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A constrained-envelope digital communications transmitter (10) places constraints on the envelope of spectrally constrained, digitally modulated communication signals (46) converted into diverse frequency channels (54) and combined into a composite signal (58). The envelope constraints achieve lower

A constrained-envelope digital communications transmitter (10) places constraints on the envelope of spectrally constrained, digitally modulated communication signals (46) converted into diverse frequency channels (54) and combined into a composite signal (58). The envelope constraints achieve lower peak-to-average power ratio without allowing significant spectral regrowth. The composite signal (58) is applied to a plurality of cascade-coupled constrained-envelope generators (64). Each constrained-envelope generator (64) detects overpeak events (66) and configures corrective impulses (68) for the overpeak events (66). The corrective impulses (68) are distributed to the respective frequency channels (54) in accordance with a predetermined distribution profile (102) and are filtered into allocated shaped pulses (120) that exhibit a constrained spectrum. The allocated shaped pulses (120) are coherently converted into the respective frequency channels (54) and combined with the composite signal (58) to reduce an unwanted signal peak.

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1. A digital communications transmitter with constrained envelope and constrained spectral regrowth over a plurality of carriers, said transmitter comprising:a combiner for forming a composite signal from a plurality of diverse frequency channels, wherein said diverse frequency channels are configur

1. A digital communications transmitter with constrained envelope and constrained spectral regrowth over a plurality of carriers, said transmitter comprising:a combiner for forming a composite signal from a plurality of diverse frequency channels, wherein said diverse frequency channels are configured to convey a plurality of digitally modulated communication signals; a monitoring circuit coupled to said combiner and configured to detect overpeak events by determining when an overpeak-capable signal responsive to said composite signal exceeds a threshold; an impulse generator coupled to said monitoring circuit for generating a corrective impulse configured to compensate for an amount by which said overpeak-capable signal is in excess of said threshold; and a distribution circuit, coupled to said impulse generator for distributing portions of said corrective impulse to said diverse frequency channels. 2. A digital communications transmitter as claimed in claim 1 additionally comprising:a plurality of pulse-shaping filters; and a plurality of mixers coupled to said plurality of pulse-shaping filters, wherein said plurality of mixers produce said plurality of diverse frequency channels. 3. A digital communications transmitter as claimed in claim 1 wherein:each of said digitally modulated communication signals conveys a predetermined amount of data per unit interval; and said composite signal is a complex signal providing complex samples at a rate greater than or equal to two times the number of frequency channels per unit interval. 4. A digital communications transmitter as claimed in claim 1 wherein:said monitoring circuit, said impulse generator, and said distribution circuit are included in a first constrained-envelope generator; and said digital communications transmitter additionally comprises a second constrained-envelope generator coupled in series with said first constrained envelope generator. 5. A digital communications transmitter as claimed in claim 1 wherein said digitally modulated communication signals are configured to exhibit one or more of CDMA, APSK, and GMSK modulations.6. A digital communications transmitter as claimed in claim 1 wherein said distribution circuit receives signals responsive to gains applied in said frequency channels.7. A digital communications transmitter as claimed in claim 6 wherein said distribution circuit is configured so that one of said portions of said corrective impulse distributed to one of said frequency channels is substantially equal to gain applied in said one frequency channel divided by total gain applied in all frequency channels.8. A digital communications transmitter as claimed in claim 1 wherein said distribution circuit receives a signal responsive to modulation types applied in said frequency channels.9. A digital communications transmitter as claimed in claim 1 wherein said distribution circuit comprises, for one of said plurality of frequency channels:a first rotation circuit; a scaling circuit coupled to said first rotation circuit; a filtering circuit coupled to one of said scaling circuit and said first rotation circuit and configured to generate a shaped pulse having a predetermined duration; and a second rotation circuit coupled to said filtering circuit and configured to generate a carrier-matched shaped pulse. 10. A digital communications transmitter as claimed in claim 9 wherein said transmitter additionally comprises:a delay circuit for delaying said composite signal by at least one-half of said predetermined duration to produce a delayed composite signal; and a combining circuit for combining said delayed composite signal with said carrier-matched shaped pulse. 11. A digital communications transmitter as claimed in claim 9 wherein said first rotation circuit is adapted to receive at least one of said portions of said corrective impulse and is adapted to receive a carrier phase stream, said carrier phase stream describing an oscillating signal used in forming one of said plurality of diverse frequency channels.12. A digital communications transmitter as claimed in claim 11 wherein said first rotation circuit includes a conjugation circuit configured to determine conjugates of phase values defined by said carrier phase stream.13. A digital communications transmitter as claimed in claim 9 wherein:said first rotation circuit is adapted to receive at least one of said portions of said corrective impulse and is adapted to receive a carrier phase stream, said carrier phase stream describing an oscillating signal used in forming one of said plurality of diverse frequency channels; said distribution circuit further comprises a delay circuit configured to delay said carrier phase stream and produce a delayed carrier phase stream; and said second rotation circuit is adapted to receive said shaped pulse and is adapted to receive said delayed carrier phase stream. 