ĐIỆN tử VIỄN THÔNG DTVT2 nhom1 bai9 khotailieu

NHÓM 1 – LỚP Đ8-ĐTVT 2
-

LƯƠNG NGỌC LONG
HOÀNG NGỌC TRUNG
HOÀNG THỊ LINH
NGÔ ANH TUẤN
PHÙNG THỊ QUỲNH
PHẠM TRỌNG HOAN

MSV: 1381510142
MSV: 1381510176
MSV: 1381510140
MSV: 1381510179
MSV: 1381510165
MSV: 1381510127

Unit 9: Audio recording systems
Task 1:
1. These problems are: easily damaged, crackle cause by dust and static, and

jumping.
2. There is digital recording system.
3. LP: long playing record
CD: compact disc
Task 3:
LPs
1 Recording system
2 Sound quality
3 Access
4 Audio pattern

5 Material
6 Playing mechanism
7 Durability
8 Size
9 Playing time
Task 4:
1.
2.
3.
4.
5.

B
E
F
C
G

analogue
Poorer than the original
serial
groove
Vinyl disc
mechanical
Easily damaged
12 inches
45 minutes

CDs
Digital

Nearly perfect
Random
Pits
Perspex
Laser
Does not deteriorate
12cm
74 minutes


6. D
7. A

Task 5:
1.
2.
3.
4.
5.
6.
7.

Distortion is caused by too high a recording level.
Hiss leads to noise generated within components.
Overheating a transistor results from damage.
The tape rubbing against the head results in dirty heads.
A build-up of oxide on the head is due to poor recording.
Jumping is the effect of scratches on records.
Interference on radios is the cause of unwanted signals.

Task 7:
An automatic doors are used in places such as airports, supermarkets, and
hospital and it would be a nuisance. If traditional door are used in these place. The
automatic doors are fitted with a microwave sensor and the sensor detects
movement. When the doors are switched on, a microwave transmitter sends out a
microwave beam. The beam is in a semicircular pattern and the door open when
you approach from any angle. The microwaves are reflected back to the sensor and
the reflected back to the sensor at the different frequency. The microprocessor
detects this change when detecting instructs the motor to open the doors. The doors
are fitted with a time-delay mechanism which remain open for about four seconds
before closing again. If person remains standing in the doorway, a safety beam will
prevent the doors from closing.