Method for optimizing the level of RF signals by comparing quality of the RF signals under different operation modes

Device for optimizing radio frequency signal level by comparing radio frequency signal quality in different operation modes

The present invention relates to an RF signal processing device and method suitable for an RF signal receiving system such as a television signal receiver for optimizing the level of a radio frequency (RF) signal.

What is desired for a television signal receiver is to receive television signals with appropriate signal strength in the entire television frequency band so that users can always enjoy good quality images and sounds. However, the signal strengths of independent television channels received in a specific geographic location are often different from each other due to the geographic location difference between each broadcasting station and the user's receiving location. When the receiver is tuned to a TV channel with undesirable signal characteristics (for example, the signal is too weak or there is too strong interference), this situation may cause several problems, including low signal-to-noise ratio (S/N). Undesirable noise of the image and cross-modulation caused by interference from adjacent frequency signals for analog reception. Moreover, these problems are particularly harmful to the reception of digital broadcast signals because the reception is completely lost when the quality of the signal falls below a certain threshold.

A traditional way to solve the weak signal problem is to selectively install an additional amplifier between the antenna and the tuner in response to the automatic gain control (AGC) signal, which is optimized for low noise figure. The automatic gain control (AGC) The signal indicates the strength of the received TV signal. For example, the title BROADCAST SIGNAL RECEIVER HAVING A LOW-NOISEAMPLIFIER INSERTED BEFORE A TUNER (with a low-noise amplifier inserted in front of the tuner) authorized on June 10, 1997, submitted by Bae et al. and transferred to Samsung Electronics Co., Ltd. The broadcast signal receiver), US Patent 5,638,141 discloses this scheme. However, this traditional solution is not the preferred solution for the above-mentioned problems, because the AGC signal does not indicate the quality of the TV signal (ie image and/or sound quality), but only the number of received TV signals (ie the signal strength). . Moreover, the AGC signal does not reflect the signal strength on adjacent channel frequencies that may cause interference problems. Therefore, there is a need for an RF signal processing circuit that optimizes the electrical output of the input television signal in each television channel in response to the quality of the television signal and/or in response to not only the strength of the tuned signal but also the strength of the adjacent signals. level.

According to an aspect of the present invention, a signal processing method includes the following steps: tuning to a channel frequency, and then measuring the quality of the information carried by the information-carrying RF signal on the tuned channel frequency in a first operating mode; starting; The attenuator then measures the quality of the information carried by the RF signal in the second mode of operation; the best reception conditions are determined by comparing the quality of the information carried by the RF signal in the first and second modes of operation.

According to another aspect of the present invention, a signal processing method includes the following steps: tuning to a channel frequency, and then measuring the quality of the information carried by the information-carrying RF signal on the tuned channel frequency in a first operating mode; Start the attenuator and then measure the quality of the information carried by the RF signal in the second mode of operation; start the amplifier and then measure the quality of the information carried by the RF signal in the third mode of operation; simultaneously start the attenuation And the amplifier, and then measure the quality of the information carried by the RF signal in the fourth operating mode; by comparing the quality of the information carried by the RF signal in the first, second, third and fourth operating modes The quality of the information determines the best reception conditions.

These and other aspects of the present invention are described below with reference to the drawings.

In the drawings: FIG. 1 is a block diagram showing a part of an analog/digital television signal receiver including a first embodiment of a signal processing device according to the principles of the present invention; FIG. 2 is a block diagram showing a portion of an analog/digital television signal receiver including a signal processing device according to the principles of the present invention A block diagram of a part of the analog/digital television signal receiver of the second embodiment of the device; FIG. 3 is a flowchart illustrating an exemplary manner of operation of the first embodiment shown in FIG. 1 according to the principles of the present invention; FIG. 4 It is a flowchart illustrating an exemplary manner of operation of the second embodiment shown in FIG. 2 according to the principles of the present invention.

The illustrations given here represent preferred embodiments of the present invention, and such illustrations are not construed as limiting the scope of the present invention in any way. In the various drawings, the same or similar reference signs are used to identify the same or similar elements.

