ĐIỆN tử VIỄN THÔNG DTVT2 nhom7 bai8 khotailieu

Audio recording systems Nhóm 7: Nguyễn Bá Duy Đỗ Văn Sang Dương Văn Hùng Vũ Văn Chinh Nguyễn Khắc Ngân Trần Minh Đức Task 1: Some of the problems associated with vinyl record are eliminated such as ‘crackle’ cause by dust and static and ‘jumping’ due to scratches on the recording suaface An analogue recording system and a digital recording system a LP : long-playing record b CD: compact disc Task : Task 3: LPs CDs Recording system anlogue digital Sound quality poorer than be original Like the original Access serial random Audio pattern grooves Pits material Metal needle perspex playing mechanism mechanical Laser Durability easily damaged Does not deteriorate Size 12 inches 12 cm Playing time 45 minutes 74 minutes Task + Task 5: 1_d: Distortion is causes by scratches on records 2_e: Noise generated within components is the cause of hiss 3_f: Overheating a transistor leads to damage 4_g: Dirty heads leads to poor recordings 5_c: A build-up of oxide on the head results in the tape rubbing againt the head 6_b: Jumping results from too hight a recording level 7_a: Unwanted signal is caused by dust on records Task 6: Task 7: Automatic doors are used in place such as airports, supermarkets, and hospitals Traditional door would be a nuisance in these places Automatic doors are fitted with a microwave sensor The sensor detects movement The doors are swithced on A microwave transmitter sends out a microwave beam The beam is in a semicircular pattern The doors open when you approach from any angle The microwaves are reflected back to the sensor The reflected microwaves are analysed by a microprocessor A person or object moves towards the doors The waves are reflected back to the sensor at a different frequency The microprocessor detects this change The microprocessor instructs the motor to open the doors The doors are fitted with a time delay mechanism The doors remain open for about four seconds before closing again A preson remains standing in the doorway A safety beam prevents the doors from closing