Integration Manual

LISA-U series - System Integration Manual
3G.G2-HW-10002-A3 Preliminary System description
Page 87 of 160
 Analog amplification, Digital amplification: +USGC, +CLVL, +CRSL, +CMUT command
 Digital filtering: +UUBF, +UDBF commands
 Hands-free algorithms (echo cancellation, Noise suppression, Automatic Gain control) +UHFP command
 Sidetone generation (feedback of uplink speech signal to downlink path): +USTN command
 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
With exception of the speech encoder/decoder, this audio processing can be controlled by AT commands.
This processing is implemented within the different blocks of the voiceband processing system:
 Sample-based Voice-band Processing (single sample processed at 16 kHz for Wide Band AMR codec or
8 kHz for all other speech codecs)
 Frame-based Voice-band Processing (frames of 320 samples for Wide Band AMR codec or 160 samples for
all other speech codecs are processed every 20 ms)
These blocks are connected by buffers (circular buffer and voiceband sample buffer) and sample rate converters
(for 8 / 16 to 47.6 kHz conversion).
Voiceband audio processing implemented in the DSP core of LISA-U series modules is summarized in Figure 48.
DAC
ADC
I
2
S Receive Data
Switch
MIC_P/N
Microphone
Analog Gain
UF
2/6
UF
1/5
Hands-
free
To
Radio TX
Scal_Mic
Digital Gain
Sidetone
SPK_P/N
Switch
I
2
S Transmit Data
Scal_Rec
Digital Gain
HS Analog
gain
Tone
Generator
From
Radio RX
Speech
level
I2Sx RX
PCM
Player
18
dB
UF
4/8
UF
3/7
DF
3/7
DF
4/8
DF
1/5
DF
2/6
Legend:
UF= uplink filter
DF = downlink filter
Mix_Afe
I2Sx TX
Figure 48: Voiceband processing system block diagram