Adaptive broadband amplifier-limiter - band amplifier

 

The invention relates to electrical engineering and can be used as part of foster radar, radio navigation and radio communication devices. The technical result consists in increasing the efficiency of detection of weak signals on the background of additive broadband noise in conditions of a priori uncertainty about the statistical characteristics of the interference, for this sample input additive mixture of signal and noise at low signal-to-noise ratio at the input, calculates the current parameter estimate of noise variance, which is used to form level fluctuations at the output of the broadband amplifier (SHU) (2), the Device also contains discretization (1), guard (3), narrow-band amplifier (4), squarer (5), calculator square root (6), the amplifier (7), the adder (8), integrator (9), the first and second multiplier products (10, 13), the drive (11) and the divisor (12). 1 Il.

The invention relates to electrical engineering and can be used as part of foster radar, radio navigation and radio communication devices operating in the conditions of additive effects of broadband noise, detection of weak signals.

Know the th amplifier (SHOW) (Y. S. Lezin introduction to theory and technique of radio systems: textbook for universities. - M.: Radio and communication, 1986, - 280 C.) a Disadvantage of the known device SHOWS is that the principle of its action is based on the selection of the first harmonic of the input additive mixture at the output of the broadband amplifier while limiting fluctuations to meander, it fails to account for possible changes in the intensity of additive broadband noise and narrowband energy input device.

The technical result of the invention is to improve the efficiency of detection of weak signals on the background of additive broadband noise.

The invention consists in that the known device is a SHOW consisting of series-connected broadband amplifier, limiter and narrow-band amplifier is additionally connected to the input of the broadband amplifier discretization, the entrance of which is an input device, in addition, the output of discriminator connected serially connected squarer, calculator square root, amplifier, adder, integrator and the first multiplier, the output of which is connected to the second regulating the input of the limiter, in addition, to the output of the Quad are connected serially connected drive and the divider output share is resident, the second input is connected to the output of the first multiplier and the output of the second multiplier connected to the second input of the adder, the output of the limiter is connected to the input of the narrowband amplifier whose output is the output of the adaptive device SHOWS.

The drawing shows a block diagram of an adaptive device SHOWS.

Adaptive device SHOW contains serially connected discretization 1, a broadband amplifier (SHU) 2, terminator 3, and narrow-band amplifier (SU) 4 whose output is the output device, the output of discriminator connected serially connected squarer 5, calculator square root (CWC) 6, the amplifier 7, the adder 8, the integrator 9 and the first multiplier 10, the output of which is connected to the second regulating the input of the limiter 3, the output of the Quad 5 connected in series United drive 11 and the divider 12, the output of which is connected to the second input of the first multiplier 10, in addition, to the output of the Quad 5 connected to the first input of the second multiplier 13, the second input is connected to the output of the first multiplier 10, and the output connected to the second subtractive input of the adder 8.

Under ideal limit input additive mixture from the outside of the U0the output swing of the limiter is a meander ħU0. The signal energy E and the spectral intensity of the interference at the output of the limiter are defined respectively by the expressions

where=4/the coefficient of the first harmonic, the resulting limitation to the level U0;FW- bandwidth SHU.

For xed U0signal-to-noise ratio at the input YY

does not depend on the energy ratio of the useful signal and additive noise, and when changing the noise intensity of the selected scheme becomes ineffective.

When describing the probabilistic characteristics of the broadband noise can be used the Laplace distribution as the probability density functions

where>0 is a parameter of the noise intensity.

Adaptation-level restrictions on the parameter of the intensity of interferenceis implemented using instantaneous nonlinear transducer characteristic of the species

If e is the amplitude of the useful signal.

Parameter estimation of intensity of interferencerequired for installation of level fluctuations at the output of SHU, is formed using a criterion based on the minimization of the average value of the functional

where n is 0, 1, 2,...

In the absence of a priori data, replacing the averaging over the ensemble averaged over time, taking into account the sampling input of the additive mixture according to the time, when n=2, the procedure of finding the rootequation (6) is expressed by the following recurrent algorithm

where xi=x(ti); ti=it; i=1...N; N is the sample size;t=1/f;f is the bandwidth of the linear channel receiver; Gi- element of a sequence of positive numbers.

The choice of Gidetermines the convergence of the adaptation algorithm (7). In the absence of a priori data, you can use the following next

Thus, in the inventive adaptive device SHOWS calculated current tint setting the intensity of additive broadband pomaceae formation threshold level of the limiter, proportional to the value of the noise intensity.

Adaptive device SHOW works as follows. At the entrance of discriminator 1 is an additive mixture of the useful signal s(t) and noise n(t)

x(t)=s(t)+n(t).

At the output of discriminator 1 is a sequence of xi=si+nithat is simultaneously applied to the inputs SHU 2 and Quad 5. Output SHU 2 sequence of samples enhanced additive mixture xiserved on a first information input of the limiter 3. Output Quad 5 sequence of samplescomes in parallel to the inputs of VPC 6, the drive 11 and the first input of the multiplier 13. Output VCC 6 are formed ADUthat are amplified with the amplification factor equal to 2 in the amplifier 7, and fed to a first input of the adder 8. At the output of the memory 11 are formed ADUserved on the input of the divider 12. At the output of divider 12 are formed ADU -served to the second input of the multiplier 10. To the second input of the multiplier 13 are samples of the current parameter estimation of noise variancethe fot to the second input of the adder 8. At the output of the adder generates samplesthrough the integrator 9 is served at the first input of the multiplier 10. From the output of the multiplier 10 times the current parameter estimation of noise varianceserved on the second regulating the input of the limiter 3, so you can install level fluctuations, coming to the first input of the limiter 3. From the output of the limiter 3, the resulting oscillation is fed to the input SU 4 whose output is the output of the adaptive device SHOWS.

The comparison of the proposed solutions with other technical solutions shows that the device SHOWS widely known. However, their use in combination with the proposed method of obtaining the current parameter estimation of noise variance, allows to obtain new properties that increases the efficiency of detection of weak signals in terms of additive effects of broadband noise with unknown statistics.

Claims

Adaptive device detection of weak signals on the background of additive broadband noise containing connected in series broadband amplifier, limiter, and is additionally connected discretization, the input which is the input device and the output of which is connected to the input of the broadband amplifier, the output of discriminator additionally connected serially connected squarer, calculator square root, amplifier, adder, integrator and the first multiplier, the output of which is connected to the second regulating the input of the limiter, the output of the Quad is additionally connected in series connected drive and the divider, the output of which is connected to the second input of the first multiplier, the output of the Quad connected to the first input of the second multiplier, the second input is connected to the output of the first multiplier and an output connected to the input of the adder.

 

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