Notes for November 9 2023

Data Processing

• With the sensor model, as long as we have the GNSS and attitude data, we should be able to orthorectify and georeference the images - not matter which angle they’re taken at
  • However, given that pointing knowledge has uncertainty, I assume as the angle we take the image at increases, the actual uncertainty in distance will increase for the point on the ground
  • Since our fields are a certain size, past a certain length then does the data become useless?
  • What frequency do we need @[email protected]? 15 Hz is the maximum - is that fine? Do we only need it during imaging?
• So from ADCS we need to know about:
  • GNSS (units, refresh rate, ???)
  • Attitude (units, refresh rate, ???)
• Really the only requirements DP has are pointing accuracy and knowledge which should be good
• Think about it from a “more data is better” perspective
  • As long as it doesn’t get in the way of downlinking good data, we should send as much “bad” data as we can
  • Need to consider downlink bandwidth

Optics

• relevant ADCS requirements: FINCH-ADCS-PointingKnowledge FINCH-ADCS-RelativePointingAccuracy FINCH-ADCS-AbsolutePointingAccuracy
• imaging pass:
  • integration time for suffieicently high SNR
  • slew rate v/s frame rate tradeoff
    • ADCS slewing capabilities? required frame rate?
• optical parameters that impact pointing accuracy:
  • spatial resolution
  • frame rate: Any frame rate may be selected between 1fps and 60fps, corresponding to frame periods from ~1s to 16.67ms respectively.
  • integration time: Integration periods may be set as short as 10μs or as long as a frame period minus ~70μs.

• SNR analysis

ADCS

Q: (For Data Processing) What is the max angle we can be offset from normal over imaging site for an acceptable image? (This angle is the limit to how far we can be from a pass directly over the imaging site). Define normal pass as a pass that is directly over the imaging site. (This angle will also limit use of star tracker if it is placed in +-y direction)

• Quality of image will decrease as angle decreases
• Even if we get one over to the side the more the merrier
• Increasing uncertainty in the angle pointing, more shallow angle will correspond
• the more directly above
• rank imaging pass by angle, start off small angles and increase