| 摘要 |
PROBLEM TO BE SOLVED: To reduce the effect of secondary distortion of an FM luminance signal with respect to an FM chrominance signal by setting a transmission band within a prescribed range. SOLUTION: A band of an FM luminance signal YFM obtained by an FM modulation circuit 404 is limited to 6-20MHz by a band pass filter 405 and a light emitting diode 407 provides an output of an infrared ray signal corresponding to the FM luminance signal YFM as a transmission signal. Furthermore, an FM modulation circuit 410 obtains an FM chrominance signal CFM. Then a carrier frequency is set to, e.g. 25.93-26.08MHz so that a frequency of a lower side band signal (primary) of the FM chrominance signal CFM is parted from a frequency band at which secondary distortion of the FM luminance signal YFM mainly takes place. A frequency band of the FM chrominance signal CFM is limited to 20-30MHz by a band pass filter 411 and an upper side band signal of the FM chrominance signal CFM is eliminated by a trap circuit 412 and a light emitting diode 414 provides an output of an infrared ray signal corresponding to the FM chrominance signal CFM. |
