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    openLRS on 458Mhz and 433Mhz and submarines

    david f
    david f
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  david f on Wed Nov 11, 2020 3:40 pm

    Hi Jonathan,

    The telemetry is a serial connection. (For openLRS the baudrate is set in the Configurator which should also be set to "Passthru".)

    My thoughts on what you need to include:

    - A general point is that latency is less of a problem for model subs than drones. (Things don't happen so quickly!)

    - 8 channels should be enough.

    - binding (I wonder if just setting a personal code in configuration would be enough? I now have the same bind code in all my TXs.)

    - channel hopping within a set legal bandwidth.

    - some method of setting configurations. (Editing code would be a bare minimum.)

    - loss of data indicator. (The odd beep lets you keep the model in range. Continuous tone gets you worried. I like the model being "talkative" this way although it can make the uninitiated think it is signal loss.)

    - telemetry (but needs much less data than for flying)

    - failsafe (with an audible prompt to make sure that you set it - easy to forget with the result that your sub stays sunk!)

    I think that is about it. I look forward to openSUB or whatever!

    David


    Last edited by david f on Thu Nov 12, 2020 9:43 am; edited 1 time in total
    C-3PO
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  C-3PO on Wed Nov 11, 2020 4:17 pm

    David,

    Thank you for ideas and suggestions. Some of these echo thoughts I have already had.

    Regarding things like binding I might go down the line of mirroring the concept of pressing a button on the receiver to bind to the RX but not to start with.

    I currently have a few setups where I have more than 2 transceivers in one system all using the same Encrypt Key - works a treat.

    I think having a simple "config" file that gets included in the complilation is the way to go

    Basically some long time ago I started using a library written to interface to various transceivers- written, supported and developed by an active, quite large group of people.

    They use the library to connect to sensors for things like weather stations etc

    https://lowpowerlab.com/category/rfm69/

    https://lowpowerlab.com/forum/

    It is feature rich and mature solution. I simply bolt on my bits either end and don't have to worry much about the comms side - that is once I got it working originally as you do have to navigate clashing interrupts!! (Yours not their's!)

    The reason I have such confidence is a simple working solution relies much on the work the low power labs crew...

    Jonathan
    david f
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  david f on Sat Nov 14, 2020 1:38 pm

    Many thanks for links to lowpowerlab, Jonathan - it looks very interesting and promising.

    I particularly like your approach of using off the shelf software for the comms and simplifying the rest. I don't think that the model submarine community could provide the same human resources for software maintenance as the flying community. (It is a numbers game.)

    I wonder if this will also mean that your approach will be less dependent on hardware selection? Scope for including LoRa etc? All we are wanting to do is reliably send a ppm stream out and get some telemetry back.

    David
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    Cheapsub

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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  Cheapsub on Mon Nov 16, 2020 7:21 pm

    Hi, Tim and guys, look like I got a lot of catch up to do.
    Fung

    david f likes this post

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    SimonH

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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty DIY 458MHz

    Post  SimonH on Tue Nov 17, 2020 10:09 pm

    Hi guys,
    I've recently joined, but currently have no sub and no radio. I work in electronics and many years ago I started a UHF rc system, but how the technology has changed! I decided it was would be easier to start by building the radio gear, and did think about designing a 40MHz system but due to a job change I no longer have access to the test kit needed to adjust the coils etc.
    As a result I've started on a system based on the arduino (pro-mini 3.3V 8MHz) as the brains and the SX1278 RF chip embedded in a DRF1278 RF module, as though intended for the spread spectrum mode it can be used narrow band mode needed to be legal. Also there is an adaptor board and a lot of library software available from Stuart Johnson via tindie.
    I'm not sure about using the openLRS software, but I intend to look at it once I have basic operational radio hardware.
    I'm thinkng of using addtional analogue input chips to support at least 4 axis of joysticks and the PCA9685 PWM chip to drive the servos, but we'll see!
    As I'm starting from scractch I have no Tx to canabalise for the digital generation so it seemed easier for me to start from the raw hardware, mind you I may regret that!
    At the moment I am still assembling the pro-mini & adaptor boards before connecting the RF modules, but I will let you know.

