RU2251723C2 - Device for controlling quality of communication line of data transfer channel - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: as a source of standard signal not separate generator of test signal according to known code structure is used, but a component of modem, to provide for substantial simplification of process under unfavorable conditions.

EFFECT: higher efficiency.

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Description

The invention relates to measuring technique and can be used to create systems for automatic quality control of a communication line of a data transmission channel without interruption in the reception of a carrier frequency modulated by an information code sequence.

A device for monitoring electronic products containing an analog-to-digital converter, a unit for outputting a control result, a meter for the mutual difference coefficient, a meter for the threshold value for the mutual difference coefficient, a unit for measuring the ratio of signal energy to noise spectral density, a comparator (see AS RF No. 2071107, cl 6 G 05 (23/02, 1996).

The disadvantage of this device is the inability to control the quality of communication lines of a data transmission channel due to the need to generate a test reference signal by the shaper of the reference signal according to a certain known code structure, which is impossible for the real time scale in the absence of any information about the code structure of the modulated signal coming from communication lines of a data transmission channel.

The purpose of the invention is to apply for a new purpose a known device for monitoring the quality of a communication line of a data transmission channel.

To achieve this goal, a device for monitoring the quality of data transmission channels, containing a mutual difference coefficient meter (IQRM), an analog-to-digital converter, a comparator, a threshold difference meter of a mutual difference coefficient, a unit for measuring the ratio of signal energy to noise spectral density, a block for outputting the control result , additionally introduced a modem, an OR element, an OR-NOT element, a trigger, a group of delay lines, a delay element, a group of AND elements, and the modem output and input from the side of the line communications are the input of the device and are connected respectively - the output is parallel to the inputs of the multiplier, phase shifter, the normalizing unit of the CWR meter and to the input of the unit for measuring the ratio of signal energy to spectral noise density, and the input is through the delay element in parallel to the inputs of the multipliers of the CWR meter, parallel to the output of the modem demodulator connected to the input of the computer, to the inputs of the OR element and to the inputs of the OR-NOT element, and each contact of the parallel output of the modem demodulator is connected to one input of the corresponding AND element from the group of AND elements, to the other inputs of which the trigger output is connected in parallel, the installation input of which is connected to the output of the OR element, and the trigger reset input to the output of the OR-NOT element, the output of which is also connected to the inputs of the integrators, the gate block of the CWR meter, the output of each AND element from the group of AND elements is connected to the corresponding pin of the parallel input of the modem modulator and to the computer output, the register output is connected to the second input of the threshold coefficient meter differences, the third input of which is connected to the output of the unit for measuring the ratio of the energy of the signal to the spectral density of noise, and the output of the threshold threshold meter of the mutual difference coefficient is connected to the second input of the comparator, to the first input of which the output of the CWR meter is connected, the outputs of the comparator are connected in parallel to the control result output unit .

The drawing shows a functional electrical diagram of the proposed device.