This application discloses a first signal processing device, which includes: a signal source, such as an antenna, for providing information-bearing RF signals, such as analog and/or digital television signals; a signal output point; a control device, which includes an attenuator and/ Or an amplifier such as a low noise coefficient amplifier and a plurality of RF switches related thereto, the control device is connected between the signal source and the signal output point, and is used to control the information carrying in response to the quality of the information carried by the RF signal The amplitude of the RF signal. The signal processing device may further include a determination device, such as a demodulator, connected to the control device for determining the quality of the information carried by the RF signal. According to the exemplary embodiment described in detail below, the quality of information is represented by several signal parameters, including automatic color control (ACC) level, image-to-sound ratio (P/S) for analog TV signal reception, signal Noise ratio (S/N), equalizer taps and bit error rate (BER) for digital TV signal reception. The method performed by the device is also disclosed herein.

Moreover, the present application discloses a second signal processing device, which includes: a signal source, such as an antenna, for providing RF signals, such as analog and/or digital television signals; a signal output point; and a first control device, which includes an attenuator And a plurality of RF switches related thereto, the control device is connected between the signal source and the signal output point, and is used to control the amplitude of the RF signal at the frequency of the tuning channel and the amplitude of the RF signal near the tuning channel The amplitude of the RF signal, where the RF signal near the tuned channel includes an RF signal that is adjacent or close to the frequency of the tuned channel. The signal processing device may further include: a memory for storing channel information related to the amplitude of the RF signal of each receivable signal in the entire frequency band, which includes the amplitude of the RF signal of the tuned channel and the channel information on the tuned channel The amplitude of the RF signal of the nearby channel; the second control device, which includes a microprocessor, is connected to the first control device, and is used to control the first control device in response to the channel information stored in the memory. A method performed by this device is also disclosed here.

Referring now to the drawings, specifically FIGS. 1 and 2, block diagrams 100 and 200 respectively show two exemplary implementations of booster/attenuator circuits 110 and 210 related to analog/digital color television signal receivers. The first and second signal processing devices and the methods executed by the respective devices can be equally applied to each of the embodiments shown in FIGS. 1 and 2.

FIG. 1 discloses an exemplary embodiment of a booster/attenuator circuit 110 related to an analog/digital television signal receiver. Broadcast off-air digital and/or analog television signals are received at an antenna (not shown), and then applied to the RF input point of the U/V splitter 20 via an RF signal transmission line (not shown) such as a coaxial cable twenty two. The U/V separator 20 separates the UHF television signal from the VHF television signal in the frequency domain, and provides the UHF television signal to the attenuator switch 118 that is a part of the booster/attenuator circuit 110. Although FIG. 1 shows the booster/attenuator circuit 110 implemented in the UHF signal processing path, it can also be implemented in the VHF signal processing path in the same manner.

The attenuator switch 118 responds to the attenuator control signal from the PLL integrated circuit 30 generated by the microprocessor 50 and sent via the I2C bus to provide a UHF television signal to the attenuator 112 (such as a 3dB impedance RF attenuator) or the boost switch 111 . The boost switch 111 receives UHF signals from the attenuator switch 118 in response to the attenuator control signal from the PLL integrated circuit 30 generated by the microprocessor 50 and sent via the I2C bus, and provides them to the boost circuit/attenuator circuit The tunable single tune (ST) filter 114 of 110 or the tunable single tune (ST) filter 122 generally located at the input end of the RF circuit in the television tuner of the television signal receiver.

