The establishment of the thesis level discuss the international technological discussion of
broadcast and television
[ISBT 2007, Beijing ] with the sound quality
清彻[Summary ]
Establishment of level divide important among Zhyuan of broadcast and television audio frequency interconnected system, especially absolute level and relative level cloly related to program sound quality foundation of concept. Record and produce system recording level correct choice of value and record and produce program voice relation of the quality esntial, choo an appropriate recording level value accurately, the ones that can guarantee to record and produce program sound quality are fine. Put accurate tting-up of sound level value (put sound thorough fare level) determine broadcast and television voice quality of quality too among putting sound Zhyuan interconnected system.
[Keyword ]
Level, recording level, the sound level is put.
科赫工业
First. Basic conception of the level
The level means a certain measuring point compares with standard value (such as the power, voltage, electric current). The electricity means the absolute level equally generally
共建1.Absolute level: Mean the power is Po=1mW, Vo=0.775 electric current Io=1.29mA of voltage, impedance Zo=600Ω豆腐干怎么做, is called OdBm. Impedance ≠ at the 600Ω, call OdBu. If Vo=1.0V, Zo≠ is at 600 o'clock, are called OdBv.
2.As to the level: It mean at circuit letting power, voltage, electric current a bit instead of power, voltage, the electric current one a bits corresponding than. Show with logarithm 向导
again, i.e. 8322 of 20logV&-#; /V₁ ,Called the relative level (dB), if 8322 of V&-#; =V₁ Hour, are called OdB of the relative level.
3.There are the following veral commonly ud gentle absolute level of relative electricity:
(1). OdB: It is the relative level, i.e. the measuring point level means consulting some level; (2). OdBm: It is the level unit taking 0.775Vrms (impedance is as 600草莓草莓Ω) as reference voltage; (3). OdBu: It is the level unit while regarding 0.775 Vrms (impedance is unlimited) as the reference voltage; (4). OdBv: It is the level unit while regarding 1.0 Vrms (impedance is unlimited) as the reference voltage; (5). dBFS: It is the signal level unit of digital audio frequency; (6). OdBFS: It is the reference level of the digital audio frequency signal of " full scale ".
Digital full scale level (OdBFS), index word A/D or D/A whom converter can be changed sharpen the analog signal level of wave very much most in the apparatus. OdBFS equal to digital audio frequency " level of considering " of " full scale " to spend a technical indic
ator with digital audio frequency apparatus of A/D and D/A converter. " full scale " mean whom converter might reach before the " digital overload " can encode the level of analog signal most.
Digital overload to describe A/D converter input signal exceed all over scale (OdBFS) situation in the range, becau OdBFS A/D high level the most absolutely converter can change, have any digital level can be by exceeding OdBFS, so all gentle level which is greater than it of electricity of OdBFS will produce one yard of yuan of the same output.
4.Full scale level value of veral kinds of different digital audio frequency apparatus
The full scale level value of the apparatus of the digital audio frequency, i.e. can encode level value most, express with its corresponding simple signal (1KHz) level in harmony.
(1). In the audio frequency system of broadcast and television of our country, the full scale level value of the digital device
In our country's broadcast and television audio frequency system, the value OdBFS corresponding analog signal level of full scale level of the digital device is 24dBu, in view of the real operating position of digital device of broadcast and television of our country, allow full degrees of level value OdBFS correspond to analog signal level continue, u for digital device of 22dBu still the prent stage.
As shown in Fig. 1, it is according to broadcasting the regulation of ctor standard GY/T192-2003 " one degree of level of Manchus of apparatus of the digital audio frequency " of films and televisions, choo the figure to record and produce the sketch map of the level of system work.
Choo the figure to record and produce the working level sketch map of the systematic recording in Fig. 1
鸡蛋丝瓜汤
(2). Full scale level value of the digital device of European Broadcasting Union
Stipulating OdBFS corresponding analog signal level is 22dBu of European Broadcasting Union (EBV R68-2000).
滚球体育
As shown in Fig. 2, explain for EBU R68-2000 full scale level technology.
The technology of Fig. 2 EBU R68-2000 full scale level explains
(3). Full degree of level of digital audio frequency apparatus of engineer's association of American movie & TV
