"signal" - key terms from Wikipedia

american signal
analog signal
audio signal
baseband signal
bold signal
chrominance signal
clock signal
control signal
desired signal
digital signal
digital signal	processing
digital signal	processor
distress signal
eeg signal
electrical signal
federal signal
feedback signal
fm signal
input signal
modeling signal	processor
optical signal
output signal
pwm signal
radar signal
rf signal
sampled signal
shaking signal
signal
signal	battalion
signal	brigade
signal	coding
signal	corps
signal	hill
signal	line
signal	mountain
signal	pathway
signal	processing
signal	processor
signal	publications
signal	publications inc
signal	regiment
signal	squadron
signal	strength
signal	to noise ratio
signal	transduction
signal	transduction pathways
signal	whip
traffic signal
video signal
voltage signal