Low GPS/GLONASS Accuracy

Coordinate accuracy depends ONLY on your smartphone or tablet's receiver. If accuracy is low, you should switch to a different device. This is a hardware limitation of the phone, and the app cannot overcome it.

What you can do

  • Move the phone or tablet holder as close to the windshield as possible so that the roof blocks as little satellite visibility as possible.
  • Keep it away from the metal dashboard or other magnetic materials.
  • Try another device — even an iPhone 7 shows excellent accuracy.
  • Use an external DIY receiver (10–20 cm accuracy).
The maximum accuracy our tests have shown with an external receiver on the free GLONASS+GPS satellite signal is 20–30 cm, which is quite sufficient for spraying.

Learn more about the DIY receiver →

Track Recorded at an Angle

Some devices output compass readings with a shifted angle relative to true north when used in a vertical position. There are three main causes:

Cause 1: Magnetic Declination

The device may not account for magnetic declination correction and shows readings relative to magnetic north (while GLONASS draws the track based on geographic north). In this case, simply toggle the heading correction switch in the app settings.

Cause 2: Compass Only Calibrated in Horizontal Position

The device works correctly only in a horizontal position (on the palm), and in the vertical orientation, as it is typically mounted in the cab, the north reading drifts. To make the track display correctly, it is sometimes enough to slightly rotate the device left and right in the holder, or use manual compass correction in the app settings. Of course, during operation the tablet holder must be rigidly fixed relative to the tractor, otherwise the heading will constantly drift.

Before starting work, it always makes sense to do a few test drives in a straight line and adjust the compass.

Cause 3: No Built-in Compass

In this case, you can disable the compass in the app, and the heading obtained from the GLONASS/GPS receiver will be used instead.

This mode has two downsides: 1) Turns are displayed with a noticeable delay, making it harder to work. 2) At low speed and when stopped, heading readings are no longer reliable.

How to Improve Accuracy

If your phone does not have a very good GPS module or the tractor cab strongly shields the satellite signal, you can connect an external GLONASS/GPS satellite receiver to improve accuracy. You can build a receiver for a parallel driving system yourself using our instructions, or order a ready-made device from us.

For pre-orders and questions, email: sale@free-gps.ru

DIY Receiver assembly instructions →

Download Agro Navigation

Or build a DIY receiver for maximum accuracy