JPH03131118A - Signal weighting circuit for adaptive matching filter - Google Patents

Abstract

PURPOSE:To apply correct weighting to an input signal by varying the amplification factor of a variable amplifier or the attenuation of a variable attenuator depending on the level of the input signal. CONSTITUTION:A correlation device 21 takes correlation between the input signal 1 of an N-value level and a reference signal 3 and the result is outputted to an amplifier or an attenuator 4. On the other hand, a controller 5 generates a control signal corresponding to the level of the reference signal 3 and the control signal varies the amplification factor of the variable amplifier or the attenuation of the attenuator 4 to make the output signal to be all identical when the correlation is a unity. Thus, a correct correlation corresponding to each level is obtained. The output signal is supplied to an integration device 23 and its integration value is multiplied with the input signal 1 at a multiplier 22 to apply correct weighting to the input signal 1, and the resulting output signal 2 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a signal weighting circuit for an adaptive matched filter, and more particularly to a weighting circuit for input signals in an adaptive matched filter having multiple taps.

[Conventional technology]

Conventionally, the weighting circuit for each tap of an adaptive matched filter is
It looks like the configuration diagram in the figure. In the figure, input signal 1
is correlated with the reference signal 3 by a multiplication operation in a correlator 21, and after being adjusted to an appropriate level in an amplifier or attenuator 26, an integrator 23 obtains an integral value of the correlation value.

This value is multiplied by the multiplier 22 to limit the amount of input signal 10 passing through, so that signal 2 can be obtained. For example, when the correlation value is 1, the input signal becomes the output signal 2 as it is, and when the correlation is O, 0 is given to one of the multipliers, and there is no output signal to prevent the output signal 2.

Now, for a signal such as a 4-phase PSK signal where the level is constant in each layer, there is no problem in standardizing the reference signal level to 1 and correlating this with the input signal. However, when applied to multi-layer multi-value, even if the correlation is 1 and the correlation is perfect, the correlation value will differ depending on the signal level. For example, A/Ns where the input signal is the minimum level 1/N and the maximum level 1.
In the case of a signal of inwt (where W is a carrier wave angular frequency and A is an integer from 1 to N), the correlation value W is expressed by the following equation.

W= (A/Ns in wt) (A/N
s i nwt )=(A/N) 2 In the above equation, (A/N) 2 represents the amplitude of the fundamental wave of the product of A/N sinwt.

Now, if N=4 and A=1 and A=4, the correlation values will be 1 and 1/16, respectively, and the absolute value of the correlation value will vary greatly depending on the level.

[゛Problem to be solved by the invention]

In the signal weighting circuit of the conventional adaptive matching filter described above, even though the signal is actually a 1 signal with completely matched correlations, the weighting may be small, so it is always This method has the disadvantage that correct correlation values cannot be obtained in the case of a multi-level input signal whose level is changing.

[Means to solve the problem]

The signal weighting circuit of the adaptive matching filter of the present invention aggregates the input modulated signal of the N value (an integer of N22) level with the reference signal and calculates the correlation with the black correlator, and the output signal level of the correlator. an amplifier or attenuator that sets the correlation value to a predetermined level; an integrator that integrates the correlation value at the predetermined level; and a multiplier that multiplies the output signal of the integrator by the input modulation signal to obtain an output signal. a variable amplifier or variable attenuation in which the amplification ratio or attenuation ratio is switched in response to a reference signal that the amplifier or attenuator multiplies with the correlator to take a correlation; It is a vessel.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

An N-valued input signal 1 is correlated with a reference signal 3 by a correlator 21 and output to an amplifier or attenuator 4.

On the other hand, the controller 5 generates a control signal corresponding to the level of the reference signal 3, and this control signal changes the amplification ratio or attenuation ratio of the variable amplifier or attenuator 4, so that when the correlation is 1, all output signals are equal. I will make it happen. For example, in the case of 4 values, the signal level is 1/4.2/4.3/4.4/4, and the correlator output is 1/16.4/16.9, respectively, even when the correlation is 1.
/16°16/16, but if this is adjusted by the variable amplifier 4 so that they all become 1, correct correlation values corresponding to each level can be obtained. If these are passed through an integrator 23 and the multiplier 22 is multiplied by the integrated value, an output signal 2 in which the input signal 1 is correctly weighted can be obtained. Even when the input level decreases, the level of reference signal 3 does not change, so the correlation value decreases by the amount that the input level decreases.This means that it is possible to always obtain a correct correlation even when the input signal is distorted. This is clear from the previous explanation.

〔Effect of the invention〕

As explained above, the present invention eliminates variations in correlation values and obtains correct correlation values by changing the amplification ratio or attenuation ratio of the variable amplifier or variable attenuator after correlation depending on the input signal level. This has the effect of correctly performing weighting.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a weighting circuit of a conventional adaptive matching filter. DESCRIPTION OF SYMBOLS 1... Input signal, 2... Output signal, 3... Reference signal, 4... Variable amplifier or variable attenuator, 5... Controller, 21... Correlator, 22... Multiplier, 23...
Integrator, 26... amplifier or attenuator.

Claims (1)

[Claims] a correlator that multiplies the input modulation signal of the N value (an integer of N≧2) level with a reference signal and correlates it; an amplifier or attenuator that sets the output signal level of the correlator to a predetermined level; In a signal weighting circuit for an adaptive matching filter, the signal weighting circuit includes an integrator that integrates a correlation value of a predetermined level, and a multiplier that multiplies the output signal of the integrator and the input modulation signal to obtain an output signal. , wherein the amplifier or attenuator is a variable amplifier or variable attenuator whose amplification ratio or attenuation ratio is switched in response to a reference signal that is multiplied by the correlator to take a correlation. Signal weighting circuit.