Iﺗﻀﻤﻴﻦ ﺍﻟﻮﺳﻊ: (1ﻣﻔﻬﻮ ﻡ ﺍﻟﺘﻀﻤﻴﻦ: ( ﺇﺭﺴﺎل ﺭﺴﺎﻝﺔ ﺇﻝﻰ ﺍﺸﺨﺹ ﻤﻌﻴﻥ ،ﻴﺴﺘﻭﺠﺏ ﺘﺤﻭﻴل ﺍﻷﻓﻜﺎﺭ ﺍﻝﻤﺭﺍﺩ ﺇﺭﺴﺎﻝﻬﺎ ﺇﻝﻰ ﻨﺹ ،ﻭﻜﺘﺎﺒﺔ ﻫﺫﺍ ﺍﻝﻨﺹ ﻓﻲ ﺭﺴﺎﻝﺔ ،ﺜﻡ ﻭﻀﻊ ﺍﻝﺭﺴﺎﻝﺔ ﻓﻲ ﻅﺭﻑ ،ﻭﺇﺭﺴﺎل ﺍﻝﻅﺭﻑ ﻋﺒﺭ ﺍﻝﺒﺭﻴﺩ ﺇﻝﻰ ﺍﻝﻭﺠﻬﺔ ﺍﻝﻤﺨﺼﺼﺔ ﻝﻬﺎ ،ﻓﺎﻝﺘﻀﻤﻴﻥ ﺍﻝﺫﻱ ﺘﻡ ﻫﻨﺎ ﻫﻭ ﺘﺠﻬﻴﺯ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﺒﺼﻭﺭﺓ ﺘﻜﻭﻥ ﻤﻨﺎﺴﺒﺔ ﻹﺭﺴﺎﻝﻬﺎ ،ﻋﺒﺭ ﻭﺴﻴﻠﺔ ﺍﻹﺭﺴﺎل ﺍﻝﻤﻨﺎﺴﺒﺔ ،ﻭﺍﻝﺫﻱ ﺴﺎﻋﺩ ﻓﻲ ﺫﻝﻙ ﻫﻭ ﻭﺠﻭﺩ ﻭﺴﻴﻠﺔ ﺤﺎﻤﻠﺔ ﻝﻬﺎ ،ﺃﻱ ﺇﻥ ﺘﺠﻬﻴﺯ ﺍﻝﻤﻌﻠﻭﻤﺔ ﻭﻓﻕ ﻤﻌﺎﻴﻴﺭ ﻤﻌﻴﻨﺔ ،ﻭ ﺇﺭﺴﺎﻝﻬﺎ ﻋﺒﺭ ﻭﺴﻴﻠﺔ ﹸﺘﻌ ّﺩل ﺨﺼﺎﺌﺼﻬﺎ ﺤﺴﺏ ﺍﻝﻐﺎﻴﺔ ،ﺘﺴﻤﻰ ﻫﺫﻩ ﺍﻝﻌﻤﻠﻴﺔ ﺒﺎﻝﺘﻀﻤﻴﻥ.
ﺍﻟﻮﺳﻊ: (2ﺗﻀﻤﻴﻦ ﺍﻟﻮﺳﻊ ﺍﻝﺘﻀﻤﻴﻥ ﻫﻭ ﺘﻌﺩﻴل ﺇﺸﺎﺭﺓ ﺍﻝﻤﻌﻠﻭﻤﺎﺕ ﻝﺒﻌﺽ ﺨﺼﺎﺌﺹ ﻤﻭﺠﺔ ﺤﺎﻤﻠﺔ ﺫﺍﺕ ﺘﺭﺩﺩ ﻋﺎل. ﻭﻴﻌﺘﺒﺭ ﺘﻀﻤﻴﻥ ﺍﻝﻭﺴﻊ ﺘﻘﻨﻴﺔ ﺘﻌﺘﻤﺩ ﻋﻠﻰ ﻀﺭﺏ ﺍﻹﺸﺎﺭﺓ ﺍﻝﺘﻲ ﺘﺤﻤل ﺍﻝﻤﻌﻠﻭﻤﺔ ﻓﻲ ﺇﺸﺎﺭﺓ ﺃﺨﺭﻯ ا دد ﺘﺴﻤﻰ ﺒﺎﻹﺸﺎﺭﺓ ﺍﻝﺤﺎﻤﻠﺔ، ) ﻭﻴﺘﻡ ﺫﻝﻙ ﺒﻌﺩ ﺇﻀﺎﻓﺔ ﺘﻭﺘﺭ ﺜﺎﺒﺕ ﻝﻺﺸﺎﺭﺓ ﺍﻝﺘﻲ ﺘﺤﻤل ﺍﻝﻤﻌﻠﻭﻤﺔ ﻤﻥ ﺃﺠل ﺇﺯﺍﻝﺔ ﺍﻝﺘﺸﻭﻴﺵ(.
