Non accurate positioning - Fail to overlapping orange dots (hedgehog view from sumaps)

Frequent questions asked online, offline, in forums are answered here
Post Reply
Posts: 1
Joined: Thu Apr 08, 2021 2:47 pm

Non accurate positioning - Fail to overlapping orange dots (hedgehog view from sumaps)

Post by dcs »

Hi there,

While our first installation of the starter set IA-03-2D-TDMA (HW4.9) we're suffering an accurate problem which we don't know how to fix.
As you can see on the screenshots below, our map has two submaps with their services zones and a handover big enough for the 4 minimum refreshes.

* 4 stationary beacons forming 2 submaps:
submap 0 -- Beacon 1 (31.9 kHz) + Beacon 3 (46.1 kHz)
submap 1 -- Beacon 2 (31.9 kHz) + Beacon 4 (46.2 kHz)

After setting up the services zones and the handover area, we place the hedgehog in the middle of the handover zone, we freeze de submaps and the map to run up the system and then, following the indications on the help video 'using submaps to build large maps' (, we click on the M1 green button to check how the hedgehog is seen by the two submaps and we get to see that our hedgehog appears in two different positions for each submap and we are not capable to get the two orange dots fully overlapped.

The help video shows that we have to align the submaps correctly by CTRL+scroll/drag while the system is running and the maps is frozen but we can't do that. When we try to do this, an error message appears saying that the map is frozen and if we try to unfreeze the map to align the submaps we lose the orange dots and the position of the hedgehog in the submaps and, of course, if we move the submaps we also lose the right position of the beacons into the x y axes.

We don't know how to carry on and fix the problem and this error provides frecuent jumps on the hedgehog tracking, big desviations on the real path and sometimes even total fails on the positioning (for ex. next to beacon 4, the dashboard shows that the hedge is next to beacon 3 (pics 03 + 04)).

Posts: 368
Joined: Sat Feb 06, 2016 4:03 pm

Re: Non accurate positioning - Fail to overlapping orange dots (hedgehog view from sumaps)

Post by smoker77 »


1. As you are using submaps with equal ultrasonic frequencies (31 kHz and 45 kHz beacons in both submaps), you should adjust TDMA sequence as described in section 9.2 of the operating manual (set TDMA sequence length to 2 for all stationary beacons, and set TDMA position in sequence to 0 for beacons from submap0 and to 1 for beacons from submap1): ... manual.pdf

2. On your last screenshot you have enabled M2 mode to see position of the mobile beacon in two submaps simultaneously.
But two positions of the mobile beacon are far from each other. The purpose of this mode is to shift submaps so the two positions will be as close as possible. Submaps will not shift automatically, you should shift them by manually.

3. We recommend to use nominal ultrasonic frequencies - 31.0 kHz instead 31.9 kHz, 45.0 kHz instead 46.2 kHz. This is better because 31 and 45 kHz are central frequencies of the corresponding filters. Try to change the frequencies.

Post Reply