It is tough to present an account of instructional broadcasting in international locations the place broadcasting is essentially or wholly a matter of private management and where the bigger and extra vital stations and networks are private commercial enterprises. With a purpose to understand how performance standards are associated, you will need to first decide all the chain from sign era to end consumer. The elements of this chain will vary relying on the service, after all. Some signals may be generated within the headend or even nearer to the subscriber, whereas others will probably be generated hundreds of miles away. Figure 15.1 illustrates an instance of the transmission components by means of which an analog video sign may be despatched.
Obviously, both the chain of community parts and the required quality of signal will be different for analog video, downstream digital services (typically sixty four or 256 QAM), and upstream digital companies (typically QPSK, sixteen QAM or 64 QAM, but some simpler modulations are still in use). movie mania