[Scan-DC] Aeronautical 8.33 kHz channel spacing

[Jeff Krauss]

As the 3rd R&O indicates, this channel splitting has been in the 
works in the US since 2001.  Back then, it was opposed by the General 
Aviation community because of cost, and opposed by the FAA because 
ACARS [Aircraft Communication Addressing and Reporting System] and 
VDL [VHF Data Link] Mode 2 data services require 25 kHz channel 
spacing.  The 3rd R&O doesn't say whether FAA took a position on 
channel splitting this time around.
The 3rd R&O doesn't mention the related issue of cable TV leakage and 
signal offsets in Part 76, which require video carrier frequencies to 
be offset from the aeronautical frequencies.  But the offset rules 
were imposed in the days of analog video, while most of the larger 
cable systems have converted to digital.
Anyway, the channel splitting is permissive, not mandatory, and only 
applies to aeronautical en-route frequencies operated by a private 
consortium (and to flight testing frequencies), and apparently not to 
air traffic control frequencies operated by the FAA.



>Message: 4
>Date: Tue, 16 Aug 2011 11:03:46 -0400
>From: "Clegg, Andrew W." <aclegg at nsf.gov>
>Subject: [Scan-DC] ULS is now ready to accept applications for
>         aeronautical    enroute stations using 8.33 kHz channel spacing
>To: <scan-dc at mailman.qth.net>
>Message-ID:
>         <36946000EC7B1E44A277E4EC11FE917F02136907 at NSF-BE-02.ad.nsf.gov>
>Content-Type: text/plain;       charset="us-ascii"
>
>A question for the aeronautical experts out there:  Would this be the
>first use of 8.33 kHz channel spacing for aeronautical comms in the
>U.S.? The Order referenced in the Public Notice notes that some parts of
>Europe are already using 8.33 kHz spacing.
>
>Cheers,
>Andy
>
>Public Notice:
>http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-11-1403A1.pdf
>
>Third Report and Order referenced in Public Notice:
>http://www.aerosupavionics.com/document/FCC-10-103A1.pdf
>