KR20090014017A - Tone sensing apparatus of a digital key phone system and method thereof - Google Patents

Abstract

A tone sensing apparatus of a digital key phone system and a method thereof are provided to add a function which senses a low frequency. An A/D converting unit(110) converts an analog tone signal into a PCM(Pulse Code Modulation) signal which is a digital signal, and a first tone sensing filter(120) includes at least one band pass filter which performs a frequency band pass function below specific frequency. A second tone sensing filter unit(130) includes at least one band pass filter which performs a frequency band pass function over specific frequency. An energy comparison unit(140) compares the amounts of energies outputted from the plural band pass filters, which are included at the first and second tone sensing filter units, to determine a frequency having the strongest energy. A controller(150) compares the maximum amount of energy with the minimum amount of energy. When the maximum amount of energy is lower than a certain energy level, the controller controls the output of the energy comparison unit to process the corresponding energy in an abnormal tone regardless of which band the frequency having the maximum energy level belongs to.

Description

TONE SENSING APPARATUS OF A DIGITAL KEY PHONE SYSTEM AND METHOD THEREOF

The present invention relates to an apparatus and method for improving tone detection in a digital key phone system, and more particularly, to an apparatus and method for improving the accuracy of tone detection in a digital key phone system by adding a low frequency sensing function.

In general, a tone signal referred to in a communication using a telephone refers to a voice signal of a user or a signal that is notified to the user by a telephone exchange or a key phone system. There are many kinds of these tone signals, for example, a dial tone that tells the user when he or she picks up the phone, and a busy tone that indicates that the other party is busy when the call is made. ), An error tone that indicates that you haven't dialed for a long time or dialed a wrong number, and a ring-back tone that tells the other party that the ringer is ringing when the call is properly dialed. These tone signals differ in frequency and frequency of sound used in different countries, but most of them use frequencies in the range of 350Hz to 620Hz.

On ordinary phones, users can hear these tones and know what's going on, so you don't need to detect them, but if your phone system or telephone exchange needs to perform a special function, you need to detect these tones separately. A need arises. For example, if the other party is busy and the user presses the auto redial button, the keyphone system can automatically redial the call every minute. If the sound you hear when you redial is a busy tone or an error tone, the keyphone system will automatically hang up and call you back after 1 minute. If the tone is ringback tone, the caller will be able to You can perform a function that tells you it's stuck. In order to perform this function, the digital keyphone system must be able to distinguish what the tone means.

Typically, the frequency of the tone used in the telecommunications network varies from country to country, but generally uses frequencies of 350 Hz, 400 Hz, 425 Hz, 440 Hz, 480 Hz and 620 Hz. In order to detect these frequencies, digital keyphone systems use band-pass filters of different frequency bands to determine which band the tone frequency is in and process. However, when a low frequency tone of less than 350 Hz that is not to be detected is applied at a large level, harmonics of high frequency are detected by the bandpass filter of the tone detection filter unit, thereby causing a problem that the tone is recognized as being detected. Can be.

The present invention relates to an apparatus and method for detecting a tone using a DSP in a digital key phone system, and an object thereof is to improve the accuracy of tone detection of a digital key phone system by adding a low frequency sensing function.

To this end, in one embodiment, the AD conversion unit for converting the analog tone signal to a digital signal and output, the first tone detection filter unit for receiving the digital signal and band-pass filtering in a frequency band smaller than the first frequency, the The magnitude of energy of the outputs of the second tone detection filter unit, the first tone detection filter unit, and the second tone detection filter unit which receive a digital signal and band-pass filter the frequency band in the frequency band equal to or greater than the first frequency and output the digital signal. An energy comparison unit for determining a frequency at which the amount of energy is the maximum by comparing a and an abnormal tone when the frequency at which the amount of energy is the maximum belongs to a band pass band of the first tone detection filter unit, and the second tone The output of the energy comparator, so as to process the normal tone when belonging to the band pass band of the sense filter unit The tone of the digital phone system comprising a control unit for controlling detection apparatus is provided.

In one embodiment, the control unit further compares the maximum amount of energy with a predetermined minimum energy level, and when it is smaller than the predetermined energy level, the controller is abnormal regardless of which band the frequency where the amount of energy is maximum belongs to. The output of the energy comparator may be controlled to process tones.

In one embodiment, the first frequency may be 350 Hz.

In one embodiment, the digital signal may be a pulse code modulation (PCM) signal.

In one embodiment, the first tone detection filter unit may include a bandpass filter that passes about 150Hz band and a bandpass filter that passes about 200Hz band.

According to the present invention, it is possible to greatly improve the accuracy of tone detection by minimizing an error of tone detection that is incorrectly recognized by harmonic components of a low frequency signal when detecting a tone on a telephone communication line through a digital key phone system.

Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a diagram illustrating a tone detector of a digital key phone system according to an embodiment of the present invention. The tone detector 100 of the digital key phone system includes an A / D converter 110, a first tone detector filter 120, a second tone detector filter 130, an energy comparator 140, and a controller 150. ). The A / D converter 110 may convert the analog tone signal into a pulse code modulation (PCM) signal that is a digital signal. Digital key phone systems and telephone exchangers can convert analog signals such as tones and voice into digital signals to adjust the volume of sound, to process signals such as signal separation, and band compression.

