Any two of the following :
(i)Transducer -A device which converts energy from one form to another form.
(ii) Repeater-A repeater is a combination of a receiver and a transmitter.
(iii) Transmitter-A transmitter process the incoming message signal so as to make it suitable for transmission through a channel and for its subsequent reception.
[Alternatively : A transmitter is a device used for sending the information in i communication system.]
(iv) Bandpass filter - A bandpass filter blocks lower and higher frequencies and allows only a selective band of frequencies to pass through.