The device for monitoring the quality of the data transmission channel contains a modem 1, consisting of a demodulator 1.1 and a modulator 1.2, a mutual difference coefficient meter (RCCI) 2, a group of elements AND 3.1-3.n (the number of elements n is determined by the number of information contacts of the parallel input of the modulator 1.2 of modem 1 ), element OR 4, element OR-NOT 5, trigger 6, register 7, unit for measuring the ratio of signal energy to spectral noise density 8 (USSR author's certificate No. 1001489, class N 04 V 3/46), meter for the threshold value of the mutual coefficient ra Lichiya 9, comparator 10, control output unit 11, analog-to-digital converter 12, group of delay lines 25.1-25.n, delay element 26, and the parallel output of demodulator 1.1 of modem 1 is connected to the computer input, to the inputs of the OR element 4, and to inputs of the element OR NOT 5, and each contact of the parallel output of the modem demodulator through the corresponding delay lines 25.1-25.n is connected to one input of the corresponding element And from the group of elements And 3.1-3.n, to the other inputs of which the output of trigger 6 is connected in parallel which is also connected to one input of the element And 20 of the meter of the threshold value of the coefficient of mutual difference 9. The installation input of the trigger 6 is connected to the output of the element OR 4, and the reset input of the trigger 6 is connected in parallel to the output of the element OR-NOT 5, the inputs of the integrators 15.1, 15.2, the input of the gate block 18 mutual difference coefficient meter 2. The output of each AND element from the group of AND 3.1-3.n elements is connected to the corresponding information pin of the parallel input of modulator 1.2 of modem 1 and to the computer output. The output of the normalizing unit 19 of the meter of the coefficient of mutual difference 2 is connected to the input of an analog-to-digital converter 12, the output of which is connected to the first input of the comparator 10, the output of the divider 24 of the meter of the threshold value of the coefficient of mutual difference 9 is connected to the other input, and the outputs of the comparator (A> B ), (A = B), (A <B) are connected to the terminal block of the control result 11. The output of the register 7 is connected to the second input of the element And 20 of the meter of the threshold value of the mutual difference coefficient 9. Input of the communication line of the demodulator 1.1 the output of the modulator 1.2 to the communication line of modem 1 is the inputs of the claimed device and connected: the input of the communication line of the demodulator 1.1 through the delay element 26 in parallel to the inputs of the multipliers 14.1, 14.2 of the coefficient of mutual difference 2, and the output of the modulator 1.2 to the communication line to another input of the multiplier 14.1, the input of the phase shifter 13, the first input of the normalizing unit of the meter of the coefficient of mutual difference 2 and to the input of the unit for measuring the ratio of signal energy to spectral noise density 8, the output of which is connected to the first input an amplifier 24 of the meter of the threshold value of the mutual difference coefficient 9. IKVR 2 includes two multipliers 14.1, 14.2, a phase shifter 13, which converts the signal from the output of modulator 1.2 according to Hilbert, two integrators 15.1, 15.2, two quadrants 16.1, 16.2, adder 17, a gate block 18 and the normalizing unit 19, and the output of the phase shifter is connected to the second input of the multiplier 14.2, the outputs of the multipliers 14.1, 14.2 are connected respectively to the inputs of the integrators 15.1, 15.2, the outputs of which are connected respectively to the inputs of the quadrants 16.1, 16.2, the outputs of which x connected to the inputs of the adder 17, the output of which is connected to the second input of the gating unit 18, the output of which is connected to the second input of the normalizing unit 19. The threshold difference meter of the mutual difference coefficient consists of an element And 20, a doubler 21, a quadrator 22, a logarithmic device 23, a divider 24 connected in series.

The principle of operation of the proposed device is based on the transition from a differential analysis of the forms and parameters of the signals of the communication line to a comprehensive analysis of the properties of these signals. A simple differentiated parametric analysis of signals with quadrature amplitude modulation shows that the number of parameters characterizing the quality of the generated signals modulated by multilevel quadrature phase modulation ranges from 20 (with a minimum number of combinations in Trellis codes) to 66 (with 32 combinations). Moreover, the deviation of a single parameter, such as instability of the carrier frequency or instability of the amplitude, can cause distortion of all combination components. The use of traditional methods of parametric control is very problematic due to the high time and hardware costs, and parametric control of such a significant set of parameters is impossible in real time.

External destabilizing factors, such as additive and multiplicative noise, caused by electromagnetic incompatibility between the information transmission channel and external electromagnetic devices performing electromagnetic radiation in a wide frequency range, can affect the communication channel of the communication channel. Despite the reliable shielding of the cable, the external effects of electromagnetic fields affect the shape of the transmitted signal. Also, in the communication channel, signal distortion can occur due to unauthorized access and attempts to read information. The received signal from the communication channel enters the modem on the receiving side of the communication system, which also performs the additional function of a driver of the reference received signal, since the modem is an active element, that is, in addition to passive filtering and transmitting digital information to the computer input, it performs signal demodulation and restoration of the original digital sequences with standard values of amplitudes, speeds and phases of transmitted video signals.

