Figure 4 and Figure 5 show examples of the radial topography in Charlotte. We conclude that many local shaded areas within the horizon are filled by short-time echoes, as measured at Charlotte. For NTSC, this is seen as smeary or distorted pictures, rather than a distinct ghost image. For 8-VSB reception, these conditions are easily corrected by the equalizer. The equalizer in the prototype 8-VSB receiver was more than adequate in Charlotte.
Indoor reception is subject to attenuation due to the building and due to low antenna height.
It is also subject to varying short term ghosts, and to. rapidly varying signal level and occasional deep attenuation as people move around the room or traffic goes by. The Charlotte tests indicated rapid signal level variations to be an important concern in receiver design, having a greater effect than the ghosting itself. Figure 8 shows two single-frequency networks serving adjacent areas. This illustrates that there is still need for coordination of co-channel radiation, and perhaps other taboos as well. In addition, operating such a system in the same band as NTSC is not generally possible.