Can you explain to me why consciousness is used here? Can I use "mind" instead? Is there a difference? signals? Is it right to use "signals"?
"Suddenly the signals crossed Helen's consciousness with a meaning."
'Signals crossed' is a phrase that means 'to be confused by conflicting data'.
Yes you may use mind in this sentence but I imagine that the author was playing on the confusion aspect and the reference to consciousness brings images of her mind being previously unconscious.