NTE832SM Integrated Circuit Tone Decoder
 
Description: The NTE832 and NTE832SM are general purpose tone decoders designed to provide a saturated transistor switch to GND when an input signal is present within the passband. The circuit consists of an I and Q detector driven by a voltage controlled oscillator which determines the center frequency of the decoder. External components are used to independently set center frequency, bandwidth, and output delay.
 
Full spec sheet:
https://www.nteinc.com/specs/7100to7199/pdf/nte7172_sm.pdf