New AM method......

[kc2ifr]

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=7016659.WKU.&OS=PN/7016659&RS=PN/70

[KA8WTK]

"Thus modulating 100% increases the total power to 150%, i.e. 50% over the unmodulated carrier power: the total in-channel transmitted power is 1.5 times the unmodulated carrier power, while the total power in the sidebands is one half the unmodulated carrier power, and the power in each sideband is one quarter the unmodulated carrier power (-6 db). The foregoing conditions are confirmed when observed on a spectrum analyzer: the "constant amplitude" carrier appears at center frequency flanked by the upper and lower sidebands at half the amplitude of the carrier (-6 dB)........."

I find this statement very interesting.

Bill

[K4QE]

Three of the inventors of this new method are hams.

Michael Dorrough - KO6NM
Dennis Lee - KB6LUZ
Al Parker - N2SAG

Michael has an excerpt from an article he wrote in Electric Radio on his QRZ.com record.

[Tom WA3KLR]

Mike Dorrough KO6NM is the father of the multi-band audio processor.  He won a Technical Emmy in 2000 for it.

Here is the Society for Broadcast Engineer's website description of him:

http://www.sbe24.org/dorrough/dorrough.asp

His own QRZ.com biography:

Friends,

I promise that I'm working on a properly self-effacing biography. Meantime,here is an excerpt from an article I put together for my friends at 'Electric Radio' a few seasons back. These paragraphs carry a little information about my background, but more importantly they express my feelings about Amplitude Modulation, my affiliation with blind and visually impaired recording archivists, and a shared passion for our radio history. A love of big broadcast iron and the recorded history of the past century led me to build a special needs archiving/radio station facility in Wisconsin. That is a life story in itself. Suffice it to say that I'm back in Southern California doing my best to keep the filaments glowing.
Let me also thank the great folks at QRZ.com for this space and for allowing me to seem like I have a photographic memory about the lives and times of my fellow Hams. With the computer sitting right next to the rig, relief for "mental vapor lock" is always just a click or two away! M.D.
(E.R. Excerpt)
"Yes, Single Side-Band is the dominant mode in the voice portion of the HF bands. Yes Single Side-Band has talk-power, generates smaller electric bills and has even worked its way into the world of short-wave broadcasting. Yes SSB is tops for passing net traffic and the time of day. If I were running a military operation where communication of intelligible voice data is a life and death proposition I’d issue SSB rigs to the troops. And YES, SSB is tiring, frenetic and ultimately a disappointing way of radio life over the long run.
The voice must be used as a percussion instrument in the SSB mode. You can hear the strained pipes of modern rice-box Hams being used not so much for conversation as to drive the output meter. Simon & Garfunkel sang about the “Sounds of Silence”, possibly because the pauses and quiet are the canvas upon which the art of speech is painted. In Amplitude Modulation mode the carrier acts as the canvas, the blank space upon which radio voices are painted. Single Side-Band is like paint sprayed into thin air. The paint (voice) must continue to spray else the fleeting illusion of space be lost. Any pause for breath can result in a cacophony of doubling.
OK, I confess to being an “AM Chauvinist”. This is not to say that AM is perfect, especially in the challenging world of HF sky-wave. Selective fading and the unfortunate and unfair power restrictions on Amateur AM are obstacles to be overcome. Anyone plying the HF band in the AM mode has been frustrated at times to observe fairly strong carriers with feeble audio attached. SSB has an advantage in talk-power, but AM’ers can close much of the talk-power gap without loosing their fidelity advantage. My early days in California were totally immersed in sound. As a young audio engineer in the early sixties I was fortunate to work for a studio that allowed experimentation.
It was during those days that I cobbled together the very first multiband audio processor. The recordings produced using these devices had greater overall punch with no loss in fidelity. It seemed that such a device might have even bigger implications for radio broadcast, where greater loudness with fidelity than competitors equaled higher ratings.
By the 1970’s the banks of discrete tube limiters and outboard crossovers had evolved into a sophisticated solid-state box known as a DAP or Discriminate Audio Processor. I traveled to radio stations all over North America installing the devices on a “try it and buy it” basis. During those early days of traveling from station to station I got to know a lot of broadcast engineers and an equal number of beautiful transmitters. I am to old broadcast gear as a soft-hearted old lady is to stray cats.
Imagine the crime of crushing the transmitters that carried the voices and music of some of the greatest talents in our history from ragtime to rock. Rigs that glowed with the warm modulation of Bing Crosby, the wit of Fred Allen and the creative genius of Orson Welles were being treated like garbage. It was a crime to loose these historical transmitters also in the context of their intrinsic value as prime examples of the high art and science of industrial design. As time wore on I would get wind of an RCA, Gates or Collins broadcast rig being turned out for scrap as the stations upped power or went solid-state. The word went out that an eccentric guy from California would gladly haul away the decommissioned gear if at all feasible.
Another long-term passion has been the collection of any and all recorded material from the entirety of the 20th century. Working with a variety of concerned preservationists an impressive archive of records, tapes and even movies and video took shape over a few decades. A large number of those concerned archivists happened to be members of the visually impaired community. Why not set up the venerable old transmitters on the short wave bands and create a new, unique broadcast service for and by visually impaired people!"
Mike Dorrough, KO6NM
Bio last modified: 2003-12-09

See also www.dorrough.com

[WA3VJB]

Mike is returning from this week's National Association of Broadcasters  convention in Las Vegas.

I may give him a phone call to thank him for his new article in Electric Radio this month (Apr. 2006) and to inquire about this document Bill/IFR has found.

