About Multi-Transmitter & Single Receiver Telemetry System

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

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  1. Feb 27, 2019 #1

    unalfaruk

    unalfaruk

    unalfaruk

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    We are working on a model rocket project, it will carry a scientific payload and it will be launched to 3 km altitude. We have a data link between the rocket and the ground station, we are using RFM96W pair now. However, we need to get data from the payload so our receiver should be able to listen to multi-transmitter. But as far as I read the datasheet of RFM96W, it doesn't support it.

    As a result, I need a system consists of 2 transmitters and 1 receiver that be able to send sampled data to the ground control system over a 3km air gap.

    What is your advice for my system?
     
  2. Feb 27, 2019 #2

    SparkyVTFlyer

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    There are a few ways to do this. If you truly can only have one receiver, then you can time the packets from the rocket and payload so that they don’t overlap. Say, once the rocket packet has finished transmitting, then the payload transmits, then keep repeating that cycle.

    If that won’t work then put two RFM96W chips in your ground receiver. You can put the payload and rocket on different frequencies, or the same frequency with a different spreading factor. Either should work.
     
  3. Feb 27, 2019 #3

    unalfaruk

    unalfaruk

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    Thank you for reply.

    You are completely right, we also thought using two transmitters and two receivers having different same frequency or spreading factor because we have to get data in real time. However, we wanted to ask you if there may be another effective way.

    Have you tried using two couples? Was there any interference?

    Regards.
     
  4. Feb 27, 2019 #4

    SparkyVTFlyer

    SparkyVTFlyer

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    I haven’t tried using two receivers together. From what I have read LoRa is very robust. I would not expect significant interference whith either different frequencies or spreading factors
     
  5. Feb 27, 2019 #5

    unalfaruk

    unalfaruk

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    OK, we will try to test all of them and report the result here.
     

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