Speakerphone/car kit hands free design
LZT 123 7895 R1A
4
1 Introduction
This application note details how to set up the GR47/GR48 GSM Module
Advanced Hands free Mode. In many applications this can provide
effective echo cancellation without using external echo-cancelling
electronics. This method is suitable for simple car-kit applications (where
placement of speaker and microphone can be defined) and may be
effective in some office speaker-phone applications.
The solution presented has limited audio level range. Where the required
audio levels exceed the limits of the Advanced Hands free system,
consider implementing an external echo-cancelling circuit as presented in
Application Note (xx).
