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Positional game changer for foot-o mapping

Latest technology at affordable price

by Geoff Peck, Ugly Gully Orienteers

I’ve been making foot-o maps for over 50 years now, and I think my latest GNSS acquisition is the biggest “game changer” I’ve seen…. sure, LIDAR is also a huge game changer, but there are still areas that don’t have LIDAR coverage whereas there is GNSS satellite coverage almost everywhere!

My GNSS history

I’ve been using GNSS devices since they became small enough to carry on foot, when the USA launched their GPS system. They have really helped in the production of orienteering maps, but still limited by their inaccuracy down under. I’ve found that most devices, including “data loggers” with better views of the satellites, are really only accurate to +/- 5m at best, and a lot less under tree cover.

They have been very good for general position and plotting isolated point features in the middle of nowhere, but can’t be used alone for “relative position” work where compass and distance methods still have to be used.

Recent developments

What has changed is that more satellite “constellations” have been launched (GLONASS, Beidou…). More recently the European Galileo system is now fully operational. Apart from increasing the number of satellites to obtain a fix, Galileo uses far better technology than the decades old GPS system, so is far more accurate.

In addition, there is now a network of reference “ground stations” (RTK) across Australia that can provide corrections for errors, such as cause by solar flares etc, in the raw satellite data. These corrections can be downloaded over the internet (NTRIP) and applied to the satellite calculations to increase accuracy.

Until recently the equipment required to use this new technology has been expensive (and bulky). However, a Spanish company has recently manufactured a small Arduino “board” featuring the newest U- Blox F9 multi constellation GNSS chip with RTK/NTRIP capability and a Bluetooth module. It was relatively easy to set up, although I am grateful to Peter Mousley for his frequent expert assistance and for explaining how RTK/NTRIP worked.

My GNSS present

Performance

I have been using this device for almost a year now and am truly impressed with its accuracy. When using NTRIP for corrections, the accuracy is in the order of 2-3 cm … yes, not a typo, that’s centimetres!

But this requires an internet connection which is not always available in remote bush (and sometimes not even available in urban areas). Also it is  only really usable within a reasonable distance of a ground station. But where available, having RTK/NTRIP has made it easy to measure the “native” accuracy of the GNSS.

Without RTK/NTRIP, the native GNSS has proved to be accurate to +/_ 1m in all situations, even under tree cover. Anyone who has  been involved in mapping will know that 1m accuracy is more than good enough for our sport, and so it has proved.

Proving my GNSS device

 My most recent project has been the Broadwater State Forest granite area. There was no RTK/NTRIP available, but I was lucky enough to have fairly good LiDAR coverage which I was able to use to check GNSS accuracy. There was 100% agreement between GNSS position and LiDAR point features at all times. So I was able to accurately plot all the boulders using the GNSS position.

More than once I marked a boulder as ‘medium boulder, S side’ then without realising returned to the same boulder from a different direction and marked it as ‘medium boulder N side’. The difference between the two positions was almost exactly the width of the boulder. When I walk back and forth along a vehicle track, keeping to the left, the GNSS shows two parallel tracks.

This GNSS gear

Apart from the Arduino board, there needs to be a dedicated remote aerial and Bluetooth module (which come as a package from the supplier), a metal “ground plane” to reduce multi-path effects, and a power supply (I used a standard USB external charger).

The Bluetooth module sends position data to a smart phone, where I use the Bluetooth GNSS app and one of Peter Effeney’s MyOmaps apps to record tracks, waypoints and display a KMZ version of the base map. Thus I can see exactly where I am when surveying.

The accuracy of all GNSS systems depends on the signal strength from the satellites. Avoiding your body getting in between the GNSS device and satellite ‘line of sight’ is one obstruction you can easily overcome. So mounting the antenna on top of your hat is essential. Unfortunately that almost guarantees getting some multi-path interference (reflected signals from the satellites). A ground plane keeps the interference  to a minimum. I use the top of an old metal tin, about 14cm diameter.

