KR0174143B1 - AFT automatic adjustment device by ambient temperature and its method - Google Patents

Abstract

The present invention reads the temperature sensing unit 60 for sensing the ambient temperature and the tuning voltage VT1 of a specific channel tuned by a key input and adds a correction voltage VT2 corresponding to the ambient temperature to the tuning voltage VT. Microcomputer 40 for outputting), RF amplifier 11 for receiving and amplifying the radio frequency (RF) received through the antenna (ANT), and the preset voltage (VT) transmitted from the microcomputer 40 is applied. A tuner unit 10 comprising a local oscillator 13 receiving the local oscillation frequency and a mixer 14 mixing the RF signal amplified by the RF amplifier 11 and the local oscillation frequency oscillated by the local oscillator 13. ), And compares the IF signal of the mixer 14 and the 45.75 MHz phase of the 45.75 MHz oscillator 20 to obtain a phase difference and transmits the phase comparator 30 to the microcomputer 40, thereby using an existing PLL. Instead, the tuner's AFT is corrected with the correction voltage corresponding to the ambient temperature. Can be adjusted automatically.

Description

AFT automatic adjustment device based on ambient temperature and method thereof.

The present invention relates to an AFT adjustment device and method, and more particularly, to AFT by ambient temperature to add a correction voltage according to the ambient temperature to a preset voltage of a specific channel so that the local oscillation frequency can be automatically adjusted to correspond to the ambient temperature. An automatic adjusting device and a method thereof.

Referring to FIG. 1, a conventional tuner and a peripheral configuration thereof are broadly divided into a tuner unit 100 that tunes a multi-channel RF signal received through an antenna ANT and converts it into an IF signal, and a tuner unit 100. It consists of an IF amplification unit 200 to amplify the IF signal selected in the). In more detail, the tuner unit 100 receives an RF amplifier 110 for amplifying a radio frequency (RF) signal received from an antenna ANT, and a preset voltage VT3 transmitted from the microcomputer 200. A PLL (Phase Lock Loop) 120 for detecting a signal, a local oscillator 130 for oscillating a local oscillation frequency corresponding to a phase difference detected in the PLL 120, and an RF signal and a local oscillator amplified by the RF amplifier 110. Composed of a mixer 140 for mixing the local oscillation frequency converted in 130, IF amplifier 200 is an IF amplifier 210 for amplifying the IF signal output from the mixer 140, and the IF amplifier ( A demodulation unit 220 for demodulating the IF signal amplified by 210, a synchronization signal separation unit 600 for separating the synchronization signal from the demodulated signal and transmitting it to the microcomputer 300, and amplifying the IF amplifier 210; 45.75 MHz supplied from a 45.75 MHz oscillator 400 consisting of an IF signal and an AFT coil L1 and a capacitor C1 Obtaining the phase difference is configured it to the phase comparator (230) for transmission to the microcomputer 300.

Referring to the AFT operation of the tuner configured as described above, when the tuning voltage VT3 for tuning a specific channel output from the microcomputer 40 is output to the PLL 120 of the tuner unit 100, the PLL 120 receives the applied tuning voltage. By controlling the oscillation frequency of the local oscillator 130. The RF signal received through the antenna ANT is amplified and applied to the mixer 140 supplied with the local oscillation frequency oscillated by the local oscillator 130, so that the mixer 140 mixes them. Converts it to an IF signal of 55.75 MHz and supplies it to an input of an IF amplifier 230.

Subsequently, the demodulator 220 receiving the IF signal amplified by the IF amplifier 210 of the IF amplifier 200 demodulates the video signal from the IF signal and uses the synchronization signal separator 600 therefrom. Since the horizontal synchronization signal is separated and supplied to the microcomputer 300, the microcomputer 300 recognizes that a specific channel is tuned. The tuning state is determined by the AFT voltage supplied from the phase comparator 230, and a tuning voltage VT3 for adjusting the tuning state is generated and supplied to the PLL 120 of the tuner unit 100. That is, the microcomputer 300 adjusts the oscillation frequency of the local oscillator 130 by changing the tuning voltage VT3 (generally composed of 12 steps of 6 steps each with respect to the tuning voltage of a specific channel) by 1 step. The tuning state is determined by the AFT voltage level generated by the phase comparator 230. Here, the phase comparator 230 contrasts the phase difference between the IF signal applied from the IF amplifier 210 and the frequency of 45.75 MHz and transmits the AFT voltage according to the result to the microcomputer 300.

In this case, in order to tune the RF signal more accurately, the local oscillation frequency is adjusted using the PLL 120, so that the PLL 120 must be configured. In particular, the local oscillator reacts sensitively according to the ambient temperature to change the oscillation frequency, thus failing to maintain accurate tuning state when the ambient temperature changes.

The present invention has been made to solve the above-described drawbacks, and does not use a conventional PLL, but automatically adjusts the AFT by the ambient temperature so as to stabilize the tuning state by correcting the tuning voltage according to the ambient temperature of the tuner. An object of the present invention is to provide an apparatus and a method thereof.

