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Large positional errors using your smartphone? Messages in this topic - RSS

Tom H
Posts: 508

Do you run TerraFlex on your smart phone or tablet?
Have you ever experienced large positional errors in your location?

Then here are some good practice tips to follow:
  • Check the cellular network coverage for your area.
    Most smart phones rely on cell network coverage to improve and stabilise its GNSS position. Smartphones also use this to improve the FFT (first time to fix) which is the time it takes your device to lock on to a 3D fix

    If you are in an area with poor network coverage then you will need to be more patient when recording features and may have to wait for 2-3 minutes for your GNSS location to fix and stabilise. This will offset any errors in the position provided a poor network connection.

    Trimble devices do not require cellular networks to augment their position, so will operate as well in areas of good or bad coverage

  • Try to leave TerraFlex running in the foreground rather than setting it to 'sleep' between each form you record.
    Leaving the app in the foreground, will keep the smart phone tracking the available satellites and generally result in more stable GNSS performance.

  • If in standby, wait 2-3 minutes before recording when you 'wake' TerraFlex
    If you do need to place TerraFlex in standby to access a call, or use other apps, you should wait 2-3 mins before recording after waking the app.
    This will give the smartphone a chance to lock on to a current GNSS signal and not try to augment the position with what could be an incorrect location for your cell network.

  • Are there any obstructions to the GNSS signal?
    Physical objects like buildings can cause the GNSS signal to multipath. Working under Tree canopy for example can weaken the GNSS signal and in turn reduce the quality.
    Take a look at the
    Trimble GPS tutorial for a better understanding of how GPS (GNSS) works and how errors can affect your position.

    Trimble devices contain larger internal antenna's and sophisticated multipath rejection technology, to mitigate these types of errors and maximise performance.

  • Verify your location using the map view.
    The easiest QA is to just verify your location using the map view. If you are not then simply wait for the position to stabilise.

Do you face these problems consistently?

If the answer is yes, then you should consider purchasing one of the Trimble professional grade GNSS embedded devices to run TerraFlex OR a professional grade external GNSS receiver.
These devices are designed to operate in difficult GNSS environments without the need for cellular corrections and provide the highest quality positions possible.

TerraFlex currently supports the following Trimble devices, external GNSS receivers and the new Catalyst SoftGNSS technology:

!!! NEW Software GNSS - Trimble Catalyst !!!:
  • Trimble Catalyst - a revolutionary technology, subscription-based software GNSS receiver running directly from you Android smartphone

    Subscription plans:

  • 1 Metre - metre accuracy in optimal conditions
  • Sub- Metre - 30cm - 75cm accuracy in optimal conditions
  • Decimetre - 10cm accuracy in optimal conditions
  • Precision - 1cm - 2cm in optimal conditions

Take a look at the How It works section for more information

GNSS Receivers:

Handheld devices with embedded GNSS receivers:
For your nearest Trimble distributor please use the Find a Dealer link
edited by Tom H on 7/17/2017
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