ST-980Plus / TME and TDR Return AB Settings options
Found under Settings | Radio Menu Settings at the top of the Programmer page there are these options. This offers a little explanation of what they do.
TMR - This mode selects the displays that are monitored in the background in addition to the primary (main) band (the one on which you are currently operating). You can mix and match between all or some of the displays for dual, tri or quad watch.
The options for this feature include M+A, M+B / M+A+B, M+C+D/ M+A+B+C, etc to allow you to monitor other channels while working a "M" a main channel. Best suggestion if you want to monitor all the "bands" of the display, set this option to M+A+B+C+D. This selection makes all the "bands" heard no matter which you are on as the main.
TDR Return AB - This option is a transmit delay time. This is the delay time before returning to the primary channel after a signal on the secondary channel drops. (In other words... the time before you can transmit after listening to a signal on another "band" of the display.)
08/26/2020