| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a headend apparatus capable of accurately performing a level control of an output signal and being produced at low cost. <P>SOLUTION: An MPU 46 for controlling each part is provided in a modulation device 35. The MPU 46 includes an A/D conversion circuit 51, a D/A conversion circuit 52, and a conversion table 53. The conversion table 53 is a table indicating a relationship between a detected voltage of an output level detecting circuit 48 and an output signal level of an output amplifier 45. The table is produced, taking into consideration variations in detected voltage in the output level detecting circuit 48. The output level detecting circuit 48 detects an output signal of the output amplifier 45 and inputs the output signal to the MPU 46. The MPU 46 takes in the detected output via the A/D conversion circuit 51, determines an output value of the D/A conversion circuit 52 based on a relationship between an output level and a detected voltage indicated by a control terminal 38, with reference to the conversion table 53, and adjusts the gain of a gain adjusting circuit 44. <P>COPYRIGHT: (C)2008,JPO&INPIT |
