Abstract: In a transmission channel, such as a tape recorder, errors in code words usually occur in bursts. Further, it is usually possible to detect only some of the erroneous code words. To conceal undetected erroneous code words, concealment starts before, and continues after, a detected erroneous code word. Thus the undetected erroneous code words in an error burst have a high probability of being concealed.

Abstract: A dropout compensator includes an estimator for forming continuous estimates of the value of a video signal subject to dropouts. In order to determine the presence of a dropout, the estimated signal is compared with the actual signal to form a difference. When the difference exceeds a predetermined amount, the estimated value is substituted for the actual value.

Abstract: A sync generator uses ROMs addressed by counters to synthesize various television sync waveforms. The ROMs can be changed or reprogrammed to generate sync signals for different standards. By dividing the sync signals into four intervals which are selected by paging signals from one counter, a reduction in required ROM capacity is achieved.

Abstract: In a flat panel cathodoluminescent display utilizing a plurality of electron guns a single line cathode is used as the electron source for all guns. Changes in electron beam current resulting from vibration of the line cathode are compensated for by the application of voltages which are related to the current changes. The compensating voltages are applied through an impedance network which relates the voltages in accordance with the envelope of vibration so that the actual compensations at the individual guns are related to the actual current changes at the respective guns.

Abstract: An evacuated envelope has a rectangular display section and a gun section at one edge of the display section. The display section includes front and back walls which are generally rectangular, in closely spaced, parallel relation, and a plurality of spaced, parallel support walls between the front and back walls forming a plurality of parallel channels. At one side of the display section is at least one keying channel which extends parallel to the channels of the display section. The gun section extends across one end of the channels and includes therein gun structure which will direct electrons into the channels.

Abstract: A television synchronization signal generator circuit is provided for generating television synchronization, blanking, and drive signals. The sync generator is programmable to provide synchronization signals in the PAL, SECAM, NTSC, and PAL-M standards at the appropriate 525 or 625 line rate. A synchronous horizontal counter is used to divide clock pulses having a frequency of 134 times the horizontal line frequency down to the horizontal line frequency. A vertical counter divides a phase advanced signal having a frequency of twice the horizontal line frequency by 525 or 625 to arrive at the vertical field rate. Logic gates decode the horizontal and vertical counter output signals to condition output signal flip-flops which are retimed by the input clock pulses to eliminate phase delays between the clock pulses and the output signals. Reset inputs are provided for synchronizing the sync generator to an external signal source.

Abstract: In an image display, the video information may be keyed to the position of the electron beam by sensing the beam deflection voltage. A keying system utilizes means for generating a reference voltage which is proportional to the anode voltage and means for comparing the reference voltage to the deflection voltage for the electron beam. When a predetermined relationship between the two voltages, such as equality, is reached; the comparing means produces an output which indicates the deflected position of the electron beam. The output of the comparing means can be used to switch the video information to modulate the electron beam.

Abstract: A digital memory may be addressed with an analog signal utilizing a circuit comprising a digital to analog converter. A comparator compares the output of the digital to analog converter to the analog address signal. The output of the comparator is coupled to means for incrementing and decrementing a digital number in response to that output. The digital number incrementing and decrementing means has an output which is coupled to the addressing input of the digital memory. Switch means alternately connects the input of the digital to analog converter to either the output of the random access memory or the output of the means for changing the digital number.

Abstract: An electron gun is controlled by a system which stores the characteristics of the gun in a random access memory. The contents of the memory feed an electron gun driver which properly biases the gun. The characteristics of the gun are stored in the memory by using a collector to sense the electron beam. A comparator is connected to the collector and a reference brightness signal generator. The output of the comparator controls the storage of the characteristics in the memory.