| 摘要 |
<p>TELEVISION TRANSMITTER COMPRISING A COMMON KLYSTRON FOR THE PICTURE AND SOUND The klystron has a grid or another electrode for controlling the density of the electron beam, which receives a pulse signal, whose amplitude, duration and period are such that the klystron can supply a power equal to its peak power during the time intervals corresponding to the sync pulses of the picture signal and such that the klystron can only supply a predetermined fraction of its peak power for the remainder of the time, said fraction corresponding to the power to be supplied during the back porch of the picture signal. The variation of the klystron characteristic during the sync pulses leads to a variation in the amplitude and the group delay ofthe intercarrier signal frequency modulated by the sound and which itself modulates a UHF carrier. This is why correction means are provided on each sound channel, in order to compensate said amplitude variation and said group delay variation throughout the duration of the sync pulses.</p> |
