OKCRadioGuy said:
The narrow-banded FM overlayed on AM IS the best idea. Too bad NO ONE will hear of it. Everyone wants digital even if it's worse.
And as also mentioned by Mike Walker, the narrowband FM-on AM is about the only thing that can be hidden on AM.
It can be done by complex methods, or as simply as providing limited interaction between audio and RF power supplies.
It is officially considered as "sloppy operation" of an AM, but when properly done, limited to a few hundred Hz maximum, does not
degrade the AM detection, and the FM detection is every bit like the FM we are accustomed to in 88-108 MHz.
I know how good it sounds because I designed my pirate transmitter in 1991 to do this on 7.415 Mhz.
With 100 watts it was heard over most of the US, and was declared as the highest audio quality ever heard on a shortwave pirate
by a reviewer who published a yearly book on the subject. I wish I could remember his name.....
And "everyone wants digital even if it's worse" is a fair generalization.
People don't know what they want anymore. It's all done for them.
Marketing specialists decide what will be sold, and literally what people will be sold "to want".
This is how business works.
Knowing for yourself exactly what you want is too much work for the majority of people.
They are far too distracted and have always relied on the marketplace to do the choosing for them.
If the buzzword is digital, then everything has to be digital. Or Hi-Def, or "extreme".
Even if it fits like a shoe on the wrong foot.
Digital will always be attempting, with ever-higher bitrates, to approach the resolution that is available in continuous-sampled analog.
To the extent it is enough samples to approximate real audio, it suceeds. This is a very subjective determination.
I cannot yet see that the complexity justifies the disappointing results, and there is far less standardization than there ever was
for example in consumer phonograph methods, formats, and equalization curves.
And the AM modulation standard is compatible throughout EVERY AM receiver ever built, literally tens of thousands of circuit designs, from
simple diode juctions at the base of the tower, crystal sets, and one tube regens to the most complex reference monitors.
This 80-plus year old standard should not be disregarded lightly.
The regenerative receivers of the 20s-30s were an incompatible RECEIVER type that actually transmitted if over-driven as was common, and
created squeals, howls and moans in your neighbor's radio, depending on how off-frequency your tuning was.
They became derisively known as "bloopers".
We have yet to coin the best word for the current incompatible (AM) transmitting mode.
I notice it is incompatible with all but communications grade receivers with intentionally narrowed bandwidths.
And it is only available by purchasing the technology from one manufacturer.
How different it is from the days when the FCC mandated a "Patent Pool" to standardize design of radios and advance the medium!