    As a thought, has anyone tried adding a serial link between the Rx and say a pool-side laptop, phone, or other terminal? either bluetooth, infra-red or even via a waterproof connector? It would seem to allow easier configuration of RF channel, node ID (for binding), failsafe settings etc. The easy way would be via switches on the Rx, but that of course means physical access to the Rx.
    regards
    Simon H

    david f likes this post

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    Cheapsub

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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  Cheapsub on Wed Nov 18, 2020 12:32 am

    I am too new at this forum.

    May be to save some time start with OpenTX/Er9X control base system. Easy to find used or new boxes.

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    tsenecal
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  tsenecal on Wed Nov 18, 2020 12:56 am

    Simon,

    its nice to see a new "face"...

    a few points to bring up from some of your questions...


    in the ancient times before i switched to OpenLRSng... i had tried somethings with older 75mhz equipment. specifically the futaba/robbe transmitters and receivers (as well as others) offered "DSC" on their receivers. DSC stood for "Direct Servo Connection" that meant you could run a cable from the transmitter's trainer port directly to a 3 pin port on the receiver (the port labeled "DSC"... if the receiver didn't have a port labeled "DSC", the receiver didn't support it)

    long story short, i made a 30 foot DSC cable to test on one of my subs... it worked... but had issues... like any other modern tethered rov, the tether will find anything to snag on.

    other questions you bring up... i fear that building both a transmitter and an rf deck will create too many unknowns. is it the transmitter that is not working right or the rf deck... build a test rf deck that can decode a ppm signal from the transmitter... using it with a known good transmitter. after you know the rf deck works, build a transmitter.

    david f likes this post

    david f
    david f
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  david f on Thu Nov 19, 2020 2:46 pm

    Hi All,

    As Tim says it's good to see new faces. He may have started something with 433Mhz for submarines!

    I would also agree with Tim's advice for Simon. At the risk of sounding old fashioned - you need a transmitter box with some sticks on it! Because:

    - Laptops, phones etc are difficult to see in sunlight if you are trying to control a sub from them.
    - Nice second hand 35Mhz TXs are cheap on ebay. (£30 or so) and for that you get  a nice box with battery, sticks and a trainer port which will give you a ppm signal output. (Cheapsub had a nice description of a "Frankentransmitter over on Subcommittee. Disable the rf side - crystal out and aerial removed as a minimum.)

    A further update on the openLRS DIY TX and RX.
    The RXs work nicely, and I would recommend anyone to have a go at building them and using them with a Hobbyking TX module. (still available for £4!)
    The DIY TX is working consistently but at a maximum power setting of 4. I don't know why! (LATER EDIT: I wonder if this is the "Smart Reset" problem mentioned on https://forum.arduino.cc/index.php?topic=670182.0    All the more reason to move on from this rf module) I have tested this with  2 different rf modules and 2 aerials (including a dipole) and also tried a separate 3.3 volt supply in case they were getting a voltage drop. Range in air is about 2/3rd of the Hobbyking but it is still adequate for a model sub test (when the virus permits!)

    Facebook posts:

