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ADPLP01 数据表(PDF) 2 Page - Analog Devices |
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ADPLP01 数据表(HTML) 2 Page - Analog Devices |
2 / 8 page AD20msp410 –2– REV. 0 Software The required Layer 1 software is supplied with the chipset. In addition, an object code license for Layers 2 and 3 of the protocol stack is available. This exact package of Layers 1,2,3 of software, coupled with the AD20msp410 chipset, is today in phones that have passed European GSM Final Type Approval. Architecture Overview A standard GSM Handset can be divided into five functional areas: • Analog and Digital Baseband Processing Subsystem • (Voice to Radio) • Layer 1 Software (Physical Layer) • Protocol Stack Software (Layers 2 and 3) • Radio Subsystem • User Interface Software (MMI) Analog Devices and The Technology Partnership (TTP) provide a cost effective and proven method of attaining the baseband processing subsystem and protocol stack software. This data sheet includes functional descriptions of the baseband processing subsystem and the Layer 1 software. The Technol- ogy Partnership can provide licenses to software and reference designs in all the other areas of a GSM hand-portable terminal. For detailed information about the individual chipset compo- nents, please refer to the ADSP-2178 (ASP), AD7015 (BBC) and ADPLP01 (PLP) data sheets for electrical characteristics and timing information. FUNCTIONAL DESCRIPTION Figure 1 is a functional block diagram of the GSM baseband processing chipset. The chipset can be viewed as a functional block that contains a number of discrete functional units. The electrical and functional interfaces to the rest of the system are briefly described at the end of this section and described in detail in the individual data sheets for each component. SPEECH DECODE PLP ASP BBC CHANNEL ENCODE INTER- LEAVE ENCRYPT CHANNEL DECODE DEINTER- LEAVE DECRYPT CONTROL + MMI + I/O SPEECH ENCODE EQUALIZER VOICE DAC VOICE ADC BASE- BAND ADC BASE- BAND DAC SPEECH ENCODE Figure 1. Functional Description UPLINK The uplink baseband processing functions include the following operations: Analog-to-Digital Voice Conversion (BBC) A conventional microphone, connected directly to the BBC, provides an analog input signal to the ADC. The voice ADC function uses a sigma-delta converter to convert and noise shape the input signal, achieving a Signal-to-Noise Ratio plus Total Harmonic Distortion (SNR+THD) of greater than 62.5 dB. The analog voice signal is sampled at 8 kHz, producing 13-bit linear values corresponding to the magnitude of the input. The resulting data is passed to the ASP through a dedicated serial port. Speech Encoding (ASP) The ASP receives the voice data stream from the BBC and encodes the data from 104 kb/s to 13 kb/s. The algorithm used is Regular Pulse Excitation, with Long Term Prediction (RPE- LTP) as specified in the 06-series of GSM recommendations. The algorithm is tested and proven to be bit-exact against the GSM test vectors including all VAD/DTX functions. After encoding the data is transferred to the PLP through a parallel port in discrete blocks of 260 bits at 20 ms intervals. Channel Coding (PLP) The information received from the ASP contains data values and filter coefficients that have different levels of priority. These are subsequently protected to different levels within the channel coding. The encode protection process incorporates block coding and convolutional encoding. In addition to the normal speech traffic channels, the channel coding function also supports data transmission at full rate and half rate. After the interleave process, if necessary, the data is encrypted using the required A5/1 or A5/2 encryption algorithm. Data is then formatted into bursts, with the required timing and training sequences and sent to the BBC through a dedicated serial port. GMSK Modulation and D/A Conversion (BBC) The BBC receives data at 270 kb/s. The on-chip lookup-table ROM modulates and spectrally shapes the data being sent. A pair of 10-bit matched differential DACs convert the modulated data from the digital domain to the analog domain and pass I and Q data to the transmit section of the radio subsystem. DOWNLINK The downlink baseband processing functions include the following operations: Analog-to-Digital Conversion (BBC) The receiver I and Q signals are sampled by a pair of ADCs at 270 kHz. The resulting digital words are transferred to the ASP through a dedicated receive path serial link and DMA control. Equalization (ASP) The equalizer recovers and demodulates the received signal and establishes local timing and frequency references for the mobile unit. The equalization algorithm is a version of the Maximum Likelihood Sequence Estimation (MLSE) using the Viterbi algorithm. Two confidence bits per symbol provide additional information about the accuracy of each decision to the channel codec’s convolutional decoder. The equalizer outputs a sequence of bits including the confidence bits. This data is transferred to the PLP through a dedicated parallel port on the ASP. At this point, the training sequence and trailing bits, contained within the burst, are discarded. Channel Decoding (PLP) The A5/1 or A5/2 decryption algorithm is used, as required, to recover the data that is ready for the deinterleave process. The deinterleave process is an exact inversion of the interleave process used by the transmit section. Data can pass directly to this function, without the A5/1 or the A5/2 decryption, con- trolled by the Layer 1 processing. The decode function then performs convolutional decoding and parity decoding. The convolutional decoder uses a Viterbi algorithm, with two soft |
类似零件编号 - ADPLP01 |
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类似说明 - ADPLP01 |
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