ﺍﻟﺬﻱ ﻳﻀﻢ ﺍﻟﻤﻌﻠﻮﻣﺔ: ﺩﺩ ﺍﻟﺘﻮﺗﺮ ﺍﻟﺬﻱ ﺗﻌﺒﻴﺮ ﻭﺗﺮﺩﺩ (3ﺗﻌﺒﻴﺮ ( ﻴﻤﻜﻥ ﺃﻥ ﻴﻜﻭﻥ ﺍﻝﺘﻭﺘﺭ ﺍﻝﺫﻱ ﻴﻀﻡ ﺍﻝﻤﻌﻠﻭﻤﺔ ﺠﻴﺒﻴﺎ ﻭ ﺩﻭﺭﻴﺎ ﻨﺒﻀﻪ .ωm=2πfm : . u m (t ) = U m cos ω m .t : mﺘﻌﻨﻲ Modulantﺃﻱ :ﺍﻝﻤﻀ ﻤـّﻥ. ﻨﻀﻴﻑ ﺇﻝﻴﻪ ﺍﻝﺘﻭﺘﺭ ﺍﻝﺜﺎﺒﺕ UOﻓﻴﺼﺒﺢ ﺍﻝﻤﺠﻤﻭﻉ: u1 (t)= um (t) +UO
ا اs= 500 µs/div :
اور ب <= 4,5div :ا دد
f m ≈ 444 Hz
(4ﺗﻌﺒﻴﺮ ﻭﺗﺮﺩﺩ ﺍﻟﺘﻮﺗﺮ ﺍﻟﺤﺎﻣﻞ: ( ﺍﻝﻤﻭﺠﺔ ﺍﻝﺤﺎﻤﻠﺔ ﺫﺍﺕ ﺘﺭﺩﺩ ﻋﺎل ﻭﻫﻲ : u p (t ) = U p . cos ω p .tﺘﻭﺘﺭ ﺍﻝﻤﻭﺠﺔ ﺍﻝﺤﺎﻤﻠﺔ. : pﺘﻌﻨﻲ Porteuseﺃﻱ :ﺍﻝﺤﺎﻤﻠﺔ.
ﺍﻝﻜﺴﺢ ﺍﻷﻓﻘﻲ ﺍﻝﻤﺴﺘﻌﻤل ﻫﻭ 10 −5 s / div :ﻭﻤﻨﻪ ﺘﺭﺩﺩ ﺍﻝﻤﻭﺠﺔ ﺍﻝﺤﺎﻤﻠﺔ f P = 18.10 4 Hz = 180kHz .ﻭﻫﻭ ﺘﺭﺭﺩ ﺠﺩ ﻋﺎل.
ﺍﻝﺤﺴﺎﺴﻴﺔ ﺍﻝﺭﺃﺴﻴﺔ <=2V/divﻭﺴﻊ ﺍﻝﻤﻭﺠﺔ ﺍﻝﺤﺎﻤﻠﺔ . U p = 4V : 1
(ﺇﻧﺠﺎﺯ ﻋﻤﻠﻴﺔ ﺍﻟﺘﻀﻤﻴﻦ: ( 5ﺇﻧﺠﺎﺯ ﻭﺘﻘﻨﻴﺎ ،ﺘﺘﻡ ﻋﻤﻠﻴﺔ ﺍﻝﺘﻀﻤﻴﻥ ﺒﻭﺍﺴﻁﺔ ﺘﺭﻜﻴﺏ ﺇﻝﻜﺘﺭﻭﻨﻲ ﺨﺎﺹ :ﺩﺍﺭﺓ ﻤﺘﻜﺎﻤﻠﺔ ﻤﻨﺠﺯﺓ ﻝﻠﺠﺩﺍﺀ .
