Making waves with DSP

What do personal computers, cellphones and compact discs (CD) have in common besides being hard on your budget?

These and most gadgets of the 21st century are all powered by something called Digital Signal Processing (DSP).

DSP is responsible for the quality of the music from a CD. It is the unseen force responsible for many of the functions of the GSM cellphone. A computer would be reduced to a desktop ornament if not for DSP. The very program that was used in typing this article is DSP-based.

DSP is the mathematics, the algorithms and the techniques used to manipulate signals after they have been converted into digital form. The signals could be any form of sensory data from the real world. (Scientist and Engineer’s Guide to DSP).

A simplified illustration of DSP is to show how it works on CD music. CD music is actually real-world sensory data, in this case sound, which is converted into digital form on the CD. During the conversion, it is inevitable that some data would be distorted by noise. Through a series of mathematical processes, DSP can be used to reduce or remove altogether unwanted noise in the music. The result, as any CD aficionado will attest to, is clearer music.

"DSP is actually a technology-enabler. Support siya for a lot of fields and makes a lot of things possible," said Dr. Rowena Guevara of the UP College of Engineering’s Department of Electronics and Electrical Engineering (CoE-EEE), and one of the pioneers of DSP in the Philippines.

Making clearer music is just one of the many applications of DSP. Many DSP applications, in fact, have yet to be discovered. This is because DSP only became possible with the advent of digital computers in the 1960s and 1970s.

"DSP is a very young field. It is only 25 years old, compared to some of the other fields of engineering which are a hundred years old or more," said Guevara.

Guevara, whose interest in DSP only started during her master’s studies at UP, is responsible for establishing the pioneering DSP laboratory in the Philippines.

"I know that CHED requires EEE (electronics and electrical engineering) and ECE (electronics and communications engineering) programs to include DSP in their third year. And this is, in effect, this year," she said. "I think I would not be wrong in saying that we at UP are pioneers in DSP in the Philippines because in 1990, we established a DSP lab."

So what kind of work is done in UP’s DSP lab?

"There are two levels in DSP. One is the development of the algorithms, and the second is the implementation. The lab, too, is actually divided into two physical labs: software development, where we simulate the DSP algorithms and make sure that they work; and the hardware division where we implement these algorithms using TI TMS 320CX generation DSP hardware," Guevara said.

The TI in the hardware name stands for Texas Instruments, which donated most of the equipment in the hardware lab.

"We are very proud of the TI Lab because it is an "elite" lab and it is the only lab of its kind in the Philippines," she said.

Texas Instruments has certain standards for a lab to become elite, according to Guevara. Other schools, which have just recently started establishing their own DSP laboratories, only fall under the regular lab categories.

Besides having donated the equipment, Texas Instruments also takes care of the maintenance and upgrading of the hardware. The commitment ensures UP’s DSP lab is always up to date in its researches and projects. Currently, the lab is working on three projects.

"One of our projects deals with biometrics, that is, image processing. We do a lot of fingerprint and facial feature analysis which is aimed at speeding up identification," Guevara said.

"Another project is the low-bit rate speech codec where we aim to reduce regular digitized voice from 64 kbps to 4 kbps. We are also working on a speech recognition program. May mga success na sa speech recognition – mga 98 percent. Yung sa codec, nag-uumpisa pa lang kami diyan. We have four groups working on it this semester."

And what is the future of DSP in the country?

Guevara said karaoke and videoke aficionados will be happy with DSP’s possible applications.

"Isa sa mga magugustahan nating mga Pinoy ay yung posibleng application ng DSP sa voice recording," Guevara said. "Yung mga sintonadong kumanta, kayang i-correct yan ng DSP! Yung mga nawawala ng hininga kayang ayusin ng DSP. This is just one of the many possible applications of DSP in the future."

There, too, is good news for frequent international direct dial (IDD) users.

"Yung project namin sa low-bit rate speech codec, kaya niyang i-reduce yung call charges," Guevara said. "Ngayon, 40 cents a minute di ba? I assume that’s at 64 kbps. If we could reduce that to say about 1 kbps, possibleng bumaba pa yon sa 7 cents per minute. Now won’t that be nice?"