M Qimn HSTG cua cka do:
Ttoalc te Khong thi tan gn qua Ion vi ptiep do se tro nen qui chim T ^ n g tniong hop ctnla eo Khong che rihiet do, co t h i xiy r a viec gh
s a i do tlioi gian do 1 dildng C(t) Ion hon thoi gian tang rihiit. Tren he CT92, vol m = 256, n = 200, thoi gian do n^t diong C(t) vao ea 2 ptnit.
104-
2. 2. So luong cUa so Boxcar.
NhU nhiing p h i n t r i n h b^y a phan 4A, chiing t a t h a y doi v a i ptniong phap Lang t r e n h e h a i bien, só eUa Boxcar Khong doi h o i n h i e u (co v a i
chiic l a da). Dieu dbi h o i Khe Khat a day l a t i r i h chirih xac, on dirih,
d i i u c h i n h dioc eua t r u e n h i e t dọ
Doi v o l ptniong phap Dich eiia t h i yeu c i u v i t r u e rihiet do den g i a n hon n h i e u (ehi can 5 g i a t r i rihiet do on d i n h ) , song yeu c i u ve so luong eua Boxcar m cang n h i e u cang t o t .
Xet t r i n h e do CT92. g i a sii t a do diong C ( t ) t a i tin so l i p l a i
ciia xung ptiin cUe Kich t h i e h mau f ~ 4<H2 (Tg "" 25 ms).
He do CO m = 256 v a HSTG = 1ms. Vi T^ ~ 25 ms nen do rong xung
ciia d t - 25ms/256 "• lOOus. Vi HST3 = 1ms nen tói t h i e u t a ptiai e a t
1/25 - 2/25 diong t i n h i e u ptiia dau do meọ NhU v i y so cuta t^ con l a i
tut t 2 5 - 256- '^5ieo cong thute (4. 5) neu l a y r = 4 t h i so* d i e n eo t h e
t r e n diong e ^ l a 40. Neu l a y r = 5 t h i so diem e h i con 25. De chon eiic d a i eiia diong ệ so diem t r e n l a qaa i t .
Gia sii do v o l t a n so l a p l a i f '^ 100 Hj (T^ *" 10 ms). Cung lam cac t i n h t o a n nhil t r e n t a eo d t < 50ps. Doan t i n h i e u ptiai c a t d i l a
1/20 - 2/10, tile l a mat d i 50 ciia so dau t i e n .
Khi do, VOI r = 3, so diem t r e n diong ê e h i c6 t h e l a 35.
Voi t a n so nay t a thay, do T^ giam nen: + Tap t a n g l i n (dt < 50ps)
+ Anh hUong HSTG manh
• To quan he d t = T^/m v o i d t >. SOUs va quan he giila HSTTC voi T^,
105-
* Muon do o t ^ só xung Kich 50CH2 - lOOCftlz, c ^ giam HS7P3
c i u dọ
*( Hi do CO tiiong quan ptni hop gifia HST3 t h i i t b i , t a n so do
v a so Cila Boxcar.
2. 3. De n g h i c a i t i e n . . A - )
De h e do Cr92 h o a t dong chirih xac v a t h u i n t i e n hon. t r a r i h rihiing h i i u chirih Khong e i n co rihU bo c h i r t i HSTG, lam min t i n h i i u . . . chung
t o i ^ n ^ h i mot so d i i m eo t h e c a i t i ^ rihii sau: K Mo rong d a i d i i u chirih nute ptiin ciic 1 clhliu K Ho r o n g d i i u chirih b i i n do xung ptiin ciic M Mo rong nute dau vao bo S & H
K T t i i e t l a p h a i Kha nang d a t t i n so xung Kich
0 - lOV 0 - lOV ± 6V
Tay v a t i l dong. « Sut dung Khoi Khong che r i h i e t do cho b i n h n ^
*( Boe Kim c i e diong t i n h i e u a n a l o g vao bo ADC.
n So ciia so Boxcar t h a y dSi d i o c t h e o d a i t i n so xung Kich:
f < 40 Hz 40 Hz <f<100 Hz f > 100 Hz m = 512 m = 256 m < 256
Kh: LU^