US 4,700,151 A · Modulation system capable of improving a transmission system

Abstract

In a modulation system responsive to a system input signal for supplying an amplifier having nonlinearities with a modulated analog signal to make the amplifier produce an amplified output signal, the system input signal conveys a baseband signal having a predetermined sampling rate for reproduction and is sampled into a sequence of sampled signals having a specific rate higher than the predetermined sampling rate. The sampled signal sequence is converted by a random access memory into a sequence of predistorted signals which compensate for the nonlinearities and which are modulated into the modulated analog signal. Each predistorted signal is adaptively modified at the specific rate with reference to the sampled signals and an additional input signal derived from the amplified output signal. When the sampled signal sequence is sampled at the predetermined sampling rate, the predistorted signal sequence may be produced by interpolating each of the sampled signals at the specific rate. The baseband signal may be either a digital signal or an analog one.

Claims13

Dependent claims

A modulation system responsive to a system input signal for supplying a modulated analog signal to an amplifier having nonlinearities said amplifier producing an amplified output signal, said system input signal conveying an information signal which has a predetermined sampling rate for reproduction, said modulation system comprising:

pre-processing means responsive to said system input signal and an additional input signal for preliminarily processing said system input signal with reference to said additional input signal to compensate for said nonlinearities at a specific rate higher than said predetermined sampling rate and to produce a sequence of pre-processed signals;
modulating means coupled to said pre-processing means for modulating said pre-processed signal sequence into said modulated analog signal;
demodulating means responsive to said amplified output signal for demodulating said amplified output signal into a demodulated signal corresponding to said system input signal;
and
signal supplying means for supplying said demodulated signal to said pre-processing means as said additional input signal.

2 more elements

Dependencies are inferred from the claim text.

Modulation system capable of improving a transmission system

Life of this patent

Modulation system capable of improving a transmission system

Life of this patent

Abstract

Claims13