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» 27Mhz - Radio Ideas
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyYesterday at 5:55 pm by tsenecal

» USS Bluefish
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyYesterday at 5:48 pm by tsenecal

» Choice of CAD software and Printer for 3D printing
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyMon Sep 26, 2022 11:35 am by david f

» 915mhz / 868mhz as a viable frequency for submarines.
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyThu Sep 22, 2022 12:35 pm by geofrancis

» JSN-SR04T Depth sounder
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptySat Sep 10, 2022 11:19 am by geofrancis

» Grantham Model Sub Day, Sunday 14th August 2022
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyFri Aug 12, 2022 2:48 pm by david f

» Sheringham 2022
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyThu Aug 04, 2022 1:51 pm by david f

» Craycraft WTC
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptySun Jul 24, 2022 4:52 pm by timgarrod

» WW2 mini sub build
915mhz / 868mhz as a viable frequency for submarines. - Page 2 EmptyWed Jul 20, 2022 4:12 pm by david f

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

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    geofrancis


    Posts : 70
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    915mhz / 868mhz as a viable frequency for submarines. - Page 2 Empty Re: 915mhz / 868mhz as a viable frequency for submarines.

    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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    tsenecal
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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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    tsenecal
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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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    tsenecal
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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.

    david f likes this post


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