TABLE OF CONTENTS Having covered a lot of theoretical ground and described the detail of a number of standards earlier in this book, the purpose of this chapter is to give practical advice in configuring, timing, testing and maintaining digital video interface systems. The techniques and tools needed to test digital interfaces are quite different to the traditional analog approach and will be described here. The great similarity between HD-SDI and SD-SDI means that the same installation and test principles apply. In practice the higher frequency of the HD signal means that the effect of a shortcoming will be more serious in HD.
Digital routers have the advantage that they need cause no loss of signal quality as they simply pass on a series of numbers. Analog routers inevitably suffer from crosstalk and noise, however well made, and this reduces signal quality on every pass.
The parallel router is complex because of the large number of conductors to be switched and is obsolete. A serial router is potentially very inexpensive as it is a single-pole device. It can be easier to build than an analog router because the digital signal is more resistant to crosstalk. Large routers can easily be implemented with SDI and the long cable drive capability means that large broadcast installations can be tackled.
A serial router can be made using wideband analog switches, so that the input waveform is passed from input to output. This is an inferior approach, as the total length of cable...
