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    openLRS and 2.4 Ghz and Submarines



    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Wed Jun 07, 2017 4:44 pm


    a few things to add to this...

    1)  FrSky has now announced that they will be selling an 868/915mhz transmitter module and receiver for LRS...  using the FrSky protocols, which allows for 16 channels, telemetry, and specific model ID.  (RX will refuse to do anything if you have the wrong model selected on your transmitter)  It has no ETA yet, but will be called the r9m (tx module) and r9 (receiver).

    this will be using 868mhz for europe, 915mhz for USA/Canada...   you will have to look and see if 868mhz is allowed in GB.

    2) the ChipLRS parts have an advantage for the europeans.. 1) it is made by a guy in russia, so shipping is quicker/cheaper than from china.  2) his prices are reasonably cheap, $20 for a receiver, $65 for a TX/RX combo, not as cheap as OrangeRX, but cheaper than hawkeye.  all of his equipment works with my ersky9x/openTX firmware based transmitters, so soldering a 3 pin connector to the receiver allows me to get full telemetry on the built in LCD display on the transmitter (and voice alerts based on telemetry triggers as well)  even ordering his stuff off ebay, it arrives within 10 days, which is faster than the chinese.

    3) you can order from the russian group with any of three frequency choices:  433/458mhz, 868mhz, or 915mhz...  so even if you stay with the 458mhz, ChipLRS might be an option for you.

    4) i have ordered a set of Nagoya 915mhz antennas for both the TX and the RX, these should show an improvement over the stock crappy antennas that all these things ship with off the shelf.
    david f
    AMS Treasurer

    Posts : 1951
    Join date : 2010-11-10
    Age : 67
    Location : Cumbria

    Re: openLRS and 2.4 Ghz and Submarines

    Post  david f on Thu Oct 05, 2017 2:02 pm

    A bit of an approaching winter "heads-up" on openLRS and my experiences.

    Well I have been operating only on openLRS 458 Mhz  since Spring 2015. My 40 Mhz gear has mostly been "raffled-off" at Club meetings!

    openLRS is still rather thin on the ground at the various national meetings I have been to (Bournville, Norwich etc.)  with a maximum of 2 people using it. So we haven't tested its ability to operate 30 sets on frequency-hopping all at once! But no need for crystals, peg-boards and the plaintive cry of "any one on Channel XX etc."

    I have only been using the Hobbyking receivers, still available at about $15 (That's about £75 of your English Pounds - feeble joke!)

    I have rationalised my use of Telemetry and I only use sensors for battery voltage and depth. I didn't find compass heading very useful or consistent - stray magnetic fields?? Battery voltage readout  is a real boon if you are using Lipo batteries. It is the only reliable system I know of for subs.

    This has reduced the "wiring loom" in the sub. The next photo shows the Arduino Nano used to handle the telemetry. Note only 5 wires.

    The next 2 photos show the inside of my standard WTC with the telemetry board above the Hobbyking receiver:

    I attach the Arduino sketch which works with this. ( I hope that Tim forgives my clumsy "hacksawing" of his software. The original software is on the SubPirates Forum https://www.subpirates.com/showthread.php?5271-Custom-Frsky-Telemetry-Hub/page4  )

    The TX option is rather limited for use by others because I am using the FrSky LCD display on my Futaba T9CP . (This LCD display is no longer available but Tim points out that many Tx's have LCD telemetry displays built in.)

    I am really pleased with this development thanks to Tim. It is not just a replacement for 40Mhz but it is a significant improvement. (BTW after my early experiments with different antennae I have gone back to the standard commercial ones - they are easily good enough.)


    // FrSkyTelemetryLRS - Version: Latest
    #include <FrSkyTelemetryLRS.h>

     FrSky Telemetry library LRS test
     (c) Pawelsky 20150724
     Not for commercial use
     FrSkyTelemetry library modified to deal with LRS format (TTL level serial instead of FrSky format...
     renamed to FrSkyTelemetryLRS
     modifications by tim senecal

     Working for voltage input (/2?) on A3 by David Forrest
     A2 gives depth input from pressure sensor.Multiply reading by 3 to give mm of water approx,
     Software from Page 4 of Subpirates
     Improvements? - get actual battery voltage. Calibrate depth sensor. Aug 2017

    #include "FrSkyTelemetryLRS.h"

