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New Camcorder Features
Overview
In this section we will briefly discuss three new features found in Sony
camcorders. These features include 8mm and Hi8 XR, Night Shot and
Laserlink. These features can be used in any camcorder, analog or digi-
tal, with the exception of 8mm XR, which is exclusive to 8mm camcorders.
8mm and Hi 8 XR (Extended Resolution)
The 8mm Hi8/XR systems were produced in an effort to increase the
resolution of new 8mm products while remaining compatible with the 8mm
and Hi8 systems. This system achieves 280 lines of horizontal resolution
versus 240 lines for 8mm. In Hi8 XR the resolution is increased from 400
lines to 440 lines. In order to understand this new technology, let's look at
the old 8mm and Hi8 frequency spectrums.
Background
The 8mm Recording Signal Spectrum below shows the down converted
chroma signal to be centered at 743 KHz. The audio signal is centered
between the 1.5 MHz and 1.7 MHz audio carriers and the video signal
takes up the rest of the spectrum. The Y signal is frequency modulated
onto a carrier so that the sync tip is at 4.2 MHz and the peak white signal
is at 5.4MHz. The rest of the area inside the Y spectrum is for the side
bands produced by the frequency modulation of the video. Since greater
picture detail is located in the higher frequencies of the Y signal, the side
bands contain the picture detail. This means that if we can extend the
side bands area, we can produce more detail.
Analog 8mm Recording Spectrum
3
This is more evident when comparing the amount of side band informa-
tion in the Hi8 spectrum. The Hi8 system allows for greater picture detail
by allowing for a wider side band area. Extending the bandwidth increases
picture quality (resolution).
Hi8 Recording Spectrum
Conventional vs. XR (Extended Resolution)
In the conventional systems discussed above, a fixed band stop filter is
used during recording to keep the audio and Y signals from interfering
with each other. These filters are necessary in a conventional system,
but they do tend to eliminate some of the detail from the video. The XR
system is dynamic and the filter is not applied until the relative level of the
YFM in the AFM region is determined. If it is determined that the ampli-
tude of the YFM signal is low enough in the AFM area, then the filter will
be switched out. The resulting signal, which is sent to the head, is shown
below. This result is an extended resolution (XR) recording.
XR Record - Filter Out
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