Constrained-envelope transmitter and method therefor

In a digital communications system, a method for transmitting a constrained-envelope communications signal comprising:

• generating a first modulated signal conveying to-be-communicated data and having a first bandwidth and a first peak-to-average amplitude ratio;
• generating a constrained bandwidth error signal in response to said first modulated signal;
• combining said constrained bandwidth error signal with said first modulated signal to produce a second modulated signal conveying said to-be-communicated data, said second modulated signal having substantially said first bandwidth and a second peak-to-average amplitude ratio, said second peak-to-average amplitude ratio being less than said first peak-to-average amplitude ratio;
• and
• linearly amplifying said second modulated signal.

A constrained-envelope digital communications transmitter circuit comprising:

• a modulated-signal generator for generating a first modulated signal conveying to-be-communicated data, having a first bandwidth and having a first peak-to-average amplitude ratio;
• a constrained-envelope generator for generating a constrained bandwidth error signal in response to said first modulated signal, said constrained bandwidth error signal exhibiting a bandwidth substantially equal to or less than said first bandwidth, and said constrained bandwidth error signal exhibiting peak amplitudes which are responsive to amounts by which magnitudes of said first modulated signal exceed a threshold;
• a delay element for delaying said first modulated signal into synchronism with said constrained bandwidth error signal;
• a combining circuit for combining said constrained bandwidth error signal with said first modulated signal to produce a second modulated signal conveying said to-be-communicated data, said second modulated signal having substantially said first bandwidth and a second peak-to-average amplitude ratio, said second peak-to-average amplitude ratio being less than said first peak-to-average amplitude ratio;
• and
• a substantially linear amplifier configured to amplify said second modulated signal.