ST70235A View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'ST70235A' PDF : 28 Pages View PDF
ST70235A
Figure 3 : DSP Front-End Receive
From
Analog
Front-end
IN
SELECT
Figure 4 : DSP Front-End Transmit
BYPASS
AFE
I/F
DEC
TEC
To DMT
Modem
From
DMT
Modem
FILTERING
CLIPPING
DELAY
EQUALIZER
INTER-
POLATOR
AFE
I/F
OUT
SELECT
To Analog
Front End
Figure 5 : DMT Modem (Rx & Tx)
To/From
DSP FE
FFT
IFFT
FEQ
FTG
ROTOR
TREILLIS
CODING
DECODING
MAPPER
DEMAPPER
To/From
TC
FEQ COEFFICIENTS
MONITOR
FEQ Update
This stream is still affected by carrier specific
channel distortion resulting in an attenuation of
the signal amplitude and a rotation of the signal
phase. To compensate, a Frequency domain
equalizer (FEQ) and a Rotor (phase shifter) are
implemented. The frequency domain equalization
performs an operation on the received vector in
order to match it with the associated point in the
constellation. The coefficient used to perform the
equalization are floating point, and may be
updated by hardware or software, using a
mechanism of active and inactive table to avoid
DMT synchro problems.In the transmit path, the
10/28
Monitor Indications
IFFT reverses the DMT symbol from frequency
domain to time domain.
The IFFT block is preceded by Fine Tune Gain
(FTG) and Rotor stages, allowing for a
compensation of the possible frequency mismatch
between the master clock frequency and the
transmitter clock frequency (which may be locked
to another reference).
The Inverse Fast Fourier Transform process is
used to transform from frequency domain to time
domain (transmit path). 256 positive frequencies
are processed, giving 512 samples in the time
domain.
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