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Method for controlling digital automatic electric-level gain

A technology of automatic gain control and automatic level, applied in the field of digital signal transmission, can solve the problems of signal power fluctuation at the receiving end, the influence of the transmission channel, and the influence of the receiving quality, etc., and achieve the effect of reducing the fluctuation range and high precision.

Inactive Publication Date: 2008-02-06
SHANGHAI JIAOTONG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

The invention solves the problem that the signal power at the receiving end will fluctuate in a large range due to the influence of the transmission channel during the wireless transmission of the digital signal, thus affecting the receiving quality

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  • Method for controlling digital automatic electric-level gain

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Embodiment Construction

[0014] The present invention will be further described below in conjunction with embodiments.

[0015] The present invention implements an automatic level gain control loop to adjust the received signal. Fig. 2 shows a digital AGC loop used in the method of the present invention. The AGC loop includes two complex multipliers, a square root detector, a logarithmic operator, a real number subtractor, a real multiplier, an integrator, and an antilogarithm operator. The control method is specifically as follows:

[0016] In a communication system based on OQAM modulation, after the OQAM signal reaches the receiver, it is first demodulated, and the complex signal obtained after demodulation is composed of I and Q signals, using (XI(n)+jXQ(n) ) To represent; (XI(n)+jXQ(n)) The two signals I and Q formed by (XI(n)+jXQ(n)) are respectively multiplied by a complex multiplier and multiplied by the digital AGC control signal M to obtain the output signal (YI(n)+jYQ (n)), this control signal ...

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Abstract

The invention is realized through an auto level gain control loop, which includes two complex multiplication units, one square root detector, logarithm arithmetic unit, real subtracter, real multiplication unit, integrator and anti-logarithm arithmetic unit. Complex signal (XI(n)+jXQ(n)) composed of I route and Q route is obtained after demodulating signal. Then, the method includes steps: complex signal is multiplied by control signal M of digital AGC so as to obtain output signal (YI(n)+jYQ(n)); error signal ERR is obtained through following operations: sending (YI(n)+jYQ(n)) to signal power detector, taking square of imaginary part and real part respectively, then adding them, taking logarithm, and minus a reference value R; control signal M of AGC is obtained through following operations: ERR multiplied by gain value K, averaging and then taking anti-logarithm. Features are: controlling and compensating electric level effectively, reducing variation range of signal power.

Description

Technical field [0001] The invention relates to a method in the technical field of digital signal transmission, in particular to a method for controlling digital automatic level gain suitable for digital television terrestrial broadcast receivers. technical background [0002] In high-speed digital signal wireless transmission systems, such as digital high-definition television (HDTV), the signal is affected by the transmission channel during the wireless transmission process, the use of the receiving antenna, etc., and the signal power at the receiving end will have a large range fluctuation. In actual situations, such as in the case of vehicle movement, when entering and leaving a building, the receiver is likely to receive a signal level of 3uV at a certain moment, and at another moment, it may just leave the building. The received signal may be 1V. Therefore, an adjustment range of nearly 110dB is required for the received signal. Figure 1 shows the frequency spectrum of ADTB...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04N5/52
Inventor 归琳管云峰孙军
Owner SHANGHAI JIAOTONG UNIV