Information Technology Reference
In-Depth Information
G.7.6
Which series of CCITT (ITU-T) specify ISDN specifications:
(a)
I-series
(b)
X-series
(c)
T-series
(d)
R-series
G.7.7
What is the base bit rate for a USA PCM-TDM system:
(a)
1.544 Mbps
(b)
64 kbps
(c)
2.048 Mbps
(d)
2 Gbps
G.7.8
What is the base bit rate for a UK PCM-TDM system:
(a)
1.544 Mbps
(b)
64 kbps
(c)
2.048 Mbps
(d)
2 Gbps
G.7.9
How many ISDN channels does the H11 (derived from USA PCM-TDM system)
support:
(a)
20
(b)
24
(c)
30
(d)
32
G.7.10
How many ISDN channels does the H12 (derived from UK PCM-TDM system)
support:
(a)
20
(b)
24
(c)
30
(d)
32
G.7.11
How does ISDN AMI (alternative mark inversion) operate:
(a)
Every bit that is sent is inverted
(b)
Every one that is sent has an alternating voltage level, but the zeros are sent
as a zero voltage level
(c)
Every zero that is sent has an alternating voltage level, but the ones are sent
as a zero voltage level
(d)
Ones are sent as negative voltages, and zeros as positive voltages
G.7.12
Why does the 01111110 bit sequence only occur at the start and end of a frame:
(a)
Bit stuffing is used whenever it appears within the data frame
(b)
It is a special code that can never occur within the data
(c)
It is coded with special voltage levels
(d)
It will hardly ever occur, so the occasional error is acceptable
G.7.13
Show why speech requires to be transmitted at 64 kbps.
G.7.14
If the bandwidth of hi-fi audio is 20 kHz and 16 bits are used to code each sample,
determine the required bit rate for single-channel transmission. Hence prove that
the bit rate required for professional hi-fi, which is sampled at 44.1 kHz is
1.4112 Mbps.
