Questions tagged [transmission]

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30
votes
3answers
11k views

Why 3 phase and not 1 phase power transmission?

Why does power transmission use three lines with three different phases? Why not three lines all in the same phase? Does it have to do with the alternators used for generating the power, or is there ...
19
votes
10answers
5k views

Is there any way to use half-bits?

As most people here know, by using 4 bits, we are able to count from 0 to 15 (0123456789ABCDEF in hexadecimal). But if we were to only count up to 9, we would still be using 4 bits, and the digits ...
16
votes
10answers
5k views

Schematics for a simple radio transmitter that can be built only with passive components?

Fantasized in some of the survivalist, post-catastrophic novels, movies or docudramas is the radio built only with handcrafted or scraped components. Beyond the popular appeal of this stories, I ...
15
votes
10answers
37k views

Why are there only 3 wires on this power line?

When I was in Alaska, I saw a high voltage line, but I didn't see the Neutral. Is this because the water is conductive enough next to it to use as neutral? Or is it just two Phases. Where I live, ...
15
votes
3answers
890 views

Are different houses out of phase?

It's hard to see but on the overhead power lines, houses seem to only be grabbing one phase of the 3-wire transmission line. If each house is using a separate phase, what makes the 3-phase system an ...
13
votes
6answers
3k views

Simulate bad cell phone reception in the lab

I'm currently developing an internet of things device that utilizes a uBlox SARA-U260 gsm/3G modem. In field testing, we have had significant software/firmware issues due to poor cell phone reception ...
11
votes
2answers
23k views

How does a signal travel down a telephone wire?

Supposing a computer gets data over telephone wire, it has to send/recieve signals, but how do things work? Does it use analog signal or a digital bits? How does it send/recieve "1"s and "0"s?
9
votes
3answers
9k views

Why does more bandwidth mean higher bit rate in digital transmission?

I understand that similar questions like this one have been asked before on this site, listed below. However, I am confused about the answers. If I explain what I think I understand, can somebody ...
8
votes
4answers
2k views

How can a low efficiency antenna be used for receiving but not for transmitting?

For the reciprocity theorem, if an antenna has a low efficiency in transmission, it has the same efficiency when receiving. In literature, it is usually said that one shouldn't use a low-efficiency ...
7
votes
2answers
7k views

Why is it desirable to inject reactive power into a transmission system?

This website explains the basics of FACTS technologies and how they can be used to exchange active and reactive power with the transmission system, namely: SSSCs - can exchange active and reactive ...
7
votes
3answers
2k views

Why does the ionosphere reflect HF but allow VHF signals to penetrate through?

Wikipedia says: ... Unlike high frequencies (HF), the ionosphere does not usually reflect VHF waves (called skywave propagation) so transmissions are restricted to the local radio horizon less ...
6
votes
1answer
10k views

wireless transmission underwater

I am looking into constructing a closed and small device with arduino sensors that goes underwater. It has to be submerged into water and back several times, and that is made by someone with a rope ...
5
votes
2answers
3k views

Coaxial cable vs shielded pair

I need to wire a sensor with analog output to an acquisition system, and the presence of a separate "shield" connection on the DAQ made me thinking: why would I use a shielded 2-wire cable versus a ...
5
votes
2answers
2k views

How do I program 2 CAN nodes to transmit continuously in succession?

Suppose I have three CAN nodes: A, B and C. We know that when two nodes transmit at the same time, the node that has the least SID will prevail over the bus and the other node will have to give the ...
5
votes
3answers
3k views

How do utilities calculate transmission lines impedance?

I'm an electrical engineering student getting into Transmission Circuit Analysis, and a question came out to me: How do utilities measure their transmission lines impedance? Do they use special ...
5
votes
1answer
651 views

Underground cables and resonances in range of frequencies

Is that true that underground cables with no power factor correction have resonances in range of frequencies which leads to multiple zero crossing distorted waveform? But why? Is that is because it ...
4
votes
3answers
2k views

Coaxial cable theory

Well I was learning transmission but I got a bit confused when I came to coaxial cables transmission at radio frequency. What I am lost is how the waves are propagating in the cable, I was thinking ...
4
votes
6answers
2k views

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 ...
4
votes
2answers
11k views

How are multiple signals propagated in a coaxial cable?

