IQ amplitude adaptive balance system in direct frequency conversion modulation

Abstract

The invention relates to an IQ-amplitude adaptive balance system during direct frequency conversion modulation in the DSP technology field. The system comprises a down-conversion module, a demodulation and frequency phase recovering module, an averager module and a feedback module, wherein, an input terminal of the down-conversion module receives RF signals to be processed and transmits baseband signals to the demodulation and frequency phase recovering module and the feedback module; the demodulation and frequency phase recovering module demodulates the baseband signals and transmits the signals to the averager module after restoring the frequency and the phase of a carrier wave; the averager module transmits the calculated power amplitude difference to the feedback module; the feedback module is arranged at an output terminal of a modulating system and receives baseband data transmitted from the modulating system and the power amplitude difference transmitted from the averager module at the same time; and the output terminal of the feedback module is connected with a sending antenna. The IQ-amplitude adaptive balance system automatically monitors, tracks and compensates for the I-Q amplitude difference produced by the changes in environmental temperature and humidity in all elements in a whole up-conversion link, and the adaptive feedback structure has high precision at the same time.

Description

technical field [0001] The invention relates to a system in the technical field of digital signal processing, in particular to an adaptive balance system of IQ amplitude in direct frequency conversion modulation. Background technique [0002] In a digital signal transmission system, it is necessary to up-convert the baseband signal to a radio frequency. Taking a digital TV transmission system as an example, an 8MHz baseband signal needs to be up-converted to a corresponding radio frequency, such as 48MHz to 866MHz. Traditional up-conversion has the following three methods: triple frequency conversion, secondary frequency conversion and direct frequency conversion. [0003] Triple frequency conversion can better filter out image spectrum, the frequency points of each analog filter are fixed, and the performance of the system is consistent at each frequency point. The LO frequency is not in the desired frequency band and is well filtered out along with the image spectrum. H...

AI Technical Summary

Problems solved by technology

However, the ADC and DAC of this technology only use a single I-channel signal, and the Q-channel signal is directly generated by the I-channel, and does not distinguish the amplitude difference between I and Q, so it cannot compensate for the amplitude difference between I and Q.

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