Total posts : 45366
The first thing you often hear is “I’m a ham” or “I’m a CBer” and “I know that 11 meter signals propagate long distances on low power sometimes. Why, I’ve talked all over the world!” You have to ask how much the person really read the site.
No one who advocates 26 MHz local broadcasting has ever denied the propagation facts. The question on the table is: Does it make a difference? The simulations show that it does not make much of a difference.
Signals propagated from long distances are not likely to overcome the local DRM signal. The listener will still hear their local broadcast just fine even under worst case conditions except at the fringes of the protected contour which will shrink somewhat. But that happens in analog broadcasting too.
The predictions are that the results will be most unlike what most HF ops have experienced. It has to be subjected to additional experiments, instead of just dismissing the idea — “It’s skip, I know it won’t work!”
Experiments have been done, but so far they focused on topics other than station-to-station interference.
> You cannot tell me that there is an antenna made that will entirely cancel out skip.
This is a straw man argument. Nobody has claimed any such perfect antenna. Read the patent on the commercially available 26 MHz antenna for the facts. Entire cancellation of skip is not needed to make it work.
> In fact, hams know that you want a low radiation angle for long distance propagation
Hams still aim their low radiation pattern toward the sky, exactly the opposite of the local broadcaster.
> I tend to be skeptical that some kind of esoteric antenna design can magically eliminate this issue.
The one patented design is not too esoteric but was judged nonobvious enough that the USPTO granted it the patent. Other designs could probably be made as well. But who has claimed magic? Nobody.
The reason for suppressing skywave is that it is just good policy not to waste radiation by sending it to places where it isn’t needed, and because the frequency coordination model assumes that all the stations are using skywave suppression. That is a realistic assumption in a fresh-start band.
> Add to that the fact that this band is extremely noise prone (primarily ignition noise).
The noise in 26 MHz and its effects on DRM transmission have been studied in live tests, in several countries and a variety of environments including some of the world’s largest cities.
The conclusions were favorable. DRM was designed for international broadcasting where the signal travels long distances and is exposed to noise and interference. These characteristics suggested that it might be suitable for local broadcasting even in noisy areas.
> Any time there is a thunderstorm, my picture freezes or goes blank– and that even happens on UHF if storms are closeby
Yep let’s not use UHF for broadcasting. Storms knock it out 😉
> That said, if someone GAVE us the 26 MHz band and said; “Hey, we can’t figure out to do with this interesting but useless piece of spectrum, so you can have it for local broadcasting!”, then I would agree that it’s better than nothing. But I would prefer someplace higher in the spectrum.
That might well happen, in fact both HF and VHF might happen.
It remains to be seen what, if anything, people will want to do with a digital HF band with a regulatory scheme intended to lower entry barriers.
For example, private individuals may not own low power FM stations. FCC rules prohibit it. But should it be forbidden in HF too? To stimulate interest and experimentation, why not let private persons be licensed for their own HF DRM local stations.
Let them try various programming and services. Why stand in their way — and keep the band standing there doing nothing.