Datasheet

3−39
The transfer curve remains a constant 24 dB above the 1:1 transfer curve for input levels above and below T2 until
the computed DRC gain coefficient falls within the dynamic range of a 5.23 format number. For input levels above
T2, k2 implements a 5:1 compression, At an input level 7.5 dB above T2 (−62.5 dB), the DRC transfer curve has risen
7.5/5 = 1.5 dB. The boost at this point is 30 dB - (7.5 dB - 1.5 dB) = 24 dB. The DRC has come out of gain saturation.
For input levels above −62.5 dB, the transfer curve exhibits 5:1compression.
Table 3−5. DRC Example 2 Parameters
DRC
PARAMETER
REQUIRED (SPECIFIED) VALUE
(NET GAIN
SAP Input-DRC
= 0 dB)
I
2
C COEFFICIENT VALUE
T2 −22 dB
Input
≥ −70 dB
DRC
−70/−6.0206= 11.626748
= 0x000005D03948
25.23 Format
T1 −102 dB
Input
≥ −150 dB
DRC
−150/−6.0206 = 24.91446
= 0x00000C750D09
25.23 Format
O2 −30 dB (−30 + 24.0824)/6.0206 = −0.982892
= 0xFFFFFF823098
25.23 Format
O1 50 dB (50 + 24.0824)/6.0206 = 12.304820
= 0x000006270458
25.23 Format
k2 5:1 Compression (1/5) − 1 = −0.8 = 0xF99999A
5.23 Format
k1 1:2 Expansion 2 − 1 = 1 = 0x0800000
5.23 Format
k0 2:1 Compression (1/2) − 1 = −0.5 = 0xFC00000
5.23 Format
For input levels below T2, k1 implements a 1:2 expansion. With a 1:2 expansion in effect, the transfer curve has
dropped 12 dB at an input level 6 dB below T2. The boost at this level is 30 dB − (12 dB − 6 dB) = 24 dB. The DRC
gain coefficient has again come out of saturation. For input levels below −76 dB and above −150 dB, the transfer curve
exhibits a 1:2 expansion.
At T1 (-150 dB), the transfer curve is 50 dB below the 1:1 transfer curve. Since O1 = 50 dB, there is no discontinuity
in the transfer function. For inputs below −150 dB, k0 implements a 2:1 compression. The change from a 2:1
compression to a 1:1 transfer at −192 dB is due to 32-bit dynamic range saturation at the DRC input.
3.7.3.3 Example 3—1:1 Transfer/Infinite Compression With Minimum Gain Saturation, 32-Bit
Dynamic Range Saturation, and Equal Threshold Settings (T1=T2)
The DRC transfer function parameters for this example are given in Table 3−6. In addition to illustrating minimum gain
saturation, this example also illustrates the operation of the DRC when T1 and T2 are set equal.