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Thread: wireless transmitter

  1. #1
    RBW Member pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs's Avatar
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    Drager Ray

    Homebuild deathtrap

    wireless transmitter

    Hi folks,
    quick question - does anyone know the frequency and operating mode used by the tank pressure transmitters that dive computer manufacturers like to sell us ?
    I'm wondering about the potential to remove the wires from my Rebreather electronics and go wireless .....

    The only image I can find of the internals is this one from a how to change the battery video..
    [/IMG]

    It looks as though the thing has a big ferrite rod antenna inside (makes sense) with a clock crystal.
    My guess is that its something low (sub 10kHz) based on range in water considerations but I've not got one to test. Anyone ever put a spectrum analyser on a coil nearby one in the past ?

    Any data / knowledge most welcome.

    I'm going to try to come up with a design for one of these things based on some other work I'm doing on underwater comms but its always simpler to copy a wheel and reinvent one....

    cheers


    Chris

  2. #2
    RBW Member Mike_Eitel is an unknown quantity at this point Mike_Eitel's Avatar
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    MeCCRxWi

    MeRAY, MeTravox,MeCCRV"x,Inspi

    Re: wireless transmitter

    Hi

    I once found the patent from UWATEC....
    If i remember right they used 8khz.

    Pitty but naturally there is no description of tge protocol.

    Years ago I used my sensor, but as you do not need enough gas, it switches of and you end up by lots of link errors..

    Realy bad, as Id like to get my pressurs wireless.

    Mike

  3. #3
    RBW Member pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs's Avatar
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    Drager Ray

    Homebuild deathtrap

    Smile Re: wireless transmitter

    Thanks . Thats a useful datum. I looked up the patent on google
    "Underwater monitoring and communication system*US 5392771 A"
    It divides the 32768 Hz clock crystal frequemcy dowm to 8192 by the looks of it and does PSK modulation via a ferrite loaded antenna of between 10 and 50 uH.

    Very tempted to experiment with a wireless sensor module and get rid of the cables in my unit...


    More to come.

  4. #4
    RBW Member Mike_Eitel is an unknown quantity at this point Mike_Eitel's Avatar
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    MeCCRxWi

    MeRAY, MeTravox,MeCCRV"x,Inspi

    Re: wireless transmitter

    Looking forward for more to come

    Have to concentrate, but i was also tempted...

    Mike

  5. #5
    RBW Member madmosche is an unknown quantity at this point madmosche's Avatar
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    Prism2, Explorer

    Re: wireless transmitter

    I thought they operated in the 20-30 kHz range but I could be wrong. I use transmitters on my breathers and bailout bottles, lets you see all of your pressures quickly on 1 screen.

  6. #6
    RBW Member pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs's Avatar
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    Drager Ray

    Homebuild deathtrap

    Re: wireless transmitter

    After reading the patebt irsclear that they settled on 32768 divided down by 4 to 8192 hz. Then they use differential phase shift keying to transmit about 24 bits of data and ident number.

    dpsk is probably chosen for receiver simplicity but today its just as easy to do fsk or plain psk using a microcontroller.
    Plans are afoot.

    Sent from my GT-I9195 using Tapatalk

  7. #7
    RBW Member pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs's Avatar
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    Drager Ray

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    Re: wireless transmitter

    Quote Originally Posted by pegcjs  View Original Post
    After reading the patebt irsclear that they settled on 32768 divided down by 4 to 8192 hz. Then they use differential phase shift keying to transmit about 24 bits of data and ident number.

    dpsk is probably chosen for receiver simplicity but today its just as easy to do fsk or plain psk using a microcontroller.
    Plans are afoot.

    Sent from my GT-I9195 using Tapatalk
    Ok expeeiments using a 30uH coil and lm567 tone decoder look good. Data to come next week when I get chance to sort it out....

    Sent from my GT-I9195 using Tapatalk

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    RBW Member aquarat is an unknown quantity at this point aquarat's Avatar
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    Cool Re: wireless transmitter

    Any more progress ? I'm very interested in this; I have two UWATEC transmitters (newer generation compatible with the Galileo Sol/Luna, MSP430, same as the unit pictured in this thread) and an older unit (oil-filled).

    I have suitable dive computers for these transmitters, but it'd be great to have an independent display device (probably in the form of a small Atmel MCU with display).

  9. #9
    RBW Member pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs will become famous soon enough pegcjs's Avatar
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    Drager Ray

    Homebuild deathtrap

    Re: wireless transmitter

    Hmm not exactly progress. I got a bench test kit working over about a metre but havnt managed to test in water yet.. needed more power and a box.i was planning to make a couple of PCBs that could be put in old gopro housings but ha to put it all on hold because work started to overlap my hobby time... most inconvenient.

    Sent from my MotoG3 using Tapatalk

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