The MSM7617 cancels echoes (acoustic or line echoes) generated in voice channels. It is a low-power CMOS LSI device with two channels.

MSM7617 echo canceling is performed by digital signal processing. It negates echoes by estimating the echo channel and then generating a pseudo-echo signal.

When used as an acoustic echo canceller, the MSM7617 can cancel acoustic echoes between speaker and microphone that occur during hands-free speaking with car phones, conferencing system phones, etc. When used as a line echo canceller, the MSM7617 can cancel line echoes returned by hybrid impedance mismatches.

By setting its mode for use as a single cross-connected channel, the MSM7617 can cancel both acoustic and line echoes.

Also, the MSM7617 can improve voice communication by using its howling detection, double talk detection, attenuation, and gain control functions to prevent and suppress howling levels, and by using its center clipping function to suppress low level noise.

Furthermore, the MSM7617 can disable echo canceling during data communication with its 2100 Hz tone detector and 2100 Hz phase reversal detector. It also provides the ability to attenuate SIN levels, to amplify SOUT levels, and to adjust input/output levels.

An economical and highly efficient echo canceller unit can be constructed by using a 2-channel single-chip CODEC like the MSM7533 together with the MSM7617.