The first tone detection filter unit 120 may include one or more band pass filters that perform a frequency band pass function of less than a specific frequency (for example, 350 Hz), and the second tone detection filter unit 130 may have a specific frequency or more. It may include one or more band pass filters that perform the frequency band pass function. For example, the first tone detection filter unit 120 includes a 150 Hz, 200 Hz bandpass filter, which is a band pass filter of less than 350 Hz, and the second tone detection filter unit 130 is a 350 Hz, 400 Hz, a band pass filter of 350 Hz or more. It may include a 425Hz, 440Hz, 480Hz, 620Hz bandpass filter. Each bandpass filter may receive the PCM signal output from the A / D converter 110 and output the amount of energy of the corresponding frequency component. In addition, bandpass filters are digital filters because they must filter the PCM signal, which is a digital signal, and they can be implemented using a DSP algorithm. On the other hand, as mentioned above, the frequency of the tone generally used is, for example, 350 Hz, 400 Hz, 425 Hz, 440 Hz, 480 Hz, and 620 Hz, so when detecting a tone having any one of these frequencies, second tone detection The filter unit 130 will output the frequency component as having the largest energy. On the other hand, even when a low frequency tone, for example, a tone less than 350 Hz, that is to be recognized as an abnormal tone is applied at a large level, the second tone detection filter unit 130 is due to the harmonic components constituting the tone of the frequency. The amount of energy output from a particular bandpass filter can be high. The periodic repetition waveform, not the sine wave, is decomposed into a sine wave having a fundamental frequency and a wave having an integer multiple of the sine wave. At this time, waves other than the fundamental wave constituting the repetitive waveform are called harmonics. A wave whose frequency is n times is called an nth harmonic para, and is also called a second or third harmonic according to the multiple of the fundamental frequency. When the vibration is a modified waveform rather than a sine wave, it must include harmonics. For example, in the case of a 150 Hz tone, the vibration may include components such as 300 Hz, 450 Hz, and 600 Hz. However, in the tone represented by the sum of the harmonic components, since the waveform of the 150 Hz component, which is the fundamental frequency, will have the greatest coefficient when compared with the waveforms of the other harmonic components, the first tone detection filter unit 120 A particular bandpass filter (in this case, a 150 Hz bandpass filter) will eventually output the greatest energy. Therefore, even if high energy is output from the specific bandpass filter of the second tone detection filter unit 130, when the first tone detection filter unit 120 outputs higher energy, the low frequency wave to be recognized as an abnormal tone is generated. It may be determined that the tone is input.

The energy comparison unit 140 compares the amount of energy output from the plurality of bandpass filters included in the first tone detection filter unit 120 and the second tone detection filter unit 130 to obtain a frequency having the largest energy. You can decide. The controller 150 is connected to the energy comparator 140. When the frequency with the maximum amount of energy belongs to 150 Hz or 200 Hz, which is a band pass band of the first tone detection filter unit 120, it is an abnormal tone. And the output of the energy comparator 140 to process the normal tone when it belongs to 350 Hz, 400 Hz, 425 Hz, 440 Hz, 480 Hz, or 620 Hz, which is a band pass band of the second tone detection filter 130. . Specifically, the energy comparator 140 may output a tone detection signal according to a corresponding frequency when it is determined to be a normal tone signal under the control of the controller 150, and do not perform any operation when it is determined to be an abnormal tone signal. Or output an error signal.

In one embodiment, the controller 150 further compares the maximum amount of energy with a predetermined minimum energy level, and when the maximum amount of energy is smaller than the predetermined level, the band at which frequency is the maximum amount of energy is the band. The output of the energy comparator 140 may be controlled to process an abnormal tone regardless of whether or not it belongs to. Through this, unintended signals due to noise on the line and operating conditions of the peripheral device are recognized as tones, thereby preventing the digital key phone system from malfunctioning.

1 illustrates the controller 150 as a separate component independent from the energy comparator 140, this is merely exemplary, and the controller 150 is integrated into or combined with the energy comparator 140. You can also do In addition, although the energy comparator 140 outputs the corresponding tone detection signal, it should be noted that the tone detection signal may be output through the controller 150 or other components of the circuit.

