KR890003047B1 - Transmission device of picture - Google Patents

Abstract

A picture signal (1) obtained by scanner is digitized by an A/D converter (2). A carrier frequency (fc) is phase inverted at the phase inverting point detected by a zero phase detector (3). The digital signal and phase inverted carrier frequency are synthesized by a synthesizer (3) and converted to analog signal by D/A converter. Signal for transmitting is obtained after modulating the analog signal.

Description

Signal Modulation Device and Method of Simulated Transmitter

1 is a block diagram of a conventional signal modulation device.

2 (a)-(d) are modulation waveform diagrams of a conventional signal modulation device.

3 is a circuit diagram of an apparatus implementing the method of the present invention.

4 (a) and 4 (b) are detailed circuit diagrams of the circuit of FIG.

5 is a modulation waveform diagram in the apparatus of the present invention.

The present invention relates to a signal modulation apparatus and method thereof of a simulated transmitter, and more particularly, to a signal modulation apparatus and method capable of generating accurate image transmission and various carrier frequencies by modulating a signal by a phase modulation method of phase change point detection. will be.

Conventionally, as shown in FIG. 1, an output signal (FIG. 2 (a)) output by the scanning device is converted into a digital signal by the analog digital converter 32 through the input 31, and thus, the second signal (b). Carrier frequency, such as degrees, is output at a constant frequency by a table stored in the ROM 33, input to the synthesizer 34, synthesized with the digitalized signal, and input to the analog converter 35, as shown in FIG. The analog synthesized waveform is transmitted to the transmission path 36. In the ROM 33, the equalized sinusoidal signal is converted into a digital value, assigned to each address, and sequentially addressed by a clock as shown in FIG. In the conventional apparatus, the synthesizer 34 generating a carrier frequency and synthesizing it with a speech signal has a very complicated multi-stage configuration, thereby increasing the circuit board area and cost. At the same time, since the synthesized signal and the carrier frequency are simply synthesized, distortion is generated when the phase change point is detected, so that accurate image reproduction is difficult on the receiving side, and various carrier frequencies cannot be generated.

The present invention detects the phase change point separately and adds it as a composite signal to the signal modulation so as to eliminate such a conventional disadvantage, and there is no distortion in the modulated signal, and at the same time, it is easy to accurately reproduce the image on the receiving side, while applying a microprocessor It is an object of the present invention to provide a signal modulator for simulating a transmitter and a method thereof, which can reduce the size of the device, reduce the price, and generate various carrier frequencies. The present invention will be described in detail with reference to the following.

First, the method of the present invention will be described step by step. The output signal obtained by the scanning device is converted into a digital signal, the phase shift points of the 0 phase and the? Phase are detected as the digital signals, and then the carrier frequency fc is the phase change point. Phase inversion, synthesize a carrier frequency having a digital signal and a phase inverted portion, and then converts it into an analog signal and then forms a waveform to generate a transmission output. As shown in FIG. 3, the output of the analog-to-digital converter 2 through the input 1 of the speech signal by the scanning device (not shown and is not shown) is supplied to the frequency synthesizer 5 and the phase change point detector 3 The output of the phase change point detector 3 is connected to the frequency synthesizer 5 and the analog / digital converter 2 through the carrier generator 4, and the frequency synthesizer 5 The output of is a configuration in which the digital / analog converter 6 is connected to the output 8 via the filter 7 and the working effects of such a device will be described with reference to the waveform diagram of FIG.

The video signal output by the scanning device as shown in FIG. 5 (a) is converted into a digital signal by the analog / digital converter 2 through the input 1, and the converted digital signal is transmitted to the phase change point detector 3. The phase change point is detected by input.

The carrier generation unit 4 generates a carrier signal (figure 5 (b)) that matches the carrier frequency fc, and inverts the phase of the carrier signal at the phase change point and outputs it to the frequency synthesizer 5.

