RU2128400C1 - Device for reception of multiple-frequency signals - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: device has communication channel matching unit, low-pass filter, analog-to- digital converter, band-pass filter, linear detector, integrating circuit, first, second, third and fourth threshold gates, IF unit, unit of linear detectors, unit of integrating circuits, unit of controlled gates, control timer, first and second units for maximal power detection, inverter, delay unit, first, second, third and fourth adders, relation calculation unit, AND gate, and displaying unit. In real reception conditions which involve reception of multiple-frequency signals, transmitted information is detected in heavy background channel noise and distortions as well as in presence of parasitic voice signals. In addition device takes into account wide dispersion of characteristics of generators of two-frequency signals. Device provides reliable detection of information signal from mix of background channel noise and parasitic voice signals even in cases of significant deviation of characteristics of generators of multiple frequency signals. EFFECT: increased precision of reception. 1 dwg

Description

 The invention relates to telecommunications, in particular, to automatic means for receiving telephone signaling signals. The present invention can be used, for example, in telecommunication systems for receiving data transmitted in a multi-frequency manner (i.e., using tone dialing).

 A device for receiving multi-frequency signals, comprising a matching block with a channel, a band-pass filter, two resonant circuits connected in series, two linear detectors, two polarized relays, a threshold element and an actuating element.

 However, this device cannot provide reliable selection of multi-frequency signals, especially for the typical case in practice, when the multi-frequency signal has to be received against the background of a spurious speech signal.

 A multi-frequency signal receiver is also known, comprising comb filters, to each of which a series-connected linear detector and an integrating filter are connected, each of the two groups formed by the comb filters being equipped with a unit for determining the highest power and an adder, the outputs of the said blocks being connected to the calculation unit relations, and the outputs of the relationship blocks are connected to the inputs of the block that determines whether the received signal is multi-frequency. However, this device is also characterized by a low accuracy of extracting the information signal, as well as a high probability of missing a distorted acoustic signal.

 The aim of the invention is to improve the accuracy of reception of multi-frequency signals.

 To achieve this goal, a device for receiving multi-frequency signals, comprising a matching unit with a communication channel, a comb filter unit, a line detector unit, an integrating unit, the first and second units for determining the highest power, the first and second adders, the first and second units for calculating the ratio and the display unit according to the invention, a band-pass filter, a low-pass filter, an analog-to-digital converter, an integrating element, an inverter, an AND logic element, a linear detector are additionally introduced p, first, second, third and fourth threshold elements, a controlled key block, a control timer, a third and fourth adder, a time delay block, wherein the output of the matching block with the communication channel is connected through an in-line low-pass filter to the input of an analog-to-digital converter, output which through a series-connected band-pass filter is connected to the input of the linear detector and the inputs of the comb filter unit, while the output of the linear detector through series-connected integrating circuit but the first threshold element is connected to the first input of the logical element And, and the outputs of the comb filter block are connected to the corresponding inputs of the linear detector block, in turn, the outputs of the linear detector block are connected to the corresponding inputs of the integrating unit block, the outputs of which are connected to the corresponding inputs of the controlled key block moreover, the control input of the managed key block is connected to the control timer, the outputs of the first, second, third and fourth sections of the managed key block are connected to the input the first block for determining the highest power and the first adder, and the outputs of the fifth, sixth, seventh and eighth sections of the block of managed keys are connected to the inputs of the second block for determining the highest power and the second adder, while the output of the first block for determining the highest power is connected to the first inputs of the first block of calculation relations, the third adder and the display unit, and the output of the second unit for determining the highest power is connected to the first input of the second unit for calculating the ratio, the second inputs of the third sum pa and the display unit, the second input of the first relationship calculation unit is connected to the output of the first adder, and the output of the first relationship calculation unit through the second threshold element is connected to the second input of the AND logic element, similarly, the second input of the second relationship calculation unit is connected to the output of the second adder, and the output the second unit for calculating the relationship through the third threshold element is connected to the third input of the logical element AND, the output of the third adder is connected to the first input of the fourth adder directly, to the second input through the inverter and the time delay unit connected in series, the output of the fourth adder through the fourth threshold element is connected to the fourth input of the logical element And, in turn, the output of the logical element And is connected to the control input of the display unit, the information inputs of which are connected to the first and second blocks of determination the greatest power.

