User's Manual

LISA-U1/LISA-H1 series - System Integration Manual
3G.G2-HW-10002-2 Advance Information System description
Page 73 of 116
 Sample-based Voice-band Processing (single sample processed at 8 kHz, every 125 µs)
 Frame-based Voice-band Processing (frames of 160 samples are processed every 20 ms)
 MIDI synthesizer running at 47.6 kHz
These three blocks are connected by buffers (circular buffer and voiceband sample buffer) and sample rate
converters (for 8 to 47.6 kHz conversion) as illustrated in the block diagram in Figure 42, which summarizes the
voiceband audio processing in the DSP.
DAC
ADC
I2S_RXD
Switch
MIC
Microphone
Analog Gain
Uplink
filter 2
Uplink
filter 1
Hands-
free
To Radio
TX
Scal_Mic
Digital Gain
Sidetone
Downlink
filter 1
Downlink
filter 2
MIDI
player
SPK_P/N
Switch
I2S_TXD
Scal_Rec
Digital Gain
Mix_AFE
Digital Gain
SPK
Analog_gain
Gain_out
Digital Gain
Tone
Generator
From
Radio RX
Speech
level
I2Sx RX
Sample Based Processing Frame Based
Processing
AMR
Player
Circular buffer
Voiceband Sample Buffer
18
dB
Power
Amplifier
Figure 42: Voiceband processing system block diagram