Locator Documentation

Adam (CSD)'s Avatar

Adam (CSD)

04 Apr, 2018 01:28 PM

I'm having a difficult time finding out how I can use locators. I am trying to create one of type "Fleet".
I found a forum post referencing the following URL: /rest/location/update/position?lat={lat}&lng={lng}&id=FLEET:{fleetname}-{unitid} but there was limited information provided. I tried a few tests but was unable to get that to work.

I found another forum post referencing http://sartopo.com/rest/location/update/fleet/XXXX but this URL does not support GET. Is there documentation available that outlines what needs to be sent via POST.

I'd also love to learn more about email locators and the format in which the email should be.

My goal is to write middleware that receives databursts from Garmin Astro dog collars and 3rd party GPS radios, decodes them, and sends them to SARTopo for tracking field resources.


  1. 1 Posted by caver456 on 04 Apr, 2018 02:04 PM

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    Hi, I am a norcal sar member who has done some middleweight for this task,
    take a look at github.com/ncssar/radiolog the file in question is
    radiolog.py and just search on fleet or fs. It is made for use on a
    computer that is on the same local network (in our sar trailer, without
    internet) as the server that is running sartopo offline. If the radios are
    plugged in to the same computer that is running sartopo offline, I think
    the flow is simplified but we have never actually tried that.

  2. 2 Posted by Adam (CSD) on 04 Apr, 2018 03:29 PM

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    After looking over what Caver456 sent, I did get the "/rest/location/update/position?lat={lat}&lng={lng}&id=FLEET:{fleetname}-{unitid}" method working. Thank you for that! I appreciate it very much.

    Would still love to see what the format of "/rest/location/update/fleet/XXXX" looks like from a POST perspective.

  3. Support Staff 3 Posted by matt on 04 Apr, 2018 11:01 PM

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    I would have to reconstruct the format, as it's built specifically to handle push notifications enterprise inreach accounts. Unless you have a strong need to use a POST, I'd just stick with /rest/location/update/position.

    Also, you should check out https://github.com/KingCountySAR/garmin-trackers-sartopo, which isn't fully polished but does the same thing (except perhaps using a Garmin receiver instead of a 3rd party radio).

    More info from the developer below. I can give you contact info if you want but I don't want to post email addresses publicly:

    We just updated the tracker.exe, consider this beta, if not alpha.

    Download .zip file: http://database.kcsara.org/alphas/garmin-trackers-2018.2.3.1.zip

    You'll want to change the arguments “TrackerConsole – sartopo.com.cmd” – You’ll want to change the 2ndargument of KCSARACOLLAR to your Fleet Name. Then when in SARTopo UI add a locator group of type=FLEET and fleet id = your 2nd argument. FYI it appears that Fleet id may be case sensitive.

  4. 4 Posted by Adam (CSD) on 05 Apr, 2018 01:05 AM

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    Thanks so much!!

    Adam Walworth

  5. 5 Posted by Adam (CSD) on 05 Apr, 2018 01:42 PM

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    Dug in a little deeper. This application from King County SAR is awesome. USB the Astro into the computer, kick in basestation mode, and run the app and it updates SARTopo. Really neat.

    For the sake of future reference of anyone who finds this thread, I'll elaborate my plan a bit.
    My biggest challenge is that we use frequencies that are very close to the MURS frequencies that the Garmins use. The amount of power that we put out with base and mobile radios can damage the Garmin units. This is a known issue that Garmin warns folks about. As a result, I cannot use a Garmin handheld unit at base without a massive filter in place.

    That is why I'm seeking to use an RTL-SDR dongle to receive the signals over the air from the astro dog collars (as well as 3rd-party GPS devices), decode the FSK, parse the data, and then send the coordinates and IDs to SARTopo.

    I really appreciate all of the responses. I've figured out the method to plot the points on SARTopo using "/rest/location/update/position?lat={lat}&lng={lng}&id=FLEET:{fleetname}-{unitid}". From here I just need to figure out how to get the data from the air and handed over to SARTopo. You know, the little details...

  6. 6 Posted by caver456 on 05 Apr, 2018 02:02 PM

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    Sounds pretty handy. From the context, just to make sure you know, Fleet
    refers to Kenwood's FleetSync protocol, where data packets (device ID, and
    gps mic data if attached) are sent with each handheld VHF radio
    transmission. Thr kenwood base radio decodes the packets and sends them
    over the com/usb port as NMEA sentences. Radiolog reads the NMEA and sends
    the http request. So, from sartopo's point of view, thete is nothing magic
    about 'FLEET' in that use case, and 'FLEET' may not be necessary for your
    case either?

  7. 7 Posted by Adam (CSD) on 05 Apr, 2018 02:21 PM

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    I'll still need FLEET for sure. That is the method in which I'll get the data up to SARTopo. No other method exists from what I can find to send coordinates and IDs.
    If you ever listen to analog radios that are sending GPS coordinates with each transmission, you'll hear the databurst. Typically at the end of the transmission but sometimes in the beginning. I'm simply intending to pull that databurst out of the air, decode the data, and then parse that into lat, long, and radio ID. The application that I'm hoping to put together would simply put those variables into a string and issue an HTTP GET with that string. So unless Kenwood's FleetSync protocol is exactly the same protocol as our non-kenwood GPS mics, I would have to custom write this to use our units. It would be a huge side benefit to be able to use one set of hardware and software that decodes both the 3rd-party GPS mics as well as the Garmin dog collars.

