M65881AFP
The index and Mantissa part of Gain Data
The gain value is set from
Mantissa part: bit17(MSB) to bit24(LSB)
The gain data is assigned 13bits, composed of Index part 5bits and of Mantissa part 8bits.
The range of Index parts is following statements.
Index part: 10100b(16.0) to 10000b(1.0) to
The range of Mantissa parts is following statements.
Mantissa part:Index part; 10100b to 00001b: Mantissa part; 11111111b to 10000000b (128 step/ Index).
Index part; 00000b:Mantissa part; 11111111b to 00000000b (256 step).
Initial value: Index part: 10000b | Mantissa part: 10000000b |
Infinity zero: Index part: 00000b | Mantissa part: 00000000b |
# Notice of GAIN value setting continuously
In case of Gain value setting continuously, for example of setting L/Rch independently, please take the interval time (pulse interval time of SCLATCH signal) more than 1/fso. For example, in the case of fso=48kHz, please take the interval time more than 21µsec.
• The Gain Data and Audio Output Level.
Gain data consists of 13bits (Index part: 5bit, Mantissa part: 8bit ). e.g. 10000b(1.0)/10000000b(0.5) means 0.5(0dB).
Table
Gain Data |
| Polarity | Output absolute | Output Level |
| maximum value | |||
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10100/11111111 | (b) |
| 15.9375 | +30.069dB |
~ |
|
| ~ | ~ |
10001/10000000 | (b) |
| 1.0 | +6.021dB |
~ |
|
| ~ | ~ |
10000/10000000 | (b) |
| 0.5 | 0dB |
01111/11111111 | (b) | + | 0.498046875 | |
~ |
| ~ | ~ | |
|
| |||
00000/10000000 | (b) |
| 0.5 ∗ | |
~ |
|
| ~ | ~ |
00000/00000001 | (b) |
| 0.00390625 ∗ | |
00000/00000000 | (b) |
| infinity zero |
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• Calculation method of Gain Value
The way to calculation of Gain value from Gain Data is following equation.
Gain value = 20log [ 2 | <Index data (decimal | × | Mantissa Data (decimal value) | ] dB |
| 128 | |||
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Rev.1.00 2003.05.08 | page 14 of 23 |