W681307DG Datasheet, PDF (90/160 Pages) Winbond – USB1.1 CODEC Microprocessor Control Unit with 32KB Mask ROM and 4KB RAM.

W681307
13.1.2
Network Power Estimation
To detect the double talk condition an estimate of the long term network power is required.
： The long term network power is estimated with the following arithmetic unit
VD _ LONG _ NETWORK _ ATTACK _ TC −16
( ) _ Nin ∗ 2 _n

( ) Pnin_n
∝
Pnin_n−1
+


−
Pnin ∗ 2VD _ LONG _ NETWORK _ ATTACK _ TC −16
n−1


( ) ^ + Vd _ Long _ Network _ Threshold ∗ 2^{VD _ LONG _ NETWORK _ ATTACK _TC−17 }
： The short term network power is estimated with the following arithmetic unit
( ₍ ) _{) PninShortn}
∝
PninShort _n−1
+
VD _ SHORT _ NETWORK _ ATTACK _ TC −16
 ^{Nin ∗ 2 n}
 _{− PninShortn−1 ∗ 2}VD _ SHORT _ NETWORK _ ATTACK
_ TC −16


： The deviation term network power is estimated with the following arithmetic unit
PninDev_n ∝ Pnin_n − Cut _ Off _ Network _ Power − PninShort_n
13.1.3
Acoustic Power Estimation
This speech will have originated at the near end and does not correspond to a reflected echo signal. Speech is deemed to occur if the long
term acoustic power exceeds a predetermined threshold or if the short term acoustic power exhibits sudden variations. If speech is being
carried over both the network and acoustic interfaces then the double talk condition occurs.
： The long term acoustic power is estimated with the following arithmetic unit
( ₍ ) _{) Painn}
∝
Pain_n−1
+
DT _ LONG _ ACOUSTIC _ ATTACK _ TC −16
 ^{Ain ∗ 2 n}
 _−
Pain ∗ 2 DT _ LONG _ ACOUSTIC _ ATTACK _ TC −16
n−1


： The short term acoustic power is estimated with the following arithmetic unit
( ₍ ) _{) PainShortn}
∝
PainShort _n−1
+


Ain ∗ 2 DT _ SHORT _ ACOUSTIC _ ATTACK _ TC −16
n
− PainShort_n−1 ∗ 2 ^{DT _ SHORT _ ACOUSTIC _ ATTACK}
_ TC −16


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Publication Release Date: May, 2007
Revision 1.3