RU2066926C1 - Method of restoration of transmitted intelligible signals after their passage via communication channel - Google Patents

Abstract

FIELD: exchange of discrete information with employment of communication systems with modulation of different kind. SUBSTANCE: method provides for determination of dimensions of the vector field, its division into signal regions and separation of uncertain zone on the boundaries of these regions. Realization of these actions is accomplished with the aid of a storage. Then reception of intelligence signals is accomplished, signals received in the analog form are divided into orthogonal components by the correction method, analog quantities of orthogonal components are numbered several times in the course of duration of a single-in-time signal pulse in accordance with the selected numbering clock period. Then belonging of the received signal to the specific region in each numbering clock period is determined, and the quantity of each received signal in each numbering clock period is corrected in amplitude and phase depending on the quantity and position of the signal vector in the previous numbering clock period. At the same time identification of the belonging of signals to the specific signal regions is accomplished after which the identified signal is transformed into a form concentrated for use by the user. EFFECT: facilitated procedure. 4 dwg

Description

 The invention relates to the field of discrete information exchange using communication systems with amplitude, phase, frequency modes of carrier frequency modulation and various combinations of these types of modulation used with various types of communication lines. From information sources, the authors know the device (see US patent N 4 546 322, CL N 04 L 27/20, 27/22, 08/24/1983) that implements a method that is the closest to the proposed method and therefore is selected as prototype. In the known device, information is transmitted according to a pre-selected scheme with a known location in the space of signal vectors (in magnitude of the amplitude "Ampl" and phase "F") of the transmitted discrete signals with a known duration of sending "T" of each signal. Next, determine the size of the vector field, within which reliable signal reception is possible. The selected field is divided into signal regions, the boundaries of which are lines equidistant from neighboring points of the arrangement of vectors of transmitted signals. Assign to each point of the signal region the same signal symbol that the point of the vector has around the circuit around which this region is formed. At the beginning of the transmission, information signals transmitted through the communication channel are received, the signal received in analog form is divided into orthogonal components by the correlation method, and their values are determined. Next, the received signals are converted from analog to digital, digitizing the analog values of the orthogonal components and determining the membership of the received signal in the form of digitized orthogonal components in a particular signal area. During the reception of information signals, phase and amplitude correction values are determined for each received signal, which ensure phase capture, carrier and reference frequency synchronization, and coarse amplitude correction. The known method does not allow for sufficiently reliable reception of discrete information signals subjected to distorting influences when passing through a communication channel. The known method does not have sufficient dynamics, allowing you to quickly respond to changes in the signal, to make changes proportional to the magnitude of the deviation. The reliability of the restoration of transmitted information signals after they pass through the communication channel can be increased by reducing the reaction time (increasing dynamism) of the system, which provides correction of the signal magnitude in phase and amplitude, as well as by reducing the influence of signal distortions on the identification of its belonging to a particular signal area. Reducing the response time of a system that provides correction of the signal magnitude in phase and amplitude is achieved in the proposed method by digitizing the orthogonal components of the received signal several times over the duration of sending “T” of each signal, obtaining several digitizing values corresponding to the selected digit “t” of digitization , determine the belonging of the signal to a specific signal area in each cycle, adjust the signal according to "Ampl" and "F" after each cycle with a delay of one digit aschy (ie belonging to any field of the signal) clock. Correction is carried out throughout the signal area in accordance with the location of the signal vector, digitized by the corresponding clock. The reduction in the influence of signal distortions on the identification of its belonging to a specific signal region in the proposed method is achieved due to the fact that uncertainty zones are allocated along the boundaries of the signal regions, the dimensions of which depend on the specified signal / noise ratio and on changes in the characteristics of the communication channel over time. When identifying a received signal, the received signals that fall into the uncertainty zone of the signal areas are not taken into account, which allows to reduce the number of errors due to interference of a different nature. An increase in the reliability of signal identification is also influenced by the fact that the identification of the belonging of the received signal to a specific area is carried out upon reaching a threshold value of the number of digitized signals belonging to the same area without taking into account the number of digitized signals falling into the uncertainty zone. The presented graphic material allows to clarify the essence of the invention.

 In FIG. 1 shows a selected vector field with signal vectors located on it, divided into signal areas; in FIG. 2 shows a vector field divided into signal regions with highlighted uncertainty zones; in FIG. 3 shows the movement of the vector of the received signal Spr (ti) for each digitalization cycle during the time of one transmission T; in FIG. 4 identification scheme of the received signal.

