discriminator
Concise Oxford English Dictionary © 2008 Oxford University Press:
discriminator/dɪˈskrɪmɪneɪtə/
▶noun
- 1 a distinguishing characteristic.
- 2 Electronics a device which only produces an output when the input exceeds a fixed value.
■ a circuit which converts a frequency-modulated signal into an amplitude-modulated one.
'discriminator' also found in these Oxford entries:

