Insane Ideas

Yes, MRAM Bob, you are correct based on the realities and facts regarding high power broadcast.

But surely there must be a micro-surgical approach to combining small signals so that full permitted output is retained.

I'm thinking the trick will be to do the combining before the final RF amp stage.

Any hope?

As Rich stated, that would be difficult.  Although if you think about FM and SCA that's sort of what's going on there.  

You have the main carrier, L+R mono signal, L-R DSB stereo signal, pilot tone and one or more SCA carriers.  Of course those are all "carried" by the main carrier as they are modulating the main carrier.  That process creates all kinds of sidebands hence the 200 kHz bandwidth.

You might get away with mixing AM signals in a linear or Class A amplifier.  Putting multiple carriers into a non-linear or Class C-D-E amplifier and trying to modulate all at once?  Well like Rich said you'd end up with quite a lot of by-product frequencies causing havoc. 

that we are facing the design and building of a whole special transmitter, and not the modification of an existing Part 15 transmitter, so long as "combining" is the objective.

Well, for now, I guess I'll tailor the project to a single destiny... namely the trying of three side-by-side frequency transmissions with a single audio source so as to create a very wide swath signal.

To do this, three separate transmitter sites will be located in a triangular pattern at ample distances to minimize co-mutual interference.

Now all I need are two more AMT5000s.

This concept could propel PhilB to billionaire status.

Yes, right now it's actually being tried!

I have a transmitter on 1640 kHz and another at 1650 kHz with synched audio, and the impression of being a thick, wide presence on the X-band is very fascinating.

The transmitters are 35 feet apart and so far I've noticed only one small and fixable artifact. The bandwidth of the audio feed is 80 to 10,240 Hz, which gives 7-octaves out of the 10-octaves of human hearing.

But, when tuned to the weaker (farther) signal, high-frequency splashover creeps in from the adjacent channel. There are too ways to fix the problem...

1.) The upper octave from 5120 to 10,240 Hz could be shaved off. That would do it;

2.) Or, the carriers could leave one guard channel in-between (1650) and operate on 1640 and 1660 kHz. I'll try that next.

Moving the AMT3000 from 1550 to 1650 required re-patching the self-made triangular loading coil, but by good luck the available taps worked perfectly without needing to do surgery.

Given that those X-band channels were equally clear as to co- and adjacent-channel interference prior to this "Part 15 AM" operation, and that all of those Part 15 systems produce equal groundwave fields at the same radius, and that those Part 15 systems radiate no sidebands that produce mutual interference:

What is the benefit of such a multiple-channel transmit system to listeners using typical AM broadcast receivers, that receive only one of those Part 15 systems at a time?

Member Rich asks: "What is the benefit to a listener using a typical AM broadcast receiver that receives only one of those Part 15 systems at a time?"

This is all speculative since no one has ever done anything of its kind.

First, it seems in my conception that having a "same program" over a wide swath of frequencies is more apt to capture the curiousity of person tuning around than a signal on only one channel;

Further, at distances from the various Part 15 transmitters, which are each located apart from each other and may have varying characteristics, some of the available channels may be preferable to others at outlying reception locations;

And, given the variations in distance reception from stations far away on those same channels, certain channels may be clearer than others at each location within the coverage zone, i.e., my girlfriend two-blocks up the hill receives a whole different set of distance signals than I get down here in the "bowl."

Extending and developing this idea by adding Part 15 transmitters to EVERY OPEN CHANNEL the LOCAL limitation of covering a small service area is strengthened by becoming THE MOST DOMINANT OMNI-PRESENT STATION ON THE DIAL IN THAT SMALL COVERAGE CIRCLE.

Still, reality as-we-know-it says that most people DO NOT tune around out of curiousity.

Most people have fixed listening habits and stay put on "their" station, being "out-of-reach" despite the quality of any other station.

We start with a positive ambition, and conclude with the pessimism that defines most of life.

What else is there?

What else is there?

As a suggestion...

The practical reality provided by due research, and experience.

Rich, you are suggesting that "practical reality" (as well as the knowledge gained by due research and experience) is... what?

Perhaps it's proof positive of negativity?

Mr. Rich offered the viewpoint:  "Your posts here seem to equate any response to them about which you disagree to show "negativity" applying generally to Part 15 operators."

Except that in this present example I have not disagreed with anything.

...in this present example I have not disagreed with anything.

Not even my reply to your post #21?

Although your response to Post # 21 only addressed the tail-end of my remarks which had turned from technology to abstract philosophy, within which your comment made reasonable sense.

At no time did you discredit my DIAL-SWATH-MULTI-FREQUENCY concept, and that makes me proud.

...At no time did you discredit my DIAL-SWATH-MULTI-FREQUENCY concept....

? ?

Readers of your concept and my responses to it are free to reach their own conclusions.

Well, not to pop anyones balloon but the networks are already broadcasting the same program simultaneousy all over the country on many, many stations.

But, it is an interesting experiment, seeing how three signals spaced a channel apart would interact to see if it becomes more obvious to the listener that may well overlook a single, weak signal.

MRAM said: "the networks are already broadcasting the same program simultaneousy all over the country on many, many stations."

And what does that accomplish? IT GETS THEM MANY LISTENERS ALL OVER THE COUNTRY!

THEREFORE, broadcasting the same programming on multiple Part 15 voices ALL AT THE SAME TIME and ALL ACROSS THE DIAL will GET US MORE LISTENERS ALL OVER THE NEIGHBORHOOD.

What we have here is a brave new idea in Part 15 expansion FULLY WITHIN THE FCC RULES and something that will INCREASE the presence of a micro radio station.