MT93L04AG Zarlink Semiconductor, MT93L04AG Datasheet - Page 35

• Manufacturer Part Number: MT93L04AG
• Description: Description = 128-Channel Voice Echo CANceller ;; Package Type = Bga ;; No. Of Pins = 365
• Manufacturer: Zarlink Semiconductor

Preliminary Information
The Exponential Decay registers (Decay Step Number and Decay Step Size) and Flat Delay register allow the
LMS adaptation step-size (MU) to be programmed over the length of the FIR filter. A programmable MU profile
allows the performance of the echo canceller to be optimized for specific applications. For example, if the
characteristic of the echo response is known to have a flat delay of several milliseconds and a roughly
exponential decay of the echo impulse response, then the MU profile can be programmed to approximate this
expected impulse response thereby improving the convergence characteristics of the Adaptive Filter. Note that
in the following register descriptions, one tap is equivalent to 125 s (64ms/512 taps).
FD
delay is defined as FD
canceller FIR filter. The valid range of FD
extended-delay mode. The default value of FD
Echo Canceller A, Flat Delay Register (FD)
Echo Canceller B, Flat Delay Register (FD)
Echo Canceller A, Decay Step Number Register (NS)
Echo Canceller B, Decay Step Number Register (NS)
Echo Canceller A, Decay Step Size Control Register (SSC)
Echo Canceller B, Decay Step Size Control Register (SSC)
7-0
Flat Delay
Amplitude of MU
1.0
NS7
FD7
7
7
2-16
7
0
Note: Bits marked with “0” are reserved bits and should be written “0”.
:
Flat Delay (FD
FD6
NS6
6
This register defines the flat delay of the MU profile, (i.e., where the MU value is 2
6
6
0
7-0
FD5
NS5
5
5
5
0
x 8 taps. For example; if FD
7-0
)
FD4
NS4
4
4
4
0
NS3
FD3
3
3
3
FIR Filter Length (512 or 1024 taps)
0
7-0
7-0
SSC2
FD2
NS2
is: 0
2
2
2
is zero.
SSC1
FD1
7-0
FD
NS1
1
1
1
7-0
= 5, then MU=2
SSC0
FD0
NS0
0
0
0
64 in normal mode and 0
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Step Size (SS)
-16
for the first 40 taps of the echo
Number of Steps (NS
Power Reset Value
04h
24h
07h
27h
06h
26h
Power Reset Value
Power Reset Value
+ Base Address
+ Base Address
+ Base Address
+ Base Address
+ Base Address
+ Base Address
FD
00h
MT93L04A
04h
00h
7-0
7-0
Time
)
-16
128 in
). The
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