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DTUsat-1: Protocol
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Protocol


The issue of this project is the development of a protocol for use on beard DTUsat, as communication to and from the satellite is digital using a radio connection. If the communication had been analog and between humans a protocol had not been required. Any errors would be ignored as "noise" or the message could be repeated. But since communication to and from DTUsat is digital and between computers a protocol is needed. Protocols are already widely used e.g. the TCP/IP protocol which is used on the Internet and FTP which is used for file transfer between computers. The reasons why a protocol is necessary for digital communication is:

  • All data has to be transferred error free. Any corruption would render the data unusable to the computers.
  • The transfer of data has to be automated. The computers have to know how to react to errors in the data and other transmission errors.

The project has three main parts:

  • An analysis of the features of the protocol. This includes error detection/correction, transparent data etc..
  • A design of the protocol with the features and functions that was determined in the analysis.
  • An implementation and test part, where the code for the protocol is documented and testet.

At present the following is known about the DTUsat protocol. It is based on the AX.25 protocol developed by amateur radio enthusiasts for digital radio communication. Besides an implementation of AX.25 the protocol contains functions so any size of data can be transmitted, which is not possible with a pure AX.25 protocol.