KR970068394A - DTME detection device using downsampling and frequency enhancement technique - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual tone multi-frequency (DTMF) detection apparatus, and more particularly to a DTMF detection apparatus using downsampling and frequency enhancement techniques. A DTMF detection apparatus according to the present invention includes: a first low-pass filter unit for inputting a tone signal and sampling at 8 KHz and passing a frequency of 2 KHz or less; A first decimator section for down-sampling at 4 KHz; A row frequency processing unit for signal processing a frequency corresponding to a number plate of the row in the signal; A thermal frequency processing unit for signal processing a frequency corresponding to a numerical plate of a column in the signal; A frequency enhancement unit for maximizing a corresponding frequency component of the signal; A band-pass filter unit for band-passing the frequency; And a logic setting unit for inputting the frequency of one row and column output from the band pass filter unit and outputting the digital signal of the telephone number plate. As described above, the DTMF detection apparatus using the downsampling and frequency enhancement techniques according to the present invention reduces the amount of signal processing by downsampling an input signal, thereby reducing the amount of signal processing in a unit digital signal processing unit Provides the ability to process channels.

Description

DTMF detection system using downsampling and frequency enhancement technique

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FIG. 1 is a block diagram illustrating a DTMF detection apparatus using a downsampling and frequency enhancement technique according to the present invention. FIG. 2 is a block diagram illustrating a DTMF detection apparatus using a downsampling and frequency enhancement technique according to the present invention. 3A shows the frequency component of the signal output from the frequency enhancement unit of FIG. 2, and FIG. 3B shows the frequency component of the signal before it enters the frequency enhancement unit of FIG.

Claims (9)

A DTMF (DTMF) detection apparatus using a downsampling and frequency enhancement technique, comprising: a first low-pass filter unit that samples a DTMF signal converted into an analog signal at 8 KHz and passes a frequency of 2 KHz or less; ; A first decimator for decreasing a sample frequency of a signal output from the first low-pass filter to 4KHz; A row frequency processor for signal processing a frequency corresponding to a number plate of a row in the signal output from the first decimator; A column frequency processor for signal processing a frequency corresponding to the telephone number plate of the column from the signal output from the first decimator unit; A frequency enhancement unit for introducing a signal processed by the row / column frequency processor and maximizing a frequency component of the signal; A band pass filter unit for passing the frequency output from the frequency enhancement unit in a corresponding frequency domain; And a logic setting unit for inputting a frequency of one row and column output from the band pass filter unit and outputting a digital signal of the pressed telephone number plate. The digital signal processing apparatus of claim 1, DTMF) detection device. The apparatus as claimed in claim 1, wherein the row frequency processing unit comprises: a second low pass filter unit for sampling the input signal at 4 KHz and low-passing the input signal at 1 KHz; a second decimator unit for down sampling at 2 KHz; And a second high pass filter unit that cuts off the second high pass filter unit. The DTMF detection apparatus of claim 1, wherein the thermal frequency processing unit comprises a high-pass filter. The apparatus as claimed in claim 1 or 3, wherein the thermal frequency processing unit receives a down-sampled signal of 4 KHz in the first decimator and passes a frequency of 1 KHz or more at a cut-off frequency of 1 KHz. DTMF detection device using enhancement technique. [2] The apparatus of claim 1, wherein the enhancement unit maximizes the frequency component by comparing the input signal with a predetermined threshold value, separating the input signal into three sections of maximum, minimum, and zero, DTMF detection system using sampling and frequency enhancement techniques. The apparatus of claim 1, wherein the first low-pass filter unit comprises an anti-aliasing filter. The apparatus as claimed in claim 1, wherein the bandpass filter unit comprises a first band pass filter unit and a second band pass filter unit. The apparatus of claim 7, wherein the first band-pass filter unit includes a 697 Hz band pass filter (BPF), a 770 Hz BPF, a 852 Hz BPF, and a 941 Hz BPF, DTMF Detection System Using. 9. The apparatus of claim 8, wherein the second bandpass filter unit includes 1209 Hz BPF, 1336 Hz BPF, 1447 Hz BPF, and 1663 Hz BPF that allow only the corresponding frequency to pass through the incoming signal. The downsampling and frequency enhancement techniques FEF detection device. ※ Note: It is disclosed by the contents of the first application.