ﻋﻨﺩ ﻤﺨﺭﺝ ﺍﻝﺩﺍﺭﺓ ﺍﻝﻤﺘﻜﺎﻤﻠﺔ ﺍﻝﻤﻨﺠﺯﺓ ﻝﻠﺠﺩﺍﺀ ﻨﺤﺼل ﻋﻠﻰ ﺩﺍﻝﺔ u s (t ) :ﺘﺘﻨﺎﺴﺏ ﺇﻀﻁﺭﺍﺩﺍ ﻤﻊ ﺍﻝﺠﺩﺍﺀ ) u1 (t ).u 2 (t : k ،ﺜﺎﺒﺘﺔ ﺍﻝﺘﻨﺎﺴﺏ ﻭﻫﻲ ﺘﺘﻌﻠﻕ ﺒﺎﻝﺩﺍﺭﺓ ﺍﻝﻤﺘﻜﺎﻤﻠﺔ . )us(t) =k. u1(t) .u2(t ﻤﻊ : ﻭﻤﻨﻪ :
u1 (t ) = u m (t ) + U O
) u 2 (t ) = u p (t
ﻭ:
) u s (t ) = k [u m (t ) + U O .].u p (t u s (t ) = k [U m cos ω m .t + U O .].U p . cos ω p .t
u (t ) = U m (t ). cos ω p .t =<
ﺒﻤﻘﺎﺭﻨﺔ
) ( 1ﻭ )( 2
ﻨﻀﻊ A = k .U p .U o :
)( 2
ﻭﺴﻊ ﺍﻝﺘﻭﺘﺭ ﺍﻝﻤﻀﻤﻥ ﻫﻭ :
ﻭ:
Um Uo
=m
ﺒﺤﻴﺙ m ،ﻫﻲ :ﻨﺴﺒﺔ ﺍﻝﺘﻀﻤﻴﻥ.
ω m = 2π . f m
ﻭﻴﻌﺒﺭ ﻋﻥ ﻨﺴﺒﺔ ﺍﻝﺘﻀﻤﻴﻥ ﺒﺩﻻﻝﺔ Um.maxﻭ Um.min :
)U M :
2
ه
Um.maxو U m :
ه
(Um.min
U M = 3div.2V / div = 6V U m = 1div.2V / div = 2V 1 1 = fm = ﺘﺭﺩﺩ ﺍﻝﺘﻭﺘﺭ ﺍﻝﻤﻀﻤﻥ ≈ 444 Hz : −6 4,5div.500.10 s / div 2,25.10 −3 s ﻣﻠﺤﻮﻇﺔ :ﺸﺭﻭﻁ ﺍﻝﺤﺼﻭل ﻋﻠﻰ ﺘﻀﻤﻴﻥ ﺠﻴﺩ: U ﺃﻥ ﺘﻜﻭﻥ ﻨﺴﺒﺔ ﺍﻝﺘﻀﻤﻴﻥ m = m < 1 :ﺃﻱ :. Uo > Um Uo -ﺃﻥ ﻴﻜﻭﻥ ﺘﺭﺩﺩ ﺍﻝﺘﻭﺘﺭ ﺍﻝﺤﺎﻤل f pﺃﻜﺒﺭ ﺒﻜﺜﻴﺭ ﻤﻥ ﺘﺭﺩﺩ ﺍﻝﺘﻭﺘﺭ ﺍﻝﻤﺭﺍﺩ ﺘﻀﻤﻴﻨﻪ ) f mﻋﻠﻰ ﺍﻷﻗل .( f p > 10 f m
ﻓﻲ ﻫﺫﻩ ﺍﻝﺤﺎﻝﺔ ﻻ ﻨﺤﺼل ﻋﻠﻰ ﺸﺒﻪ ﺍﻝﻤﻨﺤﺭﻑ ﻋﻨﺩ ﺍﺴﺘﻌﻤﺎل ﺍﻝﺭﺯ XYﻝﺭﺍﺴﻡ ﺍﻝﺘﺫﺒﺫﺏ ،ﺒل ﻨﺤﺼل ﻋﻠﻰ ﺍﻝﺸﻜل
(Iﺇﺯﺍﻟﺔ ﺍﻟﺘﻀﻤﻴﻦ: ( (1ﻣﻔﻬﻮﻡ ﺇﺯﺍﻟﺔ ﺍﻟﺘﻀﻤﻴﻦ: ( 3
ﺍﻝﺘﺎﻝﻲ:
(2ﺘﻌﺭﻴﻑ ﺍﻝﻤﺭﺸﺢ: Filtres: – ﺍﻝﻤﺭﺸﺢ ﺍﻝﻤﻤﺭﺭ ﻝﻠﺘﺭﺩﺩﺍﺕ ﺍﻝﻌﺎﻝﻴﺔ ،ﻴﺴﻤﺢ ﺒﻤﺭﻭﺭ ﺍﻹﺸﺎﺭﺍﺕ ﺫﺍﺕ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻌﺎﻝﻴﺔ ،ﻭﻫﻭ ﻤﻜﻭﻥ ﻤﻥ ﺜﻨﺎﺌﻲ ﻗﻁﺏ RCﻋﻠﻰ ﺍﻝﺘﻭﺍﻝﻲ.
