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In conclusion, the Smart Packet Radio has been developed and tested, and is in basic working order. It is set to transmit at the maximum data rate allowable for the modulation being used which is 200 kbps. The maximum transmission distance was found to be 300m, though for its intended purpose this distance is not required. Disregarding the internal settings for transmission power, the size of the antenna had a great impact on the reliable transmission distance. Using an antenna with a length of ƛ/4 gave the greatest results, though because multiple hops would be required over the length of the communications labs, the antenna size was reduced to around half of that. Coupled with minimum transmission power this reduced the reliable transmission distance to about 10 metres. The internal packet handler is also used successfully, implementing a preamble, sync byte, header byte and CRC. These features result in a great reliability of transmission though these features may wish to be disabled in future applications. The user guide written in this report was also a core component of this project. As the Smart Packet Radio is intended to be used for future project of various natures, itís essential that whoever uses them has a quick and easy method of implementing the device whether on the Windows operating system, or Linux. Although most of the final tests were successful, an error was encountered when attempting to write packets continuously to one board using the Python code mentioned earlier. The tests were successful up to about 4000 packets. For an unknown reason if an amount greater than this was selected, after a few seconds the radio would start transmitting at around one packet a second. As most of the testing was performed using the terminal program in Windows this problem wasnít encountered until the end of the project and there wasnít enough time to look into it thoroughly. It may have something to do with the asymmetrical nature of the speed at which data is being read in to the device compared to how quickly it is sent. As the ability to send this amount of packets one after the other may not be necessary in the future, it can be investigated at a later time if this feature is desired. The direct mode offered by the transceiver which bypasses the internal packet handler was also attempted. Unfortunately it was difficult to get working and the idea was scrapped as the FIFO mode offered by the module seemed like a more reliable route. If the user wishes all of the packet handling to be done at a higher level and the device to have no intelligence (i.e. only used to send and receive information) direct mode may be desirable. The hardware is set up allows this mode to be possible though more testing is needed to develop it properly. The firmware has been attached as an appendix if further analysis is required though for practical application the whole project is required for the board to operate, as parameters set by the LUFA code is not included in the main c file.

-- XiaohongWu - 2012-01-31

Topic revision: r1 - 2012-01-31 - XiaohongWu
 
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