IEEE TRANSACTIONS ON EDUCATION, VOL. 37, NO. I , FEBRUARY 1994 107

In-Class Demonstration Using: Amateur Radio U

Satellites for the Teaching of Communications Engineering at the Universiti Kebangsaan Malaysia

Ahmad Faizal Mohd. Zain, Senior Member, IEEE

Abstract- One of the most readily available demonstrations for teaching communications engineering is the Amateur Radio satellites orbiting the earth. There are several advantages to using amateur satellites for classroom demonstration. The po- sitions of the satellites are predictable, and, unlike terrestrial communications, the links are generally line of sight and more reliable. In general, the effects of the ionosphere are very minimal on electromagnetic waves with frequencies above 30 MHz. The instructor is at a liberty to use very simple station setup and go through the rudiments of radio communications. This paper describes a case study in which such satellites were used to enhance the students’ understanding and grasp of the subject at the undergraduate level. The students have been very responsive to this hands-on approach in learning. The author has observed a change in the students’ attitude and eagerness towards the course. Although the demclnstrations are simple and easy to carry out, the impact on learhing can be significant.

I. INTRODUCTION

DUCATORS and instructors in science and engineer- E ing courses have to provide demonstrations to enhance learning among students. This is more so in the case of communications engineering, where many students shy away because of difficult material like Maxwell’s equations. In his book on electromagnetism [I], Zahn says that “electromagnetic field theory is the most unpopular course in electrical engineer- ing curriculum.” Despite it’s lack of appeal, electromagnetics is the basis for communications engineering.

At the Department of Electrical, Electronic and Systems Engineering, Universiti Kebangsaan Malaysia, communica- tions engineering is initially introduced in the fifth semester. Since it is a compulsory course, the attendance of students is guaranteed. However, to ensure the students’ interest and motivation, innovative in-class demonstrations have to be improvised.

One of the most promising class demonstrations is the use of the readily available orbiting amateur space satellites. These satellites are easily accessible with simple equipment, and the demonstrations can be done on a real-time basis. This paper provides the necessary background information on the satellites and gives a simple example using one of the satellites for in-class demonstration.

Manuscript received September 1991. The author is with fie Department of Electrical, Electronic, and Systems

IEEE Log Number 9214213. Engineering, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia.

I

11. BRIEF HISTORY OF AMATEUR RADIO SATELLITES

The idea of putting an orbiting amateur satellite into space can be attributed to Stoner, who, in April 1959, wrote an article in one of the leading amateur radio magazines [ 2 ] . He suggested that amateur radio operators undertake the construc- tion of a satellite. That challenge was taken up by a group of amateurs in Califomia who organized the OSCAR Association (Orbiting Satellite Carrying Amateur Radio). More than two years later, the first amateur radio satellite, designed and built by this group was launched as a secondary payload aboard the Discoverer XXXVI rocket. Named OSCAR I, the satellite weighed 10 lb. and contained a 140 milliwatt beacon transmitting at 145 MHz. The beacon was a repetitive message of the word “HI” in Morse code at a speed controlled by a sensor corresponding to the internal satellite temperature.

That success was followed by a second launch, within six months, of another satellite named OSCAR 11. OSCAR I1 was similar to OSCAR I, both structurally and electrically. How- ever, there were some improvements over the first satellite. These were: (1) Better surface thermal coatings to achieve a cooler internal spacecraft environment; (2) better satellite temperature sensing system; and (3) lower transmitter output power of 100 milliwatts to extend the life of the onboard battery.

These successes were followed by the design of the first relay satellite - OSCAR 111. OSCAR 111 carried a 50 KHz wide, 1 watt transponder that had an uplink frequency near 146 MHz and a downlink frequency near 144 MHz. OSCAR 111 was launched on March 9, 1965, and operated for 18 days. The fourth satellite, OSCAR IV, was launched into an unplanned elliptical orbit due to a malfunction of the final stage of the launching vehicle. Although this was a disap- pointment, several contacts were made through it, including the first two-way direct contact between amateurs in U.S. and Russia.

