LinoNYC said:
While perusing the hd videos I noticed some familiar hecklers from here and elsewhere. these guys must have endless time to comb the 'net hoping to stomp out any positive mention of their enemy.
Well, Lino - that presupposes that there really IS anything positive to be said about HD AM outside of the rarified situation of New York City and possibly some other city cores with nearby strong transmitters. I would estimate that 99.99% of the land area of the US is not served by HD AM at night because it is too far from a city to receive reliable HD reception.
385 miles is not a remarkable nighttime distance at all for analog AM. In fact, I can get that type of range on a few stations in the daytime. There are numerous examples of midwest regional blowtorches on low frequencies that easily top 300 miles. At night, I can easily top 1000 miles with a listenable signal on multiple frequencies. If it weren't for a glut of ill-advised new allocations, 1500 miles would be the norm. A large portion of those, by the way, were listenable in stereo at night when they used the C-Quam system.
Contrast these numbers with a few tens of miles at the most for daytime AM HD, and possibly less at night - and you have a system that is just not robust enough for suburban listeners - who are in the station's city grade analog signal. Let alone anybody outside by a few miles or listening on skywave. There are scattered reports of people managing a few seconds of HD lock - seeing call letters, etc at a few hundred miles, but it is always short lived and digital reception is impossible. Yet - I have heard HD sideband pairs for hundreds of miles - daytime - in remote areas of the West - there are not that many HD stations on the air, so the station generating the sidebands is NOT hard to track down even if there is no trace of its analog signal. No power increase would be possible on AM to try to increase range, with robust digital sidebands like that - any power increase would just raise the noise floor world wide!
So what can be done? I think it is a working system, it just doesn't work very well. A failed experiment that should be discarded - and something else tried. The government is shutting down analog TV and moving stations, so there would be precedent for moving the band. Two times in the past, massive station moves have been done - although there are many times more stations now - a digital only band within the AM band could be established. Longwave is a possibility, as is vacated TV spectrum. It may even be that there is a flaw in the basic decode algorithm causing unreliable decode.
Something is wrong - somewhere. Instead of bickering pointlessly and being in denial, somebody needs to diagnose what the problem is, come up with a workable solution, and see what it would take to implement. Best case scenario is an algorithm re-program and digital starts working. Worst case scenario is moving the band, all HD receivers sold up to this point would be useless unless they can be re-programmed to receive it. But the present system is CLEARLY flawed because it isn't robust enough, the problem should have been addressed years ago and fixed - now it is going to be much more difficult to fix because equipment is deployed in the field.
What a MESS - I am glad I'm not an engineer at iBiquity facing the prospects of cleaning up the mess and dealing with sloppy engineering from the past. Problems are much better addressed in early phases of development, and this has all the earmarks of something rushed to the market without enough testing - at the whim of upper level managers who forced the issue against the advice of engineers. Thank goodness no lives were at stake in this case. But it is the same type of thing that forced the engineers to fly the shuttle that cold morning in 1986.
