KR20020081493A - Fsk signal generation apparatus - Google Patents

Abstract

PURPOSE: A FSK(Frequency Shift Keying) signal generator is provided, which can output an accurate FSK signal without wave distortion at a point where two sinusoidal signals are crossed. CONSTITUTION: The FSK signal generator(100) comprises a DSP(Digital Signal Processor)(110) and a D/A(Digital/Analog) converter(120) outputting a sinusoidal signal by converting a sinusoidal value from the DSP into an analog. The DSP comprises the first look-up table(111) where an address corresponding to a sampling value of the first sinusoidal wave having a fixed period is stored in a table, which outputs the address corresponding to the first sinusoidal value by being enabled if a high signal among binary signal stream inputted from the external is inputted. The DSP also comprises the second look-up table(112) where an address corresponding to a sampling value of the second sinusoidal wave is stored in a table, which outputs the address corresponding to the second sinusoidal value by being enabled if a low signal among binary signal stream inputted from the external is inputted. And a sinusoidal wave look-up table(113) has a sinusoidal value corresponding to the address stored in a table, and outputs the corresponding sinusoidal value according to the address being output from the first and the second look-up table to the D/A converter.

Description

FSK signal generator {FSK SIGNAL GENERATION APPARATUS}

The present invention relates to an FSK (Frequency Shift Keying) signal generator, and more particularly, to an FSK signal generator for outputting an accurate sinusoidal signal by preventing distortion of a waveform from occurring at a point where two sinusoidal signals intersect. It is about.

In general, a sinusoidal waveform value is read at a sampling period from a table in which sinusoidal waveform values are stored in advance, and then converted into an analog signal to obtain an accurate sinusoidal waveform.

On the other hand, in order to generate an FSK signal consisting of two sinusoids in a DSP (Digital Signal Processor), the DSP reads the address of the sinusoid from the look-up table in which the address of the sinusoid is stored according to the input binary signal sequence, and stores the sinusoidal waveform value. The sine waveform values corresponding to each address were read from the look-up table, and they were sequentially output to the D / A converter to output an FSK signal having two sine waves.

However, when the FSK signal is output by the conventional method, waveform distortion occurs because the periods of the two frequencies are different from each other where the first sinusoidal wave and the second sinusoidal wave intersect, for example, a portion where 1200 Hz and 2400 Hz are connected to each other. There is this.

Accordingly, an object of the present invention is to solve the above problems, by storing the sine wave value corresponding to the address in a separate table in advance and outputting the sine wave value according to the address, the waveform at the point where the two sine wave signals intersect. It is to output accurate FSK signal without distortion.

1 is a block diagram schematically showing the configuration of an FSK signal generator according to the present invention

2 is an exemplary view showing an example of data stored in each look-up table of the FSK signal generating apparatus according to the present invention;

<Explanation of symbols for main parts of the drawings>

110: DSP111: the first look-up table

112: second look-up table 113: sine wave look-up table

120: D / A Converter

Features of the present invention for achieving the above object,

An FSK signal generator comprising a DSP and a D / A converter for converting a sine wave value output from the DSP into an analog and outputting a sine wave signal.

The DSP,

An address corresponding to a sampling value of the first sinusoidal wave having a predetermined period is stored in a table form, and when the high signal of the binary signal sequence input from the outside is input, the first look is enabled to output an address corresponding to the first sinusoidal wave value. -Up table,

The second look for storing the address corresponding to the sampling value of the second sinusoid having a predetermined period in the form of a table, and when the low signal is input from the binary signal sequence input from the outside, outputting the address corresponding to the second sinusoidal value. -Up table,

A sine wave value corresponding to an address is stored in a table form, and a sine wave look-up that outputs a corresponding sine wave value to the D / A converter according to an address output from the first look-up table or the second look-up table. It is characterized by consisting of an up table.

Hereinafter, the configuration of the FSK signal generator according to the present invention will be described in detail with reference to FIGS. 1 and 2.

1 is a block diagram schematically showing the configuration of an FSK signal generator according to the present invention, Figure 2 is an exemplary view showing an example of data stored in each look-up table of the FSK signal generator according to the present invention.

1 and 2, the FSK signal generator 100 according to the present invention includes a DSP 110 and a D / A converter 120.

The DSP 110 is composed of a first look-up table 111, a second look-up table 112, and a sinusoidal look-up table 113.

