Getting pasture measurements with accurate locations

Hi, my use case is to get accurate location for pasture measurements. Pasture measurement can be done with a rising platemeter (the shaft hits ground level, and the plate rises based on volume of feed, see pic).

There are options available where the app uses a phone to give the gps location of that measurement (e.g. http://jenquipec20app.co.nz/ or https://platemeters.co.nz/pages/the-app), but these will be (I expect) +/- 5m.

The documentation suggests that I can use reach to provide more accurate locations (at least with android, another post tells me ios support is not yet available)

From this moment on, all apps in the Android device that use location services will automatically have access to the positional data streamed from Reach. You can just open a GIS app you want to use and start surveying.

So to make this setup work (real time),
I need:

  1. my platemeter
  2. an android phone to:
    a) run the app to record measurements
    b) provide internet for real time correction
  3. a subscription to corrections (I am based in New Zealand, this free PositioNZ service should fit the bill?
  4. Reach M2? (maybe in back pack with power source, wired to antenna that is mounted appropriately on the shaft of the platemeter (x and y location is important, z not at all). I think M2 because the platemeter would be a bit unwieldy with an RS2 mounted on it.

Does this sound like it would work? How long would the platemeter shaft need to be stationary to get a decent location? Any thoughts or suggestions

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If you have real time corrections to the rover, it can be as short as 10 seconds to get cm accuracy. You could use an M2, some of the users here and myself use the M2.

Why not be concerned with elevation data ? It’s an integral part of the coordinates determined via GNSS. You could use the top of the pole to mount the RS2 or M2 antenna… You don’t need both. Enter the antenna height to the base of the RS2 or base of antenna for M2 receiver. You will then receive x, y and z coordinates. Depending on how many times you use your instrument, you would have a basic topography of the site. The data would be invaluable to the land owner and government agency just for graphic representation of the ground surface or maybe site planning for construction sites.

I have both M2 and RS2. The RS2 is about maybe (and I’m just guessing) 25- 30% heavier (?) But it’s heavier. This is comparing both with bi-pods and M2 with battery, LoRa, LoRa antenna and GNSS antenna. This doesn’t include the phone.

Accuracy would be +/- 3cm in x, y and z for every point measured having a fixed solution.

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The RS2 would not be that bad on top of your pole unless it is a very long pole. There are a lot of people that use them on top of a 2m survey pole. It is a lot less “tinkering” than supplying power to the M2, and getting antenna extension cables etc. If you are going to be using it regular, I think the RS2 would be well worth you $$$.

Have you read the documentation about using the Lefebure NTRIP App with mock locations? https://docs.emlid.com/reachrs2/tutorials/integration/mock-location/

That link describes what you have to do to use your Emlid product to feed your Android device the corrected GPS. The only thing I didn’t see in that documentation is how to get to Developer Options. This can differ from one device to another but normally by tapping your phone settings, go down to about phone, scroll down to About phone and then tap the build number multiple times till it tells you Developer Option is now enabled. I recommend doing an Internet search on your phone/tablet to make sure these are the right directions for your make/model. Once enabled, you will set up the mock locations like in the link above.

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Below I’ve included a pic that may explain why I’m thinking M2 rather than self contained RS2. Here the blue square is a backpack with battery and M2. The pink blob is the gps antenna, wired to the backpack. The red part is a lightweight (plastic/aluminium?) mount for the antenna.
So here we just have a light antenna on the platemeter device that doesn’t interfere with the handle or affect measurement. The RS2 weighs almost one kg, so I don’t think it would work well mounted to the platemeter.

Thanks @EBE111057 for the tip about 10 seconds, that seems manageable for an experiment. I’m guessing the Reachview app would tell me the fix was accurate enough (or not), and that I could take my measurement and then go to the next point?

Elevation data is interesting in general, but most of NZ will have LIDAR available that would have sufficent accuracy for most purposes I think, courtesy of LINZ

image

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Looking at the antenna options, it seems M2 would requires a multiband antenna like this one on the store (GNSS antenna). Specs don’t list the weight, but hopefully less than 100 g?

Compare this to the M+, with this antenna (Tallysman), which is listed at 50g.

I assuming the major benefits of the M2 for me are the faster fix and accuracy compared to M+, as long as antenna doesn’t add too much weight.

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Here’s my homemade mount for the helical antenna, I’ve since been using the Harxon GPS 500 antenna. It’s calibrated and in NGS’s database. You could use a hip bag like mine for all the M2 accessories.

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Are there any advantages to the harxon? It is listed at 370g, so probably heavier than I want.
Your home made mount looks pretty professional. What sort of connection joins the antenna to the top of your pvc mount?

The Harxon is a calibrated antenna with distances to the L1/L2 phase centers and are used for precise surveying. I’ve checked the helical antenna with known passive control marks (1+ hour static observation) and horizontally I’ve obtained 2-5cm accuracy, not so good vertically (usually 5cm or more). For your purposes, it would be lighter and cheaper. Accuracy would be sufficient for your purposes.

