Abstract: The present invention provides a method to improve the frequency resolution and phase noise of a synthesized RF signal. It also results in the superior characteristics of instantaneous frequency changeability, wide frequency setting ability, and fully digital ASIC implementation ability. The synthesized RF signal is generated from a higher reference frequency using a variable pulse stretching technique. The amount of the pulse stretch in each cycle is controlled by a phase increment value and is implemented using programmable delay lines. Pulse stretching is extended beyond one cycle by pulse swallowing, allowing the generation of an RF signal from DC up to the input reference clock signal frequency.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power without the use of amplifiers. This is accomplished by the combination of two varying amplitude and phase vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit, used to determine the delay of each digital delay line. The output of each delay line is multiplexed to a switching bank which is also controlled by the vector control circuit. The output of the switching bank, in combination with a summer, is used to produce discrete amplitude adjustment of the vector.

Abstract: The present invention provides a means to implement amplitude and phase modulation digitally and directly at an RF frequency that benefits from high output power using non-linear amplifiers. This is accomplished by the combination of two constant amplitude phase varying vectors. A reference oscillator produces a carrier signal, which is supplied to two digital delay lines composed of a sequence of delay banks. The delay lines are controlled by lookup tables that are updated by the vector control circuit used to determine the delay of each digital delay line. The delay of the lines are set in such a way as to produce two vectors with the desired phase shift that, when summed together, produce a vector with the desired phase and amplitude characteristics.

Abstract: An improved VQ system for compressing a digital signal produces a compressed signal by dividing the signal to be compressed into a series of signal segments. Each signal segment comprises a plurality of signal values. The improved VQ system uses first and second tables of vector values having different degrees of signal correlation, referred to as a class-1 table and a class-2 table respectively. For a selected signal segment, the VQ system determines a vector Xbar1 representing a difference between the signal values in the selected segment and an average of a selected group of signal values in a preceding segment. For the same signal segment, the method and apparatus determines another vector Xbar2 representing a difference between the signal values in the selected signal segment and an average of a selected group of signal values in the selected signal segment. The vectors Xbar1 and Xbar2 measure different levels of correlation between the signal values of the selected signal segment.

Abstract: An improved VQ system for compressing a digital signal produces a compressed signal by dividing the signal to be compressed into a series of signal segments. Each signal segment comprises a plurality of signal values. The improved VQ system uses first and second tables of vector values having different degrees of signal correlation, referred to as a class-1 table and a class-2 table respectively. For a selected signal segment, the VQ system determines a vector Xbar1 representing a difference between the signal values in the selected segment and an average of a selected group of signal values in a preceding segment. For the same signal segment, the method and apparatus determines another vector Xbar2 representing a difference between the signal values in the selected signal segment and an average of a selected group of signal values in the selected signal segment. The vectors Xbar1 and Xbar2 measure different levels of correlation between the signal values of the selected signal segment.