In the first look-up table 111, an address corresponding to a sampling value of a first sinusoidal wave having a predetermined period is stored in a table form, and is enabled when a high signal of a binary signal sequence input from the outside is input, thereby enabling the first sinusoidal wave value. Outputs the address corresponding to Here, as shown in FIG. 2, the first look-up table 111 divides sinusoids having one period into N pieces (here, 256 pieces), and stores the sampling values corresponding to the divided values. Among the addresses of the look-up table 113, an address corresponding to the first sinusoidal wave is stored.

The second look-up table 112 stores an address corresponding to a sampling value of the second sinusoidal wave having a predetermined period in the form of a table. When the low signal is input from the binary signal sequence input from the outside, the second look-up table 112 is enabled. Outputs the address corresponding to Here, as shown in FIG. 2, the second look-up table 112 divides sinusoids having one period into N (256), and then stores the sampling values corresponding to the divided values. Among the addresses of the up table 113, an address corresponding to the second sinusoidal wave is stored.

The sine wave look-up table 113 stores sine wave values corresponding to addresses in a table form, and corresponds to corresponding addresses according to addresses output from the first look-up table 111 or the second look-up table 112. The sinusoidal value is output to the D / A converter 120. Here, the sinusoidal look-up table 113 divides N sinusoids having one period into 256 units, as shown in FIG. The sampling value of the sine wave corresponding to the divided value (256) of is stored.

The D / A converter 120 converts data (a sine wave sampling value) output from the sinusoidal look-up table 113 of the DSP 110 into an analog signal and outputs the analog signal.

Hereinafter, the operation of the FSK signal generator according to the present invention will be described in detail with reference to FIGS. 1 and 2.

First, the first look-up table 111 is enabled when the input signal is high, and the second look-up table 112 is enabled when the input signal is low.

When a '1', that is, a high signal of the binary signal string (for example, 110011) is input, it is applied to the first look-up table 111 and the second look-up table 112.

The second look-up table 112 then remains disabled, and the first look-up table 111 is enabled.

When the first look-up table 111 is enabled, the DSP 110 sequentially moves from the initial address Base AD of the first look-up table 111 to the addresses Base AD + 4, Base AD + 8... Output AD + N-5, Base AD + N-1). Then, the sine wave value corresponding to each address output from the first look-up table 111 is output from the sine wave look-up table 113, and the digital value is converted into an analog value through the D / A converter 120. Finally, the sine wave is output.

On the contrary, when '0', that is, a low signal of the binary signal string is input, it is applied to the second look-up table 112 and to the first look-up table 111.

The second look-up table 112 is then enabled, and the first look-up table 111 remains disabled.

When the second look-up table 112 is enabled, the DSP 110 sequentially moves from the initial address Base AD of the second look-up table 112 to the addresses Base AD + 4, Base AD + 8... Output AD + N-5, Base AD + N-1). Then, the sine wave value corresponding to each address output from the second look-up table 112 is output from the sine wave look-up table 113, and the digital value is converted into an analog value through the D / A converter 120. A sine wave is output.

Therefore, by generating the sine wave values corresponding to the addresses output from the first look-up table 111 and the second look-up table 112 through the sinusoidal look-up table 113, occurrence of distortion is prevented. .

As described above, according to the FSK signal generating apparatus according to the present invention, by storing the sine wave value corresponding to the address in a separate table in advance and outputting the sine wave value according to the address, the waveform at the point where the two sine wave signals intersect. It is to output accurate FSK signal without distortion.

Claims (1)

An FSK signal generator comprising a DSP and a D / A converter for converting a sine wave value output from the DSP into an analog and outputting a sine wave signal. The DSP, An address corresponding to a sampling value of the first sinusoidal wave having a predetermined period is stored in a table form, and when the high signal of the binary signal sequence input from the outside is input, the first look is enabled to output an address corresponding to the first sinusoidal wave value. -Up table, The second look for storing the address corresponding to the sampling value of the second sinusoid having a predetermined period in the form of a table, and when the low signal is input from the binary signal sequence input from the outside, outputting the address corresponding to the second sinusoidal value. -Up table, A sine wave value corresponding to an address is stored in a table form, and a sine wave look-up that outputs a corresponding sine wave value to the D / A converter according to an address output from the first look-up table or the second look-up table. An FSK signal generating device comprising an up table.