1. EE 345S Real-Time Digital Signal Processing Lab Spring 2009
Lab #5.1 Pulse Amplitude Modulation Akshaya Srivatsa

2. Outline Block Diagram of Transmitter Expressions for Transmitter
Block Diagram of Receiver
Expressions for Receiver
Inter Symbol Interference
Nyquist Criteria for ISI
Raised Cosine Filter
Interpolation Filters
Task List for Lab #3.1

3. Block Diagram of Transmitter
Bit Rate: Rd bits/sec
Symbol Rate: Rd/J bits/sec
Courtesy: Steven Tretters Chapter 11 Recitation Slides
Example of 2J Mapping

4. Expressions for Transmitter
An Impulse Modulator is
Output of Transmit Filter it

5. Block Diagram of Receiver
Removes out of band noise
Forms perfect pulse shape with Tx
Courtesy: Steven Tretters Chapter 11 Recitation Slides

6. Expressions for Receiver
Let us define g(t) as
Output of transmit filter it

7. Inter Symbol Interference
The received filter output:
(Assuming no AWGN)
We can rewrite this as:
Worst case ISI:

8. Inter Symbol Interference
Binary PSK with ISI
Binary PSK without ISI
Courtesy:
Courtesy:

9. Nyquist Criteria for ISI
The condition on g(t) that needs to be satisfied for no ISI is
The filter we will use is called the Raised Cosine Filter given by

10. Raised Cosine Filter In frequency domain, Frequency Domain Time Domain
Courtesy:

11. Square Root Raised Cosine Filter
The system should be designed in such a manner that the combined effect of Tx filter and Rx filter should be an RC filter.

12. Interpolation Sub Filters
Put
We get
Now we can define an interpolation subfilter as

13. Interpolation Sub Filters
Courtesy: Steven Tretters Chapter 11 Recitation Slides
Block Diagram for Interpolation Filter

14. Task List Tasks for Lab 5.1 are 4 level PN sequence generator
Simulation of block diagram (Tasks 2 to 4)
Raised Cosine Filter using the EXE files (Task 5 & 6)
Important Points
Download the rascos.exe from Dr. Evans website
The task list can be found at the following link

15. THE END