Herald: Ch 7 may buy Ch 56

Scott Fybush scott@fybush.com
Sun Aug 20 01:47:56 EDT 2006

> I think there actually is a technical reason for this.  I used to see
> this problem a lot more back in the 80s and early 90s than I do now,
> but there is a problem called "ingress," which, as the cable people
> explained it to me, is that if the station is the carried on the same
> cable channel as its air channel, the station's air signal conflicts
> with its cable signal, causing diagonal lines across the picture.  In
> Brookline this seems particularly common on Channel 2.
> Cablevision, which was Brookline's cable company at the time, didn't
> want to move stations to other channels because of the confusion that
> would cause, and over the years, they seem to have improved the
> situation considerably, but I remember a lot of discussions about
> that when I was on the town's Cable Monitoring Committee back then.

The Comcast system in Newton and Needham still puts 4 on 23, 5 on 24, 7 on
25 and 2 on 22, since there's so much RF from the nearby towers that those
channels would be unusable. (Instead, they're used for community calendar
announcements and the like; Worcester's WYDN 48 is transmitted on channel
5, where it's nearly unwatchable, but still meets those pesky "must-carry"

When I lived in Waltham, the then-TCI system had 4, 5 and 7 on higher
channels, then put them on 4/5/7, and I think has gone back to the older
lineup since becoming part of Comcast.

Digital cable boxes can (and do) "remap" those channels, so if you're
watching Comcast in Newton through a cable box tuned to "4," the box is
really tuned to channel 24.

In Rochester, our Time Warner system recently began transmitting our
locals (8/10/13) over its digital system, and our digital boxes remap
accordingly, thus ending the ingress problems that plagued my area (less
than a mile from the transmitters) for decades.

I recall that when the city of Rochester first got cable in the early 80s,
the system there ("American Cablevision") used special Hamlin converter
boxes that were modified (by printing a different slide-rule dial) so that
they were actually tuned one channel lower than the number displayed. So 8
was really on channel 7, 10 on 9 and 13 on 12, but the box (which had no
"channel 2," of course) showed them as 8/10/13. Channels "9", "11" and
"14" on the system were used for text announcements, and were always full
of ingress.


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