Spec clarification

Archived from groups: alt.tv.tech.hdtv (More info?)

This is part of the specs for an Olevia 37" HDTV with ATSC and NTSC
turners included. What exactly does it mean? Does it mean that the NTSC
turner can receive cable and OTA but that the ATSC can only receive OTA?

TV Tuner Input TV / CATV RF x 1, NTSC & TV/RF x 1 for ATSC

Archived from groups: alt.tv.tech.hdtv (More info?)

tim@nocomment.com wrote:

> This is part of the specs for an Olevia 37" HDTV with ATSC and NTSC
> turners included. What exactly does it mean? Does it mean that the NTSC
> turner can receive cable and OTA but that the ATSC can only receive OTA?
>
> TV Tuner Input TV / CATV RF x 1, NTSC & TV/RF x 1 for ATSC

Most likely, yes. Analog cable channels and over the air analog
stations both use NTSC encoding of the signal. The Cable-Ready TV - in
the days when all was analog - tunes to the NTSC cable channels which
were placed at 6 MHz RF spacings in the cable signals.

In the digital age, the base encoding is ATSC (Advanced Television
Standards Committee) which is sent both over cable and the air. OTA
broadcast use a signal modulation called 8-VSB. Digital cable uses QAM
with terms like QAM64 or QAM256, but cable systems can and do scramble
many of the QAM channels. QAM allows for multiple sub-channels to be
embedded in the 6 MHz carrier channel, up to 10 or SD channels or up to
2 HD channels, but the set top box reassigns the channels to the channel
assignments you see (2 to 990 or whatever).

However, the terminology appears to have evolved so that ATSC tuner =
OTA digital ATSC tuner, QAM tuner = digital cable tuner. To view
scrambled QAM channels - which may be all of them except for the free
OTA local stations, the QAM tuner needs a cable card provided the cable
company to descramble the signals.

Alan F