Acquiring the gear

GNSS setup

I purchased the main Arduino board (simple RTK2B) from ArduSimple. I added their multi band GNSS antenna – ANN-MB-00 (Galileo works on a different frequency to other systems). All for around 200 euros (A$320 at time of post).

To this I added a Keyestudio XBee 2.0 Bluetooth module (which just plugs in to the board) and made myself a plastic box to keep it fairly safe.

Parts list

  • Ardusimple simple RTK2B board
  • Multiband antenna
  • Bluetooth module
  • Ground plane (metal plate)
  • Hat (not necessarily from Bunnings, but works well!)
  • Power supply (or battery pack
  • Bluetooth GNSS app from clearEvo.com on playstore
  • Tracking app such as MyOmaps, Maprun etc

From field to computer

Geoff GNSS ready to roll w

Regrettably I’m an ‘old school’ mapper so prefer to use this technology to help me draw my survey details on drafting film in the field. I then transfer that detail, plus GNSS data, into OCAD when I get home, You may prefer a set up with tablet to draw directly into mapping software.


If you do go down this track, then please do let us know how you get on. Geoff will gladly field queries at joffpeck at hotmail.com. Feedback and reports are welcomed by Ken via this website or by Geoff.

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GNSS Devices in Mapping

Geostationary Satellites

GNS 2000 Plus

Key features

I finally found a small GNSS device that met my key criteria of;

  • handles GPS, Glonass and Galileo satellite constellations
  • small enough to affix to my helmet or hat for best satellites view
  • stores track data for later retrieval

Most either store data for later retrieval or transmit live via Bluetooth but don’t store. The GNS 2000 Plus does both if you select to transmit via Bluetooth. Bluetooth transmission is the default. Storing is effected by rapid Off-On after you turn on the only switch on the device. But make sure you observe the light pattern that confirms you are in storage mode. I find both methods work well.

Satellites in view

This was an eye opener. Without access to Galileo, in the forest I was sometimes getting (via Bluetooth GPS app) barely sufficient usable satellites for good performance.

Add in Galileo and total satellites visible was at least 22 with 12 in use. In general, more satellites in use means better accuracy. As the signal from one satellite in use deteriorates, the next best is swapped in.

What’s not so good?

I wanted a POI button on my GNSSr but very few have these. However, to my pleasant surprise I found that Bluetooth to a smart device with OruxMaps as the tracking app, gives me not just POI function but also easy capability for making notes directly.

It isn’t IPX rated for climatic conditions. However if rain is threatening I put it in a ziplock bag.

The GNS 2000 Plus records a track point to the device only every 5 seconds. However, data transmitted to a smart device via Bluetooth, whether or not also recording to the GNS device, gives 1 second intervals – in fact typically 3 records per second. See my correction post for further information.

When setting the function to record on the GNS device, carefully observe that the green light flashes quickly 3 times as the switching to effect this is time sensitive. [This section updated 24 May 2019 to note BT 1 second intervals – thanks Rob Plowright].

For mtbo I find 5 seconds acceptable. I am used to riding at 12 km/h or less while mapping (at a significant cost of disc brake pads) which means a track point every 17m. On detailed track I tend to go slower and at junctions I generally stop. For foot-o, the Bluetooth transmission gives detailed data and if desired, the GNS device recording can also be on as a backup.

Originally I was disturbed at the lack of ability to set various parameters. Now I am a convert to the simplicity.

Tracking against Trimble

The Lerderderg Track (Vic) trail was originally surveyed on foot in 2000 using a professional Trimble with mushroom antenna. So this is a very good standard against which to compare the GNS 2000 Plus while riding. The Trimble track was supplied smoothed. The pic shows a track portion.

GNS 2000 ride vs Trimble walk in bush

The GNS 2000 Plus was on my helmet thus giving it the same exposure to satellites as the Trimble mushroom antenna. I also wore on my wrist my Suunto Ambit 2S and it showed noticeably more variation. My interpretation is that the addition of Galileo satellite access has enabled the GNS 2000 Plus to virtually match the professional Trimble year 2000 model.

