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Hello, I am doing some prep for an exam. One of the past exam questions was:
state where the following would be used in the entertainment industry (TV, radio, music etc.)
1) 75 ohm coaxial cable
2) 50 ohm coaxial cable
3) 100 ohm unshielded twisted pair cable
I know 75 ohm coax would be used...
Hello, I am just trying to grasp a basic understanding of how technologies such as ATM, frame relay and T1 relate to each other.
For instance, which of the three is a physical layer protocol, and which one(s) run on top of the others ?
Or all they all independent i.e. you can choose one or the...
Hello, in order to solve the SWR for transmission line with:
1) forward measured power of -0.5dBm
2) reflected measured power of 1dBm
I want to use the formula:
SWR = 1+sqrt(Pr/Pf) / 1-sqrt(Pr/Pf)
My question is do I have to covert the measured powers out of decibels first i.ie.
-0.5dBm =...
Hello, thanks for posting that info which is very interesting, however I am still having problems.
I have since found out that the procedure required here is to use the formulas for:
1. propagation coefficient:
y=sqrt((R+jwL)(G+jwC))
and
2. formula for characteristic impedance:
Zo =...
Hello, I am trying to work out how to solve this problem.
I do not know what formula I can use to solve this problem.
If anyone can give me some help it would be much appreciated.
" If a transmission line operating at 250 MHz has a characteristic impedance Z0 of
50 Ohm and propagation...
Hello, I have taken the attached filter response graph of filter gain to frequency. My cutoff frequency is 1kHz.
How can I measure the roll off rate in db/Dec based on this graph ?
Any help would be appreciated.
Hello, I am trying to design components for this VCVS Butterworth LPF filter.
My question is regarding Ra and Rb (the feedback resistors)
I am using the formula (K-1)R by using the active filter table. My question are R1 and R2 supposed to be the same ohm value ?
thanks for any help.
Hello, I am approximating the bandwidth of an FM signal using Carson's rule.
I am finding that it is consistently less than the method of visually summing the frequency amounts between each significant sideband as viewed on a spectrum analyser.
Is there a particular reason for this ? Is it...
Hello I am doing some experiments with FM modulation.
I have an RF generator connected to a function generator and a spectrum analyser.
I have been adjusting the modulation index and measuring the amplitudes of the side frequencies.
My question is: why is there a discrepancy between my measured...
Hello, is it possible to measure the modulation index of a double sideband suppressed carrier (DSBSC) waveform ?
If so, do you just use the same formula as you would for an AM (carrier present) waveform i.e (B-A) / (B+A). Where B = max peak to peak and A= min peak to peak ?
Thanks for any help.
Hello, I am wondering what sort of visual differences you would see between an AM modulated waveform with carrier and a DSBSC waveform (suppressed carrier) in the time domain on an oscilloscope.
Any help would be appreciated.
Thanks, that covers why FM is placed where it is from a noise point of view.
So, is there any particular reason (from a noise point of view) why AM is placed at 521 to 1612 kHz ?
Thanks.
Hello, looking at the attached graph of noise voltage to frequency, I am trying to understand (from a noise point of view) why AM and FM broadcasts at the frequencies they do ?
Can anyone offer any suggestions please ?
n.b. ignore second attachment. It is incorrect.
Hello, I am analysing waveforms and their harmonics.
I did a lab experiment and need to comment on the "relationship of duty cycle and amplitude of the fundamental frequency".
I am struggling with this somewhat. Can someone please help me with that relationship ?
Thanks kindly for any help.
yes, here is it. Thanks for your help.
So, when I do the calculation for R3 as per my attached formula, I get a negative number. Obviously I cannot have a negative Ohm resistor, so how do I interpret this outcome ?
Thank you for any insight.
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