I am reading that coaxial cables can carry hundreds of MHz signals at How Stuff Works. How are these signals propagated and how are they deconstructed once they reach their destination? One idea that ...
4
votes
2answers
174 views

Y/Y/Δ or Δ/Y/Δ transformer for a series connected 12-pulse rectifier?

I'm aware that 30° shift is needed in order to obtain a 12-pulse rectification, however, I'm a bit confused about the configuration of these transformer. In most HVDC systems that appear in Alstom - ...
3
votes
3answers
906 views

What would cause a square wave to become rounded?

I have a square wave going through a thousand feet of cable. The cable has \$120 \,\Omega\$ characteristic impedance. I measured the capacitance and inductance of the cable and they are pretty close ...
3
votes
3answers
290 views

Is the impedance control of differential pair traces a transmission line problem?

I read in an article of design reference that "If the length of the interconnect PCB is greater than 1/10 th of the wavelength, we should consider using the transmission line instead of ordinary ...
3
votes
1answer
49k views

Difference between instantaneous, definite time and inverse time over current protection relays

Protection coordination is very important in transmission and distribution power networks. One of the most widely used and important protection relays are over current protection relays. What is the ...
3
votes
1answer
98 views

how will a connector affect a transmission line?

I am laying out an RS485 driver and read a few design guides which recommend a 120 Ohm termination resistor. This makes sense since the characteristic impedance of twisted pair cables is in the 100 ...
3
votes
1answer
1k views

Power loss during transmission

I have no background of electrical engineering so if my question sounds stupid then accept my apology in advance. I want to calculate the power loss during the transmission. I am using the simple ...
3
votes
1answer
2k views

SMPS design, requirement of generating High Frequency

Question: Is that requirement of converting 50Hz to a higher frequency in SMPS (Switched Mode Power Supply) is just to reduce the transformer/inductor core size? Background: Since as we all know ...
3
votes
2answers
713 views

Quarter Wavelength Matching : Missing Reflections?

With regards to the quarter wavelength impedance matcher, I understand it is used to correct a mismatch and looks as follows where \$ Z_T \$ is the matching line: I understand that we have set up the ...
3
votes
1answer
1k views

How to measure radio signal strength

I am building several types of radio antennas, and I would like to test which is the most effective. I am wondering: What is the best way to measure the strength of the received signal? It is at ~...
3
votes
1answer
1k views

How can I replace this inductor with a transmission line?

I'm new in transmission line theory, hope you can help me. I have this circuit: And I have the admittance; Yin=(1-j) x10^-3 [S] and its frequency f=100 [MHz]. What I need its first to find the ...
2
votes
4answers
1k views

Single motor driving multiple targets - possible?

I'm a veteran programmer new to the electro/mechanical world and unfamiliar with the terminology and what's already available. I have a single motor that I would like to use to drive a carousel or an ...
2
votes
2answers
85 views

Transmitting digital signal long distances, without complex parts

I'm controlling several multiplexers from NI DO modules. The multiplexers channel select inputs, A0-A4, are 5v. The DO modules output 5v TTL. On the bench I have everything working exactly the way ...
2
votes
2answers
2k views

Jerk in Power plants due to breakdown of transmission line

I read in news paper "heavy jerk in power plant due to breakdown in transmission line" what does it mean why does it happen?
2
votes
1answer
135 views

How to transmit analog signals over cable?

