Measuring the DTV signal

Since the adoption of the FCC mask for out-of-band emissions in its Sixth Recon Order, broadcasters and equipment manufacturers alike have been struggling to understand the implications not only from a performance standpoint, but also from a compliance measurement standpoint. The quality of the in-band signal is insured by measurements that bear little resemblance to what is presently done for analog television. The physical limitations of standard test equipment and the inaccuracies of broadband samples from high power RF systems make demonstrating out of band compliance very difficult. This paper explains methods of measurement used by Thomcast Communications to verify compliance of a transmission system from "DC to light." The paper gives an explanation of the technical limitations of existing equipment and methods used by broadcasters in NTSC transmission. It also offers real solutions to the measurement difficulties.