 A device for receiving multi-frequency signals (see drawing) contains a block 1 matching with a communication channel, a low-pass filter 2, an analog-to-digital converter 3, a band-pass filter 4, a linear detector 5, an integrating link 6, the first threshold element 7, a comb filter unit 8.1 - 8.8, block of linear detectors 9.1 - 9.8, block of integrating links 10.1 - 10.8, block of controlled keys 11.1 - 11.8, control timer 12, first block for determining the highest power 13, second block for determining the highest power 14, first adder 15, second adder 16, first b ok, calculating the ratio 17, the second threshold element 18, the second block calculating the ratio 19, the third threshold element 20, the third adder 21, the inverter 22, the time delay unit 23, the fourth adder 24, the fourth threshold element 25, the logical element And 26, the display unit 27 .

 The basis of the work of the claimed device is the use of several estimated information statistics, with the help of which the detection and reception of a multi-frequency signal, which is a two-frequency package, separated by pauses, is carried out.

 In real conditions of operation of the receiver of multi-frequency packages, the selection of the transmitted information should be carried out against the background of significant channel noise and distortion, as well as in the presence of spurious speech signals. In addition, it is necessary to take into account the wide variation in the parameters of the shapers of dual-frequency packages. The latter circumstance is related to the fact that in practice, tone dialing generators developed by a large number of foreign and domestic manufacturers of telephone sets can be used as a source of a useful signal. Moreover, the characteristics of these generators often differ significantly from the regulated ones.

 The inventive device provides a stable selection of a useful signal from a mixture of channel noise and spurious speech signals, even if very significant deviations of the parameters of the generators of multi-frequency packages.

 The analyzed signal from the output of the communication channel, passing through the matching unit 1 with the communication channel and through a low-pass filter 2, enters the analog-to-digital Converter 3, the output of which takes the form of a sequence of digital samples. This digital sequence is subjected to bandpass filtering in the bandpass filter 4 and is fed to the input of the linear detector 5.

 At the same time, in blocks 5-7, an estimate of the power of the incoming signal in the information frequency band is formed, for which the absolute value of the initial signal is calculated in the linear detector 5, and then its average rectified value is estimated in the integrating link 6.

 An estimate of the input signal power limited by the information frequency band is used in the inventive device when deciding on the presence of a useful signal at the moment in the communication channel. For this, the power estimate obtained at the output of the integrating link is compared with the threshold value in the threshold element 7. If a signal is present in the communication channel of a sufficient level, the value corresponding to the logical unit is set at the output of the threshold element.

 At the same time, a sequence of digital samples of the input signal from the output of the band-pass filter 4 is fed to the input of the comb filter block 8.1 - 8.8. The comb filter 8.1 - 8.8 is a combination of eight resonant filters tuned to the nominal frequencies of the useful information signal. Here the filtering of the frequency components of the input signal is carried out. In this case, the output of each of the resonance filters through the corresponding linear detectors 9.1 - 9.8 is connected to the corresponding integrating link from the block of integrating links 10.1 - 10.8. Thus, by means of blocks 8.1 - 8.8, 9.1 - 9.8 and 10.1 - 10.8, the frequency components of the spectrum of the input signal are estimated in the information frequency band.

 The decision on the presence of an information signal in the communication channel and the decoding procedure is carried out at regular intervals by a command from the control timer 12. For this, the values from the outputs of the controlled keys 11.1 - 11.8 are fed to the first and second blocks for determining the largest values 13, 14, and in the first and second adders 15 and 16. Moreover, in blocks 13, 15, 17, 18 and 14, 16, 19, 20, operating similarly, for each of the two frequency groups, the ratio of the maximum spectral component of the group to the total is estimated power spectral components.

