ĐIỆN tử VIỄN THÔNG DTVT2 nhom1 bai9 khotailieu

NHÓM – LỚP Đ8-ĐTVT - LƯƠNG NGỌC LONG HỒNG NGỌC TRUNG HỒNG THỊ LINH NGƠ 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: These problems are: easily damaged, crackle cause by dust and static, and jumping There is digital recording system LP: long playing record CD: compact disc Task 3: LPs Recording system Sound quality Access Audio pattern Material Playing mechanism Durability Size Playing time Task 4: 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 D A Task 5: 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