Abstract: A digital exciter is presented herein for use in RF broadcasting and wherein the exciter employs pilot signal compensation. This includes an input digital circuit for receiving a modulated digital data at an input sample rate for RF broadcasting at a desired RF frequency. The pilot frequency may be displaced from a desired location at the frequency band because of an error in the input sample rate. A digital compensator determines whether the pilot frequency is displaced and provides a digital correction signal in accordance therewith. A digital correction circuit corrects the pilot frequency in accordance with the correction signal.

Abstract: A digital exciter is presented herein for use in RF broadcasting and wherein the exciter employs pilot signal compensation. This includes an input digital circuit for receiving a modulated digital data at an input sample rate for RF broadcasting at a desired RF frequency. The pilot frequency may be displaced from a desired location at the frequency band because of an error in the input sample rate. A digital compensator determines whether the pilot frequency is displaced and provides a digital correction signal in accordance therewith. A digital correction circuit corrects the pilot frequency in accordance with the correction signal.

Abstract: Systems and methods are provided for generating dual outputs in a digital exciter system. A first signal path produces one of a frequency modulated audio signal, a digital information signal, and a signal comprising both frequency modulated audio and digital information. A second signal path produces one of a frequency modulated audio signal, a digital information signal, and a signal comprising both frequency modulated audio and digital information. A main exciter output provides one of the signal produced at the first signal path and the signal produced at the second signal path to an associated first signal destination. An auxiliary exciter output provides one of the signal produced at the first signal path and the signal produced at the auxiliary signal path to an associated second signal destination.

Abstract: Systems and methods are provided for generating dual outputs in a digital exciter system. A first signal path produces one of a frequency modulated audio signal, a digital information signal, and a signal comprising both frequency modulated audio and digital information. A second signal path produces one of a frequency modulated audio signal, a digital information signal, and a signal comprising both frequency modulated audio and digital information. A main exciter output provides one of the signal produced at the first signal path and the signal produced at the second signal path to an associated first signal destination.

Abstract: A circuit for use in a broadcast transmitter for adaptively compensating for carrier signal distortions caused by amplitude modulating an RF carrier signal. The circuit includes a modulator/amplifier network that receives an RF carrier signal and modulates it by a received amplitude varying signal to obtain therefrom a modulated carrier signal which may exhibit distortions caused by the amplitude modulating of the RF carrier signal. A digitally adaptive corrector precorrects the amplitude varying signal prior to application thereof to the network to compensate for any modulated carrier signal distortions. This includes a digital processor that provides signal correction as a function of digital samples representing amplitude variations of the modulated RF carrier signal.

Abstract: A pulse width modulator is presented herein and it includes a pulse width driver circuit that receives a time varying ramp signal that is modulated by a time varying analog input signal to produce a pulse width modulated drive signal comprised of turn-on pulses having widths that vary with variations in the magnitude of said input signal. A switch is turned on by each drive pulse for a time duration dependent upon the duration of each drive pulse and provides an output signal therefrom. A negative bias amplifier provides a negative bias signal that has pulsations that are synchronized with said drive pulses but of opposite phase. A combiner combines output signal with the negative bias signal to provide a combined output signal.

Abstract: A system and method are provided for providing nonlinear precorrection to an input signal. A plurality of nonlinear function blocks each receive a constituent signal, derived from the input signal. Each constituent signal has an associated value and an associated delay. The nonlinear function blocks output an intermediate signal having a value equal to that of an associated memoryless nonlinear function evaluated at the value of the constituent signal. A summation function sums the plurality of intermediate signals to obtain a system output.

Abstract: A circuit for use in a broadcast transmitter for adaptively compensating for carrier signal distortions caused by amplitude modulating an RF carrier signal. The circuit includes a modulator/amplifier network that receives an RF carrier signal and modulates it by a received amplitude varying signal to obtain therefrom a modulated carrier signal which may exhibit distortions caused by the amplitude modulating of the RF carrier signal. A digitally adaptive corrector precorrects the amplitude varying signal prior to application thereof to the network to compensate for any modulated carrier signal distortions. This includes a digital processor that provides signal correction as a function of digital samples representing amplitude variations of the modulated RF carrier signal.

Abstract: Apparatus and method are presented for adaptively compensating for carrier signal phase distortion caused by amplitude modulating an RF carrier signal. A modulator-amplifier network receives an RF carrier signal and modulates it by a received amplitude varying signal to obtain therefrom a modulated RF carrier signal which is phase shifted from the phase of the carrier signal applied to the network by an amount that varies with the value of the amplitude varying signal. A phase shifter receives the RF carrier signal and phase shifts it in accordance with the value of a received phase correction signal to provide a pre-phase shifted carrier signal that is applied to the modulator-amplifier network. A phase detector receives and compares the modulated RF carrier signal and the carrier signal and provides an error signal in accordance with the comparison.

Abstract: A linear transmitter (101) using predistortion includes a modulator (103), a predistorter (107), a digital quadrature modulator (111), an upconverter (113), a power amplifier (115), and an antenna (117). In addition, the transmitter (101) has a feedback loop including a coupler (119), a downconverter (123), a digital quadrature demodulator (125), and a trainer (131). The digital data to be transmitted is provided into the modulator (103), which converts the digital data into in-phase and quadrature component signals. The in-phase and quadrature component signals are then provided to the predistorter (107), which "predistorts" the component signals prior to amplification. The digital quadrature modulator (111) converts the component signals into a single analog signal. The upconverter (113) upconverts this signal from the predistorter (107) into the desired frequency of transmission, which is provided to the power amplifier (115) and the antenna (117) for amplification and broadcast.