SU951724A1 - Device for intercharacter interference adaptive correction - Google Patents

Description

one

The invention relates to communication technology and can be used to correct intersymbol interference in modulated signals transmitted by multiphase modulation methods.

A device for adaptive intersymbol interference correction is known, containing modulo two first and second adders, the inputs of which are the sign inputs of the amplitude amplitude of the modulated signals from the device nominal, and the output of each of which is connected via the corresponding block of the sign of the amplitude deviation of the modulated signal from the nominal to the input of a modulo-two adder unit, the output of which is connected to the input of a switchboard unit, the first control input of which is the amplitude input of the device, Ora input coupled to the clock output unit many programs, which is input a

the clock input of the device, the second input of each modulo-two adder, which is the input of the polarity of the corrected signal of the device, is connected through the corresponding memory blocks of the modulated signal to another input of the modulo-adder unit two, the output of the software block is connected to the synchronization inputs memory

To the sign of the amplitude deviation of the modulated signal from the nominal and memory blocks of the modulated signal, another synchronization output of the program block is connected to

15 to the synchronization input of the digital harmonic equalizer, the other input of which is the analog input of the device, and the output of the switch unit through the digital harmonic core 20, the rector is connected to the output of the GO device.

However, the known device has a low accuracy of adaptive correction.

The purpose of the invention is to improve the accuracy of adaptive correction by compensating for distortions arising due to integral shifts of coherent oscillations.

This goal is achieved by the fact that the device for adaptive core: intersymbol interference responses contains the first and second modulo-two adders, whose inputs are the characters of the amplitude deviation of the modulated signals from the device nominal, and the output of each of which is connected via the corresponding character storage unit From 1 are the amplitude of the modulated signal from the nominal to the input of the block of modulo-adders, the output of which is connected to the input of the block of switches, the first control input of which is in ode amplitude of the device, the second input is connected to the clock output of the program block, the input of which is the clock input of the device, the second input of each modulo-two adder, which is the input of the polarity of the corrected signal of the device, is connected through another corresponding memory blocks of the modulated signal the input of the modulo two adders, the synchronization output of the program block is connected to the synchronization inputs of the memory blocks of the sign of the amplitude deviation of the modulated signal. and the memory blocks of the modulated signal polarity, another sync output of the program block is connected to the sync input of the digital harmonic equalizer, the other input of which is the analog input of the device, and the output is the output of the device, a control signal memory block, an additional modulo two and the additional switch, the control input of the device is connected to the control input of the memory of the control signals, the output of which is connected to the input of the additional switch, the second input which, through an additional modulo two, is connected to the outputs of the memory blocks: the polarity of the modulated signal, the output of the switch unit through the additional switch is connected to another input of the digital harmonic equalizer, and the output of the synchronization of the program block is connected to the input

synchronization of the control signal storage unit.

FIG. 1 shows a block diagram of the device, 5 FIG. 2 - vector diagram.

A device for adaptive intersymbol interference correction comprises a modulo two adder 1, a memory block 2 of the sign of the amplitude deviation of the modulated signal from the nominal, a modulated signal polarity block 3, a modulated signal block H, two modulators, a software block 6, digital 15 harmonic equalizer 7, control signals memory block 8, modulo two additional adder 9, additional switch 10.

The device works as follows.

The device compensates for intersymbol interference in accordance with the following expressions: - when compensating for the common-mode, 25-influence

5 and 5 pao © 5d а | © «Sfne U)

SQ H -5gvia ®s ha | -®sgneJ

i f hm- | g: h

- when compensating for quadrature interfering influence

c, grM-br sgVia ® 5dgia7®5d ee5 (h)

L4ntjl

sgyiii rsQrMaf © s§Haf®s he5c4)

R

  where is the sign of the projection of signals subject to the interfering effect on the coherent oscillations I and D, respectively;

5 иа ;; - and egncl - the sign of the projection of signals that create an interfering effect on the coherent oscillations of J and TT COOT jj

591 С-и9д Иб, is the sign of the projection of the amplitude deviation of the modulated signals ap and ao from the nominal value relative to coherent oscillations and T, respectively. Modul two are connected to the inputs of the first adder 1. Two SgfMef signals are received from the corresponding receiver outputs (not shown), and the Sg-HOil and signals go to the inputs of the second adder 1 QO module two. The signals from the outputs of the first and second summares 1 modulo two are recorded, respectively, in the first and second blocks 2 of the memory of the sign of the amplitude deviation of the modulated signal from the nominal value. In addition, the Sgvia and egMC signals are recorded in the first and second blocks of 3 polarities the modulated signal, respectively. From the output of blocks 2 and 3, the signals are received in a unit two modules modulo two, where the signals are generated. , f and in accordance with expressions (1) - (D) Signals from the output of the k block of modulators modulo two are sent to the switch block 5, in which the selection of the appropriate direction of adjustment of the device tap transfer coefficients is determined depending on what interfering effect Compensation is common mode. Or quadrature. After integrating the signals about the sign of change of the transfer coefficient of the analyzed tap into the digital harmonic equalizer, the code number corresponding to the transfer coefficient of the tap regulator is recorded in the transfer coefficient memory part of offset 7 (not shown). The second input digital harmonic equalizer 7 from the receiver output receives analog signals a and bp, converted into digital samples by means of an analog-digital converter. In accordance with the algorithm of operation of software block 6 in digital harmonic equalizer 7, sequential (for each of the taps) multiplication of the digital words of the sample code and the controller gain is derived from the corresponding memory blocks (not shown) of the corrector 7. The resulting product , Tc, e. the digital signals at the taps of the taps controllers are sequentially summed up, as a result of which two otkroizirovanny digital signals a and eo are formed at the output of the corrector 7, which are fed into the receiver solver (not shown) for decoding and shaping the device control signals. This process continues until such transfer coefficients of tap controllers are recorded at which the amount of intersymbol interference is minimal. The ability to change the transmittance of the device tap controllers, both by direct and cross-linking, allows compensation of distortions in the a: p and a signals due to integral shifts of coherent oscillation. Suppose that the positions of the vectors of received signals in space are as shown in Fig. 2 (dots in Fig. 2 indicate the possible positions of the end of the vector of the received signal). From FIG. 2 it follows that in all the variants presented there may be cases where the vectors of the received signal coincide with one of the coherent oscillations (I or L). Suppose that signals are transmitted by the method of eight-phase modulation, as shown in FIG. 26 (similar considerations can be made for the signal space shown in FIG. 2a and c). In this case, the signal vector a can take eight positions, numbered 26 in figures 1-8. Suppose that the coherent oscillations JL and GT have shifted in phase by an angle f. The new positions of the signal vectors in FIG. 26 are marked with numbers 9-16. The resulting signal distortion is not a result of intersymbol interference, therefore the transfer coefficients of the regulators of all taps, except central ones, will remain unchanged. Suppose that the signal vector takes up the position indicated in Fig. 2b by the digit 1 When the coherent oscillations are offset by the angle D, the signal vector will take the position indicated on b digit 9. In this case, the output signal of the device is reduced by the value of Cd, in addition.

