SCHOOL ON DIGITAL RADIO COMMUNICATION FOR RESEARCH & TRAINING IN DEVELOPING COUNTRIES
Dated: Thursday, 12 February 2004
By: Rizwan Waheed
rwaheed@ictp.trieste.it
rizwan_waheed@hotmail.com
URL: http://www.geocities.com/uafweb
The 4th day started at 09:05 with lecture of Dr. M. Fitton. It was the second part of his yesterday’s presentation on “Digital Modulation”. He started with the multi-path environment and told that the received signal in this environment has large variation in magnitude due to the noise & interference. He further added that in presence of Additive White Gausian Noise (AWGN) the system performance is severely affected. Then he told about the eye diagram, Doppler Effect, random FM, time dispersion in the multi-path channel, inter-symbol interference, and a summary of the error mechanisms. At 10:00 we took the coffee break as usual and gathered at 10:20. The second lecture titled “Digital Modulation-3” was also by Dr. Fitton. Actually according to schedule there were three lectures on digital modulation and this was the last part. In this part Dr. Fitton told about the evaluation of the personal cellular communication in this sequence: GSM, HSCSD, GPRS, EDGE, UMTS, UMTS+. Then he discussed different types of multiple access techniques like FDMA, TDMA FH-CDMA, DS-CDMA, OFDMA. For the last 35 minutes, he talked on the wireless technologies covering the important issues of coding and equalization. He finished at 11:25 and the mic was given to Prof. Dr. Struzak for the lecture on “Introduction to radio regulations”. The purpose of his lecture was to tell us about the international radio regulations that specify how terrestrial and satellite radio of any kind should or should not be used in all countries. He discussed the following topics in detail:
During his lecture he explained the spectrum congestion cycle. Prof. Struzak, in all his lectures first gives the purpose of lecture, and at the end summarizes his lecture in a heading “what we learned”. Moreover, he always provides very useful references of the online material relating to his lecture. Prof. Struzak finished the lecture at 12:20 and after some questions we got the LUNCH BREAK!
After the lunch break all participants gathered in Lab at 14:00 where Mr. Carlo, Mr. Marco, Prof. Struzak and Prof. Pietrosemoli welcomed us. Everything was perfect because today they had also solved the voice problem with speakers; as it was difficult to hear at the end of the Lab, last day. Dr. Struzak gave us the following link to visit:
http://www.educatorscorner.com/index.cgi?CONTENT_ID=2483
There is JAVA animations (simulations) of wave propagations and many more. This link is really very useful and informative. Dr. Pietrosemoli explained the propagation of the waves with help of the simulation from the above mentioned website.
Then Mr. Carlo told us how to solder the N-connector on RG-213 coaxial cable. He demonstrated it to us by assembling a connector on the cable. Then all the groups practiced it. It was really very interesting to do this. Each group was doing this enthusiastically. Then, as instructed by Mr. Carlo & Mr. Marco, all groups measured the unknown load impedance one by one and some of them also found the velocity factor of the cable and then calculated the length of the cable. These experiments were done with the help of digital storage oscilloscope and pulse generator.
At 18:30 we had officially finished the 4th day of the school but as many of us were busy in soldering and measurements, so we left the lab around 19:30 for dinner. Around 20:00 Mr. Carlo again opened the lab for us, as some students wanted to continue the lab work.