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Adaptive equalizing and carrier recovering method suitable for high-order QAM and circuit thereof

An adaptive equalization and carrier recovery technology, which is applied in multi-carrier systems, shaping networks in transmitters/receivers, baseband system components, etc., can solve the problem of signal-to-noise ratio reduction, difficult carrier recovery algorithm carrier frequency offset, Signal distortion and other problems, to achieve the effect of reducing the steady-state phase error, improving the ability to capture frequency offset, and improving system performance

Inactive Publication Date: 2005-10-26
上海微科集成电路有限公司
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Problems solved by technology

[0005] For high-order QAM signals, the distance and phase difference between the constellation points become smaller, so blind equalization and carrier recovery are more difficult
If the carrier recovery is performed directly, the signal will be severely distorted due to bad channels, and the signal-to-noise ratio will be reduced. It is difficult to find an effective carrier recovery algorithm that can directly eliminate the carrier frequency offset; Rotation, equalization is difficult to fully converge, and generally only partially compensates for channel distortion

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  • Adaptive equalizing and carrier recovering method suitable for high-order QAM and circuit thereof
  • Adaptive equalizing and carrier recovering method suitable for high-order QAM and circuit thereof
  • Adaptive equalizing and carrier recovering method suitable for high-order QAM and circuit thereof

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Embodiment Construction

[0029] Further describe the present invention below in conjunction with accompanying drawing.

[0030] The self-adaptive equalization and carrier recovery hybrid algorithm and its circuit realization structure proposed by the present invention are applied to the digital TV demodulator. The digital TV demodulator supports the European digital TV broadcast standard (DVB-C), and supports 4, 16, 64, 256QAM. The circuit structure used is figure 1 The architecture shown.

[0031] The signal-to-noise ratio of the input QAM signal I and Q is 36dB, the baud rate is 6.9M, and the carrier frequency deviation is 600KHz. Feedforward equalizers 1 and 9 use 8-tap finite impulse response (FIR) filters, and the structure is transposed; feedback equalizer 3 uses a 16-tap FIR filter; loop filter 7 uses a proportional , Integral filter, its transfer function is H LP ( Z ) = K ...

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Abstract

This invention relates to a digital balance and carrier recover joint algorithm and its circuit structure used in high order quadrature amplitude modulation (QAM). Demodulation becomes difficult since the high-order QAM signal is influenced by the carrier frequency deviation and channel distortion, this invention applies four steps of blind balance, frequency discrimination, phase discrimination and the least square error adaptive balance to obtain the stable balance and carrier recover performance, which can capture the carrier frequency deviation of 9% baud rate. This invention also provides a structure for realizing the circuit.

Description

technical field [0001] The invention belongs to the technical field of digital communication, and specifically relates to an adaptive equalization and carrier recovery method for high-order QAM signals and a circuit structure thereof. Background technique [0002] Under the urgent demand for huge information transmission in the digital information age, various modern modulation and demodulation technologies are pursuing reliable high-speed transmission rates. The development of digital communication technology makes various communication applications show a trend of mutual integration, such as the trend of "three networks in one" of telephone network, cable TV network and Internet. To implement many communication applications in the same wired channel, it is necessary to save limited spectrum resources, improve spectrum utilization, and achieve high-speed data transmission. [0003] Quadrature Amplitude Modulation (QAM) technology has high spectral efficiency and strong ant...

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Application Information

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IPC IPC(8): H04L27/38
Inventor 田骏骅沈泊李铮苏佳宁郭亚炜
Owner 上海微科集成电路有限公司
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