14. A digital communications transmitter as claimed in claim 13 wherein said delay circuit delays said phase stream by at least one-half of said predetermined duration.15. A digital communications transmitter as claimed in claim 9 wherein said filtering circuit comprises a segmented pulse shaping filter having a first output for providing a leading portion of said shaped pulse and having a second output for providing a trailing portion of said shaped pulse, said first output being coupled to said second rotation circuit.16. A digital communications transmitter as claimed in claim 15 wherein said second output of said segmented pulse shaping filter couples to a third rotation circuit configured to generate a feedback-carrier-matched shaped pulse, said feedback-carrier-matched shaped pulse being routed to said combiner so that said overpeak-capable signal is responsive to said trailing portion of said shaped pulse.17. A method of operating a digital communications transmitter to constrain envelope and spectral regrowth while processing a plurality of communication signals, said method comprising:generating a plurality of digitally modulated communication signals; converting said plurality of digitally modulated communication signals into diverse frequency channels; combining said diverse frequency channels to form a composite signal; detecting overpeak events by determining when an overpeak-capable signal responsive to said composite signal exceeds a threshold; generating a corrective impulse configured to compensate for an amount by which said overpeak-capable signal is in excess of said threshold; and distributing portions of said corrective impulse to said diverse frequency channels. 18. A method as claimed in claim 17 wherein:said distributing activity generates a plurality of allocated shaped pulses in said diverse frequency channels; and said method additionally comprises adding said plurality of allocated shaped pulses in said diverse frequency channels with said composite signal. 19. A method as claimed in claim 18 wherein:said allocated shaped pulses exhibit a predetermined duration; said method additionally comprises delaying said composite signal by at least one-half of said predetermined duration to generate a delayed composite signal; and said adding activity adds said plurality of allocated shaped pulses in said diverse frequency channels with said delayed composite signal. 20. A method as claimed in claim 17 additionally comprising refraining from generating said corrective impulse when no overpeak event is detected.21. A method as claimed in claim 17 wherein said portions of said corrective impulse are distributed in accordance with a distribution profile responsive to gains applied to said digitally modulated communication signals.22. A method as claimed in claim 21 wherein one of said portions of said corrective impulse distributed to one of said frequency channels is substantially equal to gain applied in said one frequency channel divided by total gain applied in all frequency channels.23. A method as claimed in claim 17 wherein said converting activity uses a plurality of carrier phase streams to convert said digitally modulated communication signals into said diverse frequency channels, and said distributing activity comprises:rotating and scaling one of said portions of said corrective impulse by one of said carrier phase streams to produce an allocated corrective impulse; filtering said allocated corrective impulse to form an allocated shaped pulse; and converting said allocated shaped pulse to one of said diverse frequency channels. 24. A method as claimed in claim 23 wherein:said method additionally comprises delaying said one of said carrier phase streams to produce a delayed carrier phase stream; and said converting activity converts said allocated shaped pulse to said one of said diverse frequency channels using said delayed carrier phase stream. 25. A method as claimed in claim 24 wherein:said allocated shaped pulse exhibits a predetermined duration; and said delaying activity delays said phase stream by at least one-half of said predetermined duration. 26. A method as claimed in claim 23 wherein said method additionally comprises delaying said composite signal to produce a delayed composite signal, and said filtering activity comprises:generating a leading portion of said shaped pulse; combining said leading portion of said shaped pulse with said delayed composite signal; generating a trailing portion of said shaped pulse; and combining said trailing portion of said shaped pulse with said composite signal so that said detecting activity is responsive to said trailing portion of said shaped pulse. 27. A digital communications transmitter with constrained envelope and constrained spectral regrowth over a plurality of carriers, said transmitter comprising:a plurality of mixers which convert a plurality of digitally modulated communication signals to a plurality of diverse frequency channels using a plurality of carrier phase streams; a first combiner for forming a composite signal from said plurality of diverse frequency channels; a distribution circuit having inputs responsive to said composite signal and said carrier phase streams, said distribution circuit being configured to generate allocated corrective impulses that compensate for overpeak events in said composite signal, filter said allocated corrective impulses into shaped pulses having a predetermined duration, and convert said shaped pulses into said diverse frequency channels; a delay circuit for delaying said composite signal by at least one-half of said predetermined duration; and a second combiner for combining said delayed composite signal with said shaped pulses converted into said diverse frequency channels. 28. A digital communications transmitter as claimed in claim 27 wherein said distribution circuit comprises a scaling circuit which receives signals responsive to gains applied in said frequency channels and generates said allocated corrective impulses in accordance with a distribution profile responsive to said gains.29. A digital communications transmitter as claimed in claim 27 wherein said distribution circuit is configured so that said shaped pulses are converted into said diverse frequency channels so as to be coherent with said composite signal.