MT9300

Advance Information

16

Power Reset Value

00h

76543210

Echo Canceller A, Flat Delay Register (FD)

Read/Write Address: 04h + Base Address

Echo Canceller B, Flat Delay Register (FD)

Read/Write Address: 24h + Base Address

Power Reset Value

00h

76543210

Echo Canceller A, Decay Step Number Register (NS)

Read/Write Address: 07h + Base Address

Echo Canceller B, Decay Step Number Register (NS)

Read/Write Address: 27h + Base Address

Power Reset Value

04h

76543210

0

000

0

Echo Canceller A, Decay Step Size Control Register (SSC)

Read/Write Address: 06h + Base Address

Echo Canceller B, Decay Step Size Control Register (SSC)

Read/Write Address: 26h + Base Address

Note: Bits marked with “0” are reserved bits and should be written “0”.

Amplitude of MU

Time

Step Size (SS)

1.0

FIR Filter Length (512 or 1024 taps)

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

Decay Step Size Control: This register controls the step size (SS) to be used during the exponential decay of MU. The

is 04h.

Decay Step Number: This register defines the number of steps to be used for the decay of MU where each step has a

256 taps for a filter length of 512 taps.