    #define minraw  272.0
    #define maxraw  1015.0
    #define minreal  9.0
    #define maxreal  158.0
    //#define voltsdiv  84.81
    //#define voltsdiv  102.40
    #define voltsdiv  82.0 ;    // was 67 by RDF for Holland lipo
    FrSkyTelemetryLRS telemetry; // Create telemetry object

    const int analogTemp1 = A0;
    const int analogTemp2 = A1;
    const int analogAmp = A2;
    const int analogVolt = A3;

    int mVperAmp = 66;    // use 185 for 5A, 100 for 20A, and 66 for 30A
    int ACSoffset = 2500; // offset to remove negative side of range

    float amperes = 0;
    float voltage = 0;
    float actual_rpm = 0;
    float calc_speed = 0;
    float Temp1;
    float Temp2;
    float depth;

    void setup()
     // Configure the telemetry serial port

    void loop()
     actual_rpm = 3000;
     calc_speed = 2.258;

     amperes = calc_amperage_val();
     voltage = calc_voltage_val();
     telemetry.setFasData(amperes,   // Current consumption in amps
                          voltage);  // Battery voltage in volts
     depth = amperes-180;    
     telemetry.setFgsData(depth);  // Fuel level in percent -  unsigned int16 - any value between 0 and 65535
     // Set LiPo voltage sensor (FLVS) data (we use two sensors to simulate 8S battery
     // (set Voltage source to Cells in menu to use this data for battery voltage)
     float v1 = voltage/2;
     //float v2 = voltage/2;
     telemetry.setFlvsData(v1, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0);  // Cell voltages in volts (cells 1-8). Cells 9-12 are not used in this example
     // Set variometer sensor (FVAS) data
     telemetry.setFvasData(depth);  // Altitude in m (can be nevative)
     // Set GPS data
     float heading = 125.22;
     telemetry.setGpsData(39.847993, -105.104269,  // Latitude and longitude in degrees decimal (positive for N/E, negative for S/W)
                          depth,                   // Altitude in m (can be negative)
                          calc_speed,              // Speed in m/s
                          heading,                 // Course over ground in degrees
                          15, 2, 19,               // Date (year - 2000, month, day)
                          12, 00, 00);             // Time (hour, minute, second) - will be affected by timezone setings in your radio
     float accel_angle_x =  2.35;
     float accel_angle_y =  4.25;
     float accel_angle_z =  3.15;
     telemetry.setTasData(accel_angle_x,     // calculated x angle
                          accel_angle_y,     // calculated y angle
                          accel_angle_z);    // calculated z angle
     // Set temperature sensor (TEMS) data, two temperatures T1 & T2
       // Set temperature sensor (TEMS) data, two temperatures T1 & T2
     Temp1 = calc_temp_val(analogTemp1);
     Temp2 = calc_temp_val(analogTemp2);
     telemetry.setTemsData(Temp1,   // Temperature #1 in degrees Celsuis (can be negative)
                           Temp2);  // Temperature #2 in degrees Celsuis (can be negative)
     // Set RPM sensor (RPMS) data
     // (set number of blades to 2 in telemetry menu to get correct rpm value)
     telemetry.setRpmsData(actual_rpm);  // Rotations per minute
     // Send the telemetry data, note that the data will only be sent for sensors
     // that had their data set at least once. Also it will only be set in defined
     // time intervals, so not necessarily at every call to send() method.
     delay(100);  //delay for 1/10 of a second

    float fmap (float x, float in_min, float in_max, float out_min, float out_max) {
     return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;

    float calc_temp_val(int analog_pin){
     uint16_t raw_val;
     float temp, raw_float;
     temp = 0;
     raw_val = analogRead(analog_pin);
    //  raw_val = 1023 - raw_val;
     raw_float = raw_val;
     temp = fmap(raw_val, minraw, maxraw, minreal, maxreal);
    //  Serial.print("raw temp: ");
    //  Serial.print(analog_pin);
    //  Serial.print(" ");
    //  Serial.println(raw_val);
     return temp;

    float calc_voltage_val(){
     int RawValue = analogRead(analogVolt);
     voltage = RawValue;
    //  Serial.print("raw volt: ");
    //  Serial.println(RawValue);
     voltage = voltage / voltsdiv; // Gets you adjusted Volts
     return voltage;

    float calc_amperage_val(){
     int RawValue = analogRead(analogAmp);
     Serial.print("raw amps: ");
     float mVoltage = RawValue;
     mVoltage = mVoltage / 1024.0;
     mVoltage = mVoltage * 5000; // Gets you mV 5000 is VCC for 5v arduino
     Serial.print("mVolts: ");
     //Next 2 lines by RDF to output raw amps
     //amperes = abs(((mVoltage - ACSoffset) / mVperAmp));
     amperes = RawValue;
     Serial.print("Input on A2: ");
     return amperes;

    Last edited by david f on Mon Oct 09, 2017 9:00 am; edited 2 times in total


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Fri Oct 06, 2017 5:33 pm

    I too appear to be a lone wolf at the majority of meetings where submarines are around....  i have not yet met anyone actively using the 433mhz or 915mhz equipment besides myself here in the states.

    at the last fun run i traveled to (Golden Gate Park in San Francisco California, September 16 & 17)  I took 3 submarines, two running on 915mhz ChipLRS equipment (Delta and a Moebius Skipjack), 1 running on 433mhz, using a combo of DTF-UHF and Brotronics micro 4ch receiver (SWM blueback).

    i did get my hands on a thunder tiger pump, and rebuilt the delta's pump, so it now is working as expected.  I have also found that the 915mhz equipment works well enough that i will probably move over to that, unless something unexpected comes up, or the specific model works "better" on 433mhz

    like you, i find that the only real data i need to "help" me run my sub is voltage and signal strength.  the rest are purely luxury items.  i do like the pressure sensor, as well as the RPM, but they aren't necessary.

