Color Signai Recording Bandwidth - JVC HR-S10EG Service Manual

The FM luminance and down converted color signals are
mixed to become the recording current. When recorded and
played back using magnetic tape, which possesses 3-dimen-
sional distortion and nonlinearity, interference in the form
of Fo+ 2Fpc (Fo: FM carrier; Foc : down converted color
signal) becomes introduced and cannot be ignored. When
the 2Fpc component is detected and demodulated, beat
becomes produced with respect to the juminance signal and
appears in the picture. Therefore, as with the color signal,
Fe (down converted color subcarrier frequency) must be
selected so that the 2Fpc component becomes 1/4 offset
in relation to the luminance signal, i.e.:
2Fe=20—1 Fh
1 pp = 321 Fh = 40 Fh + 2 Fh (n= 161)
= 625 + 1.953 = 626.953 kHz
When Fc is determined at (40Fh + 1/8Fh), the spectrum of
the CH-1 track B-Y component appears at (nFh + 1/8Fh)
and the R-Y component at (nFh — 3/8Fh). In the CH-2
track distribution, B-Y appears at (nFh — 1/8 Fh) and R-Y
at (nFh — 5/8 Fh).
Fig. 1-13 shows the 2F pc component spectrum with respect
to the playback luminance signal at this time.
(CH-1 track
CH2track A
(R-Y) components 4/4 mel LL 1/4 Fh
Fig. 1-13 2Fpc playback spectrum
1.5.3 Color Signal Recording Bandwidth
Response curves for the highpass and lowpass filters are
indicated in Fig. 1-14.
Constant current characteristics are possessed by the down
converted color signal recording current.
Fs; Color subcarrier
(4.439619 MHz)
_
(a) HPF
aaa}
3. 05 G = Frequency (MHz)
Fe; Down converted color subcarrier frequency
(626,953 kHz)
a
(b) LPF
3B
2 3 4
——————> Frequency (MHz)
1.56
Fig, 1-14 Color signal recording bandwidth