  8. Support Staff 8 Posted by matt on 05 Apr, 2018 05:56 PM

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    Fleet isn't actually Fleetsync specific, it's just a way of tracking non-APRS locations that tend to be in groups aka fleets. For example enterprise inreach accounts can push locations to SARTopo, and those show up as fleet locators, with different device IDs but the same fleet ID for the entire inreach account.

    I'm really surprised to hear of that issue - it seems odd that even a 50W radio would damage their handhelds, unless it was right up against the antenna or something.

    Regardless, what 3rd party GPS radios are you using? Do they and/or the Garmin units use actual FSK (modulating the carrier frequency) or AFSK (modulating an audible tone)? If you're using an SDR dongle then I'd assume it's the former, but I'd potentially be interested in more strongly integrating something that decodes AFSK tones read over a microphone jack.

  9. 9 Posted by Adam (CSD) on 05 Apr, 2018 06:42 PM

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    The damage thing to Garmin is specifically related to VHF. The Astro/Alpha receivers are very sensitive in order to pick up the dogs from a long distance. Receive frequencies are as low as 151.82 and as high as 154.6 MHz. Our SAR frequencies are in the 155MHz range and of course ham radio tops out at 148MHz. Some folks even claim that the handheld radios at 4-5 watts can damage the Garmin but I have mine on the same chest pack without issue. It's really common to hear about this issue from SAR folks and hunters.

    I've been intentionally dancing around the brand of GPS mics that we're using. You see, these units are designed to function in a similar manner to the Garmin: the idea is that you plug in one of the GPS mics to your laptop via USB and it will receive the locations of all other units in the field. Unfortunately, the company refuses to provide digitally signed drivers so if you are using a computer with an up to date operating system, you simply cannot interface the GPS mic to the computer. The last known working OS was Windows 7 but if you install the windows updates, this breaks the ability to use the mics. The last update to the driver was 2009, we purchased the mics in 2014 or 2015. The developer refuses to update them. These units are NOT the ICom Redhawk but look exactly like them. Maybe they are re branded with this other company's name and are flashed with different firmware. Speculation on my part. The one nice thing about my interaction with the individual that owns this company is that he provided me with all of the details for how the radio encapsulates the data. It is FFSK and I have the payload information.
    Garmin seems to hold their exact encoding close to the chest but it seems from my Googling that they are using MSK at either 300 or 600 baud.
    Interesting point on microphone jack. Truthfully I think you could either utilize an SDR dongle or a microphone jack. In either case you're talking about minimal spend on hardware. I'd be happy with either set up. Biggest problem is that I'm not much of a developer so this will be a HUGE challenge for me.
    Due to the fundamental differences between MSK and FSK added to the multitude of frequencies that the Garmin uses, it's probably best to write software that handles only the GPS mics. We can add a notch filter or a pass filter to the Garmin to protect it from the VHF radios. That would allow us to utilize the King County SAR software with the Garmins. The custom software that I'm dreaming of would simply monitor a single frequency and a single mode making it much simpler.

  10. 10 Posted by Sparks on 02 May, 2018 02:55 AM

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    It would seem you are trying to do exactly what I want to do: show the location of the dogs on SARTopo in real-time. Is offline the only way to do this?

  11. Support Staff 11 Posted by matt on 02 May, 2018 03:06 AM

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    The KCSARA app should be able to forward locations directly to sartopo.com using the trackerconsole-sartopo.com.cmd file (edit the file to change the fleet ID).

    You can also set up the offline version to forward locations on to sartopo.com, but I would expect that mechanism to change over the next several months.

  12. 12 Posted by Adam Kelly on 02 May, 2018 10:22 AM

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    Can you let us know about any changes related to this function in the coming months? We have successfully been able to use the KCSARA program for both online and offline versions of sartopo and want to stay on top of changes if they were to occur.

    Thank you!

  13. Support Staff 13 Posted by matt on 03 May, 2018 05:40 PM

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    I will try to remember. I'm sure it will still be something that's compatible with GET/POST requests; you might need to change the endpoint but I can't picture breaking that program completely.

  14. 14 Posted by David Kovar on 09 Jul, 2018 03:21 PM

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    I am the comms officer for a New England SAR team that uses Garmin Astros heavily. I'd really like to get away from Garmin's Base Camp if at all possible. Ideally, I'd like to use a SDR combined with a Raspberry PI to pull the Garmin data frames off the air and convert them into something usable via other programs.

    The above thread is the first one I've found suggesting that others are working on this sort of thing.

    Any pointers to solutions would be most appreciated.


  15. Support Staff 15 Posted by mcosand on 26 Nov, 2018 08:06 AM

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    David, were you able to make progress on your project?
    The KCSARA program at https://database.kcsara.org/alphas was written (by me) to use the Garmin Alpha hardware but it should work with the Astro also. The Base Camp application is not needed, the program reads directly from the handheld connected to the serial port. Right now it is Windows only, but someone with experience in USB development should be able to get a port to a Raspberry or other device. I imagine you could get an SDR/mini-computer package to work with minimal user interaction, but if you're looking at a lot of dev effort you may want to give the tracker-console a shot.

    -Matt C

  16. 16 Posted by David Kovar on 26 Nov, 2018 11:52 AM

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    Alas, I got distracted but this is a very welcome reminder, thank you. We’re currently running on Windows so this should be sufficient for the moment.

    Thank you!


  17. System closed this discussion on 02 Oct, 2019 04:24 PM.

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