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The large dynamic range of the satellite-borne laser altimeter receiver is a necessary condition for obtaining high-precision ranging values. The upper and lower limits of the dynamic range reflect the ecological adaptability of the altimeter. The power of the echo signal is given in the performance of the altimeter, atmospheric reflection, and target surface reflection. If the waveform of the strong echo signal with high ground reflectivity and specular reflection appears saturated, broadened and distorted, it will interfere with the extraction of helpful information during waveform inversion and affect the accuracy of ranging. Although the waveform saturation can be corrected by the mid-to-late GLAS correction method, this paper proposes a high-sensitivity signal detection technology for a space borne laser altimeter with a large dynamic range, which is suitable for laser altimeters with any linear detection system without waveform saturation. The correction can obtain a larger dynamic range, and the mechanism analysis does not require the dual-channel gain method to obtain a larger dynamic range. In this paper, the method of combining Bessel filter and adjustable gain amplifier is utilized to optimize the design bandwidth to suppress noise, and the sensitivity is not less than 5.1nW. If the parameters are not adjusted, the dynamic range is not less than 33.7dB; if the parameters are adjusted, the sensitivity is not Below 1nW, the dynamic range is about 73.9dB. Through the ground vacuum environment test, under the condition of high signal-to-noise ratio, the ranging accuracy is better than 0.08m; when the signal-to-noise ratio is not less than 8, the ranging accuracy is not less than 0.4m.
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