Chapter 6
1.
How
do we achieve a data rate of 56 kbps in 23 channels using a DS-1 format?
One of the 24 voice channels of the DS-1 format is
used in digital transmission for synchronization, leaving 23 channels. One bit
per each channel's byte is used for control transmission. So, each of the
remaining 23 channels gets 7 bits 8,000 times a second (voice sampling rate)
for a channel rate of 56 kps (7 * 8,000).
3.
Recently,
a new scanner was announced that provided 1200 dpi resolution and over 1
billion colors.
monochrome picture at 1200 dpi with a 10-bit gray
scale?
Byte = 8 bit
Several bit = 1 pixel or group of pixel
8 binary = 256
23 channel * 8+1 = 185 bits
8000 * 185 = 1,480,000 or 1.48 mbps
8*10 inch*1200dpi (square)*10 = 1,152,000,000
Answer: 1200
dpi * 1200dpi=1,440,000 pixel (actual dot per square inch)
blue, green-each with n bits to represent its intensity. What is the least value of
n that will provide over 1
billion colors?
Red=10bits+blue=10bits+green=10
bits=2 to the 30th
at 1200dpi over T-1 line (1.544 Mbps)?
8*10*1200*154,400=0.0622
second
4.
Phototypesetters
often print black or white material at resolution of 2400 dots per
linear inch. Suppose that you want to send a 7-by-11
inch page of material generated by your PC to be printed by such a typesetter.
need in bytes.
7*11=77 square
inch
2400*2400=1,440,000
bits=443,520,000
byte=55,440,000
(55.4 byte)
you to send the file to he typesetter?
Time=bits/line
speed
443,520,000/19,200=23,100
second/3600 (60 min*6- sec)
=6.42 hour
5.
Assume
that you are to design a TDM carrier, say T489, to support 30 voice channels
using 6 bits samples and a structure similar to T-1.
Determine the bit rate required. (Look page 103-104 sample)
Example:
24*8+1=181
30 voice
channel*6 bit+1=181
181*8,000 time
per second=1.448 mbps