RU2732005C1 - Pulse signal reception method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to the reception of signals, in particular to the technique of signal extraction from noise, and can be used in any area where it is required to provide maximum signal-to-noise ratio. For this purpose, in the method of receiving pulse signals by adjusting the threshold level depending on the frequency of its excess noise, frequency f₀ of the threshold device triggering from the noise action at zero threshold value is pre-determined, setting threshold at level 0 < U₁ < U₂, then increasing threshold to level U₂, simultaneously determining frequency f of noise operations, and at frequency f = f₂ = kf₀, where k is a predetermined coefficient from the range of k = 0.01…0.9, increasing threshold by m times to level U₃ = mU₂ and receiving pulse signals.

EFFECT: technical result consists in considerable reduction of time for entering the mode.

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Description

The proposed invention relates to signal reception, in particular, to the technique of separating signals from noise and can be used in any field where maximum signal-to-noise ratio is required.

A known method of stabilizing the average frequency of noise emissions above the threshold level [1-2], which consists in determining the frequency of noise alarms at the output of the threshold device and automatic adjustment of the threshold to maintain a given response frequency.

The closest in technical essence to the proposed method is a method for receiving pulse signals [3] by adjusting the threshold level depending on the frequency of its excess noise. According to this method, the frequency f is determined by accumulating output pulses during the time T, and the threshold U in the steady state is determined by the expression U = U ₀ + U _f = U ₀ + ΔUTf ₀ exp (-U ² / 2σ ² ), where U ₀ - the initial value of the threshold; f ₀ - frequency of crossing the zero threshold by noise; σ is the root-mean-square noise value; ΔU is the unit increment of the threshold along the feedback loop when the noise crosses the threshold.

The disadvantage of this method is a slow exit to the operating mode due to the fact that in the process of establishing the operating threshold, the frequency of noise responses decreases, and the speed of the transient process, proportional to the current frequency, decreases. According to [3], the time T _{r of} reaching the operating mode with this method is 1-6 s, depending on the requirements for the accuracy of stabilization of the frequency of noise operations.

The object of the invention is to reduce the time to reach the operating mode.

, где f₃ - допустимая частота ложных срабатываний в режиме приема сигналов.This problem is solved due to the fact that in the known method of receiving pulse signals by adjusting the threshold level depending on the frequency of its excess noise, the frequency f _{0 of} the threshold device triggers from the effect of noise is preliminarily determined at a zero threshold value, the threshold is set at the level 0 <U ₁ <U ₂ , then the threshold is increased to the level U ₁ <U ₂ <U ₃ , while simultaneously determining the frequency f of noise operations, and at a frequency f = f ₂ = kf ₀ , where k is a predetermined coefficient from the range k = 0.01 ... 0.9, increase the threshold m times to the working level U ₃ = mU ₂ after which this threshold is fixed and signals are received, and,

, where f ₃ is the permissible frequency of false alarms in the signal reception mode.

An equivalent threshold U ₃ can be introduced by introducing an attenuation with a factor of m before the signal threshold processing.

The technical result of the invention is the minimum time for reaching the operating mode of the threshold signal detector while ensuring the maximum probability of signal detection.

FIG. 1 shows a diagram of a device that implements the method. FIG. 2 shows the sequence diagram of the method.

As shown in FIG. 1, the threshold detector contains a comparison circuit 1, the input of which is a signal-to-noise mixture, and a pulse former 2 is turned on at the output, generating pulses of standard amplitude and duration when the threshold of the comparison circuit is exceeded by the signal-to-noise mixture. Between the output of the pulse shaper 2 and the control input of the comparison circuit 1, a feedback circuit 3 and a circuit for raising the threshold 4 are connected, which close the noise automatic control loop. Threshold raising circuit 4 is controlled by a serially connected threshold frequency meter 5, connected to the output of the pulse shaper, and an operating threshold computer 6. The latter outputs the result of the threshold calculations to the threshold increasing circuit 4 and a sync signal for switching - to the switching circuit 7, which controls the threshold raising moment. A switch 8 is installed at the output of the pulse shaper, which opens the circuit output when a clock signal is received from the switching circuit 7. If the value of the coefficient m is fixed, then the equivalent increase in the threshold can be carried out by turning on the attenuator 9 installed at the input of the comparison circuit.

FIG. 2 shows the flow of the method. T ₁ - stabilization time; T ₂ is the time for switching the threshold; T ₃ - operating time (operating mode).

The method is carried out as follows (Fig. 2).

