Medium-wave harmonic filter

Abstract

The invention relates to a medium-wave harmonic filter used for a medium-wave navigation transmitter. The medium-wave harmonic filter consists of five sections of filtering units, wherein each section of filtering unit forms a filtering channel; each section of filtering unit is a seven-order low-pass filter which is formed by connecting four capacitors, three inductors and four relays; the capacitors and the inductors form a filter circuit part of the seven-order low-pass filter; and a relay coil end in each section of filtering unit is connected with a three-eight decoder in an external control unit. Because the relays are controlled by a level signal output by the three-eight decoder of the external control unit in each section of filtering unit, the switching between the filtering units of the control filter is controlled; the harmonic suppression performance of the medium-wave transmitter is improved, so that the second harmonic suppression performance and the third harmonic suppression performance are improved; the switching of intelligent control mode control frequency bands is realized in the medium-wave transmitter; and thus the medium-wave harmonic filter can be applied to 100W, 200W and 500W series medium-wave transmitters and has the advantages of stable work, reliable performance and popularization value.

Description

Technical field [0001] The present invention relates to the technical field of navigation communication, in particular to a medium wave harmonic filter used in a medium wave navigation transmitter. Background technique [0002] The medium wave harmonic filter is an important circuit unit of the medium wave navigation transmitter, and is currently widely used in various medium wave transmitters that adopt the principle of pulse width amplification for power amplification. However, most of the medium wave harmonic filters manufactured by the existing technology still have the defect of poor harmonic suppression performance, which causes the instantaneous harmonics generated when the transmitter is turned on to affect (interfere) other surrounding radio equipment. The current domestic use The harmonic suppression of the medium wave transmitter is -50dB. The International Civil Aviation Convention requires the harmonic suppression of the medium wave transmitter to be -60dB, and the e...

AI Technical Summary

Problems solved by technology

However, most of the medium-wave harmonic filters manufactured by the existing technology still have the defect of poor harmonic suppression performance, which causes the instantaneous harmonics generated when the transmitter is turned on to affect (interference) other radio equipment around. The harmonic suppression of the medium wave transmitter is -50dB, and the international civil aviation convention requires the harmonic suppression of the medium wave transmitter to be -60dB, and the existing medium wave transmitter still has the defect of switching the working frequency band, that is, the difficulty of frequency band switching

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