參數(shù)資料
型號: L64780
廠商: LSI Corporation
英文描述: DVB-T COFDM Demodulator(對地?cái)?shù)字視頻廣播 正交編碼頻率分割多路處理解調(diào)器)
中文描述: 的DVB - T COFDM解調(diào)器(對地?cái)?shù)字視頻廣播正交編碼頻率分割多路處理解調(diào)器)
文件頁數(shù): 26/126頁
文件大?。?/td> 953K
代理商: L64780
2-8
Architectural Overview
2.5 Fast Fourier Transform (FFT) Block
The FFT block converts from the temporal to the frequency domain
representation. It has the following modes of operation:
FFT and Inverse FFT
2 k (2048 points) and 8 k (8192 points) mode
2.6 Time Synchronization
This block finds the optimum timing for the start of the FFT window, and
synchronizes the frequency of the clock, f
CLK18
, to the received signal
The options for the duration of the symbol and the duration of the guard
interval are given in paragraph 4.4 of the DVB-T/ETSI Specification.
The block takes the sequence of complex numbers from the real-to-
complex conversion block and, to synchronize the clock, produces a
control signal for the voltage-controlled oscillator. The control voltage of
the VCXO is converted into a Sigma-Delta (
Σ/
) Modulated signal and
output as a single wire signal. This signal requires external low-pass
filtering to extract its mean value, which represents the control voltage of
the oscillator.
The transmitter repeats a segment of the signal during the guard interval.
This block detects the repeated portion of the signal. The signal
processing resists impairment from high levels of echoes or interference.
2.6.1 Timing Loop Gain
In 2 k mode, the optimal IIRGAIN is 0b01, or
.
This leads to K
I
and K
P
values of:
Equation 2.8
In 8 k mode, the optimal IIRGAIN is 0b11, or
.
α
3.125
10
2
×
K
I
1.69
K
VCXO
------------------
=
K
P
512
K
I
×
=
α
7.8
10
3
×
相關(guān)PDF資料
PDF描述
L652DU12RE 128 Megabit (16 M x 8-Bit) CMOS 3.0 Volt-only Uniform Sector Flash Memory with VersatileIO⑩ Control
L652DU12RF 128 Megabit (16 M x 8-Bit) CMOS 3.0 Volt-only Uniform Sector Flash Memory with VersatileIO⑩ Control
L652DU12RI 128 Megabit (16 M x 8-Bit) CMOS 3.0 Volt-only Uniform Sector Flash Memory with VersatileIO⑩ Control
L652DU12RK 128 Megabit (16 M x 8-Bit) CMOS 3.0 Volt-only Uniform Sector Flash Memory with VersatileIO⑩ Control
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