FM HD Asymmetric Power

[Tom Wells]

My comments would likely be incomprehensible to the FCC.

Symmetry is not only pretty much defined as an unavoidable behavior, eventually, in natural law as we experience it in life, but importantly, perceived (perceivable ) asymmetry is essentially encoding and information in and of itself, as in the the L-R signal for 38khz FM stereo diff signal.

Asymmetry on an AM is the "WhaM" you hear, as you would feel in the extreme acceleration in a sports car.

Asymmetry in life is what you make of it.

 

[badjef]

My comments would likely be incomprehensible to the FCC.

Symmetry is not only pretty much defined as an unavoidable behavior, eventually, in natural law as we experience it in life, but importantly, perceived (perceivable ) asymmetry is essentially encoding and information in and of itself, as in the the L-R signal for 38khz FM stereo diff signal.

Asymmetry on an AM is the "WhaM" you hear, as you would feel in the extreme acceleration in a sports car.

Asymmetry in life is what you make of it.

The likely response would be the bureaucratic equivalent to, "I put my shoes on all by myself".

Jeff in Sa-ra-so-ta!

 

[iyiyi]

IIRC, WMCA ran mono on their upper sideband and WFIL ran mono on their lower sideband. Cleared up a long standing adjacent interference problem. They no longer do this, yet Salem does an excellent job with both stations. QAM can seem very esoteric and confusing at first, but I believe it was invented in 1925. Easiest way to describe asymmetrical sidebands is that they offer/allow a VERSATILE method to deal with a rather large number of transmission and reception issues. Happy New Year!

 

[badjef]

IIRC, WMCA ran mono on their upper sideband and WFIL ran mono on their lower sideband. Cleared up a long standing adjacent interference problem. They no longer do this, yet Salem does an excellent job with both stations. QAM can seem very esoteric and confusing at first, but I believe it was invented in 1925. Easiest way to describe asymmetrical sidebands is that they offer/allow a VERSATILE method to deal with a rather large number of transmission and reception issues. Happy New Year!

If I am reading this correctly, this was the basis of Leonard Kahn's ISB AM stereo system.

When were WMCA and WFIL doing this?

Jeff in Sa-ra-so-ta!

 

[Ai4i]

Kahn's system was strictly ISB, the left channel was LSB and the right channel was USB.
Stereo could be detected by tuning one reciever low and another one high.
Moto's C-QuadratureAM system was more akin to NTSC and PAL color.
Harris was a bit like SECAM (FM) color.
All I know about the originally approved Maggy system is that radios did not like negative peaks.

 

[ajc_trw]

IIRC, WMCA ran mono on their upper sideband and WFIL ran mono on their lower sideband. Cleared up a long standing adjacent interference problem. They no longer do this, yet Salem does an excellent job with both stations. QAM can seem very esoteric and confusing at first, but I believe it was invented in 1925. Easiest way to describe asymmetrical sidebands is that they offer/allow a VERSATILE method to deal with a rather large number of transmission and reception issues. Happy New Year!

If I am reading this correctly, this was the basis of Leonard Kahn's ISB AM stereo system.

When were WMCA and WFIL doing this?

Jeff in Sa-ra-so-ta!

I know WFIL was doing AM Stereo (Kahn) around 1980 and made a big deal about it on-air. I was living in Jersey at the time and tried the two radio thing. I got some separation but it was lacking proved out by WFIL playing early Beatles stereo music (vocals left music right).

Years later I worked for KAZM (C-Quam) and taped some of my shows on their aircheck cassette deck. Unfortunately they only had one channel wired in (from their AM stereo receiver) so I got the mamas but not the papas.

 

[Tom Wells]

When I have all the time in the world, I'm building a sharp slope-tune L/R modulator for 262.5 khz, which I'll multiply and filter up to the desired output f.
I have two fairly well matched 1936 Philcos with parallel push pull triode outputs, just dying to run stereo by off-tuning. Dreamy.

 

[iyiyi]

Tuning one radio slightly higher and the other slightly lower would give about 10 dB separation. If the audio became distorted or raspy you had tuned too far. I actually DID use a 1937 Philco as one channel. When you did it correctly, it sounded quite well. The system was not designed for two radios, but for an actual stereo decoder. The two radio setup was only a byproduct of that type modulation. The other 4 systems could not decode using two radios. Detractors called it a "gimmick". Regardless, whether you used a PowerSide or a standard Kahn/Hazeltine exciter, pulling a patch cord feeding audio to either channel gave you zero sidebands on that side.

The deal with limiting negative peaks to 96% modulation with AM stereo is because the relationship of the amplitude modulated sidebands to the quadrature modulated carrier results in an instantaneous negative carrier shift. In other words, the 96% peak is actually 100% modulation referenced to the carrier at that moment.


-

 

[badjef]

IIRC, WMCA ran mono on their upper sideband and WFIL ran mono on their lower sideband. Cleared up a long standing adjacent interference problem. They no longer do this, yet Salem does an excellent job with both stations. QAM can seem very esoteric and confusing at first, but I believe it was invented in 1925. Easiest way to describe asymmetrical sidebands is that they offer/allow a VERSATILE method to deal with a rather large number of transmission and reception issues. Happy New Year!

If I am reading this correctly, this was the basis of Leonard Kahn's ISB AM stereo system.

When were WMCA and WFIL doing this?

Jeff in Sa-ra-so-ta!

I know WFIL was doing AM Stereo (Kahn) around 1980 and made a big deal about it on-air. I was living in Jersey at the time and tried the two radio thing. I got some separation but it was lacking proved out by WFIL playing early Beatles stereo music (vocals left music right).

Years later I worked for KAZM (C-Quam) and taped some of my shows on their aircheck cassette deck. Unfortunately they only had one channel wired in (from their AM stereo receiver) so I got the mamas but not the papas.

I heard WFIL a year earlier in 1979.
When I purchased a Fujitsu 10 AM Stereo/ FM Stereo, it came inside of a cabinet resembling a 1987 Toyota Corolla FX. As it had C-quAM, I would tune to the Kahn stations, WNBC, WQXR, etc, It would jump in stereo long enough to pique my curiosity. I contacted Leonard Kahn and he sent me "The Secret". I heard WFIL in stereo, but I think they had switched to C-quAM shortly after.

Kahn good, C-quAM, bad.

I asked about when because I remember hearing WFIL rather well in Newark around 1973/74 driving a stock radio mounted in a 1966 VW Beatle. (Spelling is right because when you were listening to WABeatleC, it was a "VW Beatle").
If they were suppressing the upper 0n WFIL and suppressing the lower on WMCA, it sounds as though they were both utilizing a forerunner of Kahn's "Powerside".

Jeff in Sa-ra-so-ta!

 

[Barry]

WNSH 94.7, New York City's new country station, recently received permission from the F.C.C. to broadcast using FM HD Asymmetric power. Apparently this allows a station to run as much as -10dB on one of the sidebands. So if owner Cumulus Media takes full advantage, the station's HD signal would be running a relatively hefty 2,300 watts ERP. That ought to get out quite well.
Does anyone know of other stations that have implemented this system?

 

[JohnnyElectron]

I believe Detroit's superpower grandfathered FM (104.3) is running an ungodly HD power level, but I think it's still symmetrical sidebands.

 

[diymedia]

Stations can apply for experimental authorization to broadcast asymmetrically, so it's not a difficult thing to do permissions-wise. Exactly how many are would involve plumbing the CDBS looking for authorization requests/applications/correspondence.