Not all plain sailing

Talking of plain sailing, this device was developed mainly for small plane including sail plane use – hence the 5 second interval. Geoff Peck and I worked on resolving a number of issues. These revolved around getting the track data from all of GPS Glonass, Galileo etc from the device through to a gpx or kml/kmz file format for OCAD.

We found the popular GPS Bluetooth app recommended by GNS 2000 Plus did not handle satellites other than GPS and Glonass! Eventually we came across GNSS Commahttps://www.facebook.com/pilablunder app which as you can see from the images above, handles data from all constellations. So we had the means of getting the data and GNSS Commander would also store it and even email it afterwards.

But I wanted the ability to manage the tracks on the phone, especially creating POIs with text info. Also on occasion having a background map whether online topo or my own orienteering or trail map. Many apps were presented but only one suited – OruxMaps. I originally looked at it askance as it had so many functions. But I found it very simple to set up and use for what I wanted. It also will upload your track to their website or GPSies.com or a few others. However, I just connect via cable to my PC and get it that way already in GPX format.

GNSS 2000 Plus with laptop

Judging by some online chat groups, it can be problematic getting a GNSS device to work with an OCAD on a laptop in the field.

So I did a test and found that using Bluetooth as COM6 at max rate on my PC made the connection. I then started OCAD 2019 Real-Time GPS. When I tried the Test function, data flowed through but an Invalid Data message displayed and stayed on for every record. However, I recalled that my trusty GPS Utility software found an invalid NMEA header in a GNS 2000 Plus file so guessed the error message might be staying on despite the rest of the data being OK.

So it proved and in live mode it worked fine. OCAD Inc should have fixed the persistent error message problem by now.


I have had a breakthrough with the Holux situation on windows 10.  
I started with installing the drivers below and my RCV-3000 now works with the ezTour software. Then to my amazement the 1200e now works also.
https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers
I still can’t get the data off in Ocad although the real time gps works but this is not a major issue for me as the export can be done from eztour.

The above from Andrew Slattery for all those Holux GPSr users out there

GNS 2000 Plus In the field

The GNS 2000 Plus got a good workout in the final stages of preparing the Lerderderg Track map. I have since used it on other maps. I mostly ride with the device on my helmet. More recently while walking to check the map for the Daylesford permanent orienteering course, I fixed it to my cap using a combo of velcro strap and 2 safety pins.

GNS2000+ on hat

With my mobile strapped to the bike bar I mostly use Bluetooth – GNSS Commander – OruxMaps principally to enable recording of POIs on the mobile along with comments. I haven’t bothered to date with loading a map of the area into OruxMaps. When in mobile range I can use the generic online maps but find they are of little or no assistance.

Getting OCAD maps into OruxMaps is simply a matter of exporting in GeoTiff format (TIF including World file), then copying those two files into my mobile OruxMaps MapsFiles folder per image below.

OruxMaps files on mobile
map files in OruxMaps app on mobile

The wrap

Despite it’s apparent limitation of recording every 5 seconds, I have found the GNS 2000 Plus to be highly satisfactory for my use in developing mtbo maps and trail maps. When I used it in checking a foot-o map, I found that it delivered dramatically better results than the original mapper’s GPSr – checked via NearMap and my many prior mappings of those tracks over the years. So I believe it is quite likely at least as good as any other GNSSr in its price range – if there is such a thing.

Geoff Peck and I have been sharing experiences re access to Galileo, SBAS, Beidou etc on GNSS devices. We have managed to surmount a number of hurdles along the way and are pleased to share our experiences. Use the Comments section to ask and we will reply there to share with all users of this blog

I bought my GNS 2000 Plus, $175, from a company Geoff recommended – Melbourne based Oz Pilot. Their online shop doesn’t specify the GNS 2000 is the Plus tri-ceiver model, but just specify that in your order and that is what you will get.

Off course

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