Digital audio FM modulation circuit of handheld ultrashort wave air radio

Abstract

The invention discloses a digital audio FM modulation circuit of a handheld ultrashort wave air radio. The circuit comprises a level regulator, an A / D converter, a digital audio equalizer, an MCU and a digital frequency modulation unit. The level regulator, the A / D converter, the digital audio equalizer and the digital frequency modulation unit are sequentially connected. The MCU is connected with the digital audio equalizer and the digital frequency modulation unit. The digital frequency modulation unit comprises a CPU processor, an SPI interface, a frequency offset reference value register, a voltage controlled oscillator and a frequency offset base coefficient register. The frequency offset reference value register, the voltage controlled oscillator and the frequency offset base coefficient register are connected with the CPU processor. The frequency offset reference value register is connected with the digital audio equalizer through the SPI interface. The voltage controlled oscillator and the frequency offset base coefficient register are connected with the MCU. The circuit can carry out accurate, fast and smooth frequency modulation processing on an audio signal, and is suitable for the demand of large data voice communication.

Description

technical field [0001] The invention relates to the technical field of ultrashort wave communication, in particular to a digital audio FM modulation circuit of a hand-held ultrashort wave air-to-air radio. Background technique [0002] Hand-held air-to-air radios in the ultra-short wave band usually refer to hand-held radios transmitted by ground wave or space wave line-of-sight. It is mainly composed of transceivers, antennas and power supplies. It is mainly used in the special communication command and dispatch system of civil aviation, railway, public security, flood control, fire prevention and other departments, especially for field tasks such as airborne, airdrop, training and air guidance and command tasks such as airport emergency support. [0003] At present, the ultra-short wave band handheld air-to-air radios mainly used in China are mainly products of Japan’s ICOM, Motorola of the United States, Daji of New Zealand, Innovation of Canada, Nissei of Japan and Kenwo...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the technical defect of using imported equipment in the ultrashort wave air-to-air communication in the prior art, it only supports the AM voice working mode, and does not support the FM voice working mode. At the same time, the existing signal frequency modulation adopts multiple analog audio signals. The technical scheme of sub-mixing modulation, filtering and amplification involves many devices, the circuit is more complicated, the control is not flexible enough, the connection is difficult, not smooth enough, the adjustment accuracy is poor, the processing speed is slow, and it is difficult to adapt to the big data voice communication. The technical problem of demand, the present invention provides the digital audio frequency FM modulation circuit of hand-held ultrashort wave air-to-air radio station

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