Up-conversion system local oscillator circuit on small aircraft

Abstract

The invention discloses an up-conversion system local oscillator circuit on small aircraft. The local oscillator circuit directly uses digital phase-locked frequency source as local oscillator signals and comprises a coupler, a sound filter, a mixer, a band-pass filter, a low pass filter, one or multiple local oscillators, one or multiple power dividers and one or multiple amplifiers. A whole output of the local oscillator circuit is generated by a 100MHz input signal, wherein a minimum stepped-frequency interval is 1MHz, and is capable of stepping 264 frequency points; and a maximum stepped-frequency interval is 264MHz. The invention provides an up-conversion system system local oscillator circuit on small aircraft. The local oscillator circuit adopts an indirect synthesis method, which greatly improves a spurious rejection ratio of local oscillator signals and reduces power dissipation of a complete machine, making output spurious of L superior to -78dBc. Meanwhile, broadband is adopted to carry out phase demodulation, and frequency of phase demodulation is improved; fast capture bandwidth is increased, and frequency agility time is improved, solving problems of spurious rejection capability of the local oscillator signals, frequency agility time and the like.

Description

technical field [0001] The invention relates to a local oscillator circuit of a small airborne up-conversion system. Background technique [0002] There are many ways to achieve frequency hopping oscillation, which can be divided into direct synthesis (crystal oscillator frequency multiplication chain) and indirect synthesis (phase-locked loop) according to the way of realization. When direct synthesis is used, the system is complex in structure, high in cost, low in clutter suppression, difficult to achieve dense jump points, large in working current, and large in size; in indirect synthesis, although the system is simple in structure, high in reliability, low in cost, High wave suppression, easy to achieve dense jump points, small operating current, and small size, but it must be combined with direct synthesis when forming broadband frequency hopping, and the slow frequency hopping speed and poor phase noise are inevitable shortcomings . At present, the frequency hopping...

AI Technical Summary

Problems solved by technology

It has the advantages of relatively simple system composition, low cost, and small volume. Because it uses indirect synthesis, its clutter suppression is good and the complexity is not high.

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