Panasonic AG-7500 - Page 6

Comparison between S-VHS and VHS
As compared with the conventional VHS system, the
performance is remarkably improved as follows.
@ Frequency shift: 3.8 MHz ~ 4.8 MHz to 5.4 MHz
~7 MHz
@ FMluminance bandwidth: Approx. 3.2 MHz to approx. 5.5
MHz
e Resolution: Approx. 240 lines to more than
400 lines
However, when the band is widened, the S/N becomes inferior
accordingly. To prevent this deterioration, in the S-VHS
system, the following measures are incorporated.
e@ The sub-emphasis circuit is introduced in the preliminary
stage of the conventional main emphasis circuit.
@ AnS-VHS tape made of newly developed magnetic material
is used exclusively for the S-VHS.
@ The use of the amorphous heads ensures high quality
pictures.
©@ VHS System
Colour
signal
© S-VHS System
Colour
signal
'
i1 2
I;
|
|
627kH2z
3
Approx.
S.SMHz
———1 Frequency
Resolution more
than approx. 400 lines
High Quality Picture
Incorporation of detail enhancer
During VHS mode a picture with fine details, such as ripples on
the surface of water ora womans long flowing hair, tends to be
reproduced flat. The detail enhancer circuit enhances the
high-frequency signals (more than 1.5 MHz) of such pictures
before they are recorded, thus enabling every detail to be
reproduced clearly (4 dB up).
HD (high-dynamic) System
This unit records audio using the following two formats:
@ Hi-Fi sound: An FM format employing a dedicated
rotary audio head permits high quality
sound recording and reproduction.
This is the same format as that used ina
conventional video recorder.
® Normal audio:
<Compatibility with conventional recording methods>
This unit can record tapes in the conventional (normal) mode,
enabling tapes recorded on it to be reproduced on a
conventional machine.
The unit can also reproduce tapes recorded on a conventional
machine.
@ Independent dedicated audio head installed
on rotary cylinder
The audio of a video tape which was formerly recorded
using a fixed head is recorded on this unit using an audio
head mounted on a rotary cylinder. The video is recorded
over the audio using a dedicated video head. This
completely new format (Figs. 1 and 2) is called a high-
dynamic system (for creating superior sound quality).
Search head (R”)
Rotary erase head
Video recording/
playback head (L)
(Amorphous head)
Dedicated rotary
audio head (R)
Rotary erase head
Dedicated rotary
audio head (L)
Video recording/-
playback head (R)
(Amorphous head)
Search head (R’)
<Rear view>