Frequency offset

In order to reduce the interference from the fringe area transmitters transmitting in the same channels, a method named frequency offset is often used. By this method, a slightly shifted RF is assigned for a transmitter which may experience interference from other transmitters.

In TV transmission, the shifted RF is calculated by the formula;

${\displaystyle f_{os}=f_{ch}+{\frac {f_{L}\cdot p}{12}}}$

where,

${\displaystyle f_{os}}$ is the offset RF,

${\displaystyle f_{ch}}$ is the standard channel frequency,

${\displaystyle p}$ is an integer such that ${\displaystyle -12<p<0}$ or ${\displaystyle 0>p>12}$

${\displaystyle f_{L}}$ is the line frequency. (15625 Hz. for 625-line systems, 15750 Hz. for System M and System J and 20475 Hz. for system E)

Precision offset is the same as frequency offset, except that in this case, the offset frequency is produced by a cesium controlled oscillator.

8p offset of channel 9 in system B can be found readily

The standard visual carrier frequency is 203.25 MHz The line frequency is 15.625 Hz.

${\displaystyle f_{os}=203250000+{\frac {15626\cdot 8}{12}}\approx 203260417}$

8n offset of the same channel is likewise

${\displaystyle f_{os}=203250000-{\frac {15626\cdot 8}{12}}\approx 203239583}$