svhs question
>> The real advantage of S-VHS is the separation of signals on the tape.
Sorry if it seems like I'm picking on you, but this is such a popular
misconception that it should be addressed so everyone understands it. The
truth of the matter is that VHS and SVHS both record the signal on the tape
in exactly the same way. In both cases, the chroma portion of the signal
is downconverted recorded along with the luminance (which is recorded at a
much higher frequency). No, they're not recorded on separate tracks, as
the vendors wanted everyone to think.
The only difference between the two recording modes is that in SVHS the
center frequency of the luminance portion of the signal was raised
somewhat, so that there would be greater bandwidth (and hence a higher
resolution). There is absolutely no diference in the recording of the
chroma signal.
As to the design of the deck, vis a vis the use of Y/C connectors, it would
help to understand the signal path in regular VHS. Composite video comes
in the input jack and is split into two components — the luminance (B&W
detail) and the 3.58MHz chrominance (color). The chroma signal is then
downconverted to a much lower frequency (621KHz) because there's no way you
can record a 3.58MHz signal on VHS tape — it would be too much information
on too little tape. Of course, this is done at the expense of much of the
detail in the color portion of the image. The two signals are then
recombined and recorded on the tape. On playback, the signal comes off the
tape, the chroma is converted back up to 3.58MHz, it's combined with the
luma signal and output as composite video. On an SVHS machine, all the Y/C
connectors do is tap the signal while it's still in the separated
luma/3.58MHz chroma state. This helps reduce the artifacts encountered
when the luma and chroma signals are combined into a composite signal, and
since there is some degradation every time this is done, keeping the
signals separate through the signal path can result in a significantly
better finished image.
Pete