Limited random frequency difference reflection control method of microwave signal

Abstract

The invention provides a limited random frequency different reflection control method of a microwave signal. The limited random frequency different reflection control method of the microwave signal comprises the following steps: step 1, setting a frequency different signal, converting the frequency difference signal to a sin signal and a cos signal when the frequency different signal passes in a FPGA (Field Programmable Gata Array), and inputting the sin signal and the cos signal to a modulator; step 2, performing demodulation on a coupling power of an input signal, then processing the coupling power, controlling a voltage-controlled attenuator, and adjusting the voltage-controlled attenuator to a proper power range; step 3, setting a power of an output signal to realize stable amplitude control on a gain at an amplitude stabilizing ring. Due to the adoption of the limited random frequency different reflection control method, the offset of a carrier wave and the suppression of an image frequency can be effectively suppressed by a calibration modulator; a spurious signal is reduced, so that the phase noise worsening degree is constant in the process of changing the frequency in a whole channel, and the reliability is realized due to a small frequency difference.

Description

technical field [0001] The invention belongs to the technical field of microwave signal control, and in particular relates to a limited arbitrary frequency difference reflection control method of microwave signals. Background technique [0002] At present, any frequency difference adjustment can be applied to devices such as radio altimeter simulators, which are important instruments for testing the accuracy of airborne radio altimeters, and can be widely used in military and civilian multi-arms and multi-aircraft altimeter inspections. The radio altimeter is an important measuring element for various aircraft and missiles, and its performance determines the control quality of the longitudinal flight path of the aircraft. Its working principle is to track the altimeter output scanning signal in real time, generate a signal with a fixed frequency difference from the scanning signal through frequency synthesis, and output it to the altimeter receiver as feedback. Any frequenc...

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Problems solved by technology

[0004] First, the main disadvantage of the equivalent length cable box simulation scheme is that the frequency difference is not continuous because the cables cannot be continuous at any length, and because the length of the cable is limited, the simulation range is limited. of

The second is to adopt the scheme of mixer + DDS. Multi-level frequency conversion not only leads to the complexity of implementation, but also introduces spurious signals that interfere with the accuracy of measurement. Currently, DDS needs multiple frequency multiplications due to frequency limitations, resulting in spurious More, and the phase noise itself is poor. After frequency doubling, the phase noise will be further deteriorated, which will not meet the test requirements when the frequency difference is small.

Moreover, the complexity of the implementation circuit is difficult to meet the needs of field testing, and the power consumption is relatively large.

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