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Within the HHI Broadband Communications System, besides some digital, optical subscriber lines an analog optical subscriber line has been installed, offering as well simultaneously three color-TV-programs, one videophone channel, four stereo-broadcast programmes and additional channels for telephone and data to the subscriber. In order to make a statement about the quality of that analog optical broadband-transmission- line employed for that, extensive measurements of the signal-to-noise ratios in the TV- and stereo-broadcast channel, the signal-to-cross- modulation ratio in the frequency range of the TV-channels, the cross-talk attenuation and the harmonic ratio in the stereo-broadcast channel have been performed. Results however show, that the quality standards for national CATV-Systems cannot be achieved by this optical analog link with its load of the frequency band and with the employment of the AM-IM-modulation for TV- and videophone signals.

In a video telephone system the video camera may not be picking up the image (on the screen) of the conversational partner. The effect is that the partners cannot exchange visual signals in the same way as in a direct conversation, and this detracts from the immediacy of the interaction. The authors describe an investigation of the significance of the effect, and outline methods using microns of overcoming it.