The tunable single tune (ST) filter 114 of the boost circuit/attenuator circuit 110 attenuates undesirable signals that may cause cross-modulation interference. The filter 114 is designed to have a wider bandwidth than the typical bandwidth of the standard tuner input filter 122. This design reduces the loss so that the noise figure performance of the amplifier 116 does not greatly degrade while providing protection against interference. The tuning signal ST for the tuner is generated by a digital-to-analog converter (DAC) integrated circuit 40 controlled by the microprocessor 50 via an I2C bus. The tunable single-tuned (ST) tuner 114 also serves as a tunable impedance matching network between the RF input point 20 and the low noise amplifier 116 to provide a gap between the antenna and the low noise amplifier 116 at a given frequency (such as the receiving frequency). Better impedance matching between. Better impedance matching improves the voltage standing wave ratio (VSWR) between the antenna and the low noise amplifier 116, resulting in a reduction in undesirable signal loss and impulse response. The low noise amplifier 116 is activated by the boost control signal from the PLL IC 30 generated by the microprocessor 50 and transmitted via the I2C bus. Although a fixed gain amplifier is used as the low noise amplifier 116 of FIG. 1, it is also possible to use a gain control amplifier with an appropriate gain control circuit. The output signal of the boost switch 111 is applied to the single-tunable tunable filter 122.

The UHF tuner circuit 120 includes a tunable single-tuned filter 122, a gain control RF amplifier 124, a tunable double-tuned (DT) filter 126, a mixer 142, a UHF local oscillator 146, and a double-tuned (DT) filter 152 . The gain of the gain control RF amplifier 124 is controlled in response to the RF AGC signal generated by the analog video and sound processing circuit 60 (for analog signal reception) or by the power detector 179 (for digital signal reception). The UHF tuner 120 converts UHF television signals into IF television signals, and is usually located in the tuner module of the television signal receiver.

The IF signal from the dual-tuned IF filter 152 is then processed in an IF signal processing circuit 150, which includes an IF amplifier 154, a SAW filter 156, and a gain control IF amplifier 158. The gain of the gain control IF amplifier 158 is controlled in response to the IF AGC signal generated by the analog video and sound processing circuit 60 (for analog signal reception) or by the power detector 179 (for digital signal reception). The output signal of the gain control IF amplifier 158 is applied to the subsequent analog signal processing circuit including the analog video and sound processing circuit 60 and the subsequent digital signal processing circuit 170. The digital signal processing circuit 170 includes an analog-to-digital converter 172 and a power detector. 179, a demodulator 174, an equalizer 176, and an error correction decoder 178.

The analog video and sound processing circuit 60 demodulates analog television signals such as NTSC, PAL, and SECAM television signals, and generates RF and IF AGC signals, which are respectively responsive to the number (ie amplitude) of the RF analog television signal The gain control RF amplifier 124 and the gain control IF amplifier 158 are controlled. The analog video and sound processing circuit 60 includes an analog-to-digital converter, and provides the microprocessor 50 with parameter information representing RF and IF AGC signals as digital data. Similarly, the analog video and sound processing circuit 60 provides the microprocessor 50 with parameter information representing the automatic chrominance control (ACC) signal and the image and sound carrier ratio (P/S) in digital form via the I2C bus, each of which represents analog Different aspects of the image quality of RF TV signals.

The digital signal processing circuit 170 processes digital television signals such as QAM, QPSK, and HD VSB signals. The analog-to-digital (A/D) converter provides the digitized IF signal to the demodulator 174 and the power detector 179, which are usually located in the digital demodulator IC. The power detector 172 generates RF and IF AGC signals that respectively control the gain control RF amplifier 124 and the gain control IF amplifier 158 in response to the amount (ie, amplitude) of the RF digital television signal. The power detector 172 provides parameter information representing such RF and IF AGC signals to the microprocessor 50 via the I2C bus. The determination of the AGC level is performed based on the digitized IF signal that has not yet been demodulated.

The demodulator 174 demodulates the digitized IF signal from the A/D converter 172 and provides a so-called "digital baseband signal". The demodulator 174 also generates parameter information representing the signal-to-noise ratio (S/N), and provides such information to the microprocessor 50 via the I2C bus, where the information represents a number of image and sound quality of the RF digital television signal. One of the aspects.

The equalizer 176 receives the digital baseband signals from the demodulator 174 and attempts to correct their impulse response. The impulse response may be degraded by the multipath effect of the transmission channel due to the shortcomings of the antenna and tuner input circuit. The equalizer 176 also generates parameter information representing filter taps, and provides such information to the microprocessor 50 via the I2C bus, where the information represents one of many aspects of the quality of the RF digital television signal. By monitoring these equalizer taps, the above circuit can be selected to reduce the effect of the shortcomings of the antenna and tuner input.

