Device for automatic correction of amplitude - frequency distortion channels of information transmission systems.

 

The invention relates to telecommunication and can be used for automatic correction signal paths for transmission systems. Technical result achieved - improving the accuracy of correction signals in a communication system. Device for automatic correction of amplitude-frequency distortion channels of communication systems includes a control generator, the communication path, checker, block matching, two multiplier, reference generator block regulators, frequency selector comparator, two integrator, two Quad, the adder, the gate block, the normalizing unit, power meter, delay line, the clock pulses and the phase shifter. 1 Il.

The invention relates to telecommunication and can be used for automatic correction of linear distortion of signals caused by the irregularity of the amplitude and phase nonlinearity (PFC) characteristics of the group and of linear channels of transmission systems.

A device for control of non-uniformity of the amplitude-frequency characteristics, containing on the transmission side control generator, the output of which seelochan to the output of the communication path, reference generator correlator analyzer status of the communication path, the control unit and the unit controllers, the outputs of which are connected to control inputs of the offset (see USSR author's certificate No. 590853, CL N 04 3/04, 1973).

The disadvantage of this device is the low accuracy of distortion correction response.

The closest to the technical nature of the claimed invention is a device for automatic correction of amplitude-frequency distortions of the paths of transmission systems containing the control generator, a communication path, checker, block matching, the multiplier, reference oscillator, a frequency selector unit controllers, two comparator, the filter reference frequency, the intermediate frequency filter, three rectifier, the control unit reference generator, a subtraction unit, a synchronization unit and two unit (see USSR author's certificate No. 1020995, CL N 04 3/04, publ. 30.05.1983,, bull. No. 20).

The disadvantage of this device is the low accuracy of the correction of the distortion of the signal transmission system of information arising from neodialectic frequency characteristics of the communication path.

This disadvantage is due to the fact that during the adjustment of the amplitude-frequency characteristics is based characteristics of the communication path.

The main task, which directed the inventive device is to improve the accuracy of distortion correction signals in the communication system.

Thus the assessment of the degree of distortion of the signal is performed by an integrated indicator in the form of a correlation coefficient (ICC) g distorted in the path of the communication signal Sand(t) and the reference signal Se(t):

wherefunction, coupled by Hilbert with Se(t) (corresponding to a phase shift of the signal 90in relation to the original); T - period of the reference signal; RHis a normalizing factor that ensures the equality g=1 the coincidence of the spectra of distorted and reference signals.

As the reference signal used multi-frequency signal with a uniform spectrum, described by the expression

where N is the number of harmonic components or the number of control frequencies;

Ukandkthe amplitude and initial phase component of the original signal; and

f0=1/T.

Frequency components of this signal are in the range of k1f0to kNwhat I specified bandwidth of the communication path. When passing the test signal through the communication path changes its spectrum and the amplitude spectrum carries information about the shape of the frequency response of the studied channel.

Similarly, the distorted signal at the output of the communication path is

where lN-ll+1=N; Ulandlthe amplitude and initial phase of the l-th component of the distorted signal.

Optimal adjustment of the frequency response is performed sequentially for each frequency sub-band by comparing the current measurement result CVR distorted and reference signals with the results of previous measurements in this subrange. If the value of the CVR increases, the adjustment of the amplitude level of the signal in this subrange continues; if the value of the CVR decreased, then return to the previous level and move to the next adjustment of the frequency sub-bands. However, the greater the attenuation level of signal component is provided including frequency sub-band, where the maximum phase distortion, i.e., is a partial rejection of the plot, with a pronounced non-linearity of the phase response curve. Such adaptive redistribution of the energy of the t connection - corrector” in relation to the reference signal, i.e. the minimum degree of signal distortion.

This technical result is achieved by the fact that in the known device for the implementation of the measurement of the coefficient of cross-correlation between the distorted and the reference signal to the current control generator, path connection, to the reference generator, the unit agreement and the first multiplier inputs of the second multiplier, phase shifter, two integrator, two Quad, the adder, the gate and normalizing blocks, power meter and clock, and implementing the optimal adjustment of the frequency response to the corrector, regulators, frequency selector and comparator inputs of the delay line.

The drawing shows a structural electrical diagram of the device. Device for automatic correction of amplitude-frequency distortions of the paths of transmission systems contains the reference oscillator 1, tract 2 communication corrector 3, block 4 of the agreement, the first and second multiplier products 5 and 6, reference generator 7, the phase shifter 8, the first and second integrators 9 and 10, the first and second Quad 11 and 12, the adder 13, the gate block 14, the normalizing unit 15, the meter 16 mascot.

The device operates as follows.

