Mode U/V Satellite Transponder
- Paper number
IAC-07-B2.I.01
- Author
Mr. Namachivayam Ganesan, India
- Year
2007
- Abstract
Narrowband techniques on VHF and UHF namely SSB and CW have attracted increasing interest among amateur radio operators over the past few years. The limitation of line of sight communication increases demand in satellite space communication. This paper deals with analyze and Design of communication payload for OSCAR (Orbiting Satellites Carrying Amateur Radio) Indian Amateur Radio Satellite Development program conducted by AMSAT-INDIA (ISRO supported venture). The ultimate goal is to develop and test an Efficient, Elegant satellite transponder using space qualified surface mount components. Designing satellite systems pay load in this new, small, and light weight design presents a new challenge to satellite developers. The motivation of the project was started when India launches its first micro- satellite (HAM-SAT) on May 5, 2005. We are glad to say that we are the first to build a satellite transponder in Indian soil dedicated for amateur radio operators in India and abroad country’s in collage level. The design constraints of 1kg total mass and 648cc total volume lead to an ambitious and challenging project ideal for training students in rigors of aerospace and electronics engineering. First the system was analyzed, and different configurations were considered. Then specification for the entire transponder was started. At first we felt we had chosen the most difficult and most expensive kind of transponders. Even for an experienced engineer it is quit a difficult task to get it run well, and especially under space conditions. Even AMSAT, probably the most experienced developer of transponder for the OSCAR satellites has not published much on their design and construction. While carrying out this project we felt comfortable. Each block in the transponder will be constructed and tested separately and combined in single system. The advantage of doing this is to provide future changes in the design and maximum isolation with each block. The overall objectives are to foster keen interest in space technology education and non profitable one. The lessons learned by the team during its 1.5 year lifetime include contributing thorough thought to the design while keeping each blocks flexible for adapting to inevitable changes, keeping the blocks as simple as possible, and being realistic at the beginning of the project about the capabilities of the satellite. Over the course of the project, the design has benefited from the ability to utilize advice from department staff, insuring that calculations are accurate and reasonable. New types of miniature hardware can be integrated into the transponder for space rating. With the price of a satellite being far below that of a conventional transponder, this may well be one of the best and easiest uses for a satellite. Of course, innovation and imagination will continue to place more and more interesting payloads. Avoiding design mistakes early will save large amount of time and money later in the project. Trying to achieve the simplest design for each blocks of the transponder is perhaps the most important rule to follow on a student projects. This will lead to less time spent on devising components from scratch and also will help in the testing and debugging efforts near the end of the construction. The transponder project fit well into the over all satellite design due to its naturally small size and relatively low power requirements. Finally, the mass and volume constraints of the transponder are very restricting, and require much innovation to achieve for all but the simplest transponder. A realistic approach to what can and cannot be done within these restraints will avoid major delays or termination completely of a worthwhile education project. FUTURE DEVELOPMENTS: Lots of new innovation ideas were generated while constructing this project, but due to lack of funds and time availability we planned to finish the project at the earliest. The future development is to modify this transponder to fit into a 10cm x 10cm x 10cm CUBESAT. The advantage of CUBESAT is that three or four satellites can be launched in a single mission. Nowadays digital system plays an important role in the communication field. The future transponder should be adapted with compatibility to process digital data and signals.
- Abstract document