US 5,489,879 A · Amplitude and phase error normalization of subcarrier generator

Abstract

A subcarrier signal generator includes a finite impulse response (FIR) filter responsive to selected FIR coefficients. A first set of FIR coefficients represents an ideal subcarrier shape and center frequency. A calibration step monitors the resulting subcarrier signal and produces a new set of FIR coefficients corresponding generally to the ideal subcarrier signal shape and center frequency, but predistorted according to the compliment of error detected in the actual subcarrier signal. By then loading the new set of FIR coefficients and operating the subcarrier generator, frequency-dependent distortions in the output stage of the subcarrier generator cancel predistortion reflected in the new FIR coefficients. As a result, a high quality subcarrier signal results without use of expensive output stage devices in the subcarrier signal generator.

Claims8

Dependent claims

A method of subcarrier generator manufacture and calibration, the subcarrier generator producing a subcarrier signal of selected shape and phase, said method of manufacture comprising the steps:

providing said subcarrier generator including a signal shaping input stage, said signal shaping input stage being responsive to a data signal input and to a parameter set defining at least signal shape, said generator further including an output stage providing said subcarrier signal in response to said input stage, said;
calculating an ideal parameter set corresponding to said signal of selected shape and phase;
applying said ideal parameter set to said subcarrier signal generator;
operating said subcarrier signal generator while concurrently monitoring said subcarrier signal;
calculating an error in said subcarrier signal relative to said selected shape and phase;
calculating a new parameter set corresponding to said selected shape and phase and further corresponding distortion as a function of said error;
and
applying said new parameter set to said subcarrier generator in subsequent operation thereof.

5 more elements

Dependencies are inferred from the claim text.

Amplitude and phase error normalization of subcarrier generator

Life of this patent

Amplitude and phase error normalization of subcarrier generator

Life of this patent

Abstract

Claims8