Abstract: Amplitude and delay equalization of a surface acoustic wave filter used in the output of the amplitude modulated stage of a TV transmitter is disclosed. The equalization is provided by designing the filter to produce an amplitude ripple maximum or minimum at the visual carrier frequency. The video applied to the amplitude modulator is processed by a transversal equalizer such that the video is preprocessed to have an inverse amplitude and phase ripple with that produced by surface acoustic wave filter.

Abstract: A measurement of the group delay and the amplitude response of the upper and lower sidebands of a transmitter is provided by amplitude modulating with a tone a video signal that modulates the transmitter carrier. The frequency of the video signal is changed to provide a search or coverage over the frequency bands of the upper and lower sidebands. A mixing and frequency selection are performed at the transmitter RF output to select a particular upper and lower sideband. An envelope detector demodulates the tone that is amplitude modulated on the selected sideband signal. The amplitude of this detected signal is indicative of the amplitude response and the phase of the detected signal relative to a reference phase is indicative of the group delay at the selected sideband signal.

Abstract: An amplitude modulation system suitable for use in television broadcasting is described including phase modulating means for phase modulating a carrier signal with an input signal to provide a first phase modulated signal having a phase according to the arc cosine of the amplitude of the input signal with the input signal normalized with unity at the maximum possible level thereof, the phase modulating means providing a second phase modulated signal having a phase according to the minus arc cosine of the amplitude of the input signal with the input signal normalized with unity at the maximum possible level thereof. The phase modulated output signals from the first and second modulators are processed over separate paths each including a delay equalized vestigial sideband filter. The two filtered, phase modulated signals processed over the two paths are amplified and then combined to provide an amplitude modulated, vestigial sideband filtered signal.

Abstract: An amplitude modulation system suitable for use in television broadcasting is described. A video signal amplitude modulates a radio frequency carrier signal. The amplitude modulated signal is then filtered by a delay equalized vestigial sideband filter. The delay equalized amplitude modulated signal from the output of the vestigial sideband filter is envelope detected over a first path and is amplitude limited over a second path. The amplitude limited signal is applied to first and second phase modulators. The envelope detected signal is processed by a video processor to one of the phase modulators providing a phase shift at the one phase modulator equal to the arc cosine of the normalized envelope detected signal. The envelope detected signal is also processed by a video processor to the second phase modulator to provide a phase shift at the second phase modulator equal to the minus (-) arc cosine of the normalized envelope detected signal.