Abstract: A signal processing system is described. The signal processing system includes at least one signal processing path and a control module. The at least one signal processing path includes at least one signal input and at least two filter units. The at least two filter units include at least one hardware filter unit. The at least one signal input is connectable to at least one external electronic component. The control module is connected to the signal input and to the at least two hardware filter units. The control module is configured to determine a frequency response deviation being associated with the at least one external electronic component. The control module further is configured to reconfigure the at least one hardware filter unit such that the frequency response deviation is compensated at least partially. Further, a signal processing method for adapting filter coefficients of a signal processing system is described.

Abstract: Disclosed is an automatic video gain control circuit, which includes an analog to digital converter, an envelope detector and an extreme value detector. The analog to digital converter converts an analog video signal to a digital video signal. The envelope detector detects a baseband amplitude signal according to the digital video signal. The extreme value detector generates an extreme value to control RF signal gain.

Abstract: A video decoder (10) for receiving an input video signal and producing output signals for a digital display (12), and involving automatic gain control (AGC) functions (20, 28), is disclosed. For each of the front-end and back-end AGC functions (20, 28), the AGC gain value applied is modified according to measurements of several attributes of the video signal, such as sync height, color burst amplitude, composite signal peak amplitude, and luma signal peak amplitude. The measurements are made, and the AGC gains are modified, on a frame-by-frame basis. Preferably, the AGC is modified using the one of the signal attributes that indicates the lowest gain. The back-end AGC function (28) modifies its gain to unity if the front-end AGC function (20) selected the luma signal peak amplitude for modifying its gain. A method for adjusting the rate of change of the AGC gain is also disclosed, in which gain increases are delayed and slowed following an AGC gain decrease because of an image-dependent signal attribute.

Abstract: A method and apparatus for automatic detection and compensation of skew between color components of a video source transmitted over a plurality of twisted pair conductors are presented. The system includes a receiver configured to receive separate components of a video source over each twisted pair conductor in a twisted pair cable. Each color component includes a reference signal. High speed comparators and samplers are used to detect the reference signal and measure the skew between the color components. Delay is applied to the first arriving color components to synchronize them in time with the last arriving color component. Skew measurement is continuous and adjustment is automatic while the receiver is receiving a video signal.

Abstract: A method and apparatus for automatic reduction of noise in video signals transmitted over conductors is presented. The present invention provides an adjustable amount of noise filtering matched to the amount of gain provided by an adjustable gain amplifier to a received video signal. One or more stages of a multi-stage discrete gain amplifier is provided with a corresponding noise filter circuit. The filter circuit is matched to the frequency response of and the amount of gain provided by the discrete gain amplifier stage. When the amplifier stage is applied to the received signal, the corresponding noise filter for that stage is invoked as well. In that manner, the amount of noise filtering applied to a video signal automatically varies with the amount of amplification provided to that signal.

Abstract: In a digital broadcast receiving apparatus for amplifying a received modulated digital signal wave with automatically adjusted gain and demodulating the modulated signal wave to a digital signal, a tuner frequency-converts the modulated digital signal wave to generate a first modulated signal. A first automatic gain control amplification unit controls gain of the tuner to make a level of the first modulated signal at a first predetermined level. An A/D converter converts the first modulated signal into a second modulated signal. A demodulator demodulates the second modulated signal to generate a first demodulated digital signal. A second automatic gain control amplifier generates a second demodulated digital signal where frequency fluctuations included in the digital modulated wave are eliminated.

Abstract: Disclosed are methods and systems for automatic gain control (AGC) in circuits. The disclosed methods and systems provide accurate and rapidly converging automatic gain control suited for video applications. According to disclosed preferred embodiments of the invention, a signal amplitude controlling method is responsive to gain underflow or overflow. A new fine gain control value is extrapolated and a new coarse gain control value is determined. The new fine gain and new coarse gain control values are applied to the signal to produce an output signal within a pre-selected output amplitude range.

Abstract: A method and device are disclosed for receiving digital television signals by a frequency tuner. The power of the signal is measured after an analog/digital conversion in the frequency tuner, and the gain thereof is controlled on the basis of this power measurement according to a predetermined control law. The power of the analog signal, tapped between an input amplifier stage and a first frequency transposition stage, or immediately after the first frequency transposition stage, is also measured. The measured power is compared with a predetermined power threshold so as to obtain first binary information, and the gain control law is set on the basis of the value of the first binary information.

Abstract: An automatic gain control (AGC) circuit of a high definition television (HDTV) signal receiver and a method to compensate for a change in amplitude of a high definition signal. The AGC circuit of the high definition signal receiver includes a non-coherent AGC signal generator for generating a first AGC signal according to the magnitude of the IF signal, a coherent AGC signal generator for generating a second AGC signal according to the magnitude of the segment synchronizing signal, and a selector for selecting the second AGC signal when the segment synchronizing signal is detected and the first AGC signal when the segment synchronizing signal is not detected and providing the selected signal to a tuner/IF demodulator.

Abstract: A video clamping apparatus is described which uses transistors manufactured in a CMOS process to clamp an input video signal to a reference level during a SYNC period. A closed-loop system is provided which includes a buffer amplifier, a sample-and-hold device, a summer, a low-pass filter and a clamping circuit. The summer compares the output of the sample-and-hold device to a reference voltage which causes an output of an analog-to-digital converter to be the digital word zero.In order to maintain a high enough bandwidth of the closed loop system, a first current source is operatively coupled to the transistors of the clamping circuit during the SYNC period. When the SYNC period has ended, the first current source is decoupled from the transistors of the clamping circuit. The transconductance of the loop is, therefore, high when needed during the SYNC period.

Abstract: A delayed automatic gain control circuit using a simple delayed AGC voltage generation section and capable of fixing a start point of AGC in an RF amplification section at a predetermined received signal level without performing a special adjusting operation even if there are variations in the characteristics of circuit sections. The delayed automatic gain control circuit has a tuner including the RF amplification section, an AGC voltage generation section for generating an AGC voltage dependent on an output signal from the tuner, and an AGC voltage setting section for converting the AGC voltage into a delayed AGC voltage which is supplied to the RF amplification section of the tuner. The AGC voltage setting section is formed by a resistor voltage divider for dividing a power supply voltage and a diode connected to one voltage dividing point of the resistor voltage divider to selectively supply the AGC control voltage to the voltage dividing point according to the level of the AGC voltage.

Abstract: An inexpensive AGC apparatus capable of concurrently satisfying a sufficient impedance matching characteristic and a linear AGC characteristic is provided. The AGC apparatus is provided with a linear correction circuit. The linear correction circuit corrects a control voltage from a control voltage generator circuit, and outputs a corrected control voltage to a variable gain amplifier circuit. The above-mentioned correction is such a correction that a variation of a decibel value of an AGC gain relative to a variation of the control voltage is linearized.

Abstract: In TV receiving apparatus, a first IF amplifier chain comprises a first gain-controlled amplifier followed in cascade connection by a second gain-controlled amplifier, and a second IF amplifier chain comprises a third gain-controlled amplifier followed in cascade connection by a fourth gain-controlled amplifier. The second and fourth gain-controlled amplifiers are controlled similarly by an AGC signal, and the first and third gain-controlled amplifiers are controlled similarly by that AGC signal delayed in similar amounts. An RF amplifier is gain-controlled responsive to that AGC signal delayed even more, and a downconverter supplies first detector response to amplified RF, which first detector response is applied to the first and second IF amplifier chains by respective frequency-selective filters. The first IF amplifier response is downconverted to generate sound IF. The second IF amplifier response is detected to recover video signal.