[opendtv] Re: Digital Better Than Analog?
- From: "Hughes Gary-DJWV76" <ghughes@xxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 30 Jul 2007 12:40:27 -0400
The FiOS network uses 3 wavelengths on the PON to the home, two
downstream, one upstream.
One downstream carries a full cable feed that is remodulated onto coax
in the home by the ONT (Optical Network Terminal). For the most part
they are using the same programming feeds as the cable MSOs so there
should be very little quality difference for the national feeds between
cable and FiOS. These services are heavily compressed (I've measured
some as low as 2-2.5 mbit/sec before Comcast got copy control working on
the 1394 output of my home cable box).
The remaining downstream and the upstream carriers are used for IP based
traffic, including internet access, voice, VOD and recently some
switched digital video (SDV) services. There is traffic shaping at the
VSO (Video Service Office), and further upstream to ensure that that
different services get their allocated bandwidth.
Regarding the original question (digital better than analog?):
Many cable operators are now running digital simulcast, where the basic
or "lifeline" services that occupy the lower 20 or so analog channels
are replicated as SD digital channels. If you have a digital cable box
it will be programmed to pick up those in preference to the analog
signal. They do indeed look better, presumably because they not
subjected to the various distortions of the analog cable plant. Last
time I measured, my local Comcast was allocating a reasonable bitrate
(6+ mbit/sec) to these channels. One of my TVs has a QAM tuner (no
Cablecard) and it was able to find these simulcast channels along with
the local HD channels so they are apparently part of the basic service
(the rate card explicitly mentions that local HD channels can be viewed
with a suitable TV at no extra fee).
Gary
Gary Hughes
Video Architect, Advanced Engineering
Motorola On Demand Solutions, MA34
80 Central St.
Boxborough, MA 01719
Email: ghughes@xxxxxxxxxxxx
Office: 978 266 7269
Mobile: 978 339 3615
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