Adaptive signal modulation system

Claim 1

An adaptive system for converting input digital signals to phase and amplitude adjusted periodic signals for passage to transmission means, said system comprising: a plurality of quadrature phase shift keying modulators (100;102....), each modulator connected to a common oscillatory means and having a plurality of digital state inputs (D1-D10), the states of said inputs (D1-D10) determining which of a plurality of quadrature phase displaced signals will be outputted; means (106,110,112) for vectorially summing the outputs of said modulators so as to enable production of a constellation of phase and amplitude displaced outputs; mapping means (132) for matching a set of digital signal inputs (Al-A4) to a different set of digital states, said digital states being connected as controlling inputs (D1-D10) to said quadrature phase shift keying modulators (100,102...), said mapping means (132) storing a plurality of sets of digital states, which plurality is greater in number than that required to represent just said digital signal inputs (A1-A4); and processor means (130) responsive to control inputs (134) to enable said set of digital signal inputs (A1-A4) to cause said mapping means (132) to output a set of digital states in accordance with the control input (134), said processor means (130) being responsive to said control inputs (134) to enable selection of any of a plurality of sets of digital states by said set of digital signal inputs (A1-A4) said vectorial summing means (106,110,112) producing phase and amplitude displaced signals in accordance with said digital states (D1-D10).

Claim 4

A system as claimed in any preceding claim, wherein said processor means (130) includes adjustment means (135) responsive to said control inputs (134) to alter said selected digital states (D1-D10) so as to modify a periodic signal phase and amplitude generated by said quadrature phase shift keying modulators (100;102) and said vectored summing means (106,110,112), the modified periodic signal, when subjected to said transmission characteristics of said transmission means, being converted to a periodic signal having desired phase and amplitude characteristics.

Claim 7

A system as claimed in any preceding claim, wherein said means for vectorially summing the outputs of said modulators (100,102) comprises a plurality of summing circuits (106,110,112), each summing circuit connected between an output of a quadrature phase shift keying modulator and an output of another quadrature phase shift keying modulator whose output has been attenuated by six dB (104,108).

Claim 8

A method for adaptively converting digital signals to phase and amplitude shifted carrier signals, comprising the steps of: (a) converting a plurality of pairs of digital signals (D1-D10) to quadrature phase shifted carrier signals; (b) attenuating one of said quadrature phase shifted carrier signals and vectorially summing it with a non-attenuated quadrature phase shifted carrier signal; (c) attenuating the vectorial sum from step (b) and combining the result with another of said quadrature phase shifted carrier signal; (d) repeating steps (b) and (c) until a last summed output appears at an output (114); and (e) controlling states of said pairs of digital signals (D1-D10) in accordance with control signals (134) and additional digital inupts (A1-A4) so as to enable a plurality of said additional digital inputs to produce digital signals in conformance with said control signals (134), there being more values of said controlling states of said pairs of digital signals (D1-D10) than are required to represent said additional digital inputs (A1-A4).