This is from an, as yet, unidentified manufacturer and appears to be of the TK102 design.

The firmware, however, is quite limited compared to most of the other TK102 versions out there with a subset of SMS commands and a very primitive stockade command.

The stockade command is the main indicator that you have one of these devices, the manual showing the stockade command as:

stockade+password+space+semi-diameter+space+alarm

So it has no way to define the centre of the stockade and, I assume, just uses it’s current position as the centre.

I have been sent a scanned manual by the user that first reported this device type but have not yet found an online version suitable for inclusion here.