This is a complete BIM geolocation solution comprising high accuracy GNSS antenna and a Ruggedised Android 6 device in a one piece unit. It is fast and agile while being easy to operate and reliably accurate on test better than the SP60 unit which was very surprising. It also uses the SPECTRA SPace app to connect to the aerial and integrate your RTK correction for MOCK location operation (See the SPace App review).
On delivery, I was surprised at how small it was, approx. 300mm long and 120mm wide at largest parts. My particular model did not come with a hand strap, and with a £6500 price tag, it would have been useful as I nervously positioned it over bodies of water to collect positions of sensors and valves. I will mention that it is a lovely secure non slip rubbery grip both dry and wet but its expensive enough not to want to drop in deep water.
The first day of testing was in fine drizzle which tends to hamper the use of touch screens but this devices touch screen was constantly accurate with or without surgical vinyl gloves. I have not tested with other gloves as these are the typical ones used by persons performing this type of work and it would not be logical to test with riggers gloves. The screen was clear and readable and although looks larger, it is the same rough size as a Samsung S5 and has the same feel and look. I had no physical fatigue using the device over the 4 hours of use as you are always moving but I will reiterate that I was not using the strap and found myself holding it behind the camera as this is a nice central balance point. I do envisage a little strain might be possible depending how it is used but nothing that would be substantial as constant use for 4 hours without a break in position is unlikely.
Its weight, without pole, is approximately the same as ruggedised Android tablet, and this is mainly how I used it. I will mention that the unit I tested had the 4800mAh Battery and the latest version comes with a 6400mAh battery but even still I had 4-5 hours continuous use from the device. The 5 hours was with no wifi on or 4G data service (Sim card removed only). I acquired Internet connectivity for RTK correction via WiFi from my Android mobile phone hotspot.
The Pole is extendable and locks in positions 1m,1.1m,1.2m and 1.3m. I did use it to set positions of fixed reference nails and Laserscan Geolocation control Points.
The first thing to notice is no external spirit bubble but there is an internal spirit bubble on the screen when selecting that mode in the apps (mobile mapper) that come with the device but ArcGIS Collector did not have this option so it is an issue to be supported in the apps. Obviously an external bubble could be employed to save on application redevelopment costs. Otherwise it does what it says on the Tin, It has a point on the bottom and locks securely into place to create a fixed distance from the reference point. However I did find the pole a hindrance as the units camera takes a picture of the centre of pole point, which is good for accurate confirmation of the measured point if locating an asset or control point in the ground but not great for rapid photgraphing and positioning of industrial assets, but fortunately the pole is not really required as I found for the following 3 reasons:-
- When collecting the geolocation points of assets you will normally be resting the unit on the asset therefore you can position it accurately enough on top of the asset.
- There is no digital spirit bubble in ArcGIS to give an accurate reading of tilt so the actual position will be slightly inaccurate due to user error.
- If you need to take a reference nail position, then the nail head diameter is the same as the pole screw fitting and thus more accurate than using a pole anyway as the device is located exactly on the reference point and not within a tolerance angle as when using a pole.
This also makes you very agile to get round and collect asset data. Talking of Agility, It brings me to my next observation.
My first impression of the SP20 gave me doubts as to the accessibility to photograph data plates but it works well. In 600 assets, I have found that I had to resort to my Bluetooth camera (Samsung Galaxy A6 mobile phone) only once to photograph an inaccessible data plate. This so far has been well beyond expectations. As with any Android 6 device, you can transfer files in a multitude of ways but I have only so far tried Bluetooth, but there are options for direct Wi-Fi or NFC too.
As far as accuracy, on test with RTK correction (remember accuracy derived from precision):-
- HRMS is 0.006m to 0.011m
- VRMS is 0.014m
- PDOP of 1.3
There is an issue of when the Fix Quality transitions from Fixed RTK to Float RTK so i.e. if your internet gets disconnected more than about 10s or your subscription is used by someone else (as on my test with a sample RTK licence), The accuracy degrades and the fix quality becomes Float RTK. This renders accuracy from 40cm to 1.2m on HRMS which is to be expected, but after about 4-5mins the unit will enter DGPS fix quality mode and the accuracy in HRMS improves phenomenally to the below conditions: –
DGPS in clear skies and open space achieved 0.119m (12cm) HRMS and 0.163m (16cm) VRMS accuracy as shown in the image on the left. Excuse the reflection in the screen but this is a real world test
And DGPS HRMS inside a GRP kiosk is reliably between 0.26m and 0.4m. Sometimes outside of this range but for inside a kiosk, this is pretty good. My main inaccuracies inside the kiosk were from the float RTK mode.
The Reason I say this is an issue is the time period it faffs around with float RTK, if it can assume DGPS immediately then there will be less wasted time waiting for improvements in accuracy. Time is money after all.
The biggest surprise is this is just as good as the SP60 in accuracy terms but with all the extra possibilities brought with the mobile mapper device.
For further information on the SP20 https://spectrageospatial.com/sp20-gnss-handheld/
There are small issues that could be improved for future models like a dual SIM version so users do not need a phone or if the SIM that supports the RTK can be voice enabled and unlimited 4G Data.
Its back cover is a little fiddly without the tool but the trick is to use the tool. It is only necessary to remove the cover to change the battery, Sim card or Micro SD card. On test It was not required to change the battery so it was not an issue but is a requirement so the tool must be carried to prevent damage opening the cover. While on the subject of the cover, the padlock symbol to represent an unlocked padlock actually looks like a locked padlock so does cause confusion if you have not read the instructions. This should not be an issue on the currently supplied model with a 6400mAh battery as you should gain an extra couple of hours, logically thinking but needs testing to prove.
The SIM card slot makes it possible to insert the SIM card in the wrong way so you must check with the picture that you have inserted it correctly. This is because the long edge is at the back. Sounds pedantic but expect service calls regarding this and no DATA Service.
Fantastic and highly accurate device for capturing geospatial information with full Android utilisation (Android 6) which is fully compatible with current data collection software and asset management infrastructure built of the tried and tested android device so its user friendly and easy to integrate apps. All this with an easy to use and highly accurate survey grade GNSS aerial, rugged and from a great stable.
Other issues discovered on testing:
SP20 Cant connect to pc to see file structure – resolved
- Check usb connection
- Applications / File Manager -> settings -> General Settings -> Restrict users access -> untick
- Swipe down from top twice to expose connection menu
- Select Cog on top bar (settings)
- Swipe up to get to bottom of menu
- select developer options / usb debugging / set to active
- Swipe down to Select USB configuration
- USB configuration / select PTP / repeat and select MTP
This should now have resolved the issue and you can now see Internal storage file system.
There is an issue that to extend battery life, it would be plausible to turn off all wireless and unused device modules on the android device but entering flight mode prevents connection to the GNSS receiver/antenna. A mode to turn off these modules would be a great help while leaving the ability for DGPS for lower accuracy non RTK enabled work. Since writing, there has been a 50% increase in battery size so this may no longer be an issue but even so, it would be nice to have a one touch mode to disable wireless without turning off the GNSS antenna connection, this might be due to it switching off BLUETOOTH in flight mode.
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