Hi and welcome here...
Everything depends on the satnav and the accuracy of the gps position.
The satnav must be able to 'understand' your files.
And it must be able to announce 'destination reached' when a delivery point is reached.
The satnav can't pinpoint your position without typical errors. The gps position accuracy mainly depends on number and geometry of satellites 'visible' and on reflection/shading errors by large buildings. The typical accuracy is somewhere around 30 yards diameter. So you may get in problems when the calculated gps position has a large error and when building doors or post boxes are close together.
Everything depends on the satnav and the accuracy of the gps position.
The satnav must be able to 'understand' your files.
And it must be able to announce 'destination reached' when a delivery point is reached.
The satnav can't pinpoint your position without typical errors. The gps position accuracy mainly depends on number and geometry of satellites 'visible' and on reflection/shading errors by large buildings. The typical accuracy is somewhere around 30 yards diameter. So you may get in problems when the calculated gps position has a large error and when building doors or post boxes are close together.
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Matthias
Matthias