Electronics and Communication Engineering - Radio Receivers - Discussion
Discussion Forum : Radio Receivers - Section 1 (Q.No. 29)
29.
In a broadcast superheterodynes receiver having no RF amplifier, the loaded Q of the antenna coupling circuit is 100. If the intermediate frequency is 455 kHz. The rejection ratio at 25 MHz will be
Discussion:
10 comments Page 1 of 1.
Manu said:
10 years ago
Explain please!
Moon said:
9 years ago
Please explain how.
JAM said:
9 years ago
Kindly explain it.
Venkat said:
9 years ago
Please explain it.
Ram charan said:
9 years ago
F (i.f.) =455khz,
f = 25Mhz, Q = 10 here
f(s.i) means imaginary frequence.
Rejection ratio = sqrt (1+Q^2P^2).
Here P = (f(s.i)/f - f(s)/f(s.i)).
F(s.i) = f + 2f(i.f).
= 25000+2 * 455.
F(s.i) = 25910.
P= {(25910/25000) - (25000/25910)}.
= .0716.
Rejection ratio = sqrt(1+Q^2P^2).
Total solve R.r.=1.116 approx.
f = 25Mhz, Q = 10 here
f(s.i) means imaginary frequence.
Rejection ratio = sqrt (1+Q^2P^2).
Here P = (f(s.i)/f - f(s)/f(s.i)).
F(s.i) = f + 2f(i.f).
= 25000+2 * 455.
F(s.i) = 25910.
P= {(25910/25000) - (25000/25910)}.
= .0716.
Rejection ratio = sqrt(1+Q^2P^2).
Total solve R.r.=1.116 approx.
Rishi Ram Sharma said:
8 years ago
No,
If Q=100 than Rejection Ratio at 25 MHZ should be near 7.22.
Because of R. R = Sqrt(1+Q^2*P^2).
Where P is same as Ram Charan Calculated.
If Q=10 than Rejection Ratio at 25 MHZ should be near 1.226.
Because of R. R=Sqrt(1+Q^2*P^2).
Where P is same as Ram Charan Calculated.
If Q=100 than Rejection Ratio at 25 MHZ should be near 7.22.
Because of R. R = Sqrt(1+Q^2*P^2).
Where P is same as Ram Charan Calculated.
If Q=10 than Rejection Ratio at 25 MHZ should be near 1.226.
Because of R. R=Sqrt(1+Q^2*P^2).
Where P is same as Ram Charan Calculated.
Jay said:
7 years ago
Yes, I agree with you @Rishi Ram.
EBENEZER said:
7 years ago
It should be 7.22.
RAHUL KUMAR said:
5 years ago
Yes, you are correct @Rishi Ram Sharma.
Ashutosh Kumar said:
3 years ago
fsi = fs+2IF.
fsi = 25*2*0.455,
fsi = 25.91MHz.
Ï=fsi/fs - fs/fsi.
Ï= 25.91/25 - 25/25.91,
Ï= 0.0715.
α= √1+(100)^2+(0.0715)^2.
α= √1+10000+0.0051,
α= √52,
α= 7.22.
fsi = 25*2*0.455,
fsi = 25.91MHz.
Ï=fsi/fs - fs/fsi.
Ï= 25.91/25 - 25/25.91,
Ï= 0.0715.
α= √1+(100)^2+(0.0715)^2.
α= √1+10000+0.0051,
α= √52,
α= 7.22.
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