UMTS/HSPA Module Series
WCDMA UGxx Audio Design Note
WCDMA_UGxx_Audio_Design_Note Confidential / Released 19 / 56
Figure 11: Five Echo Paths
In these five paths, internal air-path and direct air-path are the first influential factors. Other three factors
(vibrations through casework, vibrations through PCB, distant echoes) are secondary.
To deal with echo issue from internal air-path, you can separate microphone from internal space of
chassis by foam or rubber ring which can effectively suppress the inner echo interference. Figure 12
shows recommended design for microphone socket.
Figure 12: Microphone Socket Design
Quectel
Confidential
