For B.Tech there are 42 to 48 topics, but the in the first two semesters are the same across all streams. in the case of ECE there are more than 30 subjects you need to take a look at, regardless of the subject you are interested in.
If you’ve decided to sit for GATE you must concentrate on these topics :
Systems, networks, and signal
Electronic circuits and devices (EDC)
Digital and analog circuits
Basic electrical and electronic engineering
Instrumentation and measurement using electronic devices
Digital and analog communication
Computer architecture and organisation
Electromagnetics and the latest technology in electronic.
Additionally, if are looking to master networking and communications, you should concentrate more on telecommunications, which includes optical fibre communications Communication systems, satellites and microwaves.
Learning computer language ( C, C++ Java, .net) are always added advantages for B. Tech graduates. However, in a lot of institutions Java and. Net are not element of ECE program, therefore, you’ll have to learn from your co-workers or coaches.