The device operates as follows. Passing through the communication line, the modulated information signal after receiving and amplifying points, intermediate switching devices undergoes distortions due to the influence of the external propagation medium (communication line), the consequence of unauthorized access to the communication line, hardware distortions, etc. The computer operates in simplex mode, that is, until a frame from a communication channel is received, the computer will not transmit its information frame to the communication channel. In advance, before starting work, the value 7 of the probability of erroneous reception of the signal element R _osh , given according to the technical condition to the monitored communication channel, is entered into the register 7. An automatic control cycle is carried out at the moment of receipt of a modulated signal from a communication line at the input of demodulator 1.1. The modulated distorted information signal from the communication line S _k (t) is fed to the input of demodulator 1.1, where it is demodulated, that is, the carrier frequency modulated by a certain informational pulse code sequence using one of the modulations (for example, multi-level quadrature modulation) is converted to a sequence of rectangular video signals from the output of the demodulator 1.1 received in parallel code to the input of the computer. At the same time, a parallel signal is supplied to the inputs of the elements OR 4, OR NOT 5 and through the delay lines 25.1-25.n to the first inputs of the elements AND 3.1-3.n. In this case, a logical “0” is formed at the output of the OR-NOT 5 element, and a logical “1” is formed at the output of the OR-4 element, which is fed to the installation input of trigger 6, thereby providing a logical “1” at its output, which is fed to the second inputs of the elements AND 3.1-3.n and the first input of the element And 20. The delay lines 25.1-25.n delay the parallel demodulated signal at the end of the transient installation processes in the elements OR 4, OR NOT 5, trigger 6. Parallel code signal through delay lines 25.1-25.n arrive at the first inputs of elements And 3.1-3.n., passes through them and enters the parallel input of modulator 1.2. Modulator 1.2 modulates the code signal, which can be considered the reference S _e (t), since it has not yet experienced the influence of negative factors of the propagation medium (communication line). From the output of the communication line and from the input of the demodulator 1.2, the controlled signal S (k) is supplied through the delay element 26 to the first inputs of the multipliers 14.1 and 14.2. The delay element 26 delays the signal S _k (t) by the time necessary for the end of transients in demodulator 1.1, elements OR 4, OR NOT 5, trigger 6, elements AND 3.1-3.n, modulator 1.2. From the output of modulator 1.2, the signal S _e (t) is supplied to the second input of the multiplier 14.1 directly and through the phase shifter 13, which provides a signal coupled according to Hilbert with the signal arriving at its input at the second input of the multiplier 14.2. The results of multiplication from the outputs of the multipliers 14.1, 14.2 are fed to the signal inputs of the integrators 15.1, 15.2, where integration takes place over a time interval equal to the duration of the modulated code sequence. From the outputs of the integrators 15.1, 15.2, the signals are fed to the inputs of the quadrants 16.1, 16.2, and then from their outputs to the corresponding inputs of the adder 17. From the output of the adder 17, the signal is fed to the information input of the gating unit 18, to the control input of which, upon completion of the code sequence, by the demodulator 1.1 from the output of the OR-NOT 5 element, the beginning of the formed logical unit is a gating signal and this logical "1" is fed to the control inputs of the integrators to reset them to the zero state. From the output of the gating unit 18, the signal is fed to the input of the normalizing unit 19, consisting of a power meter of the reference signal S _e (t) and a voltage divider (not shown, in accordance with the prototype see AC of the Russian Federation No. 2071107, class 6 G 05 V 23 / 02, 1996), the reference signal S _e (t) is supplied to the other input of the normalizing block 19. The output of the normalizing unit 19 will contain a voltage representing the result of measuring the mutual difference coefficient of the monitored signal s _k (t) at the input of the demodulator 1.1 from the communication line and the reference signal S _e (t) at the output of the modulator 1.2 to the communication line, described by the following expression:

where S _k (t), S _e (t) - time functions that determine the structure of the respectively monitored and reference signals;

S $\genfrac{}{}{0ex}{}{\text{*}}{\text{uh}}$ (t) is the Hilbert time function conjugated with S _e (t);

R _e - power of the reference signal;

T is the duration of the element of the reference signal.

The measurement result g = G from the output of the normalizing unit 19 of the mutual difference coefficient 2 meter is fed to the information input of the analog-to-digital converter 12, from where the value of the voltage G converted to digital form is supplied to the first input of the comparator 10. The previously set value is received from the output of register 7 R _osh at the second input of element And 20, to the first input of which an enable signal is received from the output of trigger 6. From the output of element And 20, the value of R _Osh goes to the input of the doubler 21, in the doubler 21 the value of R _Osh doubles and with you the doubler 21 moves to the input of the quadrator 22, where the square of the doubled value P _Оh occurs; from the output of the quadrator 22, the obtained value goes to the input of the logarithmic device 23, from the output of which the signal goes to the second input of the divider 24, the first input of which receives the signal, determining the value of h ² from the output of the unit for measuring the ratio of signal energy to spectral noise density (h ² ).

At the output of the divider 24, a code combination will be present, which is the result of measuring the threshold value of the CWR for a given probability of error Р _{Ош of the} investigated channel g = G _pop = ln (2Р _extra ) ² / h ² .

