**THIS QUESTION WAS ACCIDENTALLY POSTED TWICE. PLEASE SEE HERE FOR THE ACTIVE POST***
Hi,
The organisation I work for has historically used a Zephyr 2.0 receiver with a handheld Geo7x to both find and map points with 1cm accuracy. We specifically use these instruments for long-term agricultural field trials, some of which are over 100 years old, so accuracy is important and we need it to be within 1cm because this is also the tractor systems work to (also some of our trail plots are only 1m by 1m, so even 10cm can make a big difference).
With a lot of help from our IT team around software compatibility, the Zephyr/Geo7x system has worked really well for us over the last 10 years, but as they are now switching off the 3G network in the UK, we need to upgrade and have chosen to pair a Trimble DA2 receiver with a tablet that runs QGIS/QField.
My problem is that I cannot get the two systems to find the same point location with 1cm accuracy. To test this we uploaded the same map (in WGS84) onto both systems and marked out several points using the old Zephyr/Geo7x. I then tried to navigate to these points using the DA2 and QField, but was consistently about 20cm out (see below photographs). I am almost certain there is a difference between the settings but I can't figure out what it is. Below is the device setup as I have figured it out on both systems so far.
DA2/ Trimble Mobile Manager/ QField:
Trimble Mobile Manager settings: GNSS correction source = Auto (Trimble Correction Hub); GNSS output = Auto; Geoid = EGM96 (Global);
QGIS settings: Layer CRS = WGS84, Project CRS = WGS84
QField settings: Positioning device in use = Internal Device, Antenna height = 2m (height of the pole that came with the DA2), Measure (M) attached to vertices = Timestamp (milliseconds since epoch)
Trimble Zephyr/ Geo7x:
Geo7x: GNSS Receiver port = COM3: GNSS Serial port (internal GNSS receiver); DOP type = PDOP, Max PDOP = 99.0; Min SNR = 12.0; System: Latitude/ Longitude; Datum: WGS 1984; Altitude reference = Height Above Ellipsoid (HAE)
Any insight anyone has would be hugely appreciated.
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Aislinn Pearson
Product Owner, FarmOS
aislinn.pearson@rothamsted.ac.uk
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