參數(shù)資料
型號(hào)： HDM8513
廠商： Hynix Semiconductor Inc.
英文描述： Operational Amplifier (Op-Amp) IC; Package/Case:8-DIP; Op Amp Type:General Purpose
中文描述： 的DVB /決策支持系統(tǒng)兼容接收器
文件頁(yè)數(shù)： 20/67頁(yè)
文件大?。?/td> 261K
代理商： HDM8513
20
3.2 Variable Rate Demodulator
The block diagram illustrates the overall configuration of the variable rate QPSK demodulator.
Baseband in-phase (I) and quadrature (Q) inputs are applied to the demodulator at a fixed sampling
rate. These digital samples are produced by A/D converters which employ AC coupling to minimize
DC offset.
Complex
Multiplier
Polyphase
Filters
I
Q
6
6
Narrowband
AGC
s
s
Symbol
Timing
Discriminator
Symbol
Tracking
Loop ilter
Phase
Accumulator
Sine
Cosine
Digital
Oscillator
Carrier
Tracking
Loop ilter
Nominal arrier
requency
Carrier
Phase
Discriminator
Symbol lock
I
Q
o
o
Lock
Detector
Lock
Sweep
Control
F
IGURE
15: D
EMODULATOR
B
LOCK
D
IAGRAM
The carrier frequency error associated with these samples is removed digitally during tracking
operations by a complex multiplier and a digitally controlled oscillator, sometimes called a
numerically controlled oscillator (NCO). During initial acquisition, coarse frequency error is
removed by a combination of the digital AGC within the HDM8513A and external analog tuning
circuits.
A polyphase filter performs the root raised cosine filtering of the frequency corrected baseband
samples. This filter, which implements the function of equation (1), is always configured to have an
impulse response duration of 4 symbols regardless of the programmed symbol rate. For low
symbol rates, a large number of samples are used, while for high symbol rates a relatively low
number of samples are processed for each filter output. The outputs of the polyphase filters are
applied to a digital narrowband AGC which insures that the signal is optimally scaled to the Viterbi
decoder to an accuracy of
+ or -
0.5 dB to insure optimum FEC performance.
y[k] =
Σ
h[n] x[k-n]
In addition to optimizing performance of the Viterbi decoder, the digital narrowband AGC also
insures that the performance of the symbol timing and carrier tracking loops is independent of
(1)
相關(guān)PDF資料
PDF描述
HDM8513A Linear Voltage Regulator IC; Package/Case:3-TO-92; Supply Voltage:30V; Output Voltage:5V; Current Rating:0.1A; Operating Temp. Max:70 C; Operating Temp. Min:0 C; Output Voltage Max:5V; Voltage Regulator Type:Positive Voltage
HDM8513AP Timer IC; Supply Voltage Max:16V; Package/Case:14-DIP; Current Rating:10A; Timer Type:Timer-Dual; Mounting Type:Through Hole
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HDM8515 ANALOG IC - DATASHEET REFERENCE
HDM8515P Operational Amplifier (Op-Amp) IC; Number of Amplifiers:4; Package/Case:14-DIP; Op Amp Type:Low Power; Single Supply Voltage Min (+V):3V; Dual Supply Voltage Max (+/- V):16V; Amplifier Type:Operational; Mounting Type:Through Hole
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
HDM8513A 制造商:HYNIX 制造商全稱:Hynix Semiconductor 功能描述:DVB/DSS Compliant Receiver
HDM8513AP 制造商:HYNIX 制造商全稱:Hynix Semiconductor 功能描述:DVB/DSS Compliant Receiver
HDM8513AT 制造商:HYNIX 制造商全稱:Hynix Semiconductor 功能描述:DVB/DSS Compliant Receiver
HDM8515 制造商:HYNIX 制造商全稱:Hynix Semiconductor 功能描述:DVB/DSS Compliant Receiver
HDM8515P 制造商:HYNIX 制造商全稱:Hynix Semiconductor 功能描述:DVB/DSS Compliant Receiver
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