SARA-G3 and SARA-U2 series - System Integration Manual 
UBX-13000995 - R26    System description 
    Page 74 of 217 
I2S_RXD
UBF 
2/6
UBF 
1/5
Hands-
free
To 
Radio TX
Scal_Mic
Digital Gain
I2S_TXD
Scal_Rec 
Digital Gain
Tone 
Generator
UBF 
4/8
UBF 
3/7
DBF 
3/7
DBF 
4/8
DBF 
1/5
DBF 
2/6
Legend:
UBF= Uplink Biquad Filter
DBF = Downlink Biquad Filter
NR = Noise Reduction
Sidetone
From 
Radio RX
Speech level
UPLAYFILE
Mix_Afe
URECFILE
UAPLAYUAREC
UPLAYFILEURECFILE
Mix_Afe
UAPLAYUAREC
NR
 
Figure 34: SARA-U2 “04” product versions audio processing system block diagram 
For  a  detailed  description  about  audio  parameter  tuning,  see  the  SARA-U2  series  extended  audio  processing 
blocks commands application note [39]. 
 
SARA-U2 modules audio signal processing algorithms are: 
  Speech encoding (uplink) and decoding (downlink).The following speech codecs are supported in firmware 
on the DSP for speech encoding and decoding: 
GERAN GMSK codecs 
o  GSM HR (GSM Half Rate) 
o  GSM FR (GSM Full Rate) 
o  GSM EFR (GSM Enhanced Full Rate) 
o  HR AMR (GSM Half Rate Adaptive Multi Rate – Narrow Band) 
o  FR AMR (GSM Full Rate Adaptive Multi Rate – Narrow Band) 
o  FR AMR-WB (GSM Full Rate Adaptive Multi Rate – Wide Band) 
UTRAN codecs: 
o  UMTS AMR2 (UMTS Adaptive Multi Rate version 2 – Narrow Band) 
o  UMTS AMR-WB (UMTS Adaptive Multi Rate – Wide Band) 
  Mandatory sub-functions: 
o  Discontinuous transmission, DTX (GSM 46.031, 46.041, 46.081 and 46.093 standards) 
o  Voice activity detection, VAD (GSM 46.032, 46.042, 46.082 and 46.094 standards) 
o  Background noise calculation (GSM 46.012, 46.022, 46.062 and 46.092 standards)