According to the present invention for achieving the above object, a first step of waiting for a key input for tuning a specific channel while maintaining a standby state, and storing the tuning voltage VT1 of the specific channel corresponding to the key input in the storage means. A second step of reading out, a third step of sensing an ambient temperature of the tuning means and reading out a corresponding correction voltage VT2 from the storage means, and adding a correction voltage VT2 to the preset voltage VT1; A fourth step of outputting this to the local oscillation means as the tuning voltage VT, a fifth step of tuning the specific channel by receiving the tuning voltage VT, and a sixth step of sensing the ambient temperature after tuning the specific channel; And a seventh step of checking whether the ambient temperature changes, and an eighth step of calculating the correction voltage VT4 when the ambient temperature changes and adding it to the tuning voltage VT of a specific channel and outputting it as the tuning voltage VT5. , Adjust the tuning voltage (VT5) corrected by the change of ambient temperature. Supplied to the oscillation portion means is characterized by yirueojim to perform a ninth step of tuning a particular channel.

That is, the present invention reads the temperature sensing means configured to sense the ambient temperature, and the tuning voltage VT1 of the specific channel tuned by the key input and adds the correction voltage VT2 corresponding to the ambient temperature to the preset voltage ( A control means configured to output VT, an RF amplification means adapted to amplify by receiving a radio frequency RF received through an antenna ANT, and a preset voltage VT transmitted from the control means. A local oscillation means configured to oscillate a local oscillation frequency, a tuning means consisting of a mixing means adapted to mix an RF signal amplified by the RF amplification means and a local oscillation frequency oscillated by the local oscillation means, and an IF signal of the mixing means And a phase comparison means for obtaining a phase difference in contrast to the 45.75MHz phase of the 45.75MHz oscillation means and transmitting it to the control means.

1 is a block diagram illustrating a conventional AFT adjustment;

2 is a block diagram of the present invention;

3 is a flowchart illustrating a process of performing an AFT adjustment operation according to the present invention.

Explanation of symbols on the main parts of the drawings

10: tuner unit 11: RF amplifier

12: mixer 13: local oscillator

20: 45.75MHz oscillator 30: phase comparator

40: microcomputer 50: memory unit

60: temperature sensing unit TH: thermistor

R1, R2: resistance

As shown in FIG. 2, the present invention reads a temperature sensing unit 60 for sensing an ambient temperature, and a tuning voltage VT1 of a specific channel selected by a key input and a correction voltage VT2 corresponding to the ambient temperature. A microcomputer 40 for outputting the preset voltage (VT) by adding a, RF amplifier 11 for receiving and amplifying the radio frequency (RF) received through the antenna (ANT), and is transmitted from the microcomputer 40 A local oscillator 13 that receives a pre-selection voltage VT and oscillates a local oscillation frequency, and a mixer 14 that mixes an RF signal amplified by the RF amplifier 11 and a local oscillation frequency oscillated by the local oscillator 13. A tuner 10 composed of a waveguide, a phase comparator 30 for comparing the IF signal of the mixer 14 and the 45.75 MHz phase of the 45.75 MHz oscillator 20 to obtain a phase difference and transmitting the phase difference to the microcomputer 40. It is.

In particular, the microcomputer 40 has a preset voltage VT1 of a specific channel and a correction voltage VT2 corresponding to the ambient temperature.

3 is a flowchart illustrating an operating state of the present invention, in which a memory unit stores a first step of waiting for a key input for tuning a specific channel while maintaining a standby state, and a tuning voltage VT1 of a specific channel corresponding to the key input. A second step of reading out at 60, a third step of sensing an ambient temperature of the tuner and reading out a corresponding correction voltage VT2 from the memory unit 60, and a correction voltage at the preset voltage VT1. A fourth step of adding VT2 and outputting it to the local oscillator 13 as a tuning voltage VT, a fifth step of tuning a specific channel by receiving the tuning voltage VT, and tuning a specific channel. A sixth step of detecting the ambient temperature, a seventh step of checking whether the ambient temperature changes, and calculating a correction voltage VT4 when the ambient temperature changes, and adding it to the tuning voltage VT of the specific channel to adjust the tuning voltage VT5. Eighth step of outputting), and the preset voltage (VT5) corrected by the change of ambient temperature. Is showing a ninth step of performing channel selection of a specific channel are supplied to the oscillator unit (13).