Mike's a great guy, and is among those who contributed to the filing of Comments OPPOSED to the League's threatened bandwidth coordination scheme. He also convinced Joe Walsh, WB6ACU, and Bob Heil, K9EID, to do the same. Therefore, his "AM Credentials" are even more well-established.

A number of us use one of two popular models of audio processor he invented, developed and marketed in the late 1970s into the 1980s.

DAP 610 (and A) (pictured below)

DAP 310

Mike has said the only reason he left the audio processing part of the business was because of the decision to abandon AM fidelity standards and station separation rules, now aggravated by digital trash caused by IBOC, In-Band On Channel products that extend 10kc to either side of a station's licensed broadcast frequency. Mike is convinced that had this sort of bandwidth been allowed for conventional analog transmissions it would have made a difference in the band's continued listenership and commercial viability.

Excellent reference guide, a pictoral history and description of various broadcast and studio audio processors.
http://www.261.gr/vintage.html

[k4kyv]

"Thus modulating 100% increases the total power to 150%, i.e. 50% over the unmodulated carrier power: the total in-channel transmitted power is 1.5 times the unmodulated carrier power, while the total power in the sidebands is one half the unmodulated carrier power, and the power in each sideband is one quarter the unmodulated carrier power (-6 db). The foregoing conditions are confirmed when observed on a spectrum analyzer: the "constant amplitude" carrier appears at center frequency flanked by the upper and lower sidebands at half the amplitude of the carrier (-6 dB).........

I find this statement very interesting.

Right out of any radio textbook, assuming the modulating signal to be a pure sinewave..

I haven't completely digested the patent information on the "new method."  Referenced drawings and diagrams would help, but all I could bring up on the website was text.

[KA8WTK]

What I find interesting is that the statement talks about "total in-channel power" not PEP. If Total in-channel power were the same thing as PEP (or are they?) then a 1000 watt carrier modulated 100% would transmit a 1500 watt "total in-channel" signal. "Thus modulating 100% increases the total power to 150%........."

Bill

[k4kyv]

Total in-channel power is not the same thing as pep. 

Total in-channel power is just that - the total actual power of the signal: carrier power plus sideband power, as measured using an rf ammeter to determine line current into a known  resistive load, calculating power by Ohm's law.  This is also known as average, or mean power.

Pep is the maximum instantaneous power, usually at a modulation peak.  That peak could last for only 1/10,000 of a second, while the rest of the time the power could be less than 1 percent of the  peak, but the pep would still be the value of that instantaneous peak.  Pep has little to do with the actual power of the signal.  With the proper waveform, a 10 watt signal could hit 1000 watts or more pep.

Pep is a bogus standard for determining transmitter output power, because it is not relevant to the loudness of the signal at the receiving end.  A signal can have a few very high instantaneous peaks while the average (mean) power remains low.  It is the average (mean) power that determines the loudness of the signal at the receiver detector, not the amplitude achieved by an occasional voice peak.

"Speech processors," long used by the SSB community to increase the loudness of the signal, operate on the principle of reducing the peak-to-average ratio.  At the expence of audio quality, SSB signals are made to sound "loud" by cutting down the pep, while bringing up the average power.

[WA1GFZ]

oh man it was about time we dragged out the old dead horse and beat it some more.

On a scope y=time the peak is 4X power 2X voltage

On a spectrum analyzer y= frequency AM at 100% has 2 side bands 6 dB down

it is just plain magic

[Steve - WB3HUZ]

Nothing magic about it. You are comparing peak and average powers. Of course, they will be different. Apples and oranges baby!!!!

[KA8WTK]

Good, they are different. That is what I thought.

Nice to have a double check on your thinking now and then.

Bill (I can get SO confused) KA8WTK

[WA1GFZ]

but Steve it must be magic because the poor dead horse gets a fresh beating about twice a year.

[The Slab Bacon]

I know that it is what it is. But you sometimes wonder where it comes from. You need 1/2 the DC input in audio to make 100%. So 200w of DC inpoot + 100w audio =300W inpoot x plate efficiency = outpoot. So where does the rest come from?
Must be f#*$ing magic!  he he!

The shame is that it is the instantaneous peak of the audio and not the RMS average that determines the allowable outpoot!

BUT DAMN IT, IT CANT MAKE PICKLED EGGPLANT!!     (or can it?)

                                                                      The Slab Bacon 

[WA1GFZ]

if you chase down pickled eggplant with a little square root of two the buzz is less intense

[Rob K2CU]

As I was explaining to Max the other day, when this topic first came up, the issue of high level plate modulation requiring a plate modulator capable of delivering half the final stage carrier DC input is simple. Regardless of the power level or plate load impedance, you have some DC voltage of say, value E. The DC input power is obviously E squared / impedance. At 100% modulation, an AC signal is added to the DC such as to reduce the DC to zero on negative peaks and 2 times E on positive peaks.  This means the peak (not peak to peak) value of the modulating signal is equal to E volts. The RMS value of the modulating signal, if a sine wave, is then .707 times E or (( SQRT 2) / 2 ) times E. And then the power in that modulating signal is then (.707 times E) squared and divided by impedance, whcih equals 1/2  E squared/ impedance, or 1/2 the DC input power or the RF output stage.

[k4kyv]

I know that it is what it is. But you sometimes wonder where it comes from. You need 1/2 the DC input in audio to make 100%. So 200w of DC inpoot + 100w audio =300W inpoot x plate efficiency = outpoot. So where does the rest come from?
Must be f#*$ing magic!  he he!

I think it has already been described as Fee Cee magic.

[K6JEK]

I can't seem to access the patent anymore.  I was reading it or at least trying to read it.   Is it gone or is there something funny happening with my browser?

Jon