A frequency modulation system with modulation depth compensation applied to multiple code rate communications

Abstract

The invention discloses a frequency modulation system with modulation depth compensation applied to multiple code rate communications, including a frequency synthesizer (100) and an analog modulation voltage generation module (200); first, based on the target communication code rate, set the frequency Modulation capacitance; secondly, the frequency synthesizer sets the programmable fractional frequency divider (6) through channel selection to generate a carrier signal of the corresponding frequency, and then programs the configurable loop filter (3) to realize loop disconnection; finally, the analog modulation The voltage generation module sets the input quantization voltage range of the digital-to-analog converter through channel selection. The digital-to-analog converter (8) converts the digital modulation signal into an analog voltage signal and filters it through a low-pass filter (7). The voltage is realized by the modulation capacitor. Characteristic to capacitive characteristic conversion, LC oscillator (4) realizes frequency modulation. The invention can realize multi-code rate, multi-channel, multi-modulation deep communication, and has the characteristics of low signal distortion and high module reuse rate.

Description

technical field [0001] The invention mainly relates to the field of frequency modulation design, in particular to a frequency modulation system structure using a frequency synthesizer for frequency modulation to realize multiple code rates, multiple channels, and multiple frequency modulation depths. Background technique [0002] With the increasing development of wireless communication technology, the frequency range of radio frequency system communication continues to expand, and the number of communication channels continues to increase, making it possible to integrate multiple code rates, multiple channels, and multiple frequency modulation depths into one reusable frequency modulation The demands on the system are increasing day by day. Therefore, the modulation depths of the same code rate are inconsistent, and the modulation depths of different code rates are not clearly distinguished, which has become an urgent problem to be solved in the field of frequency modulatio...

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Problems solved by technology

[0007] With the continuous increase of communication channels, the carrier frequency continues to increase, making the effective capacitance C corresponding to the carrier frequency 0 also gradually decreases, but the modulation capacity △C for frequency modulation remains unchanged. According to the formula (1), it can be seen that the modulation depth will become larger and larger, resulting in an increase in the working bandwidth of the digital processing module and an increase in design difficulty.

[0008] For the traditional frequency modulation system with multiple code rates and multiple modulation depths, its main problem is similar to that of a single code rate and a single modulation depth, that is, the modulation depth is inconsistent under each communication code rate, resulting in the demodulation part Increased design difficulty, and even data loss and distortion

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