at its output, the Wits signal a is equal in magnitude 1. Thus, to compensate for the distortions, a 1 C 1 S due to a shift in the coherent oscillation (in the considered example) a signal a must be increased due to the addition of the a signal a cross link. | - and 6- should be reduced by the addition of cross-linking. with the desired signal sign a.

. Assume that the signal vector occupies the position indicated in FIG. 26 by number 2. When shifted by angle H, the signal vector will take the position indicated by 26 in figure 26 of Fig. 26. In this case, the signal a will be reduced by an amount, and a signal will be recorded at the output of the P9 device

L-4 -,

. Thus, in order to compensate for the distortion arising due to coherent oscillation, the signal a o should be — differentiated by the addition of a signal a Q. Similarly, the a5 K signal should be reduced by the addition of a cross-link with the desired sign of the a signal. - In addition, the increase in the aQ signals in the first example and the aQ in the second example is also done by increasing the transmission coefficients of the central tap controller along the direct connections of the device.

From the considered examples it follows that the expressions (3 and () when used cannot be used, since they give a false decision.

It is necessary to convert them into

) in | SQ HaJesg a (5)

Taking into account that the coherent oscillations of I and P must be orthogonal, it is possible to compensate for the distortions due to their integral shift by normalizing the amplitudes of the signals aH and

eleven

but. In order to carry out this process, it is necessary to identify those situations where the received signals are in space with coherent oscillation. For this, the receiver (not shown) generates control signals .gfHZ and Zr- about the coincidence of the received signal a ;; with coherent oscillation I or C „

For the purpose of the necessary joint in time, the signals SQn /.- and Sgvi 7. are sent to the block 8 of the memory of signals

5172t8

management The control signal from the output of the memory block 8 is fed to the additional switch 10 only at the time corresponding to the operations in

5 central branch by cross-links and determined by program block 6.

In the additional adder 8 modulo two, the operations are implemented in

10 according to the expression S5L. In the additional switch 10, according to the control signals from block 8, the signal about the sign of the coefficient change is selected.

15 transmissions of central tap controllers over device cross-links. If the compensation of inter-character interference is performed (the device operation algorithm is described

20 with expressions (1) - {), then. If the compensation of distortions from 25 for the integral shifts of coherent oscillation is compensated (the algorithm of the device operation is described by the expression (5), then the input of the corrector 7 receives the signal from the output of the additional adder

3 (j 9 on m odul two.

As a result of this adjustment, the amplitudes of the signals a and ag will take non-nominal positions.

Thus, the proposed device improves the adaptive accuracy. correction by compensating for distortions arising due to integral, shifts of coherent Oscillations.

Claims (1)

Invention Formula A device for adaptive intersymbol interference correction, containing the first and second modulo-two adders, whose inputs are the characters of the amplitude deviation of the modulated signals from the device nominal, and the output of each of which is connected through the corresponding memory of the sign of the amplitude of the modulated signal from the nominal to the input block adders modulo two whose output is connected to the input of the switch unit, the first control input of which is the amplitude input of the device, the second input is connected to the clock output of the program block, the input of which is the clock input of the device, the second input of each modulo two that is the input of the device KtMposaHHoro device, connected via the corresponding memory blocks of the modulated signal to another input of the modulo two adders block; the synchronization output of the program block is connected to the synchronization inputs of the memory blocks; As the amplitude of the modulated signal deviates from the nominal and memory blocks of the modulated signal, another sync output of the program block is connected to the sync input of a digital harmonic equalizer whose other input is an analog input of the device and the output of the output of a device different from Tetj that , in order to increase the accuracy of adaptive correction by compensating for the distortions arising from the integral shifts of coherent 4 oscillations, a control signal memory block was inserted; A modular two adder and an additional switch, the control input of the device are connected to the control input of the control signal storage unit, the output of which is connected to the input of the additional switch, the second input of which is connected to the outputs of the memory modulated memory blocks through an additional modulator adder. signal, the output of the switch unit through an additional switch is connected to another input of the digital harmonic corrector, and the No. 1 synchronization input of the program block is connected to the sync input Signalization of the memory of control signals. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 780209, cl. H Oil In ZM, 1978 (prototype). 95172t  -.