    Jonathan Askey
    So 16 channels from handset transmitted @ UHF with ease
    Converting 16 channels back to pwm at receiver not without it's challenges - latency is an issue at the moment to work through!....… See More
    · Reply · Share · 3w
    Adam Carlson
    Jonathan, depends on how you do it. The first handful of channels you will likely want to be 8bit, say the first 4. The next channels likely do not need to be that large, especially if they are more generally for switching. With this, you can potent… See More
    · Reply · Share · 3w
    Adam Carlson
    Now if you want to send telemetry back that is a different story, but if you are not staying narrow band, then it is not an issue.
    · Reply · Share · 3w
    Jonathan Askey
    Hi Adam Carlson - thanks for info/comments
    I have 2 way comms facilitating telemetry with no latency issue to talk about - indeed it's currently throttled back- been using a platform with this functionality for a few years.… See More
    · Reply · Share · 3w
    Jonathan Askey
    Having scratched the surface with my problem it transpires that the resolution on the pwm on the Taranis radio (OpenTx) I am using is very "lumpy" - it jumps in steps of maybe 20-50us as you move a stick so no wonder my poor servo was stuttering
    Cannot work out why the Taranis is so rough - no doubt a setting (mix) but I have given up with it for now and will use a trusted radio instead (Jeti) - one that I don't like connecting to electronics in case I releases it's blue smoke
    Another case of looking in the code for the problem when it seems it was actually an external factor...
    · Reply · Share · 3w · Edited
    Jonathan Askey
    16 channels transmitted and working smoothly - the loop code contains just one function that packs newly read ppm stream data into radio packet payload and sends it at a defined interval.
    Latency is not noticable - no different to 2.4Ghz setup's
    Now to add some of the whistle and bells and fire up the telemetry code.
    This is such a simple solution!
    · Reply · Share · 2w · Edited
    David Forrest
    badge icon
    I received 2 x DRF1278DM LoRa modules from Tindie in China this morning. (I wanted to have a play with some LoRa stuff and they looked very easy to setup and use.)
    I have just got them set up and they are sending serial telemetry (battery volts & amps) back from my sub on the bench. Very pleased!
    They WERE easy to setup using the USB to TTL board (DAC02) They are on 458Mhz - I hope it is legal🙁 and potentially could be used for LoRa range testing if my sub ever gets back underwater!
    How are you getting on with transmission, Jonathan?
    · Reply · Share · 5d · Edited
    Jonathan Askey
    Hi David Forrest - yes I am doing well - good progress - I am going back to basics, with fully documented code so progress is slow.
    I may be missing something - LoRa IMHO cannot be legal - the transmission bandwidth is massive!!! LoRa can be up to 500KHz - the DRF1278DM spec recommends 125KHz - possible the default setting?
    Do you have anyway of testing bandwidth?
    · Reply · Share · 5d · Edited
    David Forrest
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    Thanks. Interpreting Ofcom regulations needs second opinions! The document I am using is IR2030 - Pages 87 & 88 cover Model Control:
    https://www.ofcom.org.uk/.../pdf_file/0028/84970/ir-2030.pdf
    The reason I am trying this is to see if LoRa gives increased range for underwater transmission. If it does, then there must be scope for telemetry at 433Mhz or ,even better, model control at 458MHz?
    I am using the default setting for the DRF1278 of 125Khz. I only have the Spectrum Analyzer function in openLRS.
    · Reply · Share · 5d
    Jonathan Askey
    David Forrest - To me it's 100% clear - maximum bandwidth is 25KHz
    They are razor sharp in their very detailed specification
    They state range 458.500-459.500MHz
    There are 40 channels of 25KHz bandwidth
    The transmission will spread 12.5KHz either side of the central channel (carrier) frequency (the bandwidth)
    To ensure you do not go out of the allocated band they are very clear
    Channel spacing 25 kHz.
    Channel numbers 1 to 40 inclusive are available with channel centre frequency of 458.4875 MHz plus (Channel Spacing times channel number).
    Channel 1 is 458.5125 (BW=25KHz 458.500 to 458.5250MHz)
    1 458.5125
    2 458.5375
    3 458.5625
    4 458.5875
    5 458.6125
    6 458.6375
    7 458.6625
    .....
    35 459.3625
    36 459.3875
    37 459.4125
    38 459.4375
    39 459.4625
    40 459.4875
    So 125KHz Lora takes the bandwidth of 5 channels
    Bandwidth is bandwidth and you are not allowed more than 25KHz!!
    Sorry....
    · Reply · Share · 4d · Edited
    Jonathan Askey
    David Forrest - if you want to mess with LoRa then I would make sure you go for mid band allocation 458.9875MHz
    Loads of people think it's not important to play by the rules with radio - it won't matter, its not important
    So much goes over the radio (e.g. remote monitoring ) that organizations pay good license fee money to use parts of the Spectrum - break these rules at your peril....
    · Reply · Share · 4d · Edited
