[opendtv] Re: Have you heard...

  • From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 13 Jun 2007 19:00:00 -0400

Tom Barry wrote:

> What is the bandwidth in both data bits and Hz for a digital
> radio channel?

The ibiquity web site has some white papers that cover this. From
memory,

In hybrid mode, FM stations become 400 KHz wide instead of 200 KHz. And
the bit rate is either 98.4 Kb/s or, squeezing down the analog a little
more, something like 123 Kb/s.

When/if going all digital, these FM-band stations get to keep the 400
KHz channel, so they can increase power and at least double their
bandiwtdh.

AM stations become 30 KHz wide, and the digital can be 20 Kb/s to
something like 56 Kb/s, but at lower and lower power levels for the
extra bits.

Unlike in the FM band, when/if going all digital, AM stations go back to
their 10 KHz bandwidth, with provisions also for 20 KHz.

In short, in hybrid mode, the digital stuff mostly occurs in the guard
bands of the analog signal, at much reduced power. In AM, believe it or
not, there's also the option for some digital buried down deep in the
analog spectrum.

Bert
 
 
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