The fifth satellite, OSCAR 5 , was designed by a group of students, mostly undergraduates, at the University of Mel- boume, Australia, and launched on January 23, 1970. It was named Australis-OSCAR-5 (A-0-5) and the Arabic numeral system was preferred over the Roman numeral system (which has since been dropped from the naming of satellites). The Russians entered the picture with the simultaneous launch of two satellites: the Radio Sputnik-1 and Radio Sputnik-2 (RS- 1 and RS-2) on October 26, 1978 [3]. Readers can refer to

0018-9359/94$04.00 0 1994 IEEE

I08 IEEE TRANSACTIONS ON EDUCATION, VOL. 31, NO. 1, FEBRUARY 1994

[3] for a detailed account of the development of the amateur satellite service.

its first scientific satellite for 1993. The satellite, KITSAT, is being developed by the Korea Institute of Technology, Taejon, in collaboration with the University of Surrey with a funding of roughly US$55.6 million. It will cany store- and-forward packet telecommunications equipment, a Korean

high-energy particle detector [81.

@. SATELLITES IN EDUCATION

cured by the Udiversity of Surrey, England, in 1979. UoSAT (University of Surrey Satellite) was different from the OS-

Funding sate!1ites for purposes was pro- language digitalker, charge-coupled device cameras, and a

CARS and Radio Sputnik communications satellites in that its primary missions were technical experimentation and educa- tion, instead of two-way communications [4].

UoSAT addressed education not only in universities, but also primary and secondary schools. There is much concern over the declining number of students who wish to enter an engineering or technical career. The UKT Satellites in the EducationU program, catalyzed by the UoSAT spacecraft program, address these issues in two ways. First, it involves spacecraft engineers working with teachers to present students with real-life examples of modem technology in a manner that is interesting and educationally valuable to students. Secondly, an element of training is attached, so that teachers can acquire knowledge and skills in the appropriate technologies. The UoSAT program offers schools, colleges, and universities a unique opportunity to take a direct part in space research, with the minimum of cost and complexity [5] .

IV. THE MICROSATS

The most important event to date for amateur radio space communications was the simultaneous deployment of six spacecrafts on January 22, 1990. This was the second time amateur radio had experienced a multiple-satellite launch (the Soviet amateurs had successfully placed RS-3 through RS- 8 into orbit on December 17, 1981) [3]. The six satellites, UoSATs D and E and four microsats were secondary payloads with the remote sensing satellite, SPOT-2, aboard the Arianne 4 space vehicle.

The six new OSCAR satellites were part of two main projects. The first, the UoSAT project, was coordinated by ra- dio amateurs at the University of Surrey. This project produced two of the new satellites, UoSAT-OSCAR-14 and UoSAT- OSCAR-15. They are the third and fourth satellites developed under the UoSAT program. The second, the Microsat project, was coordinated by the Radio Amateur Satellite Corporation of North America (AMSAT-NA). This project produced four of the new satellites: AMSAT-OSCAR- 16 (PACSAT), DOVE- OSCAR- 17, Webersat-OSCAR- 18, and LUSAT-OSCAR- 19. These satellites were sponsored by AMSAT-NA, Amsat Brazil, Weber State College in Utah, and AMSAT Argentina, respec- tively.

Two weeks after the successful launch of OSCARS 14-19, Japanese radio amateurs deployed Fuji-2 or Fuji-Oscar-20, the second satellite produced by the Japanese amateur satellite program [6].

Pakistan and South Korea have also joined the space race and satellite prqgram. Pakistan launched its first experimental

V. DOVE

One of the four microsats launched was DOVE, an acronym for Digital Orbiting Voice Encoder. It is the work of Dr. J. T. de Castro, president of the Brazilian Radio Amateur Satellite Organization (BRAMSAT). Dove is specially dedicated for education. The satellite transmits’ FM digital voice signals on 145.825 MHz, including telemetry and special purpose voice transmissions. DOVE has a 808-km high sun-synchronous circular orbit that is inclined at 99’ with reference to the equator. It has a period of 101.4 min. It’s sun-synchronous orbit keeps the satellite’s pass time to around 10:30 a.m. and 10:30 p.m. local time at any point on the earth, with at least two morning or evening passes. This is very convenient for demonstration purposes, as it allows the demonstration to be carried out without the need to predict the time of the satellite’s pass.

One of the unique features of the microsats is the modular design. DOVE is divided into five equal 1.5-in. high modules, as shown in Fig. 1. Module 1 contains a special receiver for ex- perimental communications work. Module 2 contains DOVE’s computer based on the NEC V-40, which is compatible with the Intel 80C188. Module 3 is a power module with battery charge regulator and Ni-cad batteries. The batteries are charged by DOVE’s highly efficient solar cells, which almost totally cover its entire outer surface. Module 4 contains the speech digitizer/synthesizer. DOVE’s 2-m transmitter is located at the bottom in compartment 5 and is attached to the antenna system [91.

