Dale McClure’s Summer

1. Dale McClure’s Summer • KySat subsystems researched • Antenna design • S-Band communication • IARU frequency request form • APRS-IS compatibility

2. Antenna Design • Use ¼ wave monopole antennas for all radio systems • Resulting radiation pattern is relatively uniform, with few nulls • The only significant null will occur when the satellite is directly overhead • This occurs very rarely

3. Problems With Current Design • Small ground plane • The cube will not be a very efficient ground plane for the ¼ wavelength monopoles • Antenna simulation software does not give correct values for input impedance • Small portions of the VHF antenna are parallel to the sides of the cube

4. Previous Designs • Cross-Dipole phased array • This would provide a more uniform radiation pattern • Theoretically, there would be no nulls • This design would be heavy, and require a complex mounting system • There was not enough time to fully design this antenna

5. Previous Designs • Standard ½ wavelength dipole • This would be more efficient than monopoles because of the small ground plane • Mounting would be difficult since there would be twice the length of total antenna • With more antennas present, the chances of them interfering with each other goes up

6. S-Band Communication • Currently using the Microhard MHX-2400 • 1W output power • Configurable data rate (9,600-115,000 baud) • FHSS (Frequency-Hopping Spread Spectrum)

7. S-Band Radio Problems • Not enough power • Transmit power = 30dBm • Transmit antenna gain = -3dB • Line loss = -1dB • Space loss = -165dB • Receiver gain = 44dB  !! • Pointing loss = -3dB • Line loss = -1dB • Polarization loss = -3dB • Implementation loss = -3dB • Receiver sensitivity = 105dBm • In order to close the link budget a 44dBi antenna is needed!

8. S-Band Radio Problems • Other Problems • Transceivers are unable to compensate for Doppler shift • Long path length may adversely affect the frequency hoping pattern • Due to these problems, the S-Band radio was changed to an experimental payload

9. IARU Frequency Allocation • Worked on filling out the IARU frequency request form • Acquired Stanford University’s application • The KySat form is 80% done now

10. APRS Compatibility • APRS-IS overview (Automatic Packet Reporting System – Internet Service) • Ham radio operators receive an APRS packet • If the Ham user is APRS-IS compatible, this packet is sent to a central APRS-IS server • This server repeats the packet to all other servers on the network • The packet is then received by the findu.com server and logged for approximately two weeks • This is a way for UK to receive packets picked up by KySat users from around the world

11. APRS Compatibility • Ground station software • Special software is required to inject packets into APRS-IS • Instead of using this software, packets can be injected using a telnet program such as HyperTerminal • In order to do this, a logon string must be sent first • After being logged in, a packet can be injected in TNC-2 format • If the packet format is slightly wrong, it will not appear on findu.com • This was discovered after a great deal of trial and error

12. APRS Compatibility • Ground station software • Special software is required to inject packets into APRS-IS • Instead of using this software, packets can be injected using a telnet program such as HyperTerminal • This was discovered after a great deal of trial and error