Ublox LISA-U1 Series System Integration Manual

Also see for LISA-U100: Integration manual

Contents

Ublox LISA-U1 Series System Integration Manual Manual pdf 76 page image

LISA-U1 series - System Integration Manual3G.G2-HW-10002-3 Preliminary System descriptionPage 76 of 125I2S_TX data are composed of 16 bit words, dual mono (the words are written on both channels). Data arein 2’s complement notation. MSB is transmitted first. The bits are written on I2S_CLK rising or falling edge(configurable)I2S_RX data are read as 16 bit words, mono (words are read only on the timeslot with WA high). Data isread in 2’s complement notation. MSB is read first. The bits are read on the I2S_CLK edge opposite toI2S_TX writing edge (configurable)I2S_CLK frequency is 16 bits x 2 channels x 8 kHz = 256 kHzThe modes are configurable through a specific AT command (refer to the related chapter in u-blox ATCommands Manual [2], +UI2S AT command) and the following parameters can be set:MSB can be 1 bit delayed or non-delayed on I2S_WA edgeI2S_TX data can change on rising or falling edge of I2S_CLK signal (rising edge in this example)I2S_RX data are read on the opposite front of I2S_CLK signal1.11.3 Voiceband processing systemThe voiceband processing on the LISA-U120 and LISA-U130 modules is implemented in the DSP core inside thebaseband chipset. The analog audio front-end of the chipset is connected to the digital system through 16 bitADC converters in the uplink path, and through 16 bit DAC converters in the downlink path. External digitalaudio devices can be interfaced directly to the DSP digital processing part via the I2S digital interface. The analogamplifiers are skipped in this case.Possible processing of audio signal are:Speech encoding (uplink) and decoding (downlink).The following speech codecs are supported in firmwareon the DSP:Fullrate, enhanced full rate, and half rate speech encoding and decodingAdaptive multi rate (full rate and half rate) speech encoding and decodingMandatory sub-functions:Discontinuous transmission, DTX (GSM 46.031, 46.041, 46.081 and 46.093 standards)Voice activity detection, VAD (GSM 46.032, 46.042, 46.082 and 46.094 standards)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 [2])Signal routing: +USPM commandAnalog amplification, Digital amplification: +USGC,+CLVL, +CRSL, +CMUT commandDigital filtering: +UUBF, +UDBF commandsHands-free algorithms (echo cancellation, Noise suppression, Automatic Gain control) +UHFP commandSidetone generation (feedback of uplink speech signal to downlink path): +USTN commandPlaying/mixing of alert tones:Service tones: Tone generator with 3 sinus tones +UPAR commandUser generated tones: Tone generator with a single sinus tone +UTGN commandPCM audio files (for prompting): The storage format of PCM audio files is 8 kHz sample rate, signed 16bits, little endian, monoWith exception of the speech encoder/decoder, this audio processing can be controlled by AT commands.This processing is implemented within three different blocks of the voiceband processing system:Sample-based Voice-band Processing (single sample processed at 8 kHz / 16 kHz)Frame-based Voice-band Processing (frames of 160 / 320 samples are processed every 20 ms)