Introduction - Introduction to Digital Signal Processing and Filter Design - page 2

mobile phones, besides voice, music, and other audio signals—all of which are
classified as multimedia—because of limited hardware in the mobile phones and
not the software that has already been developed. However, the computers can
be used to carry out the same functions more efficiently with greater memory and
large bandwidth. We see a seamless integration of wireless telephones and com-
puters already developing in the market at present. The new technologies being
used in the abovementioned applications are known by such terms as CDMA,
TDMA, 1 spread spectrum, echo cancellation, channel coding, adaptive equaliza-
tion, ADPCM coding, and data encryption and decryption, some of which are
used in the software to be introduced in the third-generation (G3) mobile phones.
2. Speech Processing . The quality of speech transmission in real time over
telecommunications networks from wired (landline) telephones or wireless (cel-
lular) telephones is very high. Speech recognition, speech synthesis, speaker
verification, speech enhancement, text-to-speech translation, and speech-to-text
dictation are some of the other applications of speech processing.
3. Consumer Electronics . We have already mentioned cellular or mobile
phones. Then we have HDTV, digital cameras, digital phones, answering
machines, fax and modems, music synthesizers, recording and mixing of music
signals to produce CD and DVDs. Surround-sound entertainment systems includ-
ing CD and DVD players, laser printers, copying machines, and scanners are
found in many homes. But the TV set, PC, telephones, CD-DVD players, and
scanners are present in our homes as separate systems. However, the TV set can
be used to read email and access the Internet just like the PC; the PC can be
used to tune and view TV channels, and record and play music as well as data
on CD-DVD in addition to their use to make telephone calls on VoIP. This trend
toward the development of fewer systems with multiple applications is expected
to accelerate in the near future.
4. Biomedical Systems . The variety of machines used in hospitals and biomed-
ical applications is staggering. Included are X-ray machines, MRI, PET scanning,
bone scanning, CT scanning, ultrasound imaging, fetal monitoring, patient moni-
toring, and ECG and EEC mapping. Another example of advanced digital signal
processing is found in hearing aids and cardiac pacemakers.
5. Image Processing . Image enhancement, image restoration, image under-
standing, computer vision, radar and sonar processing, geophysical and seismic
data processing, remote sensing, and weather monitoring are some of the applica-
tions of image processing. Reconstruction of two-dimensional (2D) images from
several pictures taken at different angles and three-dimensional (3D) images from
several contiguous slices has been used in many applications.
6. Military Electronics . The applications of digital signal processing in mili-
tary and defense electronics systems use very advanced techniques. Some of the
applications are GPS and navigation, radar and sonar image processing, detection
1 Code- and time-division multiple access. In the following sections we will mention several technical
terms and well-known acronyms without any explanation or definition. A few of them will be
described in detail in the remaining part of this topic.