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» 27Mhz - Radio Ideas
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyTue Jan 24, 2023 4:05 pm by geofrancis

» 915mhz / 868mhz as a viable frequency for submarines.
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyTue Dec 20, 2022 8:21 pm by maxx78

» Not the hobby I expected :)
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyMon Dec 12, 2022 9:07 pm by cat

» Upholder build instructions
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptySun Dec 11, 2022 5:57 am by lenD

» Antennas - Underwater
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyFri Dec 09, 2022 9:50 am by david f

» Single Channel Remote for submarines
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyFri Dec 02, 2022 2:59 pm by david f

» self contained compressor and solenoid valve for bladder systems.
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyThu Nov 24, 2022 5:58 pm by geofrancis

» New to this forum and first submarine
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyFri Oct 14, 2022 6:15 pm by Tom(ADMIN)

» USS Bluefish
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyFri Oct 14, 2022 1:52 am by Cheapsub

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    915mhz / 868mhz as a viable frequency for submarines.

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    geofrancis


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    Post  geofrancis Sat Sep 17, 2022 8:29 am

    I have just bought a frsky R9 tx module and a jumper R900 receiver to give 868mhz a try. im using it on a rover to drive around the streets so signal penetration is the highest priority. my plan was to use 458 openlrs but its getting hard to come by and expensive.

    I got the R9 module for £16 off ebay and the receiver was £16 new can do 16 channels with telemetry.

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    Post  tsenecal Tue Sep 20, 2022 10:38 pm

    geofrancis, please keep us posted on your progress.

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    geofrancis


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    Post  geofrancis Wed Sep 21, 2022 11:49 am

    I have ran into some issues with unstable servo output but im not sure if its the tx module or the receiver or a combination of the pair, so i have ordered a frsky r9 receiver to try and figure out where the problem is.
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    geofrancis


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    Post  geofrancis Wed Sep 21, 2022 11:52 am

    geofrancis wrote:I have ran into some issues with unstable servo output but im not sure if its the tx module or the receiver or a combination of the pair, so i have ordered a frsky r9 receiver to try and figure out where the problem is.

    you can build UHF TX modules using the r9 protocol, just look for the diy 5 in 1 modules. basically take a 4 in 1 multiprotocol module or even an arduino board and add a RFM95 (100mw) or RFM95W (1000mw) to give it 868mhz capabilities.

    https://github.com/pascallanger/DIY-Multiprotocol-TX-Module
    https://www.rcgroups.com/forums/showthread.php?2165676-DIY-Multiprotocol-TX-Module
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    Post  tsenecal Wed Sep 21, 2022 3:06 pm

    Geofrancis,

    i ran into "jitters" when using the 433mhz equipment.  wrapping the servo wire through a ferrite ring got rid of it.
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    Post  tsenecal Wed Sep 21, 2022 10:08 pm

    Geofrancis,

    if you decide to stay with the r9 version of the 915mhz equipment, FrSky already has a couple transmitters that have two rf decks (their own 2.4ghz access protocol) and 915mhz (their r9 version of access)

    https://www.frsky-rc.com/product/tandem-x20/
    https://www.frsky-rc.com/product/tandem-x18/

    they make "S" versions of both models, with better gimbles, etc.

    then you would only need to add a "simple" 4-in-1 module to cover all the other 2.4ghz protocols.

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    geofrancis


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    Post  geofrancis Thu Sep 22, 2022 12:35 pm

    I have a custom frsky taranis x9d with an internal 4 in 1 module that I added years ago along with a switch to select between it and the rear bay,  so converting my already installed 4 in 1 module to a 5 in 1 with an extra module isnt a big deal for me. My r9 external module wont be running frsky for long as its getting flashed with some experimental firmware for mavlink telemetry for use with boats and rovers as a backup to the 4G network connection. I just need to make sure the hardware works first. MLRS

    you can buy the jumper T18 with an internal 5 in 1 module pre installed for around £200.

    The unstable output I was getting was unrelated to servos, as I have my receiver connected to a pixhawk flight controller via SBUS and I could see the inputs fluctuating on the configuration software.

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    Post  tsenecal Mon Dec 19, 2022 10:57 pm

    maxx78 wrote:

    i use the RX with a flightcontroller for drones (Matek F411) so i set the failsafes in the FC. The FC also works to keep the Sub level (don't know the english term for  "Lageregler")
    The nice benefit is that i get telemetry so i know battery voltage and used capacity.
    Telemetry does not seem to work well while submerged but i get updates when surfaced.