2 is a flowchart of tone detection in a digital key phone system according to an embodiment. First, the analog tone signal is converted into a digital PCM signal through the A / D converter 110 (S210). The converted PCM signal is bandpass filtered in a plurality of bandpass filters included in the first tone detection filter 120 and the second tone detection filter 130 (S220). The energy comparison unit 140 receives the outputs of the plurality of bandpass filters to determine the frequency having the maximum energy (S230). Next, it is determined whether the maximum energy is equal to or greater than a predetermined tone sensing minimum energy level (S240). If the maximum energy is less than the predetermined tone detection minimum energy level, the system may process it as an abnormal tone (S270). If the maximum energy is greater than or equal to the predetermined tone detection minimum energy level, the flow proceeds to step S250, and it is determined whether the frequency having the maximum energy is, for example, 150 Hz or 200 Hz. If the frequency with the maximum energy is 150Hz or 200Hz, since this corresponds to a low frequency tone that should not be detected as a tone, the system may process it as an abnormal tone (S270). However, if the frequency with the maximum energy does not correspond to 150 Hz or 200 Hz, appropriate tone detection output can be performed depending on whether the frequency corresponds to 350 Hz, 400 Hz, 425 Hz, 440 Hz, 480 Hz, or 620 Hz ( S260).

On the other hand, the steps of the flowchart is not limited to the above embodiment, it should be noted that the order may be changed or may be performed at the same time without departing from the spirit of the invention. For example, determining whether the maximum energy is equal to or greater than a predetermined tone sensing minimum energy level (S240) may be performed after determining whether a frequency having the maximum energy belongs to a low frequency band (S250). In operation S230, the determining of the frequency having the maximum energy may be performed after the operation S240.

The above embodiments can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, which are also implemented in the form of carrier wave (eg, transmission over the Internet). It also includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the above embodiments can be easily inferred by programmers in the art to which the present invention belongs.

Although the invention has been described with reference to various embodiments, those skilled in the art are not limited to these embodiments, and many other embodiments other than those described by way of example are also included within the spirit and scope of the invention. You will know.

1 is a diagram illustrating a tone detector of a digital key phone system according to an embodiment of the present invention.

2 is a flowchart of tone detection in a digital key phone system according to an embodiment of the present invention.

<Description of main parts of drawing>

110: A / D converter

120: first tone detection filter

130: second tone detection filter

140: energy comparison unit

150: control unit

Claims (11)

Tone detection device of digital keyphone system, An AD converter converting the analog tone signal into a digital signal and outputting the digital signal; A first tone detection filter unit receiving the digital signal and outputting band-pass filtering in a frequency band smaller than a first frequency; A second tone detection filter unit which receives the digital signal and outputs a band pass filtering in a frequency band equal to or greater than the first frequency; An energy comparison unit which receives the outputs of the first tone detection filter unit and the second tone detection filter unit and compares magnitudes of the energy of the outputs to determine a frequency having the maximum amount of energy; And Comparing the energy to process an abnormal tone when the frequency with the maximum amount of energy belongs to the band pass band of the first tone detection filter unit, and to process a normal tone when it belongs to the band pass band of the second tone detection filter unit. Control unit to control negative output Tone detection device of the digital key phone system comprising a. The method of claim 1, The control unit further compares the maximum amount of energy with a predetermined minimum energy level, and when it is smaller than the predetermined energy level, processes the abnormal tone regardless of which band the frequency where the amount of energy is maximum belongs to. Tone detection device of the digital key phone system for controlling the output of the energy comparison unit. The method according to claim 1 or 2, And said first frequency is 350 Hz. The method according to claim 1 or 2, And a digital signal is a pulse code modulation (PCM) signal. The method according to claim 1 or 2, And the first tone detection filter unit includes a bandpass filter for passing a band of about 150Hz and a bandpass filter for passing a band of about 200Hz. Tone detection method in digital keyphone system, Converting an analog tone signal into a digital signal using an AD converter and outputting the digital signal; Receiving the digital signal and performing bandpass filtering on a frequency band smaller than a first frequency and a frequency band greater than or equal to the first frequency; Determining the frequency at which the amount of energy is maximum by receiving the bandpass filtered outputs and comparing the magnitudes of the energy of the outputs; And Processing as an abnormal tone when the frequency with the maximum amount of energy belongs to a bandpass band smaller than the first frequency, and processing as a normal tone when belonging to a bandpass band above the first frequency How to include. The method of claim 6, Comparing the maximum amount of energy with a predetermined minimum energy level, and if the energy level is less than the predetermined energy level, processing the abnormal tone irrespective of which band the frequency where the amount of energy is maximum belongs to; Way. The method according to claim 6 or 7, And said first frequency is 350 Hz. The method according to claim 6 or 7, The digital signal is a PCM signal. The method of claim 8, And outputting bandpass filtering in a frequency band smaller than 350 Hz, outputting the bandpass filtering to pass about 150 Hz and about 200 Hz bands. A computer readable recording medium storing computer executable instructions for performing a tone sensing method in a digital keyphone system, the method comprising: Converting an analog tone signal into a digital signal using an AD converter and outputting the digital signal; Receiving the digital signal and performing bandpass filtering on a frequency band smaller than a first frequency and a frequency band greater than or equal to the first frequency; Determining the frequency at which the amount of energy is maximum by receiving the bandpass filtered outputs and comparing the magnitudes of the energy of the outputs; And Treating as an abnormal tone when the frequency that is the maximum amount of energy belongs to a bandpass band smaller than the first frequency, and treating it as a normal tone when belonging to a bandpass band of the first frequency or more. Computer-readable recording medium comprising a.

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