| 摘要 |
The transmission unit (SEN) has a delta sigma modulator (MOD) for the digitisation of the analogue or the quasi-analogue electrical signals. The modulator includes an integrator stage (I) and an amplifier in the form of a comparator. One-bit coding is carried out by means of a bistable flip-flop (FF). An electrical to optical converter (EO) receives the digitised signals and converts them into optical signals. The digital optical transmission system is a passive optical distributed network in which analogue TV signals are optically transmitted so that they can be readily recovered in a receiver. There is an optical to electrical converter in each receiver and a passive electrical filter is also incorporated. The filter may be a passive low-pass type, or in some cases a passive band-pass filter. |
