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distant receiving antenna by the far flung waves; then another to
amplify the audio-frequency currents from the detector so that they
are strong enough to work a loudspeaker instead of the less
convenient headphones. This somewhat elaborated system is
indicated—but still only in broadest outline—by the block diagram,
Fig. 1.11.
We have already shown the analogy between audio and video
signals and in order to obtain a simple block diagram of a television
broadcasting system we can, in Fig. 1.11, replace the microphone by
a television camera, the a.f. amplifier by a video amplifier and the
loudspeaker by a picture tube. We must remember, however ...