Re: [Swprograms] Promo of Channel 6 (U.S.) as low end FM band

[Glenn Hauser <wghauser@xxxxxxxxx>]

Steve, et al., I guess you haven`t seen the following in WTFDA or DXLD 5-086.
As for offsets, those on channel 6 have nothing to do with offsets on channel
5. Five could be plus, six could be minus, no problem. Offsets are to lessen
co-channel interference on the same channel among stations adjacent
geographically. I suspect this subject is more OT than usual for this list, hi.
73, Glenn Hauser

** U S A. Re: [WTFDA] Odd? FM audio on TV6

``WNYZ-LP Channel 6 in NYC is broadcasting their audio using FM width 
modulation and a FM stereo generator. This is the first time I have ever caught
this combination. They are actively trying to promote this operation  as a FM
and TV dualcast. Does the FCC care? (Karl J. Zuk)``

Strangely enough, this might be legal.....

73.1570 limits full-power stations to aural modulation that doesn't
"...exceed 100% on peaks of frequent recurrence,..." then defines 100%
as +/-25 kHz.  FM modulation is +/-75 kHz, or 300% by TV definitions.  [0 =
note below]

74.790 is a list of the full-power regulations that also apply to low-power
stations. 73.1570 is NOT on this list!  

``Will TV sets be forgiving enough to decode FM stereo as TV stereo? (probably
not).`` 

I would be quite sure TV sets will NOT decode this as TV stereo. The
pilot frequency is different -- 15.734 kHz for TV, vs. 19 kHz for FM.   If the
TV set doesn't see a 15.734 kHz pilot it won't turn the stereo
decoder on.

Even if it did, the TV set contains a DBX volume expander in the L-R
channel. It would attempt to expand the non-compressed FM L-R signal,
completely screwing up the separation (among other serious problems)
-- 
[0] Strangely, it also says "...unless some other peak modulation level is
specified in an instrument of authorization.", suggesting that the FCC might
issue TV licenses specifying a different aural modulation level! (Doug Smith
W9WI, Pleasant View (Nashville), TN  EM66, http://www.w9wi.com WTFDA via DXLD)

--- Steve Coletti <scoletti@xxxxxxxxxx> wrote:
> Correct me if i'm wrong, but isn't the standard for the TV stereo system a
> 15.575kHz pilot, the same as the NTSC video horizontal lock pulse/blanking?
> Channel 6 is using the FM Stereo standard (19kHz pilot) since it is locking
> FM Stereo in on FM tuners.  It is a shoutcut to having an FM station and a
> TV station with one license.  How legal it is to use a different standard is
> questionable.
> 
> We actually did some testing today from a Queens location and found that the
> stereo lit when the receiver  tuned in 87.8 Mhz.  Channel 6 audio is
> supposed to be at 87.75MHz, either exactly or assigned a +/- 10khz offset
> for the entire channel to lessen cochannel interference.  WNYZ-LP is Plus
> offset which explained why 87.8 was a better tune.  It is unlikely that the
> station will be reassigned a Minus offset, channel 5 is a Plus offset and
> that would technically be adjacent channel interference.
> 
> Tomorrow we're setting the rotator for the TV back up and will check out the
> visual.  Where I live off the side of the beam there is hardly anything we
> can get of channel 6.  There is too much splash from channel 5's audio.
> 
> -Steve


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