CSE 123 Lecture Notes - Lecture 23: Intersymbol Interference, Bandlimiting, Baud

• School: UCSD
• Department: Computer Science and Engineering
• Course: CSE 123
• Professor: Alex Snoeren

Document Summary

For any bandlimited channel, it has a max freq f. Reality: you cannot change that freq very fast! (depends on how high it is!) Attempting to signal too fast will mix symbols. In a bandlimited channel with max freq f, we can send at max (baud) rate of 2f w/o isi. You get a sine wave every period! How often i"m changing the signal baud rate. But i don"t have to send 1 bit at a time! Bit rate is a multiple of baud rate! Nyquist limits # symbols/sec we can send, but doesn"t talk about info content in each symbol. If you can send m different levels, for every level you can send, you can send more bits. 4 levels gets you 2 bits (log2m in general) Channel capacity: c < 2 b log2(m) Noise limits how many different levels you can send!