COFDM - PALSpectrum Analyser Display

Spectrum Analyser display :

DTTB

(COFDM)

Vision Carrier

Sound Carriers

Chroma

PAL

Dependent upon

Resolution B/W

setting.

eg. If Res. B/W = 300KHz

“A”= D + 10Log (6.6 / 0.3)

= 23.5 dB

A

D = DTTB to PAL ratio ( eg D = 10 dB )

DTTB power = average heating power

PAL power = the equivalent CW power of

peak sync Vision Carrier power

Note : It is usually less than this value as resolution B/W shape collects more power than the ideal rectangular filter. When Res. B/W approaches or is less than the separation between the carriers of COFDM : A = D + 10Log (No. of Carriers)

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