来看IMDB的官方解释:
The dead-man's switch Ma-Ma is wearing doesn't work that way. You know when someone's hooked up to a heart monitor, it makes a zig-zag line and emits a regular beep - then when their heart stops it turns into a flat line and changes to a constant tone? It's that flat line and constant tone which triggers the detonators, not the loss of the signal. Dredd throws Ma-Ma beyond the reach of the signal before she dies, so that flat line and constant tone never reach the detonator mechanism.
那个心跳信号器的工作原理并不是大家想的那样。当这个人活着的时候,他的信号是锯齿状的脉冲,而死了之后就变成一条直线。这条直线就是炸弹引信的触发器,而非“失去信号”是炸弹的触发器。Dredd把马马扔出了信号接收范围,即扔到一楼,在此过程中马马发出的信号一直是锯齿脉冲的。但到了一楼的时候,马马虽然死了并发出了直线信号,但那时候已经超出了接受范围,所以不会爆炸。