The frequency synthesizer 5 synthesizes the digital signal output from the analog-to-digital converter 2 and the digital signal output from the carrier generator 4 and then converts the digital / analog converter 6 into a filter 7. It will be sent by filtering. In the present invention, the phase change point can be detected by distinguishing the phase change point into 0 phase and π phase, so that transmission distortion can be minimized, so that the demodulated signal same as the original signal can be demodulated during demodulation, and the carrier frequency (fc ) Is generated using a microprocessor in the carrier generator 4, so that various carrier frequencies can be generated.

In FIG. 4 (a), a detailed circuit of the phase change point detector 3 is shown, and the picture signals corresponding to the n-1, n, and n + 1th clocks of the clock signal (FIG. 5 (c)) are respectively shown. It inputs to the digital comparators 35 and 36, and detects phases of 0 phase and (pi) phase.

That is, if only one of the zero phases of which the amplitude value of the signal decreases and the increasing? Phase of which the amplitude value of the signal increases increases and decreases, the remaining ones become the remaining phases. Therefore, zero phases are detected by the digital comparators 35 and 36.

That is, in FIG. 4 (a), the outputs of the latches 32 and 33 are connected to the inputs (+,-) of the comparator 35, respectively, and at the same time, the outputs of the latches 33 and 34 are inputs of the comparator 36 ( -, +), The latches 32, 33, 34 are driven in the same clock.

First, the digital output of the analog digital converter 2 is continuously supplied to the latch 33 in synchronization with the clock. For example, when the clock n-1, the digital value 0101 of 5 is applied to the latch 32 and the clock width n ), When the digital value 001 of 3 is applied to the latch 32, the digital value of 5 is shifted from the latch 32 to the latch 32 so that the output of the comparator 35 is kept low.

At this time, since the output of the comparator 35 is 'low' no matter what value the latch 34 has, the output of the AND gate 37 is 'low'.

Next, when the clock (n + 1) is input to the latch 32, the value of 8 is 1000, the digital values of 5, 3, and 8 are latched into the latches 32, 33, and 34, respectively, and their outputs are also 5, 3, 8 As a result, the outputs of the comparators 35 and 36 may be 'high' at the same time, and the output of the AND gate 37 may be 'high' to indicate that it is an inflection point.

Therefore, the n-th clock detected by the phase change point detector is inverted to the digital value amplitude generated by the carrier generator and input to the frequency synthesizer 5.

In the carrier generator 4, the carrier frequency fc can be variously generated as a microprocessor by the following equation.

Where fd is the digital value specifying the address.

fs: single sample frequency.

INT: Address bit integer argument that specifies table lookup.

The carrier frequency selected in this equation is addressed sequentially by the period TS, where the sample number is INT (TS / TC).

4 (b) is a detailed configuration diagram of the frequency synthesizer 5 in the third diagram, and combines the output signal output from the analog / digital converter 2 and the output from the carrier generator 4.

That is, the sum signal output from the analog / digital converter 2 is stored in the accumulator 53 in the microprocessor 41, and the corresponding digital value in the carrier generator 4 is stored in the register 54, and the adder ( 55 is added to and output to the digital-to-analog converter 6.

In addition, the analog-to-digital converter 2 is controlled by the signal from the carrier generator 4 to take the same phase value.

As described above, according to the present invention, the use of the microprocessor enables various carrier frequencies to be generated, and the phase modulation method by detecting the phase modulation point increases the transmission efficiency and the transmission quality.

Claims (2)

The output signal obtained by the scanning device is converted into a digital signal, the phase shift point of zero phase is detected as this digital signal, and then the carrier frequency fc is phase inverted at the phase change point, and the phase inverted from the digital signal. A signal modulation method of a simulated transmitter for synthesizing a carrier frequency having a signal and converting it into an analog signal and then shaping a waveform to generate a transmission output. The input 1 of the speech signal by the scanning device is connected to the input of the analog / digital converter 2, and the output of the analog / digital converter 2 is shared with the frequency synthesizer 5 and the phase change point detection section 3. The output of the phase change point detector 3 is connected to the frequency synthesizer 5 and the analog / digital converter 2 through the carrier generator 4, and the output of the frequency synthesizer 5 is a digital to analog converter. 6) A signal modulator of a simulated transmitter connected to an output (8) via a filter (7).

Images