The output signal of the equalizer 176 is applied to the error correction decoder 178, and the error correction decoder 178 performs error correction on the digital baseband signal through a Reed-Solomon decoding process. The error correction decoder 178 generates parameter information representing bit error rate (BER), and provides such information to the microprocessor 50 via the I2C bus, wherein the information represents various aspects of the image and sound quality of the RF digital television signal one.

The output signal of the error correction decoder 178 is then processed by a subsequent signal processing circuit (not shown). The microprocessor 50 controls the operation of the boost/attenuation circuit 110 in the manner disclosed in FIG. 3 via the PLL IC 30 and the digital-to-analog converter (DAC) IC 40 according to the various parameter information.

FIG. 2 discloses another exemplary embodiment of the boost/attenuation circuit 210 related to the analog/digital television signal receiver. In this embodiment, the attenuator 112 with the attenuator switch 118 is now located between the RF input 22 and the U/V splitter 20 so that VHF and UHF televisions can be attenuated in response to the attenuator control signal generated by the PLL IC 30 Signal, the PLL IC 30 is controlled by the microprocessor 50 via the I2C bus. The UHF television signal is filtered by a tunable single tune (ST) filter 114 in the same manner as described in conjunction with FIG. 1 in response to the boost control signal, and then amplified by the low noise amplifier 116. The VHF television signal separated from the UHF television signal by the U/V separator 20 is applied to the VHF tuner circuit 130. The VHF tuner circuit 130 includes a tunable single-tuning (ST) IF filter 132, an RF amplifier 134, and a tunable double-tuning (DT) filter 136, mixer 144, VHF local oscillator 144, and double-tuned (DT) IF filter 152. The dual-tuned (DT) IF filter 152 is used as a common component for VHF and UHF signal processing. The VHF tuner circuit 130 converts the TV VHF signal into a TV IF signal, and is usually located in the tuner module of the TV signal receiver. The functions of the IF signal processing circuit 150, the analog video and sound processing circuit 60, and the digital signal processing circuit 170 are the same as those described in conjunction with FIG. 1. The microprocessor 50 controls the operation of the boost/attenuation circuit 110 in the manner disclosed in FIG. 4 via the PLL IC 30 and the digital-to-analog converter (DAC) IC 40 according to the various parameter information.

Referring now to FIG. 3, a flowchart 300 discloses an exemplary mode of operation of the boost/decay circuit 110 shown in FIG. 1, which supplements various modes of operation of the entire circuit disclosed herein. In step 302, the TV tuner is tuned to a specific UHF TV channel. In step 304, the microprocessor 50 retrieves the previously stored AGC parameter data from the memory 55. Usually when the user initially installs the television signal receiver, the AGC level of the independent receivable channels in the entire VHF/UHF television band is determined, and such independent AGC information can be stored in a memory to form a so-called " Memory scan list".

In step 306, the microprocessor 50 compares the stored AGC level of the tuned channel with a predetermined threshold. If the current AGC level is not lower than the threshold, as in step 314, the boost/attenuation circuit 110 is bypassed. However, if the level is lower than the threshold, then in step 308, the microprocessor 50 obtains the AGC level of the adjacent channel signal from the memory 55. In step 310, if one of the adjacent channel AGC levels is greater than a predetermined level, the boost/decay circuit 110 is bypassed. Otherwise, in step 312, the low noise amplifier 116 is activated and applied.

In step 316, various parameters representing the quality of the information carried by the tuned UHF television signal, such as EQ tap, BER, SNR, ACC, and P/S, are measured as described above. If such a parameter indicates that the signal quality is unacceptable, the attenuator 112 is activated and applied, as shown in step 318. If such a parameter indicates that the signal quality is acceptable, the television signal receiver continues to receive the tuning signal as shown in step 326, and as shown in step 328, the channel data for this specific channel can be stored in the memory 55, and the data includes the measured Parameter data and the current operating mode of the boost/attenuation circuit 110 (ie, whether to activate the low noise amplifier 116).

