| 摘要 |
In order to display a second programme picture inset in a first programme picture the receiver has a tuner which is switched to the second programme during successive quarter line periods in successive lines. The switching frequency is greater than the line frequency and is inaudible via the loudspeaker. The second programme signals are stored, and are read out at a fast rate when the display scan reaches the inset region. Each displayed line of the second programme picture is formed of signals received in different quarter line periods in four successive lines. To avoid discontinuities in the signal so formed an analog-digital converter, a shift register, and a digital-analog converter are serially-connected at the input to the store. |