According to the present invention configured as described above, when a key for tuning a specific channel is input (S2) (S3) while maintaining a standby state (S1), the microcomputer 40 selects a memory unit 50 for tuning the channel corresponding to the key input. The tuning voltage VT1 corresponding to the key input is read out (S4) and applied to the local oscillator (13). Then, the mixer 12 mixes the RF signal amplified by the RF amplifier 11 and the local oscillator supplied from the local oscillator 13 and applies it to the input terminal of the phase comparator 30. The phase comparator 30 then compares the phase of the IF signal supplied from the mixer 12 with a frequency of 45.75 MHz and transmits the result to the microcomputer 40. Recognizing the phase difference between the IF signal supplied from the phase comparator 30 and the frequency of 45.75 MHz, the microcomputer 40 determines whether the channel being received is tuned correctly and receives the tuning voltage VT1 for adjusting the local. Since the oscillator 13 is supplied, accurate tuning is achieved.

In addition, in the present invention, the microcomputer 40 includes a thermistor TH before reading the preset voltage VT1 corresponding to the key input from the memory unit 50 and outputting it to the local oscillator 13. The ambient temperature of the tuner detected by the unit 60 is recognized (S5). In addition, the correction voltage VT2 for correcting the tuning voltage VT1 according to the ambient temperature is read out from the memory unit 50 and added to the read tuning voltage VT1 to calculate the tuning voltage VT. This is applied to the local oscillator 13. Accordingly, the local oscillator 13 is supplied with the tuning voltage VT2, which is added to the tuning voltage VT1 corresponding to the key input, and the tuning voltage VT2, which is variable by the ambient temperature, to correspond to the key input even when the ambient temperature changes. The channel can be tuned more accurately (S7).

In this way, while tuning the specific channel by correcting the tuning voltage VT by the key input and the ambient temperature, the microcomputer 40 continuously detects the ambient temperature detected by the temperature sensing unit 60 (S8). When it is determined that a new key input is made or the temperature is changed (S9), the microcomputer 40 reads the tuning voltage VT1, the correction voltage VT4, and the memory unit 50 again (S10) to calculate them. One station voltage VT5 is obtained and applied to the local oscillator 13. Accordingly, since the tuning voltage VT5 changed due to a new key input or temperature change is supplied to the local oscillator 13, the channel corresponding to the key input can be tuned more accurately even if the ambient temperature is changed while receiving and tuning a specific channel. It is (S11). Of course, if the ambient temperature fluctuates even after performing such an operation, as described above, the local oscillator may be continuously read to the tuning voltage VT that reads the correction voltage VT2 corresponding to the fluctuating temperature and adds it to the tuning voltage VT1. Adjust the oscillation frequency in 13).

The present invention adjusts the oscillation frequency of the local oscillator of the local oscillator to accurately tune the specific channel by reading the preset voltage VT1 of the specific channel selected by the key input from the memory unit and correcting the correction voltage according to the ambient temperature. You can do it.

In particular, by removing the PLL included in the tuner can reduce the production cost of the tuner, it is possible to increase the commercialization of the tuner by reducing the malfunction of the tuner by the PLL.

Claims (4)

A temperature sensing unit 60 for sensing the ambient temperature; A microcomputer 40 that reads the tuning voltage VT1 of a specific channel selected by key input and adds the correction voltage VT2 corresponding to the ambient temperature to output the tuning voltage VT; An RF amplifier 11 for receiving and amplifying a radio frequency RF received through an antenna ANT and a local oscillator for generating a local oscillation frequency by receiving a preset voltage VT transmitted from the microcomputer 40 ( 13) a tuner unit 10 including a mixer 14 for mixing the RF signal amplified by the RF amplifier 11 and the local oscillation frequency oscillated by the local oscillator 13; It is composed of a phase comparator 30 which obtains a phase difference by comparing the IF signal of the mixer 14 and the phase of 45.75 MHz of the 45.75 MHz oscillator 20 and transmits it to the microcomputer 40. AFT regulator. The apparatus of claim 1, wherein the temperature sensing unit (60) comprises a thermistor (TH) whose resistance is variable according to the ambient temperature. The ambient temperature of claim 1, wherein a memory unit 50 having a preset channel voltage VT1 of a specific channel and a correction voltage VT2 corresponding to the ambient temperature is connected to the microcomputer 40. Automatic AFT Adjuster. A first step of waiting for a key input for tuning a specific channel while maintaining a standby state; Reading a preset voltage VT1 of a specific channel corresponding to a key input from the memory unit 60; Sensing the ambient temperature of the tuner and reading a corresponding correction voltage VT2 from the memory unit 60; A fourth step of adding the correction voltage VT2 to the preset voltage VT1 and outputting the corrected voltage VT2 to the local oscillator 13 as the preset voltage VT; A fifth step of tuning a specific channel by receiving the preset voltage VT; Detecting a surrounding temperature after tuning a specific channel; A seventh step of checking whether the ambient temperature changes; An eighth step of calculating a correction voltage VT4 when the ambient temperature changes, adding the correction voltage to the tuning voltage VT of a specific channel, and outputting the tuning voltage VT5; An automatic AFT adjustment method according to the ambient temperature, characterized in that to perform the ninth step of tuning a specific channel by supplying the tuning voltage (VT5) corrected by the ambient temperature change to the local oscillator (13).