ﺍﻝﻤﺭﺸﺢ ﺍﻝﻤﻤﺭﺭ ﻝﻠﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﻨﺨﻔﻀﺔ ،ﻴﺴﻤﺢ ﺒﻤﺭﻭﺭ ﺍﻹﺸﺎﺭﺍﺕ ﺫﺍﺕ ﺍﻝﺘﺭﺩﺩﺍﺕ ﺍﻝﻤﻨﺨﻔﻀﺔ ،ﻭﻫﺫﺍ ﺍﻝﻨﻭﻉ ﻫﻭ ﺍﻝﺫﻱ ﻋﻠﻰ ﺴﻨﺴﺘﻌﻤﻠﻪﻹﺯﺍﻝﺔ ﺍﻝﻤﻭﺠﺔ ﺍﻝﺤﺎﻤﻠﺔ .ﻭﻫﻭ ﻤﻜﻭﻥ ﻤﻥ ﺜﻨﺎﺌﻲ ﻗﻁﺏRCﺍﻝﺘﻭﺍﺯﻱ.
ﺍﻝﺠﺯﺀ ﺍﻝﻤﺘﺒﻘﻰ ﻤﻥ ﺍﻝﺤﺎﻤﻠﺔ ،ﺘﺘﻡ ﺇﺯﺍﻝﺘﻪ ﺒﺎﺴﺘﻌﻤﺎل ﻜﺎﺸﻑ ﺍﻝﻐﻼﻑ. ﺒﺘﺠﻤﻴﻊ ﺼﻤﺎﻡ ﺜﻨﺎﺌﻲ ﻭﺜﻨﺎﺌﻲ ﻗﻁﺏ) RCﻋﻠﻰ ﺍﻝﺘﻭﺍﺯﻱ( ﻨﺤﺼل ﻋﻠﻰ ﻜﺎﺸﻑ ﺍﻝﻐﻼﻑ ﻭﻫﻭ ﺭﺒﺎﻋﻲ ﻗﻁﺏ.
ﺘﺒﻴﺎﻨﺔ ﺩﺍﺭﺓ ﻜﺎﺸﻑ ﺍﻝﻐﻼﻑ ﻤﻠﺤﻭﻅﺔ:ﻝﻠﺤﺼﻭل ﻋﻠﻰ ﻜﺸﻑ ﻏﻼﻑ ﺠﻴﺩ ﻴﻨﺒﻐﻲ ﺃﻥ ﺘﹸﺤﻘﻕ ﺜﺎﺒﺘﺔ ﺍﻝﺯﻤﻥ ﻝﺜﻨﺎﺌﻲ ﺍﻝﻘﻁﺏ RC :ﺍﻝﻤﺘﺭﺍﺠﺤﺔ ﺍﻝﺘﺎﻝﻴﺔ: : T pدور ا "*+ا)(" : Tmدور ا! رة ا' َـّ."# T p ≤ τ ≤ Tm 09إزا" ا '>? @A7 -/ف اآ;" ا ة ( - ، U o :+أ* ذ ( ) 0 2 3ددات ا+7 8/)9 ، "/0م ا5 D9 C 2زا" اآ;" ا ة ( . :+
Sbiro abdelkrim Lycée agricole oulad –taima région d’Agadir Maroc Mail :
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