SU866757A1 - Device for receiving signals with adaptive correction of intersymbol interference - Google Patents

Description

The invention relates to telecommunications. It is known that a device for receiving signals with adaptive correction of inter-symbol interference (MCI), containing a series-connected band-pass filter and an amplifier, the output of which is connected through the first and second demodulators to the first inputs of the analog-to-digital converters, the other inputs of the two demodulators In addition to the oscillation, the output of the first demodulator is connected to the first input of the clock-oscillator; and also the successively connected adsorption corrector and descrambler 11. However, the known device has insufficient noise immunity. The purpose of the invention is to improve noise immunity. To achieve this goal, the device for receiving signals with adaptive correction of the MCI, contains a series-connected bandpass filter and an amplifier, the output of which is connected via the first and second demodulators to the first inputs of analog-to-digital converters, the other inputs of both demodulators are connected with the outputs of the carrier-free oscillator, the output of the first demodulator is connected to the first input of the clock oscillator, as well as the serially connected adaptive equalizer and descrambler, the intermediate memory block, the subchannel selection shaper unit, the operation mode setting unit and the gain setting unit, the output of the operation mode setting unit are connected to the second input of the clock selection unit and one output of the subchannel selector signal generator, the other input of which is connected to the output of the selection unit clock oscillations, and outputs - with the second inputs of analog-digital converters, the outputs of which are connected to the inputs of the block of intermediate memory, the output of which is connected to the adaptive correction rum, which is associated with the gain setting unit. The drawing shows a structural electrical circuit of the proposed device. The device contains a band-pass filter 1, an amplifier 2, demodulators 3 and 4, analog-digital converters 5 and 6, a carrier oscillator 7, a clock oscillator 8, an adaptive equalizer 9, switch 10, an intermediate memory block 11, a driver 12 subchannel select signal, block 13 Setting the operation mode, block 14 setting the gain.

The device works as follows.

The modulated data signal supplied to the device is limited by a spectrum by a band-pass filter 1, and then fed to the amplifier 2c by an automatic gain control (AGC), which serves to maintain at its output a predetermined signal level with allowable changes in the input signal level. 2, the signal is supplied to demodulators 3 and 4, to the other inputs of which the carrier oscillations are supplied from the carrier oscillator selection unit 7. The carrier oscillation on the demodulator 3 differs in phase from the carrier oscillation on demodulator 4 by 90. The signal from the demodulator 3 is fed to the analog-to-digital converter 5 and the block 8 of the clock oscillation, and from the demodulator 4 to the analog-to-digital Converter 6. According to the signal from the demodulator 3 in block 8 for the selection of clock oscillations, the phase is adjusted to the raised demodulated clock series signal, which are sent to the analog-to-digital converters 5 and 6

In analog-digital converters 5 and 6, analog signals are gated at reference times, storing and storing the amplitudes of the received sampling voltages and converting these voltages into digit-digit code numbers.

Suppose that signals generated by dual band modulation are received. Then the gating of the demodulated signals is performed simultaneously in the English-digital converters 5 and 6 for each received linear element according to the signals received from the outputs of the imaging unit 12. Also in the intermediate memory unit 11, and in the adaptive equalizer 9, two input signals are received in succession bit number of samples obtained as a result of conversion. After completion of the conversion process in the adaptive equalizer 9, in accordance with the selected operation algorithm, the transfer coefficients of the tap adjusters are changed first in the forward link and then in the cross links to compensate the ISI.

Suppose data signals are transmitted by single-band modulation techniques. In this case, the transmission and reception of signals can be considered as alternate transmission and reception of half-speed signal elements on two mutually orthogonal carrier oscillations whose frequency is equal to the central frequency of the spectrum. In this case, if the received signal element is recorded with respect to one carrier wave, then the next element will be registered with respect to the second one, orthogonal to the first one, the carrier wave, etc. Therefore, when analyzing the MCI in the signals at the outputs of demodulators 3 and 4, it is necessary to consider a pair of successively accepted linear elements. As a consequence, from the analyzed pair of linear elements in analog-digital converters 5 and 6, the signals from the generator 12 are alternately gated first from the output of demodulator 3 and then from the output of demodulator 4, which is equivalent to the delay of the first signal by time equal to one period of linear elements. In this case, there is a need for intermediate storage of signal samples, which is carried out by intermediate memory unit 11, from which two P-bit numbers of samples are fed to the adaptive equalizer 9 at the required time. The presence of block 11 makes it possible to increase the time required for the implementation of the necessary operations by the adaptive correction package 9 due to its operation during the reception of each pair of consecutive linear elements, which makes it possible to use less fast-acting elements when implementing it.

Further, the ISI compensation process in signals generated by single-band modulation methods is carried out by the adaptive equalizer 9 taking into account the features of receiving such signals at the center frequency.

Claims (1)

When receiving signals generated by both single-band and dual-band modulation methods, an increase in the transmission coefficient of the adaptive equalizer 9 (a change in the scale of its operation) is made. With an increase in the transmission coefficient (introduction of scale), the adaptive equalizer 9 will not have a residual MIS, which will lead to an increase in the noise immunity and transmission distance of the data signals, which can occur under conditions of higher initial distortions of the characteristics of the KTCH. 9 increases simultaneously with a corresponding decrease in the level of the signals at the outputs of demodulators 3 and 4, the process of implementing the analyzer and the decoder of the receiver is not complicated. a. To increase the transfer ratio of the adaptive equalizer 9 by the signals coming from the gain setting unit 14, the transmission coefficients of the centrifugal taps regulators are increased by the direct connections of the adaptive equalizer 9. The switchings required when switching from one mode of operation ) to another, produced by the signals received from the mode setting unit 13 to the formaker 12 subchannel selection signals and the block 8 allocation of the clock oscillation. Thus, in the proposed device. Noise immunity increases. Apparatus of the Invention A device for receiving signals with adaptive intersymbol correction, interference, containing sequentially connected band-pass filter and an amplifier, the output of which is connected through the first and second demodulators to the first inputs of analog-digital converters, the other inputs of both demodulators are connected to the outputs of a carrier oscillator , the output of the first demodulator is connected to the first input of the clock selection unit, as well as the serially connected adaptive equalizer and the decl A ler, characterized in that, in order to increase noise immunity, an intermediate memory block, a subchannel selection signal generator, an operation mode setting unit and a gain installation unit are inserted, the output of the mode setting unit being connected to the input of the clock selection unit and one input of the signal conditioner select a subchannel, another input of which is connected to the output of the clock-oscillator; and the outputs are connected to the second inputs of analog-digital converters, the outputs of which are connected to the inputs of the industrial unit daily memory, the output of which is connected to an adaptive equalizer, which is associated with a gain setting unit. Sources of information taken into account during the examination 1. The CCITT document COM 16A, 1975, USA, (prototype). ECHO