From the output of the divider 24, the _{gpop value is} supplied to the second input of the comparator 10, where the values of g and g _pores are compared. Depending on the result of g> g _thresh, g _<thresh, g = g _thresh one of the three respective outputs of the comparator 10 will be a unit that is supplied to one input of unit 11 outputting a result of monitoring (for information display "Evaluation: pass" “Evaluation: Limit Value”, “Evaluation: Unsuitable”). The decision is made that the set of communication line parameters that determine the value of the mutual difference coefficient g is normal or not normal, and the set of deviations of the values of these parameters from the nominal values does not give an error probability greater than a given, less than a given or equal to a given one.

The technical result consists in obtaining a coefficient of mutual difference between the monitored and the reference signals, as a comprehensive indicator of the quality of the communication line of the data transmission channel, and the source of the reference signal is not a single driver of the test reference signal according to a certain known code structure, but an integral part of the modem, which significantly simplifies the automation of the control process, allows for non-parametric control in real time without using mations set of complex expensive test equipment and in the absence of any information about the structure of the code modulated signal from the link data channel.

The disadvantage of this device is the inability to control the quality of communication lines of a data transmission channel due to the need to generate a test reference signal by the shaper of the reference signal according to a certain known code structure, which is impossible for the real time scale in the absence of any information about the code structure of the modulated signal coming from communication lines of a data transmission channel.

The use of this device allows to increase the reliability of the control of the data transmission channel, since the indicator g in the proposed case quantitatively determines the correspondence of the technical condition of the communication line to the transmission of information with a given or less error probability. A side economic effect is the reduction of time and hardware costs for assessing the quality of the channel, since if the CWR is below the threshold value, then there is no need to measure each individual parameter from the entire set of parameters characterizing the quality of the communication line of the data transmission channel.

Claims (1)

A device for monitoring the quality of a communication line of a data transmission channel, comprising a mutual difference coefficient meter (IKVK), in which the output of the phase shifter of the KVK meter is connected to the second input of the second multiplier of the KVK meter, the outputs of the first and second multipliers of the KVK meter are connected respectively to the inputs of the first and second integrators of the meter KVK, the outputs of which are connected respectively to the inputs of the first and second quadrants of the KVK meter, the outputs of which are connected respectively to the inputs of the adder KVK measuring device, the output of which is connected to the second input of the gate device of the KVK measuring device, the output of which is connected to the second input of the normalizing unit of the KVK measuring device, an analog-to-digital converter, a comparator, a meter for the threshold value of the mutual difference coefficient, consisting of a series I connected element, a doubler, a quadrator, a logarithmic device and a divider, a unit for measuring the ratio of signal energy to noise spectral density, a unit for outputting a control result, the output of a unit for measuring the ratio signal energy to the spectral density of noise is connected to one input of the comparator, the outputs of which are connected to the input of the output block of the control result, characterized in that the modem, OR element, OR element, NOT trigger, trigger group of delay lines, delay element, group of elements And, moreover, the output and modem input from the side of the communication line are the input of the device and are connected accordingly - the output is parallel to the inputs of the first multiplier, phase shifter and the normalizing block of the KVK meter and to the input of the measurement unit from the signal energy to the noise spectral density, and the input through the delay element in parallel to the inputs of the first and second multipliers of the KVK meter, the parallel output of the modem demodulator is connected to the computer input, to the inputs of the OR element and to the inputs of the OR-NOT element, and each contact of the parallel output the modem demodulator is connected through the corresponding delay lines to one input of the corresponding element And from the group of elements And, to the other inputs of which the trigger output is connected in parallel, the installation input of which is sub is output of the OR element, and the trigger trigger input is output of the OR-NOT element, the output of which is also connected to the inputs of the first and second integrators of the KVK meter block, the gate gate of the KVK meter, the output of each AND element from the group of And elements is connected to the corresponding parallel the input of the modem modulator and to the output of the computer, from the trigger output, the signal is fed to the first input of the AND element of the threshold value of the mutual difference coefficient, the second input of which receives the signal from the output of the register, the signal from the output of the unit for measuring the ratio of the energy of the signal to the spectral density of noise is transmitted to the first input of the divider meter of the threshold value of the coefficient of mutual difference, the signal goes to the second input of the comparator from the output of the divider of the meter of the threshold value of the coefficient of mutual difference, the signal goes to the information the input of the analog-to-digital converter, the converted signal is fed to the first input of the comparator.