frequency locker

hi everybody

I was told during a discussion that it is possible to lock a circuit under a particular frequency such that it will only give a desired output if it receives the desired frequency. It is not a pic. the other thing he told me is that the ic is an LM.... hope that info will do
can anyone telf me the ic ?

PLL (Phase Locked Loop) - and the LM567 is one used as a tone decoder.

thanks for that
now that i know that. I will need more information on where it is used, how it is configured and can i use it to calibrate my own remote controle decoder? IF yes pls explain to me how i can do that.
thanks once again

Download it's datasheet, which tells you how to use it.

However, it's been decades sinse remote controls used tone decoding.