MSM7603 查看數據表（PDF） - Oki Electric Industry

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MSM7603

Echo Canceler

Oki Electric Industry 

¡ Semiconductor

MSM7603/7603B

NOTES ON USE

1. Set echo return loss (ERL) to be attenuated. If the echo return loss is set to be

amplified, the echo cannot be eliminated.

Refer to the characteristics diagram for E. R. L. vs. echo attenuation quantity.

2. Set the level of the analog input so that the PCM codec does not overflow.

3. The recommended input level is –10 to –20 dBm0. Refer to the characteristics

diagram for the RIN input level vs. echo attenuation quantity.

4. Applying the tone signal to this echo canceler for long duration may decrease echo

attenuation.

When used with the HD pin "L" (howling detector ON), this echo canceler may

operate faultily if, while a signal is input to the RIN pin, a tone signal with a higher

level than the signal being input to RIN is input to the SIN pin.

A signal should therefore be input either to the RIN pin or to the SIN pin. If,

however, the tone signal is input to the SIN pin while a signal is input to the RIN pin,

the ADP, HD, or HCL pin must be set to "H".

5. For changes in the echo path (retransmit, circuit switching during transmission,

and so on), convergence may be difficult.

Perform a reset to make it converge.

If the state of the echo path changes after a reset, convergence may again be difficult.

In cases such as a change in the echo path, perform a reset each time.

6. When turning the power ON, set the PWDWN pin to "1" and input the basic clock

simultaneously with power ON.

If the device is put into power down mode immediately after power ON, be sure

to input 10 or more clocks of the basic clock before setting to the power down mode.

7. After power ON, be sure to reset the device.

8. After the power down mode is released (when PWDWN pin is changed to a "1" from

a "0"), be sure to reset the device.

9. If this canceler is used to cancel acoustic echoes, an echo attenuation may be less

than 30 dB.

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