Questions tagged [propagation]
119 questions
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How is it possible to drive VGA displays at such high pixel clock frequencies?
I'm working on a digital circuit using discrete components to drive a 640x480 VGA display in a 80x30 text mode.
For a 640x480 display, the pixel clock is 25.175MHz, which has a period around 40ns. I don't understand how I'm supposed to be able…
supershirobon
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What does a chip's propagation delay vary on?
When looking up datasheets on logic gates, propagation delay is usually shown as a range. Sometimes there's a "typical" value in the middle, but there's a min and max listed. On what does the range vary?
Take this chip for…
AltF4
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8
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Why is propagation delay a function of supply voltage?
In the context of FPGAs, it was brought to my attention today that propagation delay varies with supply voltage. When I asked why this was so, one of the FPGA designers stated that a logic gate is essentially an amplifier (which I do agree with) and…
pr871
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Are there types of standard coaxial cable with a propagation velocity of 0.9c? What would be the application?
Reading this answer I was surprised to hear that there are "excellent" kinds of coaxial cable with a propagation speed of 0.9c; 90% the speed of light.
The bargain basement number is about 2/3c, and coaxial cable with a faster propagation velocity…
uhoh
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Why do EM waves with longer wavelengths propagate longer distances?
AM radio signals use carrier waves which are quite longer than in FM case. We know that in free space both high and low freq. RF signals should take the same distance in same period of time.
There must be a reason why in literature the longer EM…
user16307
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6
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4 answers
How does a logic gate behave with an input changing faster than its propagation delay?
I am attempting to create a simple logic circuit simulator. I am having a hard time figuring out how does a logic gate behave with an input changing faster than its propagation delay.
When attempting to connect a high frequency clock to an invertor…
David Porizek
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6
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8 answers
Nature of electromagnetic waves
We know that light is an electromagnetic wave. So is a radio frequency wave. From what I understand, the 50 Hz power frequency wave in our 230 V supply at home (60Hz and a lesser voltage in countries other than India) is also an electromagnetic…
Vishnudas Thaniel S
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5
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2 answers
How does modules in an asynchronous circuit know when to signal that their output is ready?
I have recently become fascinated by asynchronous CPUs, which have no central clock and each module instead sends a signal, when their data has been processed. However, I have been wondering how such modules actually know when their output is ready…
Sam Olesen
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4
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2 answers
Visualizing the propagation of signals in digital electronic circuits
I am currently studying Computer Science, and in my Digital Electronics course, I was taught the basic stuff required for computer design.
Also, I've recently started watching Ben Eater's videos on building a small computer on a breadboard, and I've…
Kushagr Jaiswal
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4
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What kind of modulation technique and carrier frequency is used for interplanetary communication such as between the Earth and Mars?
I have just come across this wind sound coming from pressure sensor of Insight lander which is in Mars at the moment.
I know basically that AM, FM, PSK, FSK ect. all have disadvantages and advantages depending on the bandwidth, terrain, distance…
user16307
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6 answers
Why does more bandwidth guarantee high bit rate?
The definition of bandwidth is frequency range and it seems to be correct to say that higher bandwidth guarantees higher data rate.
However, i do not understand why it does.
Data rate depends on modulation scheme and nowdays QAM, which is…
장영록
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4
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2 answers
Atmospheric attenuation calculation for a 1550nm link budget
My apologies in advance if this is the wrong place to ask this question. I was told that there were some RF communications experts here, so i figured there might be some FSO experience here as well.
Anyway, I am trying to put together a link budget…
user2387855
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4
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1 answer
How much is the propagation velocity affected by the characteristic impedance?
Someone posted the (very educational!) video Similiarities of Wave Behavior from 1959 in another answer, and after watching the part about impedance mismatches, it strikes me that the propagation velocity in the two sections with a different…
pipe
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How to interpret these antenna radiation patterns?
The datasheet for this chip antenna shows a couple of radiation plots, but I don't know how they correspond to the physical orientation of the antenna.
I want to orient the antenna so that the nice, omnidirectional "co-pol H-Plane" is parallel to…
bitsmack
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What phenomena does "Coherence Bandwidth" explain?
Could anyone please provide a simple explanation of what Coherence Bandwidth means, and how is that related to Delay Spread.
I read some articles but they don't help me to form the relation between the two concepts. I know that the Delay Spread is…
Kristof Tak
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