    I have not yet had the time to test the new FrSky brand 915mhz equipment, but it has arrived, and i have looked at it to make sure it binds, etc.   need to install it in the delta to test it.
    david f
    AMS Treasurer

    Posts : 1951
    Join date : 2010-11-10
    Age : 67
    Location : Cumbria

    Re: openLRS and 2.4 Ghz and Submarines

    Post  david f on Tue Oct 10, 2017 9:25 am

    Looking back at your post before last and the use of 868 Mhz in the UK. It doesn't seem to be available:


    So it is 458 or nothing for us here.

    You make the very good point about signal strength being an important part of telemetry. I use the TX module sounder all the time but muted with a bit of tape stuck on it to avoid annoying my fellows at the pond side!

    I realise that if we had been marketing this technology again we should have pitched it as an improvement rather than as a 40Mhz replacement.

    It would seem that most model submariners are a bit conservative and will cling on to 40Mhz until their crystals fracture!


    PS Just made a mention of openLRS on the SubCommittee forum. It can only help.


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Mon Nov 20, 2017 4:11 pm

    due to demand, i made 3 videos on how to configure the ChipLRS brand of 433/458 mhz equipment. they have a few quirks of their own that don't seem to get covered by more generic OpenLRSng videos...

    how to bind and set failsafe: https://www.youtube.com/watch?v=50mAgYoCL7M
    how to set up and use the configurator, with specific details for ChipLRS: https://www.youtube.com/watch?v=lp3fm-oeQrU
    a quick video showing simple telemetry with OpenLRSng and ersky9x: https://www.youtube.com/watch?v=yw9wOFiG8zE

    if there are any questions, ask, and hopefully we can find an answer, maybe with a matching video.


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Mon Nov 20, 2017 10:24 pm

    david f wrote:....

    PS Just made a mention of openLRS on the SubCommittee forum. It can only help.

    i have been mentioning it there since 2014... doesn't seem to help...


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Mon Nov 20, 2017 10:29 pm

    david f wrote:Looking back at your post before last and the use of 868 Mhz in the UK. It doesn't seem to be available:


    So it is 458 or nothing for us here.

    did a quick and dirty google search, and found a pdf put out by "Ofcom"

    Ofcom UK Frequency Allocation:

    High band devices
    The high band (868–870 MHz) is primarily used by wireless alarm systems,
    including fire, intruder and social alarms which are each subject to different
    operational and technical requirements. The band is subdivided further into a
    number of sub-bands, based primarily on technical characteristics such as power
    and duty cycle. Parts of the band are specifically identified for alarm systems,
    although alarms may also operate in the part of the band identified for non-specific
    devices. One of the alarm sub-bands is identified specifically for social alarms.
    Underlay systems may utilise the whole 863–870 MHz band and typically deploy
    spread spectrum or other wideband RF technologies. Applications are non-specific
    and may include any of the applications associated specifically with the low, mid and
    high bands.
    Apart from the three types of alarm system already identified (i.e. fire, intruder and
    social alarms), a number of other applications take advantage of the non-specific aspect of the regulations. These applications include home/office automation, access control, remote controllers, medical, telecare, smart meters, telemetry
    and automotive."

    emphasis on content is mine.

    defining what "remote controllers" means in this context is unknown by me, but definitely needs to be clarified. I also have no idea what "Ofcom" is or what its purpose in life is.

    Posts : 119
    Join date : 2010-12-01
    Age : 58
    Location : Ellesmere Port

    Re: openLRS and 2.4 Ghz and Submarines

    Post  thegrimreaper on Tue Nov 21, 2017 9:08 am

    Hi Tim,


    OfCom is the official office for our communications here in the U.K. they govern the airways and have far reaching powers through our courts over anything to do with cable or wireless transmitions within the borders of the U.K.

    Regards Mark.


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Tue Nov 21, 2017 9:03 pm


    i figured you guys would know who Ofcom is, and it appears i hit the right site by sheer accident.  they appear to be the equivalent to our FCC here in the states.   i would definitely see if they have a specific definition of "remote controller", and verify if the devices we/you use will fall under that definition. if the definition works, that would make 868mhz a viable alternative. I ran my 915mhz equipment at a recent model sub regatta, with as good a performance from the 3 915mhz subs as i did from the single 433mhz sub.


    Posts : 97
    Join date : 2015-04-01

    Re: openLRS and 2.4 Ghz and Submarines

    Post  tsenecal on Fri Nov 24, 2017 4:31 pm

    just so that you understand why i have gone to the effort for the research on the 868mhz equipment... there are several commercial products that are either available or will be available soon that are 868mhz, designed specifically "for the european market"... i also understand that "european market" doesn't necessarily mean "UK"... but it does bear researching to verify


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    Re: openLRS and 2.4 Ghz and Submarines

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