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參數(shù)資料
| 型號： | S5N8944B |
| 廠商： | SAMSUNG SEMICONDUCTOR CO. LTD. |
| 英文描述： | G.Lite ADSL Transceiver for CO and CPE |
| 中文描述： | G. Lite的寬帶收發(fā)器對CO和CPE |
| 文件頁數(shù)： | 12/21頁 |
| 文件大小： | 183K |
| 代理商： | S5N8944B |
drivers and hybrid components to connect the PSTN. The ADSL Transceiver provides all the
digital functions as depicted in Figure 4.
12
S5N8944B
G.Lite ADSL Transceiver for CO and CPE
Preliminary Information (Rev.2.1 )
CONFIDENTIAL
The input bit stream is divided into bit slices and they are fed into the QAM which are allocated
to 128 subchannels according to the bit loading table. The bit slices are then converted to
frequency-domain complex samples by the QAM encoders. The 256 complex samples are
changed to 256 time-domain samples by IFFT. The Tx filter performs band separation and
interpolation functions.
The received signals are attenuated and distorted in terms of both phase and amplitude. PLL
fixes the phase errors within 4 samples using the 276kHz pilot tone transmitted from the CO
side. The ones over 4 samples are fixed by the sync recovery algorithm using a known
synchronization symbol. The TEQ is a filter that adaptively alters the channel so that the
impulse response is reduced to the length of the cyclic prefix which will be removed prior to FFT.
The FEQ is a one tap complex adaptive filter for each subchannel, which adjusts the gains and
phases of the received signals. The equalizers are adaptively updated due to the transmission
channel environment.
In FDM-based DMT (Discrete MultiTone) modulation, the frequency band, 0 to 552kHz, is
divided into 128 equi-spaced subchannels, of which 26kHz (#6) to 134kHz (#31) is allocated for
the upstream, and 142kHz (#33) to 548kHz (#127) for the downstream. The Nyquist rate,
therefore, should be 1.104MHz(276kHz) .
DMT inherently transmits an optimized time-variable spectrum. This spectrum is adjusted
according to the desired data rate and the transmission characteristics (transfer function and
noise spectrum) on each and every subchannel. For this, CO and CPE transmit 128 4kHz-wide
tone downstream and upstream respectively to each other during initialization. They measure
the quality of each of these received tones and then decide whether a tone has sufficient quality
to be used for further transmission and, if so, how much data this tone should carry relative to
the other tones that are used. They inform the bit loading result to each other.
Figure 4: Functional Block Diagram of the S5N8944B
ATM
Framer
ATM
or
Non-ATM
Host
FEC
Codec
QAM
Codec
FEQ
TEQ
IFFT
256/64
TX
Filter
FFT
256/64
RX
Filter
DSP
DAC
ADC
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PDF描述 |
|---|---|
| S5N8947 | MCU for ADSL/Cable Modem |
| S5N8947X | MCU for ADSL/Cable Modem |
| S5N8950 | G.dmt ADSL Transceiver for CO and CPE |
| S5N8951 | G.dmt ADSL Analog Front End IC |
| S5N8951X | G.dmt ADSL Analog Front End IC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| S5N8947 | 制造商:SAMSUNG 制造商全稱:Samsung semiconductor 功能描述:MCU for ADSL/Cable Modem |
| S5N8947X | 制造商:SAMSUNG 制造商全稱:Samsung semiconductor 功能描述:MCU for ADSL/Cable Modem |
| S5N8950 | 制造商:SAMSUNG 制造商全稱:Samsung semiconductor 功能描述:G.dmt ADSL Transceiver for CO and CPE |
| S5N8951 | 制造商:SAMSUNG 制造商全稱:Samsung semiconductor 功能描述:G.dmt ADSL Analog Front End IC |
| S5N8951X | 制造商:SAMSUNG 制造商全稱:Samsung semiconductor 功能描述:G.dmt ADSL Analog Front End IC |
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