VI. IN-CLASS DEMONSTRATION OF DOVE

Dove’s transmission sequence consists of three main el- ements: identifier, bulletins, and telemetry. The format of the transmissions is totally programmable by ground com- mand stations. The mode of transmissions are synthesized voice, digitized voice, and 1,200 baud packet radio. The identifier-bulletins-telemetry-packet (IBTP) sequence typically takes 3.5-4 min. and then repeats itself. As of this writing, DOVE’s digitalker has not been turned on. However, packet transmissions have been successfully received.

The demonstration setup is shown in Fig. 2. The radio used is model TH205AT, made by the Kenwood Corporation of Japan. It is a simple FM transceiver with a whip antenna, and is priced at about US$250. When DOVE is within line of sight, signal levels are strong enough to be picked up even by this inefficient antenna. Furthermore, since the satellite is low earth orbiting, antenna pointing is not very critical, and thus the

BADq-l’ in June 1990 17” it had a be used for

‘It is rather unfortunate that DOVE stopped transmitting in the VHF band as of mid-1992. This is mainlv due to software uroblems. and we houe that short lifetime Of about six months and

class demonstration. South Korea has scheduled the launch of this will be rectified in the ne& future.

ZAIN: IN-CLASS DEMONSTRATION USING AMATEUR RADIO SATELLITES FOR THE TEACHING OF TELECOMMUNICATIONS ENGINEERING 109

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El

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Fig. 1. A view of DOVE with its covers on and an exploded view showing the modules. Reprinted with permission from May 1989 QST [9]. Drawing by Dick Jansson.

ORTHOGONAL DIPOLES

ANTENNA PERSONAL COMPUTER

>1=1 1 WHIP

- U - TERMINAL

NODE VHF

TRANSCEIVER CONTROLLER

Fig. 2. Demonstration setup using the whip antenna and orthogonal dipoles.

demonstration can be carried out without the need to track the satellite’s path accurately. The audio output is fed to the packet radio assembler/disassembler unit-more commonly known as the terminal node controller (TNCewhich decodes the signal. The TNC is model PK-232, made by Advanced Electronics Applications, Inc., Lynnwood, WA, and costs about US$350. Both the radio and the TNC can be readily obtained from most amateur radio stores. The decoded signal is accessed by the computer through the serial RS-232 standard port. Fig. 3 shows a sample of the received IBTP on packet.

Polarization demonstrations are done by using two orthog- onal horizontal dipoles tuned to 145.825 MHz instead of the whip antenna. Each of the dipoles is fed by a coaxial line through a switch to the radio, as shown in Fig. 2. When the satellite is in the acquisition of signal (AOS) window, the dipoles are manually switched altemately. This allows the students to see which orientation gives a higher signal level.

The reception of DOVE’s signal is consistent and simple, so no difficulties have occurred in setting up the demonstrations. It so happens that the time of the class is from 1O:OO a.m. to 11:OO a.m. every Tuesday and Wednesday. This is right in the window of DOVE’s orbital morning pass. Students are shown the effects of polarization, Doppler shift, path loss, and various other communications parameters. For example, Doppler shift

DOVE-l*>TLM: 00:5A G1:5A 02:88 03:32 04:iB 05:5A 06:6C 0 7 : 5 3 08:bE 09:74 OA:A4 0B:ED OClE8 0D:DC OE:2B OF:25 1O:DB 11:A7 12:01 l 3 : D C 1 4 : 9 5 15:AC 1 6 : 6 9 17:6A 18:6C 19:67 1A:fiB 1B:04 10:71 1D:60 1E:CC 1F:69 20:D3 D@VE-l*>TLM: 21:C6 22:70 2 3 : 3 3 24:2A 25:28 26:18 27:74 28:09 29:01 2A:02 2b:ZD 20:03 2D:86 2E:62 2F:9F 30:D8 31:A7 32:12 33:D2 34:A5 35:A2 36:AB 37:AA 38:84 D@VE-l*>STATUS: 80 00 G O 88 00 18 BB 02 00 BO 00 0 0 OA 0 C 3C 05 OB 0 0 03 04 30VE-l‘>BRAMST: reetings to the delegates to the AIAA/USU small satellite

conference from AMSAT. The DOVE Spacecraft IS transmictlnq 3 01”s watts. DOVE will be reset Soon for software upioading. 73 de BM dove-l*>BCRXMT: vmax=758079 battob=740556 temp= DOVE-l‘>LSTAT:

DOVE-l’,WASH: wash addr:lO40:0000. edac=Ox8b

I P : O X ~ O O O O : O i:i3081 f : i 3 0 8 i .