    David Forrest - if you want to mess with LoRa then I would make sure you go for mid band allocation 458.9875MHz
    Loads of people think it's not important to play by the rules with radio - it won't matter, its not important
    So much goes over the radio (e.g. remote monitoring ) that organizations pay good license fee money to use parts of the Spectrum - break these rules at your peril....
    · Reply · Share · 4d · Edited
    David Forrest
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    Steady on, Jonathan! I respect all the regulations and I would hardly be discussing anything that infringed regulations in such a public space, in any case.
    An experiment with LoRa this afternoon (a range check using the published telemetry frequency … See More
    · Reply · Share · 4d · Edited
    Jonathan Askey
    David Forrest- apologies - I meant no offence. I have seen on many forums (and another sub one) where people dismiss the regulations as "not a problem", I am not saying that is what you have done or you are willfully breaking the law..
    Having used radio as a hobby for 45 years legally it does annoy me when people turn a blind eye - rant over!
    Was your LoRa setup @ 25KHz bandwidth?
    I am not sure you are comparing apples with apples.
    IMHO - the RF22 unit is outdated and ineffcient.
    It would be interesting to put an RFM69 up against your project and see how they compare...
    I easily get 500-1000m direct line of site without trying
    · Reply · Share · 4d · Edited
    David Forrest
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    I bought the DRF1278DM modules because they seemed to be an easy route into some experiments with LoRa. They do serial communication "straight out of the box" so I could use them with my existing telemetry setup. (I had them up and working within t… See More
    · Reply · Share · 3d · Edited
    Jonathan Askey
    David Forrest Would an outbound transmission from the model on 433MHz (telemetry) if used alongside openLRS on 459Mhz to control the model cause interference issues?
    My experience would be that the close proximity of the 2 frequencies and more specifi… See More
    · Reply · Share · 3d
    Jonathan Askey
    This is a very short video that helps explain LoRa bandwidth
    https://youtu.be/dxYY097QNs0
    LoRa CHIRP
    YOUTUBE.COM
    LoRa CHIRP
    LoRa CHIRP
    · Reply · Share · 4d · Edited
    Jonathan Askey
    David Forrest - I was interested in your post re telemetry. When you break away from openLRS and are in control of your own architecture things can get interesting.
    I have a few projects that use multiple transceivers and processing shared across mulitple Arduinos.
    At the moment my shore based transceiver requests an ACK from the model based transceiver every 5 packets.
    The ACK model response itself is a packet that can be packed with 60 odd bytes of telemetry data - so is sort of a "free" way to get telemetry back to shore.
    I appreciate space is limited in many subs - I am playing with mutliple model based transceivers to see if any merit of a "combined" packet reception - transceivers would be mounted in different parts of the model with antennas in different aspects.
    I am also for now testing the merit of an additional shore based transceiver that is working in reception mode only and sniffing the live comms between RC tranny and model
    This would be used to show the status/health of comms and also telemetry - it's possible if processing power available to move this back to the main Arduino interfaced to the ppm stream from the RC handset
    I have used this concept a few times - when I fire a gun on a warship I have a shore based sound system plugged into a somewhat large PA speaker. The remote sound system has it's own transceiver and sniffs the packets and can trigger sounds accordingly.
    · Reply · Share · 4d · Edited
    Jonathan Askey
    I forgot to mention - I have also included a fail safe interrupt pin tied to an interrupt function on the receiver end.
    This would allow you to trigger the fail safe sequence from an external system easily - this could be a sensor of some sort (pressure,moisture,voltage,light), a micro switch etc etc
    · Reply · Share · 4d · Edited
    David Forrest
    badge icon
    That's a very useful, clear explanation. (I particularly like the waterfall display to show the "chirp".)
    35 & 40 Mhz are much easier to understand - 30 channels or so all spaced 10KHz apart. One person, one channel! (Crystals anyone?)
    So on 458Mhz - 40 channels spaced 25kHz apart. Then along comes LoRa spanning 5 channels (Using 125KHz bandwidth). One person 5 channels! Only 8 simultaneous users would use up the entire allocated space? A problem? Not allowed?
    I take it that LoRa doesn't use frequency hopping which openLRS does? I have the feeling that frequency hopping is one reason why openLRS works well for models submerged in water. It is really against the laws of physics, (Jim)!
    · Reply · Share · 4d · Edited
    Jonathan Askey
    Quick video of 16ch on UHF to show latency - this is with telemetry streaming back from model (yet to fix the display)
    Spent hours working on removing the servo jitter but it's now history!
    Sorry about the orientation...(now fixed)
    · Reply · Sha


