Abstract: RF power amplifier distortion can be accurately measured in the presence of multi-frequency input signals, by using a swept local oscillator to tune RF input and output receivers. The power detected by the input receiver is compared with a threshold associated with the carrier. Whenever the power detected by the input receiver exceeds the threshold—indicating that the input receiver is tuned on carrier energy—the signal path through the output receiver is blanked. The sweeping action combined with selective blanking of the output receiver creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. This distortion power is digitized and can be processed to control pre-distortion correction circuitry or gain/phase adjustment circuitry of a feed-forward error correction loop.

Abstract: RF power amplifier distortion is measured in the presence of multi-frequency input signals, by sweeping a local oscillator to tune RF input and output receivers. When the power detected by the input receiver exceeds a carrier energy threshold, the operation of a predistortion processor is blanked. This creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. The unnecessary complexity of using controllably interrupted high isolation switches in the signal flow path of the output receiver in certain applications may be effectively obviated by buffer amplifier—passband filter stages. These buffer-filter stages provide additional gain to offset the fact that the signal level extracted from the output amplifier is very low, and prevent producing IMDs in the swept receiver's mixer. They are preferably implemented of the same bandpass filter in the swept input receiver.

Abstract: RF power amplifier distortion is measured in the presence of multi-frequency input signals, by sweeping a local oscillator to tune RF input and output receivers. When the power detected by the input receiver exceeds a carrier energy threshold, the operation of a predistortion processor is blanked. This creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. The unnecessary complexity of using controllably interrupted high isolation switches in the signal flow path of the output receiver in certain applications may be effectively obviated by buffer amplifier—passband filter stages. These buffer-filter stages provide additional gain to offset the fact that the signal level extracted from the output amplifier is very low, and prevent producing IMDs in the swept receiver's mixer. They are preferably implemented of the same bandpass filter in the swept input receiver.

Abstract: RF power amplifier distortion can be accurately measured in the presence of multi-frequency input signals, by using a swept local oscillator to tune RF input and output receivers. The power detected by the input receiver is compared with a threshold associated with the carrier. Whenever the power detected by the input receiver exceeds the threshold—indicating that the input receiver is tuned on carrier energy—the signal path through the output receiver is blanked. The sweeping action combined with selective blanking of the output receiver creates an adaptive notch filter, which allows for the direct measurement of low level distortion power in the presence of high power carriers. This distortion power is digitized and can be processed to control pre-distortion correction circuitry or gain/phase adjustment circuitry of a feed-forward error correction loop.

Abstract: The present invention teaches a paging transmitter that has an exciter that upconverts a modulated signal to an intermediate frequency (IF) above that of the transmit frequency. By so doing, the paging transmitter can broadcast a large range of transmit frequencies. Additionally, filtering of unwanted byproducts during the upconversion process is significantly simplified.

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.