ps8 - MIT OpenCourseWare http/ 2.161 Signal...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
MIT OpenCourseWare 2.161 Signal Processing: Continuous and Discrete Fall 2008 For information about citing these materials or our Terms of Use, visit: .
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
| F ( j W ) | 0 | F ( j ( W - W ) ) | s c r a m b l e r W W a W a s c r a m b l e d s p e e c h o r i g i n a l s p e e c h 0 W A 1 W - W A a 1 MASSACHUSETTS INSTITUTE OF TECHNOLOGY DEPARTMENT OF MECHANICAL ENGINEERING 2.161 Signal Processing - Continuous and Discrete Fall Term 2008 Problem Set 8: FIR Linear Filters Assigned: November 6, 2008 Due: November 18, 2008 Problem 1: A Mini-project: An Audio Scrambler Hint: We looked at this problem in Quiz 1. Look at the published solution. Text-messaging is out-of-date! You and I have been communicating by sending voice-messages to each other as “.wav” files. It’s not that I am paranoid, but everybody is out to get me! In particular, “they” have been intercepting all of our voice messages. But we are going to outwit “them” by using MATLAB to scramble our voice messages before sending them, making them unintelligible using a secret encoding scheme, and then we will descrambling the messages when we get them. your task is to design and implement the speech encoder and decoder. the requirement is that the scrambled message should occupy the same audio bandwidth (approximately 300 3000 Hz) as the original message, and the descrambled message should have good fidelity. We will use a frequency domain “mirroring” scheme, where the frequency components are flipped, so that high frequencies are translated to low frequencies and vice-versa. A spectral com- ponent with frequency Ω 1 will be translated to a new frequency Ω a Ω 1 , where Ω a is known to the sender and recipient. The resulting waveform is unintelligible until the frequency relationships have
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 5

ps8 - MIT OpenCourseWare http/ 2.161 Signal...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online