    Last edited by david f on Mon Nov 30, 2020 11:24 am; edited 3 times in total
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    tsenecal
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    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 Empty Re: openLRS on 458Mhz and 433Mhz and submarines

    Post  tsenecal on Fri Nov 20, 2020 4:35 am

    Simon,

    both David and i have "been there, done that"... my two attempts at transmitters:

    newest: https://www.rcgroups.com/forums/showthread.php?2857877-Pistol-radio

    and something a little less "normal":

    https://www.rcgroups.com/forums/showthread.php?2191827-tablet-based-setup


    of the two, i still use the "pistol radio" daily... its been 5 years since i last did anything with the tablet...

    david f likes this post

    C-3PO
    C-3PO

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    Post  C-3PO on Fri Nov 27, 2020 11:42 am

    SimonH wrote:Hi guys,
    I've recently joined, but currently have no sub and no radio. I work in electronics and many years ago I started a UHF rc system, but how the technology has changed! I decided it was would be easier to start by building the radio gear, and did think about designing a 40MHz system but due to a job change I no longer have access to the test kit needed to adjust the coils etc.
    As a result I've started on a system based on the arduino (pro-mini 3.3V 8MHz) as the brains and the SX1278 RF chip embedded in a DRF1278 RF module, as though intended for the spread spectrum mode it can be used narrow band mode needed to be legal. Also there is an adaptor board and a lot of library software available from Stuart Johnson via tindie.
    I'm not sure about using the openLRS software, but I intend to look at it once I have basic operational radio hardware.
    I'm thinkng of using addtional analogue input chips to support at least 4 axis of joysticks and the PCA9685 PWM chip to drive the servos, but we'll see!
    As I'm starting from scractch I have no Tx to canabalise for the digital generation so it seemed easier for me to start from the raw hardware, mind you I may regret that!
    At the moment I am still assembling the pro-mini & adaptor boards before connecting the RF modules, but I will let you know.

    As a thought, has anyone tried adding a serial link between the Rx and say a pool-side laptop, phone, or other terminal? either bluetooth, infra-red or even via a waterproof connector? It would seem to allow easier configuration of RF channel, node ID (for binding), failsafe settings etc. The easy way would be via switches on the Rx, but that of course means physical access to the Rx.
    regards
    Simon H


    Hi Simon,

    Looks like a great project - will track your progress with interest...

    Regarding pool side phone/laptop why not use esp32 Web server & wifi (concept example in video below) crude and an early version but I think you get the idea - 2 way comms - no cables!

    https://www.youtube.com/watch?v=VrlplSqj2mc&feature=youtu.be

    Regards
    Jonathan
    C-3PO
    C-3PO

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    Post  C-3PO on Sun Nov 29, 2020 9:59 am

    Spent an age eliminating servo jitter (caused by ppm read from handset)

    Progress encouraging - need to get it wet asap to see if it has any merit

    16ch with telemetry streaming back - pleased with latency but still room for fine tuning



    Regards
    Jonathan

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    david f
    david f
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    Post  david f Yesterday at 10:29 am

    Your system is looking very promising.

    I wonder if these units to convert PPM to PWM would help you and perhaps make the software simpler? They are working well on the DIY openLRS receiver and at the very least make the servo connections much easier.

    JHEMCU SPP 8CH Signal Converter Module Support SBUS PPM PWM Output for Receiver
    ID: 1549017 (Banggood UK)
    Price:US$8.76

    openLRS on 458Mhz and 433Mhz and  submarines - Page 9 43a44c10

    https://www.banggood.com/JHEMCU-SPP-8CH-Signal-Converter-Module-Support-SBUS-PPM-PWM-Output-for-Receiver-p-1549017.html?rmmds=myorder&cur_warehouse=CN

    I  can confirm that the DRF1278DM module running alongside an RX running openLRS on 458Mhz does create bad interference. This is only on the bench but my experience says that it will not get any better underwater! So a SEPARATE telemetry channel does not look like a good way forward.

    David

      Current date/time is Thu Dec 03, 2020 11:01 am