VU meter
VU meter (buoy you meter, VU Meter) is a measuring instrument to order a feeling of volume (volume unit) in acoustic equipment. The VU meter was developed in 1939 by Bell Laboratories and CBS, NBC to watch the standard level of the communication track.
Table of contents
Definition at the time of the development
I assume the output voltage when I add a sine wave of 1kHz to a load circuit of impedance 600 Ω and used electricity of 1mW 0dBm and assume +4dBm 0VU, but am different by the industry.
The instructions range of the VU meter is +3 from -20, and a unit is dB. It is 300 msec in the time required before a needle being located in the instructions level for the signal voltage (it fluctuates). This delay theoretically means that I cannot show the maximum (so-called peak level) of the voltage and orders the value that is approximately equal to the mean when I add a consecutive sine wave (I do not show the peak level).
Standard of the VU meter
A standard about the VU meter includes ANSI C16.5-1942, British Standard BS 6840 and IEC 60,268-17. JIS C 1504-1976 was in Japan, but was abolished once in 1993.
Characteristic of the VU meter
VU[ explanatory note 1] (Volume Unit[1]) which I made the level of the voice signal for newly in the transmission channel where the VU meter handled a voice frequency signal of characteristic impedance 600 Ω by the definition It is a sound-level meter to order it by という unit [2]. VU is as follows.
| Scale notation (VU) | Input voltage (dBm)[ explanatory note 2] | Allowance (db) |
|---|---|---|
| -20 | -16 | - |
| -10 | -6 | +-0.6 |
| -7 | -3 | +-0.5 |
| -5 | -1 | +-0.4 |
| -3 | + 1 | +-0.3 |
| -2 | + 2 | +-0.2 |
| -1 | + 3 | |
| 0 | + 4 | |
| + 1 | + 5 | |
| + 2 | + 6 | |
| + 3 | + 7 |
The VU meter is made from a voltmeter with a full-wave rectifier, the variable attenuator that characteristic impedance maintains the same, three components of the outside series resistance [4].
As for the characteristic impedance of the VU meter, +-3% of 7,500 Ω is preferable [5]; [explanatory note 3].
The instructions range of the VU meter is +3VU from -20VU. When I input 1KHz sine wave signal equal to 0VU after no signal, it is 300ms, error ± 30ms at time before a needle passing the point of 99% of 0VU. The stitches exceed a point of 0VU by all means and it is lowest and exceeds 1% and, however, it is the best and produces an overshot not to reach 1.5% [6]. That, as for the return time, do not be greatly different from reply speed [7].
Explanatory note
- I utter with ^ "vee-you". In addition, vu is appointed in IEC 60,268-17 ed.1.0 to write it by a small letter, but becomes the capital letter like "VU meter "in JIS C 1504-1976.
- ^ input voltage (dBm) assumed the voltage (0.775V) indicating 1mW for 600 Ω 0db
- Japan Standards Association (1976). where the characteristic impedance of the meter except the outside series resistance (3,600 Ω) is prescribed in ^ JIS 1504-1976 3,900 Ω +-200 Ω C 1506-1976(Report).
Reference
- ^ International Electrotechnical Commision (1990-09). IEC 60268-17(Report) (1 ed.).
- ^ Japan Standards Association (1976). C 1506-1976(Report).
- ^ Japan Standards Association (1976). C 1506-1976(Report).
- ^ International Electrotechnical Commision (1990-09). IEC 60268-17(Report) (1 ed.).
- ^ International Electrotechnical Commision (1990-09). IEC 60268-17(Report) (1 ed.).
- ^ International Electrotechnical Commision (1990-09). IEC 60268-17(Report) (1 ed.). Japan Standards Association (1976). C 1506-1976(Report).
- ^ International Electrotechnical Commision (1990-09). IEC 60268-17(Report) (1 ed.).
Allied item
This article is taken from the Japanese Wikipedia VU meter
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