電信號

electrical signal

lightning / electricity / electric (bound form) / to get (or give) an electric shock / phone call or telegram etc / to send via telephone or telegram etc

telecommunications

letter / mail / CL:封[feng1] / to trust / to believe / to profess faith in / truthful / confidence / trust / at will / at random

signal

roar / cry / CL:個|个[ge4]

ordinal number / day of a month / mark / sign / business establishment / size / ship suffix / horn (wind instrument) / bugle call / assumed name / to take a pulse / classifier used to indicate number of people