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[Discuss-gnuradio] IBOC and AM don't mix.

From: Tim Pozar
Subject: [Discuss-gnuradio] IBOC and AM don't mix.
Date: Wed, 16 Oct 2002 13:43:25 -0700
User-agent: Mutt/

This was identified as a problem some months ago. In fact IBOC is
not approved out side of daylight hours as you have much larger
coverage with AM then with skywave coverage at night.  But here are
some real-life experiances with IBOC on AM...


  The DX lists have been very active with posts about IBOC
on AM.  One post is copied below as an example.

  I would be curious what people on the west coast think of
IBOC.  In an example I heard, the signal of 710 kHz KABC, Los
Angeles, suffered a coverage loss due to 700 Cincinnati's
transmissions of IBOC.  In fairness, I don't know if 710 cares
that someone in Nevada is listening to their station, but for
those of us that listen to stations outside of their "primary
service areas," IBOC could pose a big problem.

  FredVobbe, address@hidden

  [The posting copied by Fred is from an AM DXer is Seaside,
OR who writes:  "After listening for two days of IBOC from
KIXI-880, I can tell you that this white noise is going to be a
problem for all DXers....  I hope [it] is all a bad dream and
maybe we will wake up and it will be just that, a dream....]



  Internet postings show AM IBOC is causing some problems
with local analog reception of the station sending the IBOC
signal.  KIXI's analog signal in Seattle carried a "frying bacon
sound" and the fidelity of the station was reduced during IBOC
tests (but iBiquity rolls off the high frequency response as part
of their system requirements, so that part of the problem was
expected).  Also, spectrum analyzer tests showed that the
station's digital sidebands exceeded the FCC's emissions mask
by over 10 dB.

  Jump to New York.  WOR lites up their iBiquity subcarriers
on Friday, and shuts them off on Monday thanks to the frying
bacon gremlin.

  Why are these problems showing up so late in the game?  If
these Internet postings are true, this is a terrifying situation.

  Mike Sullivan 


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