
Rev. 2.0, 11/00, page 806 of 1037
28.15.6
Noise Detection
If drop-out of a pulse of the horizontal sync signal occurred, set a supplemented pulse at the
timing set in HPWR and with the set pulse width.
Set the noise detection window with HWR of about 1/4 of the horizontal sync signal, and the
pulse with equal High and Low periods will be obtained.
(1) Example of Setting
Assumed that a supplemented pulse is set when fosc = 10MHz under the conditions
φ
s =
5MHz, NTSC:TH = 63.6 (
µ
s) and Hpuls = 4.7 (
µ
s), the set values of the supplemented pulse
timing (HRTR7-0), supplemented pulse width (HPWR3-0) and noise detection window
timing (NWR5-0) are expressed by the following equations.
(Value of HRTR7-0)
×
2/
φ
s = TH
((Value of HPWR3-0) + 1)
×
2/
φ
s = Hpuls
((Value of NWR5-0) + 1)
×
2/
φ
s = 1/4
×
TH
Where, TH is the cycle of the horizontal sync signal (
µ
s), Hpuls is the pulse width of the
horizontal sync signal (
µ
s) and
φ
s is the servo clock (Hz) (fosc/2).
Accordingly,
(Value of HRTR7 to HRTR0)
×
0.4 (
µ
s) = 63.6 (
µ
s)
∴
HRTR7-0=H'9F
((Value of HPWR3 to HPWR0) + 1)
×
0.4 (
µ
s) = 4.7 (
µ
s)
∴
HRTR3-0=H'B
((Value of NWR5 to NWR0) + 1)
×
0.4 (
µ
s) = 16 (
µ
s)
∴
NWR5-0=H'27
Also, the noise mask period is computed as follows.
((Value of HRTR7 to HRTR0) + 1)
−
24)
×
2/
φ
s = 54 (
µ
s)
Where, 24 is a constant required for a structural reason.
Figure 28.75 shows the set period for HRTR, HPWR and NWR.
Содержание Hitachi H8S/2191
Страница 123: ...Rev 2 0 11 00 page 96 of 1037...
Страница 149: ...Rev 2 0 11 00 page 122 of 1037...
Страница 197: ...Rev 2 0 11 00 page 170 of 1037...
Страница 247: ...Rev 2 0 11 00 page 220 of 1037...
Страница 249: ...Rev 2 0 11 00 page 222 of 1037...
Страница 347: ...Rev 2 0 11 00 page 320 of 1037...
Страница 357: ...Rev 2 0 11 00 page 330 of 1037...
Страница 417: ...Rev 2 0 11 00 page 390 of 1037...
Страница 431: ...Rev 2 0 11 00 page 404 of 1037...
Страница 439: ...Rev 2 0 11 00 page 412 of 1037...
Страница 457: ...Rev 2 0 11 00 page 430 of 1037...
Страница 525: ...Rev 2 0 11 00 page 498 of 1037...
Страница 543: ...Rev 2 0 11 00 page 516 of 1037...
Страница 639: ...Rev 2 0 11 00 page 612 of 1037 28 1 2 Block Diagram Figure 28 1 shows a block diagram of the servo circuits...
Страница 845: ...Rev 2 0 11 00 page 818 of 1037...