METHOD FOR THRESHOLD DETECTION OF OPTICAL SIGNALS Russian patent published in 2022 - IPC G01R19/175 H01L31/107 

FIELD: optical technology.

SUBSTANCE: invention relates to the reception of optical signals, in particular to the technique of receiving signals using avalanche photodiodes, and can be used in location, communication and other photoelectronic systems. The method for threshold detection of optical signals using an avalanche photodiode includes threshold signal processing and the formation of output pulses using a threshold device when the signal from the output of the photodiode exceeds the specified trigger threshold. In this case, the non-multipliable component of the square of the noise current brought to the output of the photodiode is preliminarily determined, and the second threshold I_thr2, brought to the output of the photodiode, is set within the limits of , the square of the non-multipliable noise current brought to the output of the photodiode. The bias voltage of the photodiode is set at a level at which the signal-to-noise ratio is maximum, after which the offset voltage is reduced until the estimate ϕ₂ of the relative frequency of exceeding the threshold I_thr2 by microplasma emissions drops to the maximum permissible level where is the number of allowed intervals at the control interval T₂; ΔT is the allowed time interval; n₂ the number of exceedances of the threshold I_thr2 during T₂; Q_M is the permissible probability of occurrence of microplasmas during T₂; t is the parameter of the statistical spread of the estimate ϕ₂. After that, the bias voltage is fixed and the threshold I_thr1 is set at a level at which the frequency f₁ (1/s) of noise exceeding the threshold I_thr1 has a stationary value f₁ << f₀, where f₀ is the frequency of noise crossing the zero level. At the same time, the input of I_thr1 is blocked for the time of each exceeding of the threshold of I_thr2. After setting the threshold I_thr1, it is increased by a factor of , where f_p is the maximum permissible frequency of false alarms in operating mode. Then the threshold I_thr1 is fixed and signals are received.

EFFECT: achieving the maximum sensitivity in all operating conditions, taking into account microplasma breakdowns and normal noise with a minimum time to reach the optimal avalanche mode.

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