On the transmission side control generator 1 generates a multi-frequency signal at frequency fi, i=1, 2, ... , N, with equal amplitudes Uli=const(i)=Ul. This signal is fed to the input of tract 2, where is distorted due to uneven frequency response and non-linearity of the phase response curve tract 2 connection. Output path 2 due distorted signal Sand(t) passes through the corrector 3 and is fed to the input of block 4 of the agreement.

With the first block of 4 matching signal is fed to the first inputs of the multiplier products 5 and 6. On the second inputs of the multiplier products 5 and 6 from the output of the reference oscillator 7 is supplied reference frequency signal Se(t) with a uniform spectrum, and to the input of the first multiplier 5, the reference signal is supplied, and the input of the second multiplier 6 through the phase shifter 8. The results of the multiplication of the reference and distorted signals from the output of the multiplier products 5 and 6 serves for informational inputs of the respective integrators 9 and 10 and further to the respective inputs of Quad 11 and 12, the outputs are connected to respective inputs of the adder 13.

At time t=T the end of the period of the reference signal Se(t) opens the gate block 14, through umutara 13 is supplied to the information input of the normalizing unit 15. Normalization is performed by dividing the coefficient g on the measurement result of the power of the distorted signal applied to the calibration input of the normalizing unit 15 from the output of the meter 16 power signal, whose input is connected to the second output unit 4 of the agreement.

Synchronization of the moments of the beginning of the formation of periods of the reference signal in the reference generator 7, the opening of the gate unit 15 and reset the integrators 9 and 10 in the initial state by using the generator 17 clock pulses, the output of which is connected to the control inputs of these blocks. The generator input 17 of clock pulses connected to the output of tract 2 connection and is used to run the generator. The repetition period of the pulses from the output of the generator 17 is equal to the duration T of the reference signal Se(t).

The measurement results of the normalized values CVRthe distorted and reference signals are used for sequential optimal adjustment of the levels of the components of U1on each frequency fisince frequency f1. To this end, the measurement resultoutput from the normalizing unit 15 is fed to the delay line 18 and Peet the current value of the measurement result CVRreceived at the first input, with the value of the CVRmeasured in the previous cycle generator 17 and received with a delay to the second input of the comparator 19.

Ifthen from the first output of the comparator 19 to the first information input unit 20 controls signal with which the unit 20 controls the level adjustment of the i-th component of the signal corrector 3. Ifthen with the second output of the comparator 19 to the second information input unit 20 controls a signal providing such management corrector 3, which is restored to its previous level of the amplitude of the i-th component of the distorted signal. Ifthen both outputs of the comparator 19 are signals that prevent the status corrector 3 unit 20 controls.

In addition, in the case ofthe signal from the second output of the comparator 19 is supplied to the control input of switch 21 frequencies, providing the selection of the frequency range in which adjustment of the frequency response of the communication path. The switch 21 frequency performed by the circuit of the shift register, the condition of the comparator 19 on one of the outputs of the switch 21 appears the voltage level of the logical unit, which connects a respective control unit 20 to the corrector 3.

Thus, the effectiveness of the proposed technical solution is to increase the accuracy of distortion correction signals in the communication system by adaptive adjustment of the levels of attenuation in the sub-bands of the bandwidth of the communication path by the maximum value of the correlation coefficient of the distorted and the reference frequency signal. When this is formed such AFC circuit “path connection - checker”, in which a portion with a maximum value of the phase distortion signal is provided by the lowest gear ratio that promotes optimal redistribution of the energy of the signal within the selected frequency band.

Claims

Device for automatic correction of amplitude-frequency distortion paths of information transfer systems containing serially connected control generator, the communication path, checker, block matching, and the first multiplier, reference oscillator, the output of which is connected to the second input of the first multiplier, unit controllers, the outputs of which are connected to the control inputs correctrices fact, that added a second multiplier, two integrator, two Quad, the adder, the gate block, the normalizing unit, power meter, the delay line, the clock pulses and the phase shifter, an input connected to the output of the reference oscillator, and the output of the phase shifter connected to the second input of the second multiplier, the first input with the first input of the first multiplier connected to the first output of the block matching, the second output of which is connected to the input of the power meter, the output of which is connected to the calibration input of the normalizing unit, the outputs of each multiplier products connected to information inputs of the respective integrators the outputs are connected to inputs of respective Quad, the outputs are connected to respective inputs of the adder, the output of which is connected with the information input gate unit, the output of which is connected to the information input of the normalizing unit, the output of which is connected to the first input of the comparator and the input of the delay line, the output of which is connected to the second comparator input, a first output of which is connected to the first information input unit controllers, and the second comparator output is connected CNY whose input is connected to the output of the communication path, with the release of the communication path is connected to the generator input clock pulses, the output of which is connected to the control inputs of the reference oscillator, both integrators and gate block.

 

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