pada paper ini telah dilakukan penelitian tentang pembuatan sistem interfacing yang digunakan untuk pengatur putaran antena penerima dan pengambilan data oleh spectrum analyzer secara otomatis.Sistem ini dapat diset dengan resolusi minimum 0,6odan sekaligus melakukan penggambaran pola radiasi menggunakan software yang ditampilkan pada monitor personal komputer (PC). Hardware pada sistem ini menggunakan mikrokontroller sebagai pengendali gerakan antena, kabel RS 232 untuk komunikasi serial antar spectrum dan komputer, pengiriman dan pengambilan data oleh spectrum analyzer menggunakan kode ASCII, sedangkan visualisasinya dilakukan dengan software visual basic. Sistem ini diharapkan dapat membantu mahasiswa dalam praktek pengukuran pola radiasi secara otomatis dan dapat membandingkan hasilnya dengan cara manual. Hasil penggambaran pola radiasi secara otomatis, pancaran radiasinya (main loop) terfokus/terarah pada sudut 0˚, sedangkan penggambaran secara manual terlihat adanya side loop dan pancaran radiasinya tidak tepat berada pada 0oyaitu meleset kurang lebih 500. Berdasarkan data tersebut dapat dikatakan bahwa penggukuran menggunakan sistem ini lebih cepat dan akurat dibandingan dengan pengukuran secara manual.

Dual adaptive robust control for uncertain nonlinear active suspension systems actuated by asymmetric electrohydraulic actuators

This study investigates the vibration control issue of active suspension systems. Unlike previous results that neglect the actuator dynamics or consider the impractical symmetrical hydraulic cylinder model, this paper incorporates more reasonable asymmetric electrohydraulic actuator into active suspension system and derives its dynamic model. However, whether active suspension or electrohydraulic actuator suffers from nonlinearities (e.g. nonlinear spring, nonlinear damper and nonlinear actuator dynamics) and parameters uncertainties (e.g. the variations of sprung mass and hydraulic fluid’s bulk modulus as well as hydraulic cylinder original control volumes) , which were rarely synthetically considered in the existing researches.To address these issues, we develop a novel dual adaptive robust controller (ARC). An ARC is firstly designed for main-loop system for stabilizing the car body and improving ride comfort in the presence of nonlinearities and parameter uncertainties as well as road disturbances. In order to meet the constraints requirements of suspension system, the tunable parameters in main-loop control law are optimized by solving linear matrix inequality with kidney-inspired algorithm. Another ARC is further synthesized for sub-loop system to deal with the nonlinear and uncertain dynamics in electrohydraulic actuator for ensuring the force tracking performance. Meanwhile, the uncertain parameters are estimated online to compensate the model deviation. The terminal control law is able to guarantee the asymptotic stability of close-loop system within Lyapunov framework. Finally, the effectiveness and robustness of the proposed controller are demonstrated via excessive simulation experiments over different road conditions.

The prototype of a wireless measurement card

This publication contains the description of the prototype of wireless measurement card that share measurement data via global Internet network. The created measurement card aims to improving the process of obtaining measurement results by enabling remote measurement and sharing results via the Internet. At the beginning of the article, discussed issues are generally presented, which solution is presented device. In the next sections presented the main functional assumptions, describe the most important components included in the prototype and present the algorithm of the main loop of the device program.

Numerical Simulation and Analyses of Flow Rate Exchange between Accumulator and Main loop

In order to study the dynamic behaviors of heat and mass transfer between accumulator and mechanically pumped two–phase loop (MPTL) system, a transient numerical model is developed by using thetime–dependent Navier–Stokes equations. By comparison between simulation and test results, it is found that the error of numerical model is in the range of ±10%, which verifies the validityand accuracy of the model. Simulation results show that the accumulator will exchange fluid with the main loop in responseto heat load variations. In this case, the temperature and pressure of two phase fluid in accumulator, and the total system flow resistance will be affected. The rate of mass transferbetween accumulator and main loop will increase along with the charge amount of working fluid, and also for the variation trend of temperature and pressure of two phase fluid in the accumulator. The model can be used to study the operating state, flow and heat characteristics of MPTL system.