In step 320, the various parameters are measured again to determine the effect of the attenuator 112. As shown in step 324, if the measured parameter indicates that the image and/or sound quality has improved, the attenuator 112 continues to be activated and applied. However, as shown in step 322, if the parameter indicates that the application of the attenuator 112 does not improve the image and/or sound quality, a message "channel unreceivable" is displayed on the screen, and such information is stored in the memory 50.

Referring now to FIG. 4, a flowchart 400 discloses an exemplary mode of operation of the boost/attenuation circuit 210 shown in FIG. 2, which supplements various modes of operation of the entire circuit disclosed herein. In step 402, the TV tuner is tuned to a specific VHF or UHF TV channel. When tuning a VHF channel, various parameters that indicate the quality of the information carried by the tuned VHF television signal are measured. Specifically, these parameters are measured in two different modes of the boost/decay circuit 210. As shown in step 412, in the "normal" mode, the attenuator 118 is bypassed so that the VHF television signal is directly applied to the tunable single tune (ST) filter 132 via the U/V splitter 20. As shown in step 416, in the "select attenuator" mode, the attenuator 118 is activated and the VHF television signal is applied. The measured parameter data in each operation mode is stored in the memory 55, as shown in steps 414 and 418.

After measuring various parameter information, in step 422, the amplitude of the VHF television signal is determined by estimating the AGC signal. If the VHF television signals are so weak that they may not be suitable for proper reception, the attenuator 118 is disabled and bypassed, as shown in step 426.

In step 420, the results of the measurement in different operating modes are compared, and the mode that provides better image and/or sound conditions is continued to be used. That is, as shown in step 424, if the application of the attenuator 118 provides better image and/or sound conditions, the attenuator 118 is activated and applied to the reception of the tuned channel. Otherwise, as shown in step 426, the attenuator 424 is bypassed. In step 428, the information representing the selected operation mode for this particular TV channel (ie, use or not use of the attenuator 116) is stored in the memory 55 for future access to this channel.

When tuning to a UHF channel, various parameters representing the quality of the information carried by the tuned television channel are measured in four different operating modes of the boost/attenuation circuit 210. As shown in step 472, in the "normal mode, both the attenuator 118 and the low noise amplifier 116 are bypassed so that the UHF television signal is directly applied to the tunable single tune (ST) filter 122 via the U/V splitter 20. As shown in step 476, in the "select attenuator" mode, the attenuator 118 is activated and the UHF television signal is applied, but the low noise amplifier 116 is bypassed. As shown in step 480, in the "select boost" mode, the low noise amplifier 116 is activated and the UHF television signal is applied, but the attenuator 118 is bypassed. In the "select attenuator + boost" mode, both the attenuator 118 and the low noise amplifier 116 are activated and UHF television signals are applied. The measured parameter data in each operation mode is stored in the memory 55, as shown in steps 474, 478, 482, and 486.

In step 488, compare the results of all measurements in different operating modes, and continue to use the mode that provides better image and/or sound conditions, as shown in step 490. In step 492, information representing the optimal operation of the selected boost/attenuation circuit 210 for this particular UHF television channel (ie whether to activate one or both of the attenuator 118 and the low noise amplifier) is stored in the memory 55, For future access to this channel.

Although the present invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of the present disclosure. Therefore, this application is intended to include any variations, uses, or adaptations of the present invention that utilize the principles of the present invention. Moreover, this application intends to include modifications of the present disclosure within well-known practices or practices in the field to which the present invention belongs, and the modifications fall within the scope of the appended claims.

For example, the boost/attenuation circuit 110 and its control method may be used in an analog/digital broadcast wireless receiver, and the boost/attenuation circuit 110 may be located between the antenna and the RF input point of the front circuit of the TV tuner module Anywhere. That is, the boost/attenuation circuit 110 may be implemented in a television signal receiver, may be located in a separate module outside the television signal receiver, or may be implemented in an antenna assembly.

The term "television signal receiver" as used herein includes any television signal receiver with or without a display. For example, the term "television signal receiver" includes, but is not limited to, video recorders (VCR), DVD players, and set-top boxes.