How is Montag monitoring his own cage?

Montag monitored his cage from the Hobo camp.... he watch his death on the news.

On the screen, a man turned a corner. The Mechanical Hound rushed forward into the viewer, suddenly. The helicopter light shot down a dozen brilliant pillars that built a cage all about the man.

A voice cried, "There's Montag ! The search is done!"

The innocent man stood bewildered, a cigarette burning in his hand. He stared at the Hound, not knowing what it was. He probably never knew. He glanced up at the sky and the wailing sirens. The cameras rushed down. The Hound leapt up into the air with a rhythm and a sense of timing that was incredibly beautiful. Its needle shot out. It was suspended for a moment in their gaze, as if to give the vast audience time to appreciate everything, the raw look of the victim's face, the empty street, the steel animal a bullet nosing the target.

"Montag, don't move!" said a voice from the sky.

The camera fell upon the victim, even as did the Hound. Both reached him simultaneously. The victim was seized by Hound and camera in a great spidering, clenching grip. He screamed. He screamed. He screamed!