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Satellite GPS locator with Iridium and LTE in the Arctic

_._ 5313 22
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Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
  • I wanted to present a project that I have spent a total of several weeks of my life on.
    A GPS tracker that sends data to the cloud via Iridium satellites or the LTE mobile network. The project was battle-tested on an expedition yacht that reached Spitzbergen by sailing through the open waters of the Arctic Ocean visiting, among other places: Polish Polar Station Hornsund.

    GPS device on a yacht with a display and antennas. .

    Laptop and GPS tracker on a yacht on a rainy day. A group of walruses lying on a beach near the sea. Ice chunks and the sea are visible in the background. Sailing yacht on Arctic waters with snow-covered mountains in the background. View from the yacht on calm ocean waters and snow-covered mountain shores in the distance. View from the yacht on calm ocean waters and snow-covered mountain shores in the distance. Two people walking in a snowy landscape with satellite dishes in the background. Orange amphibious vehicle and yacht in the background with snowy mountains. National flags and the flag of the Polish Polar Station Hornsund on a mast against snowy mountains and a gray sky. A wooden building of the Polish Polar Station Hornsund against a snowy landscape with a signpost indicating directions and distances to various locations. A wooden building of the Polish Polar Station Hornsund against a snowy landscape with a signpost indicating directions and distances to various locations.

    Background
    I travel quite a lot on my motorbike and 4x4 vehicle, both on and off-road. In the case of the latter, navigation is done using topographical maps, we record and drive along so-called tracks, which are routes saved using navigation devices and apps like Garmin. These tracks can be saved and shared with others using GPX format.
    I am the author of the application for drawing such tracks (https://gpxlab.net), and because we record routes while driving somewhere, I use GPS locators mounted in vehicles that send position data to a server. This data can be exported to GPX.
    The most interesting journeys are to inaccessible places, where there is often no mobile network coverage and civilisation is even hundreds of kilometres away: oceans, deserts, exotic countries. In such places, basically the only way to communicate with the world is via Iridium, which is used, for example, by the Garmin InReach. This is an important topic because these devices not only allow you to record GPX tracks, but also allow you to send messages or call for help when there is a serious problem.

    The next step, as an amateur electronics technician, is to build your own tracker. While building a locator using the GSM network is relatively simple: controller + gps + sim800l, a project with LTE and satellite communication requires more expensive and better components.

    The ultimate motivation for building the project was the opportunity to join the crew of the yacht S/Y Southern Star, which sails in the Arctic.

    Below is a description of the device that was successfully spun out.


    GPS prototype with LTE and Iridium communication in a transparent case with an OLED display. .
    Electronic circuit diagram showing a GPS Tracker project. Design of GPS Proto Board v1.0 PCB with visible components and circuit traces.


    Assumptions
    - is to work everywhere (!)
    - in civilisation sends data up to 10 s via LTE
    - outside civilisation sends data every 1 hour via Iridium
    - data recording on SD card
    - clear data display
    - relatively easy expansion, exposed IO pins
    - connection of additional sensors (I2C)
    - power supply 12V (car / ship)
    - backup power supply from batteries (approx. 2 hours)
    - Environmentally resistant housing

    Hardware consists of the following blocks:
    - microcontroller: STM32F401 on BlackPill board
    - receiver GPS: NEO 8M
    - Iridium transceiver: RockBlock 9603N
    - LTE module: SIM7600G, SIM card from 1NCE (coverage in more than 170 countries)
    - 128x64 OLED display on SPI
    - SD module
    - power supply module
    - emergency power supply module (Waveshare)
    - the PCB that holds the whole thing together

    Firmware I wrote in C using the FreeRTOS and CMSISv1 implementation provided by STM (CubeMX). The real-time system made it easy to distribute tasks between different blocks of the program like a person thread for displaying or collecting data from the GPS module. I used the BlackPill module from the STM32F401 because of the increased amount of RAM, so there was no problem to fit the programme data without exorbitant optimisation. The STM32F401 offers three hardware UARTs to which GPS, LTE and Iridium are connected. However, to make debugging easy, I used a trick with hardware UART emulation, so you can connect a separate UART->USB converter under one pin and track the device's performance.
    The microcontroller is programmed using the STLink dongle.

