MT93L04 Zarlink Semiconductor, MT93L04 Datasheet - Page 38

• Manufacturer Part Number: MT93L04
• Description: 128-channel Voice Echo Canceller
• Manufacturer: Zarlink Semiconductor

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 µs (64 ms/512 taps).
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)
Amplitude of MU
NS7
1.0
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
6
6
0
FD5
NS5
5
5
5
0
7-0
)
FD4
4
4
NS4
4
0
NS3
FD3
3
3
3
FIR Filter Length (512 or 1024 taps)
0
Zarlink Semiconductor Inc.
SSC2
FD2
NS2
2
2
MT93L04
2
38
SSC1
FD1
NS1
1
1
1
SSC0
FD0
NS0
0
0
0
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Read/Write Address:
Step Size (SS)
Number of Steps (NS
Power Reset Value
04h
07h
06h
24h
27h
26h
Power Reset Value
Power Reset Value
+ Base Address
+ Base Address
+ Base Address
+ Base Address
+ Base Address
+ Base Address
00h
04h
00h
Data Sheet
7-0
Time
)