Testing Ourselves Levent Sevgi DoQuf University Electronics and Communication Eng. Dept. Zeamet Sokak, No 21, Acibadem - KadikOy Istanbul, Turkey Email: [email protected][email protected] http://www3.dogus.edu.trllsevgi
I'm sure you all remember David, the new antenna engineer who was very happy when he calibrated the antennas he found in his company's warehouse . Now, David is going to place a kind of antenna tracking system on the roof at home. Instead of buying it as a built-in system, he is willing to design the system by himself. The quiz of this issue is about designing a rooftop-antenna tracking system. It comes from Prof. Dr. Salman Kurtulan and his PhD student, Miss Yaprak Yal91n (Figure 1). Dr. Kurtulan has been with the Control Engineering Department of the ElectricalElectronics Faculty at Istanbul Technical University (lTD) since 1982. He received the BS, MS, and PhD degrees, all in Electrical Engineering, from lTV in 1982, 1985, and 1992, respectively. He has also developed and presented many innovative technical training programs related to industrial automation. His current research interests include discrete-event systems, industrial automation and control, digital design, electrical transportation, and electrical drives. Dr. Kurtulan has established an excellent lTD-SIEMENS Industrial Automation Lab, and has been its Director for nearly two decades. Miss Ya191n received the BSc and MSc degrees, all in Electrical Engineering, from lTV in 2002 and 2004, respectively. She is currently a research and teaching assistant at the same university, pursuing her PhD degree. Her research interests include industrial automation and control, model-based predictive control, and energy-based control for port-controlled Hamiltonian systems.
The Quiz for this Issue
Figure 1. Salman Kurtulan (I) and Yaprak Yal~ln.
The tracking system should be able to operate in two different modes. David wants to increase or decrease angles by pressing azimuth and elevation up and down keys (four keys) in the manual mode. Thus, he will be able to adjust the direction of the antenna by himself. In auto mode, the pointing operation will be done by the control system tracking automatically to the given azimuth and elevation angles of a fixed transmitter. The deviation effects of wind and other disturbances, such as birds, cats, etc., should also be considered. The maximum wind speed will be assumed to be 150 km/h. Could you please help David in his work and design such a system?
The antenna weighs around 15 kg, and the diameter of the dish is 45 cm. The main objective of the antenna tracking system is to achieve the pointing of the antenna to the given azimuth and elevation angles of any fixed transmitter. The servo system should thus have two degrees of freedom (azimuth and elevation). The nominal speed of the servo system should be 6 rpm. The friction coefficient of the gearbox is k = 0.2 .
1. L. Sevgi, S. c;aklr, and G. c;aklr, "Antenna Calibration for EMC Tests and Measurements," IEEE Antennas and Propagation Magazine, 50, 3, June 2008, pp. 215-224.
IEEE Antennas and Propagation Magazine, Vol. 51, No.1, February 2009