In my current project, I need to transmit 4 analog signals (A1, A2, A3 and A4) on a cable from one PCB to another. I am working at 3 VDC and the distance between them is relatively short (< 30 cm). ...
2
votes
2answers
2k views

EIRP and Radiated Field Strength

I have a question regarding Field Strength: I was told it is independent from the frequency, is that true? If so, why? Moreover, I came accross this equation for converting the Field Strength to ...
2
votes
2answers
100 views

Transmitting data in a house which strongly attenuates RF signals

Is there a way to transmit data throughout my house without RF? My application: I want to spread sensors and actuators in my home. Due to the nature of these things I do not need high data rates, a ...
2
votes
1answer
3k views

Wireless power transmission calculations

I have been able to calculate and fix components for the transmitter circuit of wireless power transmission system but I am still having some challenges. They are: 1. How can I calculate theoretically ...
2
votes
2answers
400 views

Characteristic impedance of a transmission line

characteristic impedance of a transmission line depends on frequency of transmission as can be seen by its expression. What will be the characteristic impedance of TL if my signal has two frequency ...
2
votes
2answers
832 views

Capacitance and Inductance properties of coaxial transmission lines

I'm interested to understand what affect the capacitance (between cable core and shielding) and the inductance have on a signal transmitting down a coaxial cable.
2
votes
1answer
139 views

Differential pairs or single ended signals for 1m cable

I have one control board and 3 additional boards for the power electronics, that send and receive data from the control board over a distance of ~1m (3ft). All signals are single ended. I have to ...
2
votes
1answer
58 views

Edge betweenness centralities for distribution grids [closed]

Graph centralities like edge betweenness centralities are commonly used to study the vulnerability in transmission networks, can they equally be used to study radial distribution networks ?
2
votes
0answers
395 views

Parallel transmission lines impedance

I just want to know the correct way to calculate \$Z_{in}\$ in this network. It's very simple but I think I might be doing something wrong. Is it ok to calculate the impedance over one line and get \$...
1
vote
4answers
137 views

Voltage transmission

For the sake of understanding, I shall refer to voltage as a "pushing force that causes electrons to move and hence generate current." Now, I know that this force is "built up" and does not flow(...
1
vote
1answer
374 views

Activate relays by different voltages

I want to make an auto transmission circuit using a magnetic pickup sensor with output 0-3.5 AC Volts. My device has 3 gears (1, 2, 3) and the one that's activated depends on sensors output. For ...
1
vote
1answer
47 views

From how wide a range of angles can a grid of dipole antennas efficiently receive a power beam?

This paper on solar power satellite concepts makes brief reference to the ground receiver receiving an elliptical beam due to the angle it is at to the transmitter (2nd paragraph). The angle isn't ...
1
vote
2answers
696 views

Sending analog signal over twisted pair in noisy enviroment

I need to transmit several analog signals from one board to another (maximum 1m distance) in a very noisy environment (power electronics converter operating at 20kHz). The range of frequencies of the ...
1
vote
2answers
2k views

Length of Transmission Line & Characteristic Impedance

Just a simple Question for clarification: Does the physical length of transmission line affect its impedance? We all understand that the height of dielectric (space between line and ground) affects ...
1
vote
4answers
469 views

Transmission Line Question

I have a question concerning reflections due to impedance mismatching. Now, assuming a lossless TL, the latter is modelled by sections of lumped L-C segments where L in a series (sub)element of the ...
1
vote
1answer
714 views

Transmission line, cable impedance

I am currently doing a design where I basically have two different types of (digital) signals. The first signal group is fully differential (P/N pair). The other group are single ended signals ...
1
vote
1answer
854 views

Satellite uplink/downlink frequencies

Sorry if this was asked before. I was unable to find such a question elsewhere in SE. Why does space-wave communication (ie/ satellites) utilize different ground-station (GS1) broadcast and satellite ...
1
vote
1answer
131 views

How to transmit CAN signals wirelessly without line of sight (LOS)

I have a scenario where I have an OBD-II interface transmitting data via CAN across six wires to a display. I will have power on either side of the wires, but I cannot assume that the wires will have ...