I do not know about satellite, but in wireless communications in general, the term 1+1 “hot standby” means that you will have two pieces of equipment (lets say two transmitters) that are receiving the same signal to be transmitted. They do process the signal and generate power to be directed to the antenna system (dish or whatever).Only one of the transmitters will be “online”. The standby one will be sending power to a “dummy load”, a resistor that will disipate that power.
In the event of failure of the main unit (detected as a drop of power, a shift of frequency or any other abnormality),the failed unit will get “offline” and the standby will take its place.
Switching times are very low (bellow 1 second), since the equipment was ready to carry service always.
In a “warm standby”,you may have severak transmitters carryng service and on frequency programable unit that work as a stanby for all the ones in service.
in case of failure of any of the units in service, the standby will turn on, reprogram itself to asume the identity of the dead one, and take over.
Switching is slower,and if two units die at the same time, or before repairs could be done, someone will be on the dark.
Hope it helps, or at leats it will get you scientifically confused.