    Side note: the FC has a pressure sensor normally used for altitude on planes/drones. This actually can be used to see if the sub is watertight. The dive system creates an overpressure inside the WTC which reads as altitude in the FC. So no or small change in altitude = no leak.


    so, i have had the flight controller (Matek f411-wte) long enough that i have it set up with INAV.  by set up i mean it controls two motors, a set of diving planes, a rudder and a servo output for the ballast tank controller, including the stabilized pitch control for the rear diving planes.

    what i have not been able to do is configure anything remotely close to what i would call a proper failsafe.

    maxx78, can you tell me what you did for your failsafe?   in my world a failsafe needs to set everything but ballast tank to neutral, which gets set to "empty" (what ever servo position that is for a specific sub)

    in INAV, there is nowhere i can find where i can do that...  failsafe is a single page where i tell INAV which of 3 modes to use:  nothing, land, or RTH (return to home)  none of which work in any way i can imagine for a submarine.
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    Post  geofrancis Mon Dec 19, 2022 11:32 pm

    Since its not an output that your actively controlling with the flight controller and you're going to be using the ballast in manual pass through its just going to obey the failsafe output values of your receiver. So you should be setting failsafe positions on your receiver to set the outputs of the ballast tank.
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    Post  maxx78 Tue Dec 20, 2022 9:23 am

    Hi Tsenecal,

    failsafe took me a while to figure out. The drone related stuff does not make sense for a sub. it set it to "Do nothing"

    There is a section in INAV where you can "program". What i have done there is something like:

    If Failsafe = true then RC channel x is 2000.

    2000 being the impulse length send on that channel.

    i will try to get some screenshots this evening, please feel free to remind me if i forget  915mhz / 868mhz as a viable frequency for submarines. - Page 2 1f60a

    I am also want to set it up in the future with a delay for the ballast tank. so if you loose connection first the dive planes set to "surface" and after 5-10 sec the ballast tank is emptied.
    That way ballast only is emptied for longer failsafes and a short dip below receiving range does not effect it.


    @ geofrancis:

    you can't do failsafe settings in the ExpressLRS receivers when used in serial mode.
    They send a info to the flightcontroller, that a failsafe occured and the FC has to handle that. Which makes sense for drones where you can have different failsafe settings depending on the configuration.

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    Post  tsenecal Tue Dec 20, 2022 5:39 pm

    Geofrancis,

    as Maxx78 stated, the elrs receivers are not really made like the receivers we know and love.  they communicate with the flight controller using a 64 byte block of data using a serial protocol.   one of the values in that block is a failsafe value.

    this allows the Flight Controller to be notified that the receiver is no longer communicating with the transmitter.  to them, at that time, nothing else really matters.

    for elrs, the Flight Controller is the master of all.  "Failsafe" is just another mode the Flight Controller knows.  INAV gives you three choices of what to do when in "Failsafe" mode:  do nothing, land, or return to home, with "home"  being the GPS coordinates of where the flight started.

    ...except if you are using what is called an elrs pwm receiver, like the Happy Model epw6.  They are designed to work with standard fixed wing aircraft, just like classic receivers, and do have a way for you to set the pwm ouput setting for all channels when failsafe happens.


    Maxx78,

    thank you very much for the heads up on the "program" feature for INAV.  that does all make sense, I knew that this is not a special situation that some one else had not come across.   my assumption was i would set the failsafe option to "land", and then be able to define what "land" meant, but i could not find anywhere where i could set my own meaning for "land".    i will look at the programming tab tonight.   in my digging around, i did find using the CLI, you can set a failsafe delay variable (failsafe_delay) to the appropriate time to wait before invoking the failsafe procedure:

    https://github.com/iNavFlight/inav/blob/master/docs/Failsafe.md#failsafe-settings



    one final note. there are a bunch of "adapters" that convert that 64 byte block to pwm outputs, so you can theoretically use the standard serial receivers with servos directly, but how they set up failsafe values for servos differs from device to device, and sometimes is less than optimal. the ones i bought for two of my receivers to test with have hardcoded values that can't be changed, and are less than optimal for a submarine... basically set channel three to "low" and everything else to "neutral".
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    Post  maxx78 Tue Dec 20, 2022 8:21 pm

    So here is the screenshot:

    ignore line #0 and 1

    915mhz / 868mhz as a viable frequency for submarines. - Page 2 Screen11


    Logic condition 2 checks if the CRSF LQ (link quality) is lower than 50. Dont remember why i used that value, i think its the failsafe limit
    Logic condition 3 overrides RC Channel 4 to a value of 1500. This puts the ESC in neutral.
    Logic condition 4 overrides RC Channel 1 to a value of 1000. Which is for the balast tank.

    i am somehow missing the dive planes....strange.

    i am using INAV 5.0

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