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Test GPS Without Ferrite Inductors and Capacitors #14

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kb1lqc opened this issue Nov 2, 2016 · 3 comments
Closed
11 tasks done

Test GPS Without Ferrite Inductors and Capacitors #14

kb1lqc opened this issue Nov 2, 2016 · 3 comments
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Testing
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Rev D | Minimalis...

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kb1lqc commented Nov 2, 2016 •
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The GPS is a prime spot to remove components from. We may not actually need the 900MHz RF protection ferrites and capacitors.

Inductors

  • L23
  • L6
  • L20
  • L21
  • L22

Capacitors

  • C24
  • C55
  • C68
  • C69
  • C70

Testing in Hardware on Rev B

  • Tested

Basic testing of removing these parts or shorting around them and verifying that when transmitting the GPS remains locked is a good real-world test.
@kb1lqc kb1lqc added the Testing label Nov 2, 2016
@kb1lqc kb1lqc added this to the Rev D | Minimalist Design milestone Nov 2, 2016
@kb1lqc kb1lqc self-assigned this Nov 2, 2016
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kb1lqc commented Nov 3, 2016

Tested at full power (152 in Balloon Flight Software/Firmware) without capacitors but with all inductors and GPS lock was achieved. 1Hz telemetry transmission interval over RF was the fastest I could have it do with this firmware.

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kb1lqc commented Nov 3, 2016

GPS lock achieved with inductors and capacitors removed! Tried removing antenna to cause reflections which didn't affect the GPS lock (quality = 2) either. Placed my hand on the RF section to increase parasitics as well as handled the GPIO circuitry to try to mess it up with skin conduction but it remained locked.

Was transmitting at full power (152) with the HAB flight software/firmware. The only think I didn't try was bring a second Faraday super close to this Faraday. Since they all operate on similar frequencies this seems unlikely to cause an issue.

@kb1lqc kb1lqc closed this as completed Nov 3, 2016
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kb1lqc commented Nov 10, 2016 •
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Moved to RevD branch. Removed the following:

Inductors

  • L23
  • L6
  • L20
  • L21
  • L22

Capacitors

  • C24
  • C55
  • C68
  • C69
  • C70

@kb1lqd kb1lqd mentioned this issue Nov 13, 2016
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