Abstract: A system for overlaying a computer generated video signal on an NTSC video signal includes horizontal and vertical pulse processor circuits for generating a horizontal start signal and a vertical reset signal, respectively, in accordance with NTSC standards, and a clocking system for receiving the vertical reset signal and the horizontal start signal and for generating control signals to control the read out of video data from the video generator of a computer so that it is read out at an NTSC rate. The system further includes a video insert keyer circuit for combining the NTSC video signal and the computer generated video signal and for generating a composite video signal for transmission to a monitor or standard television.

Abstract: A two terminal electronic filter network is provided for connection across TV antenna input terminals to reduce interference from noncommercial FM radio stations operating within a frequency band near the TV channel 6 frequency band. The two terminal electronic filter circuit which exhibits a rapid change of reactance for changes in frequency, and having a resonant frequency provides sufficient FM signal rejection without significant attenuation of any VHF channel by the provision of a highly reactive network tuned below the resonant frequency of the filter network as a whole.

Abstract: An audio signal monitoring system is disclosed, which provides simultaneous visual indication of instantaneous peaks of a monitored audio signal and of peaks which are sustained for a predetermined period of time. A high impedance buffer combined with a precision full wave rectifier receives the monitored audio signal and generates a corresponding d.c. signal which varies according to the amplitude level of the audio signal. A peak detection circuit is connected to receive the d.c. signal and drive a meter movement to indicate instantaneous peaks in the audio signal level. A comparator circuit is connected to receive the d.c. signal and compare the d.c. signal with several predetermined threshold levels. Separate indicators corresponding to each threshold level are selectively energized by the comparator circuit whenever the d.c. signal exceeds the respective threshold levels for a sustained period of time.