For the mount, I just went to a hardware store and got some 2"dia PVC pipe. I drilled the holes with a drill press to get the exact center for the bipod mount and antenna mount. I used end caps for the pipe for the mounts. There’s only two small screws to mount the antenna to the end cap, so I counter sanked the base of the antenna into the end cap about half the width of the cap (about 5mm). This gave a more stabled mount with the available two screws. For the bipod mount, I drilled a 5/8" hole with the drill press and used a female 5/8"x 11" survey adapter. I was pleased with this as it just came in my mind figuring a mount. You could do the same for your handle. In fact, you could just tape the mount to the handle or make some kind of quick connect/disconnect. The parts cost was less than $5 or about. I’ve been meaning to make a revised mount to include the LoRa radios but just hadn’t gotten around to it. There’s other mounts that are better than mine, one guy 3D printed a mount to include the M2, battery and LoRa radio/antenna in one unit. It’s pretty slick. Just search under M2 antenna mount.

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Hi @markbneal,

Indeed, you can use Reach M2 with a multi-band GNSS antenna for your survey. However, here are some things you should know before making a final decision:

  • You should provide proper ventilation to prevent overheating of Reach M2. It can be hard to provide it in a backpack

  • If you’re going to work in rainy weather, you need to think about how to protect Reach M2. It doesn’t have protection from water and dust

When you get a Fix solution, we usually recommend 40 secs to collect a point.

Also, I checked that the NTRIP station that you want to use transmits corrections in RTCM3 and NZGD2000. So, I think it should work fine. This guide about coordinate systems in New Zealand will help you set your rover for a survey with this NTRIP base.

It’s possible to output the position for both Android and iOS via TCP connection. However, for Android devices, you can also configure the transmission of coordinates via Bluetooth.

We’ve never seen the use of our receiver with a platemeter before. So, I’d be curious to see how your research will go!

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Thanks for the feedback. I’ve ordered my gear and will look into the cooling and moisture/dust protection options.

For the Android device (i.e phone), is there a minimum OS version (or other specs) that I should consider?

Hi @markbneal,

ReachView 3 can work with Android 5.1 and up. Other than that, there are no special requirements.

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Posting an update on progress.
My Reach M2 has arrived, and now in a functional prototype!

Platemeter
I have mounted to a Platemeters G1000 platemeter (Described here, available in NZ from Farmsource here. Alternatively, the Trutest EC20 here has similar capabilities. Probably the main consideration is third party software integration, which differs by device.

Accuracy
Without corrections, reported accuracy for latitude and longitude are sub-meter. I am now getting corrections via LINZ Positionz service described here - Thank you LINZ! Note, after signup, service is available after 6pm next business day. That brings latitude and longitude accuracy to 5cm, more than sufficient for our purposes!

Mounting
I have a first version prototype mounted as per pictures. Regarding the design choice of a semi-flexible mount for the antenna, farms (even research farms) are a place where things will get knocked around, and if the antenna is knocked for any reason, I’d rather it moves out of the way then crack (@$USD200 a pop). The flexible lead was donated by one of my children via their desk lamp, available here - Thanks Brian for the suggestion! While a flexible lead reduces reproducibility for height data, the height data is not super important, as our friends at LINZ are pulling together LIDAR data for all of NZ - thanks again LINZ!

Once I had it in my hand, the small size and low-ish power draw meant mounting everything on the platemeter was a good option over what i’d originally envisaged in a backpack. A range of parts came (or are on their way), and I’m still looking for the final enclosure for the USB powerbank and reach device. 10mm M2.5 bolts are used for the antenna mount (be careful not to go to deep in the antenna), with an elbow, some plastic, tape and a hose clamp - I may add some silicone for waterproofing.

Power
The USB powerbank is 5Ah from memory, peak output 1A. I understand the draw to be average 200mA, so that should be plenty of juice, though the specs also list max draw of 3A here, so perhaps testing may show if this creates some some problems?

Data Collection
The platemeter app is available on iPhone and android, but an android is required for the phone gps data to be replaced with the rtk location data. The model I will be trying hasn’t arrived yet, but is a Samsung XCover 5. This was chosen for IP68 water tightness and apparently ability to use while wearing gloves. Purchased from Spark.

the XCover 5 combines IP68 watertightness and dust resistance with the convenience of a replaceable battery. Increased touch sensitivity lets you use the immersive 5.3” HD+ display while wearing gloves or with damp hands.

Cost
Platemeter ~$NZD1,150
Reach M2 kit ~$NZD1,000
XCover Phone ~$500
Powerbank, mounting pieces & enclosure ~$250?
Total cost ~$3,000

Pictures
prototype antenna mount

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I like your design Mark ! Especially the flexible mount for the antenna. Pretty smart design !

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Hi @markbneal,

Wow, you really did a great job! Nice that you shared this with us!

