Why is it so hard to receive DTV signals in some locations?
When it comes to digital television, it’s an “all or nothing at all” proposition. Once the signal is acquired, a steady stream of data assures you’ll get a perfect picture and great audio. If that bitstream is interrupted, however, there will be nothing – just a blank screen. Its as if the signal went over a cliff! In areas with lots of buildings and multipath, frequent signal dropout causes this “cliff effect”. The fix is to use a higher-gain antenna and perhaps even a preamp – assuming the multipath can be tamed. Fortunately, current model set-top DTV receivers are light years ahead of early models in terms of multipath performance. The key to widespread rollout of digital TV is carriage of local DTV stations on cable TV systems. Today, better than 70% of all US households are getting television via cable or satellite, so you can see how important it is for broadcasters and cable/DSS providers to sign carriage agreements.