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DO\IE-1 *>TIME- 1 : PHT: uptime IS 043/02:09:22. Time IS Sat Sep 15 04:18:39 1990

Fig. 3. A sample of DOVE’s IBTP on packet.

is observed aurally with the change in pitch of the audio tone as the satellite passes over the horizon. At low elevation angles, the signal cannot be properly decoded by the terminal node controller because of the shift in tone frequency.

Informal discussions with students indicate a change in their attitude towards the course. Class attendance has also improved. They are more eager to learn and participate in class discussions. The author feels that the demonstrations have succeeded in heightening the interest of students in the subject.

VII. CONCLUSION

This paper described the Amateur Radio Satellite service and chose the DOVE satellite as one example for class demonstration. The satellite’s predictable orbit and strong radio signals make it an easy and reliable source of VHF signals for demonstrations purposes. The demonstration has heightened the interest of students in the communications engineering course. They are able to witness a first-hand account of satellite communication. With the enthusiasm that this class has instilled, the students are now actively trying to set up an amateur radio society in Universiti Kebangsaan Malaysia. Once that setup is established, other aspects of communications can be demonstrated.

ACKNOWLEDGMENT

The author wishes to thank the reviewers for their excellent comments. The students of course KE3272 (Communica- tions Systems) deserve special thanks, without whom the demonstrations might not have been initiated and carried out. Appreciation is also due to Chek Wah Ab. Rahman for typing the original manuscript.

REFERENCES

[ 11 M. Zahn, Electromagnetic Field Theory-A Prohlem Solving Approach. New York: Wiley, 1979.

[2] D. Stoner, “Semiconductors,” CQ, pp. 84, Apr. 1959. [3] M. Davidoff, The Satellite Experimenter’s Handhook. Newington, CT:

A W L , 1985.

110 lEEE TRANSACTlONS ON EDUCATION, VOL. 31, NO. 1 , FEBRUARY 1994

[4] J. W. Ward, “/3xperimental Oscars,” 73 Mug., pp. 62-64, May 1989. [5] C. I. UnderwTd, M. N. Sweeting, and J. K. Gilbert, “The role of UoSAT

spacecraft in Qpace education,” J.I.E.R.E, vol. 57, no. 5 , pp. 52065213, 1987.

[6] D. Loughmillbr, “Successful Oscar launch ushers in the T90s,” QST, pp. 52-53, Apr. 1990.

[7] Special issue pn the launching of BADR-1, Suparco Times (Pakistan), vol. VIll, no. 3, J u l . S e p . 1990.

[8] “South Korea readies science and communications satellites,’’ The Inst., IEEE, pp. 4, vol. 15, no. 5 , 1991.

[9] D. Loughmiller and B. McGwier, “Microsat: The next generation of Oscar satellites,’’ QST, pp. 3 7 4 0 , May 1989.

Ahmad Faizal Mohd. Zain (S’87, M’90, SM’92) received the B.Eng. (Hons) degree in electronic en- gineering and the M.Eng. degree in microwave com- munications engineering, both from the University of Sheffield, U.K., in 1979 and 1981, respectively, and the Ph.D. degree in electrical engineering from Pennsylvania State University, University Park, PA, in 1990.

Upon obtaining his first degree, he joined the Electronics Unit, Department of Physics, Universiti Kebangsaan Malaysia, in 1979 as a tutor. He then

took a leave of absence to further his studies and was appointed as a lecturer in 1981 after graduating with the M.Eng. degree. In 1984 he again took a leave of absence to pursue the Ph.D. degree at Pennsylvania State University, doing research in ionospheric modification and heating experiments at the High Power Auroral Stimulation (HIPAS) facility in Fairbanks, AK. He was a research and teaching assistant at Penn State from 1986 to 1990. In 1990, he retumed to the Electrical, Electronic, and Systems Engineering Department, Universiti Kebangsaan Malaysia, and presently heads the Telecommunications and Telematics Division. His current research interests are in RF and antenna engineering, radio propagation in the tropics, space and mobile communications, and electrical engineering education, including computer-aided instruction applications.

Dr. Zain was a committee member of the IEEE Malaysia section (1991-92). He is a corporate member of the Institution of Engineers Malaysia (IEM) and a licensed professional engineer with the Board of Engineers Malaysia.