A basic explanation of free to air TV transmission
Free to air TV (a Radio Frequency (RF) transmission) is a line of sight transmission. Terrain, weather, TV antenna location and type, and other factors, all effect the strength and quality of the signal. Not everyone gets the same level of service.This is why, in the Dandenong ranges, there are black spot translators in Ferntree Gully, Upwey, Selby and Monbulk etc. The RF signal is also prone to massive reduction in strength through poor connections, poor quality cable etc. That old ribbon cable installation is no longer good enough.
Analog TV
One quality of analog TV is that as signal strength / quality decreases through the factors mentioned above, so does picture quality. As the signal level drops the picture goes grainy, snowy, etc, until it becomes unwatchable.
Digital TV
Digital TV is much more all or nothing. A digital set top box or digital TV can’t give anything but DVD quality picture. TV picture quality is therefore no longer an indicator of TV signal quality / strength. The equipment gets enough signal and the bit error ratio (BER) is sufficient or it won’t lock on to the signal. Perfect picture or unwatchable pixelation.
Equipment
While most of metropolitan Melbourne has signal levels that will run virtually any set top box or digital TV it is important to be aware that installing a STB or Digital TV in the Dandenong Ranges, without prior signal testing, will rely mostly on luck. And yes, some digital TVs and digital set top boxes are better than others in their ability to lock onto poor signal levels with high levels of errors in the data. See my product recommendation page for more on this.