Have you already managed to test this device in the field?

I’ve finished my second stage prototype to waterproofing level that will hopefully stand up to a couple of months of field testing.

Design choices are largely to have this plug and play in remote locations if one component craps out or needs to be replaced (e.g. usb powerbank). That also explains oversized enclosure (most powerbanks are larger in a flatter form factor), and minimum of soldering.

Some pictures
Here you see a waterproof charging port (for the powerbank) installed into the left side of the enclosure. The cable on the port is quite stiff, USB C on both ends, and so I needed an adaptor to USB A to match up with the cord for the powerbank (I learnt a lot about USB connectors!). Installed on the right side of the enclosure, you see the on off button.

The enclosure is mounted to the platemeter courtesy of the flexible shaft which has a thread and nut at the top of the enclosure, and a bolt that goes through the back of the enclosure in the middle (nut on the inside visible in the picture).

prototype enclosure 2a

This second picture shows the shim between the flexible cord and the hose clamps for alignment (paddle pop sticks!). Also you see the mounting through the top, and the bolt goes through the lowest hose clamp.

What might not be obvious is that the lower clamp is mounted at the lowest point to still be on the top part of the platemeter, which is height adjustable, so as not to interfere with the height adjustment. That also explains why the enclosure is mounted in landscape rather than portrait, so as to not interfere with the highest possible measurement of the device when the height adjustment for the handle is in the lowest position.

Here you have all the items stuffed in the enclosure. You may well imagine doing this a bit more neatly, though they may wait for the next version. The powerbank is mounted on double sided tape. The other pieces seem like they might be ok as is, with cords for packing! The external power button is wired into an inline button (usb connectors each end) that I bought to as to have easy access to neat solder pads and pre-wired connectors (I’ve mentioned before that my soldering is not awesome!)

prototype enclosure 2c

And here we have the enclosure, and devices switched on. You see the status lights for the usb powerbank, and the the Emlid Reach M2. Note the reach leds are brightest when the device is mounted closer to flat, than on its edge. I also hit the places that weren’t naturally waterproof (particularly top hole) with silicon after I took these pics.

Parts
Some of the pieces I used, not quite a full bill of materials since I used some on hand cables/bits and pieces:
Hoseclamps
https://nz.element14.com/duratool/d01895/hose-clamp-assortment-26pcs/dp/2444369
Elbow for antenna mount
https://nz.element14.com/amphenol-connex/132172/adaptor-sma-jack-sma-plug-50ohm/dp/2112479
Bolts for antenna mount
https://nz.element14.com/tr-fastenings/m2-510prstmcz100/pan-head-pozidriv-screw-steel/dp/2770695
Flexible lead for mounting antenna:


Waterproof charging port (due to length and cable stiffness, you might want to change this)
https://nz.element14.com/multicomp-pro/mp002446/usb-cable-3-1-c2-c-rcpt-c-rcpt/dp/3369655
Charging port cap
https://nz.element14.com/multicomp-pro/mp002451/dust-cap-mini-usb-c2-thermoplastic/dp/3369660
Waterproof on off switch (requires soldering)
https://nz.element14.com/apem/ipr1sad2/switch-spst-4a-12vdc-solder/dp/1082441
The enclosure I used (You may find a more suitable one with a final list of components and easy access to cables and connectors under non-lockdown conditions to minimise size and weight)
https://nz.element14.com/fibox/pc-150-60-ht/enclosure-pc-grey-smoked-transparent/dp/2473470
USB cable with inline power switch

An adapter I bought to make all the other cables I had fit together!
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Hi @markbneal,

That’s cool! I like to read more about your setup and how everything works. I’d just want to note that your Reach M2 is in a sealed container and can overheat. You may need to organize an additional ventilation system.

UPD. Fixed the typos

I’m hoping there is enough air volume for the heat dissipation to be fine. Otherwise I’d have to strip off the shell to connect to a heat sink? Do we have any reporting available for the temperature (from the Reach device), or any automated shutdown for when temperature gets beyond desired operating range?

Hi @markbneal,

Operating temperature for Reach M2 from -20 to +65 ºC. It may indeed shut down automatically if it overheats. However, we don’t recommend stripping off the shell 🙂. I can suggest a few other options:

  • For example, make some holes in the container for ventilation
  • Place your external battery and receiver away from each other. The battery can heat itself and heat Reach M2

However, we can’t be completely sure that the receiver will overheat because it depends on the conditions. In this case, you can do some local tests and check how your Reach M2 will work.

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I’m going to assume for now it won’t be a problem - we’ll see what happens!

I’m not keen to make holes that would compromise watertightness. However, I do note an option listed under vented enclosures here that has a vent plug that looks like it allows air to escape - would this be of value?

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Hi @markbneal,

I can hardly tell you if this device can help. In any case, I should warn you that overheating can negatively affect Reach’s operation. That’s why if you do any tests, you should do them carefully. I’ll be glad if it all works out!