I am not sure if you are referring to the FCAB operation, or PNT Tassie regarding the end of train transponder.
I have grabbed the you tube video clip from the link, but have yet to fully digest the contents.
Unfortunately, I am not able to understand Spanish.
But, there seemed to be mention of a rearward facing camera in the FCAB loco.
If however, you are referring to the Tassie operations while I was employed down there, at that time there was no GPS factored into the radio system.
Being Driver Only Operation, there was the USRR style end of train unit transmitting to the monitor in the cab.
Advising of brake pipe pressure at the end of the train.
But, this did not relay any info to either Train Control or the following train.
I am not sure just how things operate down there now, as I departed in 2007.
I believe that computer generated track warrants are now transmitted via radio.
And, Block Posts appear to be utilized, I presume for following train movements.
But, while I was toiling down there, the Track Warrant was scribbled out by the driver while in route.
If following a train, you had to call that driver on the radio to obtain km pegs that he was clear of to proceed to a km peg 5 kms in the rear of that train.
With the then three northbound trains working the South Line it became hectic on the train radio.
The train radio was not discrete and all communications with train on the Tassie system were heard.
The ETU may today have GPS factored into the radio system.