| 摘要 |
PURPOSE:To precisely receive an optical signal arriving via the space without a data error. CONSTITUTION:Optical filters 11, 21 have a different wavelength transmission characteristic and at least one of them transmits an optical signal. Light receiving elements 12, 22 are provided respectively corresponding to the optical filters 11, 21 and generate an electric signal with a quantity in response to the luminous quantity of the light transmitted through the optical filters 11, 21. DC voltage conversion sections 13, 23 amplify electric signals ES1, ES2 so that the relative gain with respect to the electric signals ES1, ES3 outputted from the light receiving elements 12, 22 is a prescribed gain compensating the difference from the transmission luminous quantity with respect to an external light in the optical filters 11, 21. A differential amplifier section 3 generates an electric signal ES5 having a level corresponding to the level difference between the electric signals ES2, ES4 after the difference from the transmitted luminous quantity of the optical filters 11, 21 is compensated by the DC voltage conversion sections 13, 23. |