По окончании переходного процесса переключения в момент времени t₃ фиксируют порог на уровне U₃, открывают ключ 8 и, тем самым, переходят в рабочий режим приема сигналов.At the moment of time t ₁ , the initial level of the threshold U _{1 is set} and the key 8 is locked, blocking the appearance at the output of triggering from exceeding the threshold by noise. During the time T ₁ = t ₂ -t ₁ , the threshold is stabilized by adjusting it by the value of ΔU for each noise excess of the threshold of the comparison circuit 1 and the corresponding actuation of the pulse former 2. The addition of ΔU is formed using the feedback circuit 3 associated with the increase circuit threshold 4, that is, using the automatic noise control SHARP [3]. At time t ₂ , the stabilization process is stopped and the threshold is raised to the level U ₃ = mU ₂ , where

At the end of the transient switching process at the time t _{3, the} threshold is fixed at the level U ₃ , the key 8 is opened and, thus, the signal is received in the operating mode.

The period T ₁ should provide an output to a stable mode of frequency f ₂ . The frequency f _{2 is} selected from the condition that two opposite requirements are fulfilled. On the one hand, the frequency f ₂ should be as close to f ₀ as possible in order to minimize the time T ₁ reaches the stabilization mode. On the other hand, the difference between f ₂ and f ₀ must be significant in order to provide the necessary accuracy in the calculation and setting of the operating threshold. For existing initial data, the ratio f ₂ / f ₀ should be in the range of 0.01 <f ₂ / f ₀ <0.9.

The frequency f of crossing the threshold U by a normal process with variance σ ² and the correlation coefficient R (τ) is determined by the expression [3]

- частота пересечения нулевого порога.Where

- the frequency of crossing the zero threshold.

From (1) and Fig. 2 follows

And correspondingly,

where U ₃ and f ₃ are the operating values of the threshold and the frequency of noise operations after the moment t _{3 of} entering the operating mode.

The stabilization period T ₁ is determined by the well-known method [3], and T ₁ and the time to reach the mode T _pr , provided by the prototype, are related by the obvious relationship

Example 1. f ₀ = 10 ⁷ Hz; f ₂ = 0.8 f ₀ = 8⋅10 ⁶ Hz; f ₃ = 100 Hz; T _pr = 1 s (low stabilization accuracy). The proposed method with these initial data provides a stabilization period T ₁ = 1.25⋅10 ^-4 s.

The switching time T ₂ is determined by the speed of the electronics used and can be ignored.

The prototype provides an exit to the mode in T _pr = 1-6 s [3]. Thus, the maximum gain of the proposed method in terms of speed is T _pr / T ₁ = 80,000 times.

This method allows:

- Significantly reduce the time required for the threshold detector to reach the operating mode to 1 ms or less.

- Ensure operation in frequency mode, which is essential for a number of applications, for example, in frequency rangefinders, when updating information with a frequency of up to 1000 Hz.

- Provide work with non-stationary noise.

- Provide the maximum value of the threshold noise ratio with high accuracy.

These conclusions are confirmed by computer modeling and testing of prototypes. Thus, the solution to the task was confirmed - a significant reduction in the time to reach the operating mode.

Sources of information

1. US pat. No. 3516751. Optical radiation pulse control receiver. 1970.

2. Burd A.M., Leichenko Yu.A., Motenko B.N., Popov A.C. Temperature stabilization of a photodetector with APD // Instruments and experimental techniques. - 1975. - No. 4, - S. 176-178.

3. Vilner V.G. Design of threshold devices with noise threshold stabilization. // Optical and mechanical industry. - 1984 - No. 5, - S. 39-41. - prototype.

4.G. Korn, T. Korn. Handbook of mathematics (for scientists and engineers). - "Science", M., 1973 - 832 p.

Claims (2)

1. A method for receiving pulse signals by adjusting the threshold level depending on the frequency of its excess noise, characterized in that the frequency f _{0 of} the threshold device triggers from the effect of noise at a zero value of the threshold is pre-determined, the threshold is set at the level 0 <U ₁ <U ₂ , then the threshold is increased to the level U ₁ <U ₂ <U ₃ , while simultaneously determining the frequency f of noise operations, and at a frequency f = f ₂ = kf ₀ , where k is a preset coefficient from the range k = 0.01 ... 0.9, increase the threshold m times to the operating level U ₃ = mU ₂ , after which this threshold is fixed and signals are received, and

, where f ₃ is the permissible frequency of false alarms in the signal reception mode. 2. A method according to claim 1, characterized in that the equivalent threshold U ₃ is introduced by introducing an attenuation with a coefficient m before the threshold signal processing.

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