"Narrower" Band FM

[Ben Zonia]

What if you were on a first adjacent channel and you used 50-60 kHz deviation instead of 75 kHz deviation, and processing that would compensate somewhat, allowing some peaks between 60-75 kHz, would it be easier to tune in and capture as a first adjacent with less interference from IBOC? Aren't the IBOC sidebands supposed to be on the very edge of the adjacent channel? Or would you need a very narrow IF filter setting to take advantage of it, in this age of interference from IBOC sidebands? Many first adjacent stations are still 50 to 65 miles away, even Class Bs to each other, like WWWW and WDKL, and WFBE and WMMQ.

[audiophile]

IBOC is really IBAC. It goes to center of the adjacent channel.

[k8jd]

The authorities came up with the devation for BCFM , for the best IF noise supression etc, using 1940's tech . It has been used so long, it's hard to make any major changes in spectrum use etc.

[Ben Zonia]

I just checked the spacing between WWWW-FM 102.9 and WDKL 102.7. WBRB-FM...WDKL was around 52 miles from the old location to the WOIA...WWWW-FM location near the gravel pit near Wagner Rd. WWWW-FM had moved about three miles further away to West of Zeeb Rd. Now the distance between WWWW-FM 102.9 to WDKL 102.7 is an incredibly short 36.68 miles! That has to be some kind of Commercial 92-108 MHz Class B to Class B first adjacent short spaced record, except maybe some pre 1964 authorizations on the opposite sides of a mountain range. Anybody know of any that are less?

I know that some of you Great Lakes area radio geeks will think of this, so I checked WDRV 97.1 to WWDV 96.9 and it's 45.21 miles.

WWWW-FM has a very well designed antenna from ERI that avoids unnecessarily deep nulls in the MEASURED pattern.

WWDV has a FCC ENVELOPE pattern that is 17.1 dB maximum to minimum, in excess of the 15 dB normally allowed domestically by the FCC.

Just checked WFBE 95.1 to WMMQ 94.9 and it is 51.51 miles from the WTRX North Tower.

In the NCE-FM 88-92 MHz Band, there are different rules, more similar to the early 1960s Commercial contour overlap rules, in which both classes of stations, A and B, were protected to the 1 mV/m (now usually called 60 dBu F(50,50)) contour. Thus, both with DAs, WFUM 91.1 and WRCJ 90.9 are only 34.43 miles apart, and are Class Bs only protected to the 60 dBu contour.

[billmich88888]

i live off 275, there has been moderate degradation of 102.9 in western wayne area

[ftballfan]

Then there are the 104.7s in Columbia, SC (WNOK) and Charlotte, NC (WKQC). Both are heavily directional but do run 100,000 watts in the direction away from each other.

There do appear to be some hills between Baltimore and York.

[k8jd]

Narrower AM HD ?
I just took a look at an AM HD siglnal .It covers 30 kHz of the band spectrum ! The "main" carrier is at 1340 kHz, the basic AM sidebands go +/- 5 kHz, the Digital AM stereo "carrier" is at +/-10 KHz and the digital signals extend above 1350 another 5 kHz and below 1330 by another 5 kHz.
Looks like it takes up, at least , half of both the upper adjacent and lower adjacent channel !