    In brief: .
    - every 10 s the device adds a report to the queue with position, speed, course and altitude
    - if LTE is available, reports are sent immediately
    - if LTE is not available or an hour has passed since the last report was sent, an attempt is made to send via Iridium
    - in order to send via Iridium, the status of "network availability" is monitored, i.e. whether the transceiver "sees" the satellite or not
    - in addition, a snapshot of the reports is saved to the SD card every 10 s
    - a separate thread controls the display of information with GPS, LTE and Iridium status, GPS data and UTC clock from GPS.
    The firmware was written on my knee, so of course it could be done better, display more information and add more logic.

    GPS: .
    The NEO 8M GNSS module sends data every 1 s via the UART in NMEA format. The module has an external low-cost GPS antenna connected. Importantly, although the module supports Baidou and Glonass, the antenna itself has a filter on the GPS frequency, so the other GNSS systems were unlikely to be used for positioning in this case. The unit catches a fix after about a minute and is able to determine position with perhaps 4 or more satellites. For parsing NMEA there is a very good library https://github.com/kosma/minmea.

    Iridium:
    The Iridium module is a RockBlock board with an Iridium 9603N transceiver. It communicates via UART using dedicated AT commands. In addition, there is a pin informing about the visibility of the satellite network, which is important, because the module is able to send something sometimes every few minutes, when a satellite happens to fly over the device. RockBlock is an intermediary between us and Iridium so you need to pay for line availability and purchase a data package.

    LTE: .
    After various adventures with LTE, I used the SIM7600G module together with a SIM card from 1nce, so the device should have coverage in about 170 countries worldwide. The LTE module is connected to an external antenna for the band LTE and interestingly, in tests in the Arctic, the device was catching the signal much earlier than iPhone and Android mobile phones. Communication over the UART using AT commands.

    Display: .
    OLED 128x64 bought from majfriends, operated via SPI.

    Power supply: .
    The project has two components for power supply, the first to a standard step-down inverter with a capacity of up to 3A set at 5V so that the device can be powered with voltages from 7V to about 32V. It works with 12-14V battery voltages without problems. As an option, the board supports a UPS power module with three batteries, which provide continuous operation of the device for about 2 hr. In addition, there are several electrolytes, as both LTE and Iridium have spikes in power requirements when communicating with the grid.

    Cloud: .
    The device was intended to send data to the system I created earlier. SkySpy is an application that collects data from GPS locators, displays it on a map and allows you to export the data to GPX.

    Body: .
    I bought it "by eye" before I made the board I was designing to fit it. It is housed in G 214C polycarbonate, and the transparent lid simplified the assembly of the display.

    PCB: .
    I did the design on the fly in EasyEDA, as there were ready-made public components available in the cloud to represent the modules used, which sped up the work considerably. I sent the board design to be done in JLCPCB. Of course, there were errors, but a few path cuts and jumpers took care of the problem. The layout of the components was chosen to fit them all in, which also caused some problems such as the lack of a switch and a hard-to-reach SD card slot.

    Prototype: .
    I made the first approach on a simple contact board, so I tested the modules before I had a finished device that would be hard to modify anymore.

    GPS device prototype on a breadboard with connected various electronic components. GPS device prototype on a breadboard with components and an OLED display. PCB board with a GPS project placed in a casing on a desk. PCB with mounted electronic components Mobile GPS tracker with OLED screen and various components on a PCB. Interior of an electronic GPS tracker with visible components. GPS device in a transparent case with an OLED display and three blue batteries. Interior of a prototype GPS tracker with display and batteries. Transparent electronic device enclosure on a wooden table with visible wires and an antenna. Transparent electronic device enclosure on a wooden table with visible wires and an antenna.

    Tests:
    The motivation to finish the project was the plan for a sea expedition to Spitzbergen.

    I mounted the device above the yacht's gangway, where I had access to 12V power. The three external antennas for LTE, Iridium, GPS were simply next door. We also had a Garmin InReach satellite phone and an Iridium Edge terminal on board, so there was something to compare the project's performance with.

    We set off from Tromso in northern Norway and, due to a storm in the Barents Sea, sailed through the fjords to the north-east. When the weather window appeared we headed north towards Bear Island and on to Spitzbergen. From the south, the first base on Spitzbergen is the Polish Polar Station Hornsund, which we visited courtesy of the scientists. Sailing further north we reached Prince Charles Land and the highest point of the expedition 78°44'N, then sailed down to Isfjord to the port of Longyearbyen.


