The carriage I was most familiar with had talkie tooter radios that controlled the carriage directly. They also made a blast off of a horn on the carriage itself so you could confirm your transmission from the remote to the carriage. Our horn on the carriage lasted like a month and we never bothered fixing it. We used those hand held remotes as well as radios so the yarderman(engineer) and hillside man(chokerman) could communicate.
Our set-up worked like this:
Engineer sends the carriage down the hillside by releasing the skyline brake and feathering the yarder mainline brake, so the carriage is freewheeling on the skyline and its descent is being controlled by feathering the mainline brake on the yarder. Don't get to jerky with that lever boy or you'll have cables snapping and dancing before ya know it. A good engineer knows what his mainline spool looks like for how far down the hill the chokerman is working and can race that carriage down there slowing it up real smoothly just when need be. There's an art to it for sure.
Chokerman on radio tells engineer "little bit, little bit, good" as carriage slowly rolls to a stop he hit's the button once, this clamps the skyline brake in the carriage, anchoring the carriage to the skyline.
Then the Chokerman hits the button again and the motor revs up in the carriage and starts pulling slack through feeding it out at a nice even rate(I've worked with non slack pulling carriages before, they suck) and when ya get good at it you can use that rate of feed to time up big swings or doll some out and stop the feed in order to swing across obstacles. A good chokerman makes every use of any advantage to get those chokers to the wood in the easiest possible manner.
Once the chokerman has got to where they're going they push the button to stop the slack pulling feed, and then let the engineer know "got enough" so they can stop having to focus on dolling out the mainline nicely.
Then when all the chokers are hooked up and the chokerman is in the clear he hits another button(our talkie tooters had two buttons)twice to release the mainline brake. Now the carriage is still clamped to sky but the mainline brake is free so the mainline will just run right through the carriage.
Now the chokerman tells the engineer "go ahead" and the engineer steps on it and starts winching in mainline pulling the drag of logs towards the carriage.
As the drag approachs the carriage the chokerman on the radio again says "carriage" and this lets the engineer know to let up on it a little as the chokerman then pushes the 2nd button 3 times this releases the skyline brake and clamps the mainline brake so that then the logs are held up in the air with the chokers near the carriage for ground clearance and the skyline brakes are released. So when the engineer steps on her again then the carriage with logs clamped up nice goes racing up the skyline all the way to the yarder.
Then the engineer controls everything when it's right in front of him to set the logs down unhook the chokers and then it starts all over again.
A 'turn'
That's about how our set-up worked for a single basic turn. I ain't even gonna try and explain downhill yarding. To much typing.