RU2128401C1 - 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 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 adders, relation calculation unit, AND gate, and displaying unit. Device uses several information processing statistical methods by means of which device provides detection and reception of multiple-frequency signal. Device provides detection of information signal from mix of background channel noise and parasitic voice signals. Information processing statistics use evaluates signal power information bandwidth, evaluation of sign of derivative of sum of extreme spectral constituents for two groups of signal frequencies and distribution of input signal power over frequency band. EFFECT: increased precision of reception. 1 dwg

Description

 The invention relates to the field of telecommunications, and in particular, to automatic means for receiving telephone signaling signals. This invention can be used, for example, in telecommunication systems for receiving telephone numbers transmitted by multi-frequency method (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, the outputs of which are connected to a total power determination unit, the outputs of one group of comb filter outputs are connected to a signal power determination unit of this group, the outputs of another comb filter group are connected to a power determination unit of another group, the outputs of said blocks power definitions are connected to the adder, while the outputs of the adder and the total power calculation unit are connected to the power comparison unit. However, this device is also characterized by a high 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, a first and second unit for determining the highest power, a first adder and a display unit according to the invention, an additional bandpass filter is introduced, low-pass filter, analog-to-digital converter, linear detector, the first and third threshold elements, a block of controlled keys, a control timer, the second and third total ry, a ratio calculation unit, a time delay unit, and the output of the matching unit with the communication channel through a series-connected low-pass filter is connected to the input of an analog-to-digital converter, the output of which is connected through a series-bandpass filter to the input of the linear detector and the inputs of the comb filter unit, the output of the linear detector through series-connected integrating link and the first threshold element is connected to the first input of the logical element And, and the outputs of the comb unit of that filter are connected to the corresponding inputs of the linear detector block, the outputs of which 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, the control input of the managed key block being connected to the control timer, and the outputs of all controlled keys are connected to the inputs of the second adder, the output of the latter is connected to the first input of the ratio calculation unit, the second input of which is connected to the output of the first adder, and the output through the second pore the burner element is connected to the second input of the logical element AND, in addition, the outputs of the first to fourth sections of the managed key block are connected to the input of the first block for determining the highest power, and the outputs of the fifth and eighth sections of the managed key block are connected to the input of the second block of the highest power determination, while the output of the first unit for determining the highest power is connected to the first input of the first adder, and the output of the second unit for determining the highest power is connected to the second input of the first adder, the output of which it is also connected directly to the first input of the third adder and through a series-connected inverter and time delay unit to the second input of the third adder, and the output of the third adder through the third threshold element is connected to the third input of the logical element AND, the output of which is connected to the control input of the display unit, information inputs which are connected to the first and second blocks for determining the highest 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, block calcul lized relationship 17, a second threshold element 18, an inverter 19, delay time unit 20, a third adder 21, the third threshold element 22, an AND gate 23, a display unit 24.

 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 is carried out. This device provides the selection of a useful signal from a mixture of channel noise and spurious speech signals.

 As information statistics, we use an estimate of the signal power in the information frequency band, an estimate of the sign of the derivative of the sum of the extreme spectral components for two groups of signal frequencies, and the distribution of the input signal power over the frequency range.

 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 as the first information statistics 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 highest power 13 and 14 and the first adder fifteen.

 In the first and second blocks for determining the highest power 13 and 14, extreme values are determined for the first and second frequency groups, respectively, i.e. they identify the numbers of sections of the comb filter block 8.1 - 8.8, in which the absolute maximums of the envelopes are fixed and the values stored in them are read into the first adder 15. The value from the output of the first adder 15 is fed to the first input of the ratio calculation unit 17, the second input of which receives the estimate the sum of all spectral components from the second adder 16. Then, in the ratio calculation unit 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.

 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 values from the output of the first adder 15 are also supplied directly to the first input of the third adder 21, and to the second through the inverter 19 and the time delay unit 20 connected in series. As a result, the peak values of the spectral components at the output of the unit of integrating links 10.1 - 10.8 increase by the output of the third threshold element 22 is held at a logic zero value. 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 third threshold element.

 The final decision on the presence or absence of a multi-frequency signal in the communication channel is made in the logical element And 23 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 24.

 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. Zayonchikovsky E.A., Pshenichnikov A.P., Romantsov V.M. Automatic long distance communication. -M.: Radio and Communications, 1984, p. 111 - 113.

 2. US Patent N 5592544, cl. H 04 M 1/515, 1/7/97.

Claims (1)

 A device for receiving multi-frequency signals, comprising a matching unit with a communication channel, a comb filter unit, a non-linear detector unit, an integrating unit block, a first and second maximum power determination unit, a first adder and a display unit, characterized in that a band-pass filter is additionally introduced into the device, low-pass filter, analog-to-digital converter, linear detector, the first and third threshold elements, a block of controlled keys, a control timer, second and third adders, a calculation unit relations, a time delay unit, wherein the output of the matching unit with the communication channel is connected through an in-line low-pass filter to the input of an analog-to-digital converter, the output of which is connected through an in-line bandpass filter 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 link and the first threshold element is connected to the first input of the logical element And, and the outputs of the comb filter unit are connected the corresponding inputs of the block of linear detectors, the outputs of which are connected to the corresponding inputs of the block of integrating links, the outputs of which are connected to the corresponding inputs of the block of managed keys, the control input of the block of controlled keys connected to the control timer, and the outputs of all controlled keys connected to the inputs of the second adder, the output of the latter is connected to the first input of the ratio calculation unit, the second input of which is connected to the output of the first adder, and the output through the second threshold element is connected to the second input of AND gate; in addition, the outputs of the first and fourth sections of the managed key block are connected to the input of the first block of determining the highest power, and the outputs of the fifth and eighth sections of the controlled key block are connected to the input of the second block of determining the highest power, while the output of the first block determining the maximum power is connected to the first input of the first adder, and the output of the second unit for determining the maximum power is connected to the second input of the first adder, the output of which is also connected directly directly to the first input of the third adder and through the inverter and the time delay unit connected in series to the second input of the third adder, the output of the third adder through the third threshold element is connected to the third input of the AND gate, the output of which 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.