Frequency modulation-type transmitting apparatus

#The entire disclosure of Japanese Patent Application No. 2005-291933 including specifications, claims, drawings, and abstracts is incorporated herein by references.

#1. Field of the Invention

#The present invention relates to a frequency modulation-type transmitting apparatus that can automatically adjust a frequency modulation factor.

#Preferred embodiments of the present invention will be described in detail based on the following drawings, wherein:

#FIG. 1 is a block diagram showing a transmission circuit in accordance with a preferred embodiment of the present invention;

#FIG. 2 is a block diagram showing another transmission circuit in accordance with a preferred embodiment of the present invention;

#FIG. 1 shows a transmitting apparatus 200 in accordance with a preferred embodiment of the present invention. The transmitting apparatus 200, as shown in FIG. 1, includes a front-end processing circuit 10, a frequency modulation circuit 12, an amplifying circuit 14, an antenna 16, a variable amplifier 20 and a level detector 22. The front-end processing circuit 10, the frequency modulation circuit 12, the amplifying circuit 14 and the antenna 16 constituting the transmitting apparatus 200 are functionally similar to the corresponding components of the conventional transmitting apparatus 100 shown in FIG. 11.

#The variable amplifier 20 and the level detector 22 are located between the front-end processing circuit 10 and the frequency modulation circuit 12. The variable amplifier 20 receives the composite signal Sc produced from the front-end processing circuit 10, and amplifies the composite signal Sc by an amplification factor (gain) corresponding to a feedback signal produced from the level detector 22. The variable amplifier 20 outputs the amplified signal to the frequency modulation circuit 12 and to the level detector 22.

#The level detector 22 receives the output signal of the variable amplifier 20 and returns a feedback signal to the variable amplifier 20 to control the amplification factor (gain) of the variable amplifier 20 so that the output signal is maintained at a constant level (amplitude).