    Map showing yacht route from Tromso to Spitsbergen.
    .

    As expected, the locator sent data to the server every 10 s in the coastal water zone, i.e. the entire Norwegian fjords have LTE coverage. Coverage was lost approximately 20 Nm (37 km from the Norwegian coast). On the ocean in polar areas, the only way to communicate is with Iridium and here we had satellites almost all the time overhead, so without much problem the device sent positions every 1 h. LTE coverage reappeared around Isfjord where Longyearbyen, the capital of Svalbard and the largest settlement on the island of Spitzbergen, is located.

    Commercialisation: .
    The project essentially ends with this expedition. It is unlikely to make sense to develop it further due to the horrendous cost of Iridium transmission via RockBlock, i.e. £13 for line rental for a month and £14 for the cheapest package of 100 credits or 5kB (!?). In comparison, it is cheaper to subscribe to Garmin InReach, which sends credits every 10 minutes. For me, on the other hand, this has been the hardest electronic project I have completed to date. It forced me to learn both STM and FreeRTOS, so in that respect it was worth it, and there is the eternal satisfaction that it actually worked in the Arctic :) .

    For those interested, links:
    - full route as sent by the locator after corrections: https://app.gpxlab.net/share/5b85c2e5-82e0-42d7-afcc-8595f449a423
    - RockBlock 9603N: https://www.groundcontrol.com/product/rockblo...-compact-plug-and-play-satellite-transmitter/
    - S/Y Southern Star: https://www.sysouthernstar.com/

    Cool? Ranking DIY
    About Author
    _._
    Level 11  
    Offline 
    _._ wrote 46 posts with rating 247. Been with us since 2013 year.
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  • #2 21114132
    gulson
    System Administrator
    Revelation, huge interest in your project. 300 views, 20 plus in 5h.
    I envy the travelling.
    If you give me a Parcel Post in Private Message, I'll send a small gift :) .
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  • #3 21114404
    Krzysztof Kamienski
    Level 43  
    Actually beautiful device, but I would like to ask why the Author - Colleague chose the most expensive operator of satellite communications , "Irydium", because after all Turaya, Inmarsat or Globalstar are much cheaper ? And I didn't notice the "mushroom", i.e. the possibility of sending an emergency signal. Unless other devices on the yacht provide this. For example AIS.
  • #4 21114488
    _._
    Level 11  
    >>21114404 .

    Well not really, the plan was to operate above 70*N and 70*S, so polar areas and there neither Turaya, Inmarsat nor Globalstar have coverage. Ba, our onboard AIS from Raymarine "ran out" around 75*N and only displayed that something was sailing but without showing a map.

    You don't need a mushroom, i.e. there are versions of transceivers in the form of a mushroom, but then the whole receiver is in the mushroom; it makes sense, for example, if you need a few metres of cable from the antenna. Then it is better to have the electronics close to the antenna and use the cable to transmit a digital signal.

    As for emergency signals, the satellite phone from Garmin and the Iridium GO, both have small built-in antennas, not a big mushroom.

    For the project, a small dedicated screw antenna to communicate with the Iridium was enough.
  • #5 21114517
    TechEkspert
    Editor
    Very interesting project and story, maybe you would like to appear on the elektroda.pl podcast?
    https://www.elektroda.pl/rtvforum/audio.php
    The expedition and project looks like you are pushing some of your limits :)

    Good hint with the cards https://1nce.com/en-eu/1nce-connect
    I don't know if there is an equivalent at similar prices even if it would only work in Poland.

    I did not know that with Iridium you can start a module similar to LTE,
    unfortunately the prices as it is in the case of Iridium cosmic....

    Arctic topics appear on the electrode not for the first time, maybe you will find familiar views:
    Living on a polar station - Technology provides survival options .
    Life on the polar station - Electronics and geophysics jobs
  • #6 21114845
    sq3evp
    Level 37  
    Interesting project, worth getting to know more about the project I think.
    Congratulations on your interesting journey.
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  • #7 21115093
    szeryf3
    Level 29  
    A very interesting premise which resulted in, for me, a super design and execution.
    Thanks to you I've scoured the internet and learned something new.
    Maybe you will actually agree to do a podcast.
  • #8 21115260
    ptero
    Level 24  
    How many writes will the SD card hold? Wouldn't it be better to a RAM buffer of some kind with backup and write, say, once an hour or in the event of a power failure?

