Realization method of combined digital down conversion and frequency offset correction circuit
A technology of digital down-conversion and frequency offset correction, which is applied in electrical components, transmitter/receiver shaping networks, transmission systems, etc., to achieve the effect of reducing resource waste
Inactive Publication Date: 2013-12-04
SHANGHAI HUAHONG INTEGRATED CIRCUIT
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[0005] The purpose of the present invention is to solve the problem of high resource usage caused by multiple frequency shifts during the digital down-conversion and frequency offset correction processing in the demodulator during the communication process , while reducing the waste of resources in its operation process
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[0024] The content of the above-mentioned invention will be described in detail below in conjunction with the drawings.
[0025] When the radio frequency signal transmitted wirelessly reaches the receiving end, it needs to go through a series of signal processing devices, such as figure 1 Shown in. First, the radio frequency signal enters the receiver through the receiving antenna, and enters the tuner Tuner module 100 for down-conversion processing. In a receiver with a secondary mixing structure, the tuner Tuner outputs an analog intermediate frequency signal ①. In this embodiment, the Tuner output Take an analog IF signal of 36MHz as an example, and then enter the analog-to-digital conversion AD module 200 for sampling. The sampling frequency of AD is 30MHz. The digital IF signal output by the analog-to-digital AD module ② enters the demodulator 300 for channel demodulation to obtain the original transmission data After streaming, it enters the decoder 400 for source decoding...
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The invention provides a combined digital down conversion and frequency offset correction circuit which comprises a Hilbert-huang transformation module, a frequency accumulation module, a D trigger, a Sin and Cos look-up table module and a frequency moving module. The invention also relates to a realization method of the combined digital down conversion and frequency offset correction circuit. The method includes the following steps that: 1. after a receipt signal is entered into a digital down conversion (DDC) and a frequency offset calibration (FOC) of a demodulator, a digital intermediate frequency signal is entered into the Hilbert-huang transformation module so that a real number signal is turned into two IQ complex number signals; 2. a frequency offset estimation result which is a feedback from a frequency offset estimation module is entered into the frequency accumulation module and performs frequency offset accumulation with a preset intermediate frequency, and then the accumulation result is entered into the Sin and Cos look-up table module; 3. input frequency is operated to obtain an address of the look-up table and the address is used to look up the table so as to respectively obtain a present frequency and corresponding results of Sin and Cos; 4. two IQ signals and the results of Sin and Cos output by the Sin and Cos look-up table are entered into the frequency moving module, and IQ complex number signals are multiplied by the results of Sin and Cos so as to obtain signals processed by digit down conversion and frequency offset correction. A problem of high resource usage caused by multi-time frequency moving in processes of digit down conversion and frequency offset correction can be solved. And wasting of resources during an operation process can be reduced.
Description
technical field [0001] The invention relates to an implementation method of frequency conversion and frequency offset correction in the field of digital communication, in particular to a circuit for joint digital down-conversion and frequency offset correction and an implementation method thereof. Background technique [0002] CMMB (China Mobile Multimedia Broadcasting) is the China Mobile Multimedia Broadcasting industry standard promulgated by the State Administration of Radio, Film and Television of China in October 2006. The standard came into effect on November 1, 2006. It is a wireless broadcast system based on multi-carrier OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) technology. It adopts advanced channel error correction coding and multi-carrier OFDM modulation technology to improve anti-interference ability and mobility. Supportability, while using the time slot transmission method to reduce the power consumption of...
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IPC IPC(8): H04B1/12H04B1/16H04L25/03
Inventor 刘鹏
Owner SHANGHAI HUAHONG INTEGRATED CIRCUIT