DIGITAL BROADCAST TRANSMITTING DEVICE AND EXCITER

摘要

According to an embodiment, a digital broadcast transmitting device and an exciter have an AGC function. In a level adjusting unit which receives an input of a baseband digital signal from a modulation processing unit, a comparator generates an error signal from a difference between a level signal obtained by digitizing a feedback signal from a power amplifier by A/D converter and a reference voltage generated by a reference generating unit, and an AGC multiplier/divider carries out digital multiplying/dividing coefficient to the baseband digital signal with or by a gain coefficient such that the error signal becomes 0. Thereby, AGC which controls transmission output from the power amplifier at a fixed level is carried out.

主权项

1. A digital broadcast transmitting device which converts a broadcast TS signal to be input, into a signal of a digital broadcast radio wave format which is subjected to quadrature modulation, supplies the signal to a power amplifier, and transmits from an antenna a broadcast radio signal amplified by the power amplifier, the digital broadcast transmitting device comprising:
a power amplifier which outputs part of a transmitted broadcast radio signal as a feedback signal; a controlling means which sends out output setting data for setting an output level of the broadcast radio wave; an A/D converter means which receives an input of the feedback signal, and outputs an input feedback signal as an A/D-converted level signal; a converting means which converts the broadcast TS signal to be input, into a baseband digital signal, and outputs the baseband digital signal; a level adjusting means which includes
a reference generating means which receives an input of the level signal, the baseband digital signal and the output setting data, and generates and outputs a reference voltage corresponding to the output setting data,a comparing means which receives an input of the reference voltage and the level signal, and outputs a difference between the reference voltage and the level signal as an error signal,an AGC multiplying/dividing means which receives an input of the error signal and the baseband digital signal, multiplies or divides the baseband digital signal with or by an internal gain coefficient such that the error signal becomes 0, converts a multiplication/division result into an AGC baseband signal, and outputs the AGC baseband signal, andan output adjusting means which multiplies the AGC baseband digital signal with an output gain coefficient based on the output setting data, converts a multiplication result into a digital signal corresponding to the output level of the broadcast radio wave, and outputs the digital signal; and an exciter which includes
a D/A converter means which D/A-converts the digital signal output from the level adjusting means, into a baseband analog signal, and outputs the baseband analog signal, andan analog processing unit which performs quadrature modulation on a D/A-converted signal to be input, amplifies the D/A-converted signal, converts the signal into an exciter signal which is a radio frequency signal of a broadcast radio wave format, and outputs the exciter signal.