Cirrus Logic Inc.

Other

Robert J Hankinson

Otto Sponring

Scott Curry

A method and system in which the numeric values to which counters in resampling control circuitry may be reduced. As a result, smaller registers to hold such reduced numeric values may be designed into hardware implementing said circuitry. These smaller registers present savings in processing power and hardware allocation, thereby potentially improving response times and cost efficiency of said hardware.

Reduction of numeric counting levels in resampling

An analog to digital converter circuit having sync control is constructed to monitor the sync condition of the digital output. When sync is lost, for example due to a low input signal level or due to an out of phase situation, the gain of the output increased to relatively high level so as to enhance the possibility of detecting the sync condition. As soon as sync is reestablished the gain is immediately turned down to a level lower than the blanking level and then gradually increased to the blanking level. The gain levels at startup and during the sync reestablishment intervals are fixed but under selective control.

System and method for multi-level gain control

An automatic step generator that monitors and corrects the sampling rate in a video signal. The invention isolates a sampling window in the prevailing sampling rate, the window advantageously being 144 lines for NTSC, or 231 lines for PAL, or some other preselected window wherein the sample count therein at an ideal sampling rate approximates an integer power of 2. The invention then calculates the numeric difference between that ideal sample count in the window and the preselected integer power of 2. The actual sample count in the window is then determined, and is adjusted by the numeric difference between the ideal count and the integer power of 2. Variations in this adjusted actual sample count and the integer power of 2 will thus represent variations between the actual sampling rate and the ideal sampling rate. A step value to correct the actual sampling rate to achieve the ideal rate may then be derived by dividing the adjusted actual sample count by the integer power of 2. In binary, this division is simply a shift right in bit significance. The step value may thus be derived directly and immediately from the adjusted sample count.

Automatic step generator for self-correction of sampling

Method and system for reducing numeric counting levels in resampling

A video signal decoder using a sample clock tied to a frequency that is an integer multiple of four times the color subcarrier (4*Fsc). By using a 4*Fsc rate on a given input wave, the decoder determines the phase shift between the sample clock and the original wave being sampled. Then, the decoder calculates the color based upon that shift. Circuitry for implementing the decoder contains two major circuit paths. The decoding process consists of two main phases and each path performs a different function during each phase. During the first phase, the first path calculates constants based upon a user's hue and saturation adjustments used for chroma demodulation. Also during the first phase, the second path examines the color burst signal and from that signal finds the black level of the incoming video signal. During the second phase, the first path decodes the color in the TV signal using the constants calculated during the first phase. Also during the second phase, the second path pulls the luma information out of the signal line.

System and method for decoding a quadrature ampliture modulated signal

A clocking circuit for extracting data from a video signal where the data is imbedded with other data and where the clocking rate for obtaining the data is slow as compared to the actual data rate. The circuit derives a calculated starting point for the data, using a double sample rate and a derivative to determine the beginning of the first data pulse. A clock signal is then derived which is calculated to between the leading and trailing edges of any received data pulse.

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Carrollton, TX, United States of America

Robert J Hankinson