Post subject: RF question
Unread postPosted: Sat Apr 02,
2005 12:42 pm
A television receiver tuned to a channel at 220
MHz comprises a front end
amplifier (G = 18 dB, F = 2.5 dB), mixer
(G = 16 dB, F = 12 dB) and IF
amplifier (F = 2 dB, Bn = 6 MHz). It
is connected to an antenna of gain 6 dB
via 15m of 300 ohm ribbon
lead with an attenuation of 0.12 dB/m. Calculate
(a) The noise figure
of the receiver.
(b) The signal (in mV) at the antenna terminals
required to produce an
output signal to noise ratio of 40 dB for
(i) a suburban area, (i) a
quiet semi-rural area.
(c) The corresponding
electric field strength in the neighbourhood of
The improvement in S/N (for both cases (i) and (ii) above) which
would result from
- replacing the ribbon cable with a polyfoam cable,
- leaving the cable the same, but fitting
another antenna with a
gain of 10 dB
- leaving the cable and antenna
as originally and fitting a masthead
amplifier with F = 2 dB and
G = 20 dB.
Assume in each case that the signal field strength is
Anyone gives some hints for solving this question
thanks in advance.
Unread postPosted: Sat Apr 02, 2005 9:20 pm
Most tutors that
help you with college homework problems get paid. What are you offering?
Sun Apr 03, 2005 3:02 am
Do I have to show my work?
Unread postPosted: Wed
May 18, 2005 10:07 pm
Start with the cascaded Noise Factor calculation...
Ftotal = 1 + F1 + F2/G1 + F3/(G1*G2) + F4/(G1*G2*G3) + ...