Redundant Telemetry Design

Discussion in 'Rocketry Electronics and Software' started by unalfaruk, Jan 27, 2019.

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  1. Jan 27, 2019 #1

    unalfaruk

    unalfaruk

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    We are, as a team, a competitor for model rocket competition. And we need to use two flight computers in the rocket and two ground control stations(GCS) for redundancy. We can design our custom computer and custom GCS, however, we can't predict the risks of using two telemetries together for redundancy.

    We plan to design the rocket layer by layer, and we use two layers for flight computers. One of them will use XBee 2.4 GHz telemetry, the other will use RFM96W/RFM95W 433MHz/868MHz/915MHz telemetry. Is there anyone who experienced this design?
     
  2. Jan 27, 2019 #2

    SparkyVTFlyer

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    One system will work just fine. Redundant isn't necessary. I use the RFM96 LoRa on 433MHz frequently and get 10Km range or more. A ground station does not need to be complicated. A simple microcontroller hooked up to a RFM96 chip and a bluetooth chip will work fine and you can see the data over your smartphone. There are many other options. You've seen how I did it on my Github site.

    Or you can just spend a little more money and buy a commercial unit like the TeleMega and not worry about any development.
     
  3. Jan 27, 2019 #3

    cwbullet

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    Use one telemetry and one tracker if you need backup.
     
  4. Jan 27, 2019 #4

    UhClem

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    Need? Is it a requirement of the competition or just something you want to do?
     
  5. Jan 27, 2019 #5

    mikec

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    It's worth remembering that many of these rocket competitions have requirements that may seem nonsensical to experienced rocketeers. For example, one college team who flew at our site had to have redundant igniters for staging.

    As for the OP's problem -- you could use the same types of transmitters on different frequencies or (in the case of the XBee) hopping channel/DT setting. That way you wouldn't have to understand two completely different systems. XBee 2.4 GHz systems have fairly limited range, though. I've always used 900 MHz for rockets.
     
    Last edited: Jan 27, 2019
  6. Jan 27, 2019 #6

    blackjack2564

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    Yes it will work fine without any cross interference. i used a Telemega [433] and Missleworks [910] many times.
    This bay held 3 altimeters 2 GPS and a 3rd GPS in nosecone tip for our test mule. Upon completion of testing we went with just 2 altimeters and 2 GPS.

    DSCN0011.jpg DSCN0184.jpg

    Electronics were recessed into bay for protecting antennas upon landing. Chute was in nomex, burrito folded between antennas.
     
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  7. Jan 27, 2019 #7

    cerving

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    What telemetry data is required? Only GPS data, or do you need live flight data (altitude, velocity, etc.) too? And what is your expected apogee?
     
  8. Jan 27, 2019 #8

    unalfaruk

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    Yes, we need backup.

    Using redundant systems is a requirement. Also, it is advised to use a commercial alternative as a redundant, however, you can use a custom design for both of them.
     
  9. Jan 27, 2019 #9

    unalfaruk

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    Wowww, here is a perfect answer for me. As an additional info, your pictures help me about the location of antennas. If you have a GitHub repo or blog page, I'd like to follow your works.
     
  10. Jan 27, 2019 #10

    unalfaruk

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    We need live flight data(altitude,velocity,tilt,GPS,mission time etc.). If we can complete our computer early than the deadline, we plan to transmit video using analog telemetry.
     
  11. Jan 27, 2019 #11

    unalfaruk

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    You're absolutely right, but using a redundant system is a requirement. Their explanation is "If the main system fails, the second system shall complete the mission."
     
  12. Jan 27, 2019 #12

    dhbarr

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    In case no one has mentioned it I would specifically recommend AGAINST using two custom setups, either identical or different.

    One home brew with a commercial backup is probably tolerable. But unless there's a compelling reason to devote a bunch of resources, I'd just go with two commercial units.
     
  13. Jan 27, 2019 #13

    tfish

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    unalfaruk,

    Mind if I ask which competition you are competing in?

    Tony Alcocer
    Spaceport America Cup - Range Safety Officer
     
  14. Jan 27, 2019 #14

    blackjack2564

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    Much more info in this thread, warning much reading ,as I document everything for this project. Pay attention to GPS mounted in NC with phenolic tip replacing metal one for radio transparency. Tons of graphs and data to look at, including satellites in view during flight.
    This project is in 3 phases...1/3 scale...1/2 scale...full scale AND spin stabilized!

    https://www.rocketryforum.com/threads/full-scale-sparrow-hv-arcus-2-stage-sounding-rocket.132380/

    Good luck with your project!
     
  15. Jan 28, 2019 #15

    unalfaruk

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    We are engineering students and newly graduated people, so we want to improve our development skills. Therefore, we have to design at least one flight computer.
     
  16. Jan 28, 2019 #16

    unalfaruk

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    We were a participant in "cansatcompetition.com" in the last year. Now our team got bigger and we split it. Now, I am in the rocket team that is a participant in "teknofestistanbul.org/en".
     

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