 A method of recovering transmitted information signals after passing through a communication channel consists of the following actions. Previously, depending on the type and condition of the telecommunication channel and the equipment used, the sizes of the vector field are determined, within which reliable signal reception is possible. The data transmission and reception scheme provides for a certain organization of the location of signal vectors A, B, and the duration of information packets T. The selected field is divided into signal areas a, b, (see Fig. 1) in accordance with the accepted arrangement of vectors A, B of transmitted signals on a vector field, at the same time, each point of the signal region is assigned the same value as the vector of the transmitted signal, around which this region is formed, according to the scheme. Uncertainty zones are distinguished along the boundaries of the signal fields, the sizes of which depend on the given signal-to-noise ratio, type and level of interference, and assign each symbol of the uncertainty zone an additional symbol "'" that distinguishes these points from other points of the given signal field (see Fig. 2, where each point of the zone of uncertainty corresponding to the signal region is assigned signal symbols A ', B',). The implementation of these actions is carried out, for example, using a storage device with the required amount of memory, the memory cells of which contain the necessary number of bits, providing the ability to perform these actions. Carry out the reception of information signals that have passed through the communication channel in accordance with the adopted scheme.

 When receiving information signals, synchronize the operation of transmitting and receiving systems. Synchronization is carried out on service signals that are transmitted at the beginning and (or) during transmission in accordance with the adopted scheme. The received information signal Sp is the transmitted information signal Sp distorted when passing through the communication channel. In turn, the transmitted information signal Sp is a signal with a sending duration T and modulated in amplitude and phase in accordance with the selected scheme. The signal received in analog form is divided into orthogonal components by the correlation method and their values Xpr, Ypr are determined. Next, the received signals are converted from analogue to digital form Xc, Yc, by digitizing the analog values Xpr, Ypr of the orthogonal signal components several times over the duration of sending T.

 At the time of sending T, several digitization values are obtained, the number of which depends on the selected tact time t (see Fig. 3). The following considerations influence the choice of the value of the sampling cycle time. On the one hand, it is desirable to reduce the tact time in order to increase the dynamism of tracking signal changes, and on the other hand, the tact duration should be approximately equal to such a value that during the transition process at the beginning and end of the information transmission T, no more than one or two digitizations are obtained. Knowing the digitization values of the orthogonal components of the signal Xc (ti), Yc (ti) determine the belonging of the received signal to a specific signal area in one clock cycle Spr (ti).

 Next, identification of the belonging of the received signal to a specific signal area is carried out. Signal identification is carried out upon reaching the threshold value of the number N Spr (ti) belonging to the same region (see Fig. 4a). When calculating the number of signals Spr (ti) belonging to a specific area, signals that fall into the uncertainty zone are not taken into account. Upon reaching the threshold value N Spr (ti), the received signal Sppr is identified as the transmitted Sp with the sending duration T (see Fig. 4b), belonging in accordance with the scheme to this signal area.

 Simultaneously with the identification of the signal, the received signal is corrected according to Ampl and F. The control correction is carried out according to service signals, for which the values of T, F and Ampl are agreed in advance in accordance with the applied scheme. In addition, Ampl and F are corrected when each of the received signals is received. Correction of the signals according to F and Ampl is carried out after each cycle of digitizing the quantities Xc (ti), Yc (ti) with a delay of one cycle, provided that both of these signals Spr (ti-1), Spr (ti) belong to the same signal region including the zone of uncertainty. The values of the signal correction values depend on the location of the previous clock signal at a particular point in the signal area and on the selected correction function.

 The last action of this method is the conversion of the received and identified information signal into a form convenient for use by the consumer.

Claims (1)

 A method of recovering transmitted information signals after passing them through a communication channel, which consists in allocating a vector field within which reliable signal reception is possible, dividing the selected field in accordance with the accepted arrangement of the vectors of the transmitted signals in amplitude and phase into signal areas, assign each point of the signal region has the same signal symbol, which has the scheme of the vector of the transmitted signal around which the region is formed, receive information signals transmitted through the communication channel, divide the signals received in analog form into orthogonal components by the correlation method, determine their values in analog form, convert the values of orthogonal components from analog to digital, digitizing the analog values of orthogonal components, determine the ownership of the received signal in the form its digitized orthogonal components to a specific signal area, determine the corrected value for the received signal in amplitude and phase e, the signal is identified by its belonging to a specific area, the identified signal is converted into a form convenient for use by the consumer, characterized in that they identify zones of uncertainty along the boundaries of the signal areas, assign an additional signal symbol to each point of these zones, digitize several orthogonal components of each signal times during the duration of a single-time signal sending in accordance with the selected digitization cycle, determine the membership received drove to each specific signal region in each digitization cycle, adjust the magnitude of the received signal in each digitization cycle depending on the size and location of the signal vector in the previous digitization cycle belonging to the same region, identify the belonging of the received signal to a specific signal region upon reaching the threshold the number of signals digitized in previous clock cycles belonging to the same region, excluding the number of signals digitized in previous clock cycles boiling zone of uncertainty.

Images