500mw output tests for RC submarine at 915mhz for under water control

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  • Sinksalot
    Commander
    • Mar 2020
    • 332

    500mw output tests for RC submarine at 915mhz for under water control

    H there,

    First test was me putting the receiver 4 and 1/2 foot under water while I held the transmitter in my hand. while I was over the spot.. Passed test

    Second test was the receiver was about 2 feet and 10 inch under water with my buddy with the transmitter was about 100 to 125 feet away. Passed test

    Transmitter is outputting 500mw of power for now, but can go as high as 2 watts. But at 500mw its running great with the test. This radio, module and receiver were bought from a drone hobby shop but can be gotten off Amazon or Ebay too.

    Receiver and servos were in a water tight clear box to make it easy to see the servos move.

    If you wish I can post a video of the 2nd test.
  • Sinksalot
    Commander
    • Mar 2020
    • 332

    #2
    Originally posted by Das Boot

    500mw to 2 watts is a lot of power for an RC transmitter. How long does the battery last during constant transmit? Also, at 915 MHz continuous transmit, at that power level, isn’t exactly safe for your brain box.
    915mhz module has a input for a external battery to plug into if you running at the higher output setting. They wouldn't sell it if it isn't safe. A ton of drone users run this setuo for long range use.

    Comment

    • redboat219
      Admiral
      • Dec 2008
      • 2735

      #3
      Sorry just had to post this
      https://getyarn.io/yarn-clip/42f4d76...a-6d0913ec2f8e
      Make it simple, make strong, make it work!

      Comment

      • Sinksalot
        Commander
        • Mar 2020
        • 332

        #4
        Originally posted by redboat219
        LOL, that did bring a smile to my face.

        Comment

        • Sinksalot
          Commander
          • Mar 2020
          • 332

          #5
          Here is the video about me talking about the radio and at the end of the video is the 2nd test.

          This is a test of the Crossfire module on a TX16S transmitter and 8 channel receiver. The receiver was about 2 to 3 feet under water and transmitter over 10...

          Comment

          • Das Boot
            Rear Admiral
            • Dec 2019
            • 1149

            #6
            A radio control system is made up of two elements, the transmitter you hold in your hands and the receiver you put inside your drone. In this guide we're covering the basics of a radio transmitter (Tx), and what to look for when buying one. We did our best to uncover the best RC Transmitter for 2018.

            Last edited by Das Boot; 11-01-2022, 03:51 AM.
            Of the 40,000 men who served on German submarines, 30,000 never returned.”

            Comment

            • SubDude
              Captain
              • Dec 2019
              • 803

              #7
              If I recall correctly, two years ago Bob tried a 900Mhz radio that was supposedly high power with abysmal results in a video. I wonder what the difference is? Power output? Equipment? This is encouraging to say the least.

              Comment

              • redboat219
                Admiral
                • Dec 2008
                • 2735

                #8
                 
                Make it simple, make strong, make it work!

                Comment

                • Sinksalot
                  Commander
                  • Mar 2020
                  • 332

                  #9
                  I know that Bob used a Frsky transmitter in that test, with most likely a R9M 915mhz module, If my guess is right, that module has 4 power setting 10mw,100mv, 500mw and 1 watt. Did he change the power setting I dont know. If he did not change the power then most likely he ran his test at 10mw. Another thing, I think that was a pool Bob tested it in. I have not tested in a pool yet, just fresh water. Also the 915mhz module in that frsky cost $50, the TBS Crossfire version I got cost over $200 and has more options and many more firmware updates to make it better. Same goes for the receiver.

                  Comment

                  • Schmitty1944
                    Lieutenant Commander
                    • Mar 2021
                    • 108

                    #10
                    This is fantastic, Very nice scientific test you gave it too. Next step of course is to try it in a sub.

                    Jason

                    Comment

                    • Sinksalot
                      Commander
                      • Mar 2020
                      • 332

                      #11
                      Originally posted by Schmitty1944
                      This is fantastic, Very nice scientific test you gave it too. Next step of course is to try it in a sub.

                      Jason
                      Only problem, its dam cold outside now.

                      Dave

                      Comment

                      • Thorbrandr
                        Lieutenant Commander
                        • Mar 2022
                        • 124

                        #12
                        Interesting. Modern waveforms can boost performance a lot more than raw power alone. Did you test the telemetry?

                        Chris

                        Comment

                        • Sinksalot
                          Commander
                          • Mar 2020
                          • 332

                          #13
                          Originally posted by Thorbrandr
                          Interesting. Modern waveforms can boost performance a lot more than raw power alone. Did you test the telemetry?

                          Chris
                          No telemetry hasnt been check yet. When my buddy walked 100 feet away from me to the edge of the water, he had to walk behind tons of trees, While I had the receiver 2 and 1/2 feet underwater the transmitter said telemetry lost, but he still had control of the servos. Once he cleared the trees the transmitter said the telemetry started working again. I do want to add a battery sensor to see the main battery volts thru telemetry.

                          Dave

                          Comment

                          • Thorbrandr
                            Lieutenant Commander
                            • Mar 2022
                            • 124

                            #14
                            if you look at 100 m vs the 30km this particular radio TX/RX system is supposed to operate at, that is about a 27-28 dB boost in power. Fresh water attenuation is usually <10 dB/m. I would expect the possibility of a few meters. if salt water, < 1 m. I suspect the telemetry will crap out long before the control.

                            Comment

                            • Sinksalot
                              Commander
                              • Mar 2020
                              • 332

                              #15
                              Originally posted by Thorbrandr
                              if you look at 100 m vs the 30km this particular radio TX/RX system is supposed to operate at, that is about a 27-28 dB boost in power. Fresh water attenuation is usually <10 dB/m. I would expect the possibility of a few meters. if salt water, < 1 m. I suspect the telemetry will crap out long before the control.
                              In the video I posted my buddy was 100 to 125 feet away when I tested the receiver under water. There is no way in hell I would have my rc submarine fully underwater that far away. If I take it fully under I want to see the sub.

                              Comment

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