 We consider the operation of this part of the device for the first frequency group (blocks 13, 15-18). In the first block for determining the highest values 13, the maximum (out of four) value of the spectral component is determined and the section numbers of the comb filter unit 8.1 - 8.4 are fixed, in which this maximum is fixed. The value stored in it is read into the first block for calculating the ratio 17, the second input of which receives the estimate of the sum of all spectral components of the first frequency group from the first adder 15. Then, in the block for calculating the ratio 17, their ratio is calculated. If the obtained value is greater than a certain threshold value specified in the second threshold element 18, then according to this information feature it is considered that the input signal is useful and the value corresponding to the logical unit is set at the output of the second threshold element 18.

 The functioning of blocks 14, 16, 19, 20 occurs similarly to the considered one, and in the case of detecting a stable maximum in the spectral components of the second frequency group in the threshold element 20, a value corresponding to a logical unit is also set.

 To ensure the best conditions for receiving multi-frequency code combinations in this device, the sign of the derivative of the sum of spectral components, the largest for each of the two frequency groups, is checked. For this, the value from the output of the third adder 21 is also supplied directly to the first input of the fourth adder 24, and to the second through the inverter 22 and the time delay unit 23 connected in series. As a result, the peak values of the spectral components at the output of the unit of integrating units 10.1 - 10.8 increase, at the output of the fourth threshold element 25, a logic zero value is held. Upon reaching its maximum value, a decision is made about the presence of a useful signal (multi-frequency code combination) and the value of the logical unit is set at the output of the fourth threshold element 25.

 The final decision on the presence or absence of a multi-frequency signal in the communication channel is made in the logical element And 26 in the case when all three information signs are positive. Then, the corresponding command to convert the two-frequency combination into the digit of the dialed number is received at the display unit 27.

 The implementation of this device is most appropriate to implement on the basis of traditional digital circuitry ("hard logic") or using signal microprocessors.

Sources of information
1. Zayonchkovsky E. V., Pshenichnikov A. P., Romantsov V. M. Automatic long distance communication. - M.: Radio and Communications, 1984, pp. 111 - 113.

 2. US Patent N 5428680, cl. H 04 M 1/50, 06/27/95 (prototype).

Claims (1)

 A device for receiving multi-frequency signals, comprising a matching unit with a communication channel, a comb filter unit, a line detector unit, an integrating unit block, a first and second maximum power determining unit, a first and second adder, a first and second ratio calculating unit, and a display unit, characterized in that a band-pass filter, a low-pass filter, an analog-to-digital converter, an integrating element, an inverter, an AND logic element, a linear detector, first, second, three the fourth and fourth threshold elements, a controlled key block, a control timer, a third and fourth adder, a time delay block, the output of the matching block with the communication channel being connected through an in-line low-pass filter to the input of an analog-to-digital converter, the output of which is through a series-connected band-pass filter connected to the input of the linear detector and the inputs of the comb filter unit, while the output of the linear detector through sequentially connected integrating link and the first threshold the element is connected to the first input of the logical element And, and the outputs of the comb filter block are connected to the corresponding inputs of the linear detector block, in turn, the outputs of the linear detector block are connected to the corresponding inputs of the integrating unit block, the outputs of which are connected to the corresponding inputs of the managed key block, and the control input the managed key block is connected to the control timer, the outputs of the first, second, third and fourth sections of the managed key block are connected to the inputs of the first block power and the first adder, and the outputs of the fifth, sixth, seventh and eighth sections of the managed key block are connected to the inputs of the second unit for determining the maximum power and the second adder, while the output of the first unit for determining the highest power is connected to the first inputs of the first unit for calculating the ratio, the third the adder and the display unit, and the output of the second unit for determining the highest power is connected to the first input of the second unit for calculating the ratio, the second inputs of the third adder and the display unit I, the second input of the first relationship calculation unit is connected to the output of the first adder, and the output of the first relationship calculation unit through the second threshold element is connected to the second input of the AND logic element, similarly, the second input of the second relationship calculation unit is connected to the output of the second adder, and the output of the second calculation unit relations through the third threshold element is connected to the third input of the logical element AND, the output of the third adder is connected directly to the first input of the fourth adder, to the second input through p consequently included inverter and time delay unit, the output of the fourth adder through the fourth threshold element is connected to the fourth input of the logical element And, in turn, the output of the logical element And is connected to the control input of the display unit, the information inputs of which are connected to the first and second blocks for determining the highest power.