SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R08
Objective Specification
System description
Page 63 of 188
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)
Function configurable via specific AT commands (refer to the
u-blox AT Commands Manual
o
Signal routing: +USPM command
o
Analog amplification, digital amplification: +USGC, +CLVL, +CRSL, +CMUT command
o
Digital filtering: +UUBF, +UDBF commands
o
Hands-free algorithms (echo cancellation, Noise suppression, Automatic Gain control) +UHFP
command
o
Sidetone generation (feedback of uplink speech signal to downlink path): +USTN command
o
Playing/mixing of alert tones:
Service tones: Tone generator with 3 sinus tones +UPAR command
User generated tones: Tone generator with a single sinus tone +UTGN command
PCM audio files (for prompting): The storage format of PCM audio files is 8 kHz sample rate, signed
16 bits, little endian, mono