    Apart from that - great project !
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  • #9 21115329
    sq3evp
    Level 37  
    ptero wrote:
    How many writes will the SD card last? Isn't it better to some kind of RAM buffer with backup and save say once an hour, or in case of a power failure?
    .
    In the case of an aircraft, that's a lot, but in the case of a boat, an hour is probably acceptable?
  • #10 21116318
    max-bit
    Level 34  
    I think only Iridium (price) provides planetary connectivity in general, and probably because the US Department of Defense has a hand in it.
    Prices
    Link
    Knocks your socks off
  • #11 21116465
    _._
    Level 11  
    max-bit wrote:
    I guess only Iridium (price) provides general planetary connectivity and I guess that's because the U.S. Department of Defense has a hand in it.


    Iridium was created with funding from Motorola in the 1990s with the idea that it would be a technology that would allow people to call from anywhere in the world. In the meantime, the market has moved on to GSM and it has become apparent that the terrestrial network works perfectly well for most customers, and few Iridium customers want to be in the middle of a desert or ocean to have to make a call from there. So in short the market went away and the project money stopped rolling in.

    In business circles, Iridium is a model case study of a brilliant idea and technology that was implemented without regard to cost and without market verification, which basically led to bankruptcy. In contrast, the technology is indeed global so it is of strategic importance to the US. They got funding and their services are used, for example, by the US Amundsen Scott base at the South Pole in Antarctica.

    By the way, the 5G NTN (Non Terrestrial Network) is slowly being developed, where a phone will be able to communicate directly with a satellite in Low Earth Orbit or with a ground base station.

    Here is more on the history and adventures of Iridium:
    https://www.youtube.com/watch?v=CP0VKd66Jyc
  • #12 21117759
    kamil3211
    Level 10  
    I think I would use a 7 seg display instead of one like this. It would save a bit of energy especially since it's only the digits that change and the descriptions next to the display. You probably need an additional microcontroller, but such a module and display surely has one already in it.
  • #16 21120615
    max-bit
    Level 34  
    You can't use Starlink because you have an area assigned there from which you "operate". - this is the "normal" version
    Of course there are global options but the prices are rising fast
    Besides, there antennas are large.
    Fact starlink is combining with something like this DirectToCell

    It looks interesting, but what will it be like in reality ?
  • #17 21122079
    gemiel
    Level 25  
    max-bit wrote:
    I guess only Iridium (price) provides planetary connectivity in general and probably because the US Department of Defence has its hand on it.
    Prices
    Link
    Knocks your socks off


    Yacht prices aren't small either. If it were a scooter locator, it would indeed be expensive. But sailing around the remote corners of the globe, it's better to be assured of continuous operation, even at a considerable cost.
  • #18 21122082
    max-bit
    Level 34  
    There are professional and off-the-shelf systems for satellite location if that is how we want to approach :) .
  • #19 21122219
    sq3evp
    Level 37  
    max-bit wrote:
    There are professional and off-the-shelf systems for satellite location if that is how we want to approach :)
    .
    I think there are even a few manufacturers, known and bought.
  • #23 21251624
    TechEkspert
    Editor
    Interesting video footage, for me it complemented the conversation, there are places we talked about in the episode. If you were interested in the non-electronic topics in episode #29 then it is worth seeing the episodes from the links above. Polar topics are touched on there, often in broader terms. Nice colours and shots, I can't really name it but there is an aesthetic/plasticity/colour scheme to these videos that I like.

Topic summary

A user presented a project involving a GPS tracker designed for Arctic expeditions, capable of transmitting data via Iridium satellites and LTE networks. The device was tested on a yacht during a journey to Spitzbergen, where traditional satellite services like Turaya, Inmarsat, and Globalstar lacked coverage. The discussion highlighted the advantages of using Iridium for global connectivity, despite its higher costs, and addressed concerns about emergency signaling capabilities. Participants expressed interest in the project, suggesting potential podcast appearances and discussing alternative technologies like Starlink and Swarm for satellite communication. The author later shared project code on GitHub and linked to video content documenting the expedition.
Summary generated by the language model.
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