Originally Posted by Mister B
With most of my experience from the analog days, I always wonder how far off axis will work even with strong signals as is being discussed in this Minneapolis scenario? With analog reception that ION station would have had a very pronounced ghost if the antenna had been aimed at the remainder of the transmitters. Does anyone have a "rule of thumb" on how far off axis will still give a good digital signal nowadays, or does that just take some experimentation on each individual situation?
Yes, in analog days we called them ghosts and you could calculate the time delay by measuring the distance on the screen between the main image and the ghost.
Today we call them multipath reflections (some engineers still use the term ghosts or echos). How much you can get away with depends upon the time difference between the the primary signal and the reflection, how strong the reflection is, and how well your tuner is able to handle multipath.
The relative amplitude of the reflections becomes more critical as they increase in time difference from the primary signal.
See the echo table in attachment #1 which comes from page 22 ofATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010atsc.org/cms/standards/a_74-2010.pdf
Converter boxes were also required to meet equalizer specifications for multipath to be eligible for the coupon program.
DTV Converter Box Cupon Program
Information Sheet for Manufacturers
The second attachment shows the specs.
All one can do is try it and see.