Communications Subsystem

1
Communications Subsystem

• Advisor Mike Hammer (ldh3)
• Members Fawaz Allahwala (fa33)
• Jeff Baldwin (jsb39)
• Chris Danis (cgd3)
• Cindy Jih (ctj4)
• Michelle Mellers (msm39)
• Victor De la Rosa (vd29)
• Taneh Wonoloh (atw22)

2
Space Segment Requirements

• Mass Budget - less than 140 g
• Comm Board 54.88 g
• Patch Antenna 16.29 g
• Power Budget
• Transmit 0.843 amps or 2.7819 watts
• Receive 0.68 amps or .2244 watts
• Idle - .015 amps or 0.0495 watts
• There might be too much power being drawn from
  the idle state. If this is so, will have to
  consider powering down communications board
  instead of letting it go into idle state.
• Output Power
• 1 watt

3
Ground Segment Requirements

• Antenna tuned to operate with minimum SWR in
  440MHz band

4
Semester Goals Space Segment

• Fully functional comm board
• test RF amplifier
• Perform measurement tests
• Finish software for interface with CDH
• Complete interface testing with CDH
• Finish software for protocol
• Complete testing of protocol with ground station

5
Work Completed Space Segment

• Populated 4th revision of board
• Ran elementary tests on board
• Verifed that the board can
• Transmit
• Receive
• Communicate with external memory
• Communicate with RF 211 chip
• Perform serial communication
• Generate 433 MHz message
• Found threshold power for transmitting
• Started testing of RF Amplifier still in
  progress
• Ran inconclusive tests due to lack of calibrated
  output, but amplifier is amplifying! Question is
  if it is enough.
• Ran tests to confirm Power Budget
• Started protocol code and interface code still
  in progress

6
Semester Goals Ground Segment

• Internet connectivity in ham shack
• Multi-satellite capability in software
• Radio interfacing
• Antenna rotor interfacing
• Antenna construction installation
• Comm tutorial

7
Work Completed Ground Station

• Antenna tuned to 441.87MHz (SWR of 1.1) and ready
  to be mounted
• Connected radio to computer and test antenna
• Finished coils on antenna and ground plane
• Full backup made of ground computer
• Internet connectivity established in ham shack
• Database interface code completed tested
• GUI bugs fixed fully functional
• Radio tuning
• Multi-satellite capability
• Comm tutorial completed

8
Work to be Done Timeline Space Segmemt

• Finish protocol and interface code will be done
  before school starts next semester
• Interface test between CDH will test with CDH
  before school starts next semester
• Protocol test between comm board ground station

9
Work to be Done Timeline Ground Segment

• Radio interface should be complete in 1 week from
  now
• Rotor control testing (?)
• GS computer OS upgrades first week of next
  semester
• Antenna mounting first week of next semester

10
Risks Mitigation Space Segment

• Must coordinate with CDH to do interface testing
  have decided to return a week early
• Must find a way to test RF amp accurately talk
  to Kevin Feeney about possibilities