Questions tagged [telecommunication]

Use this tag for questions about communications technology and its applications.

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What is the best way to enhance an existing LTE signal on a mountain hut?

I'm traveling to a mountain hut in Austria every year which is in the middle of nowhere. If you're lucky you can sometimes get one bar and a weak Long-Term Evolution (LTE) or Edge connection for a few ...
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Attenuation along microstrip

I just wanted to know why signal attenuation decreases with length across a micro strip transmission line. Isn't it meant to decrease but experiments show otherwise.
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What are the differences between a standing wave ratio meter and a frequency counter?

Im having a hard time understanding what the differences are, I see things on google saying they are both at once and I am really confused.
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Differences between satellite dishes and Hertzian antennas

I have a text of notes for the electronics and telecommunication course, there is a section that talks about both the parabolic reflector antennas and the Hertzian antennas, in a test a question asked ...
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Faraday's law applied to a coil in an electromagnetic field

According to Faraday's law, we have the law: where "e" is the electromotive force which is equal to the derivative of the phase of the vector "b" through the surface s of the loop ...
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Does channel capacity depend on the valence of the signal to be transmitted?

Say I have a channel with bandwidth W and I want to send data at a rate Rb. Do my SNR requirements vary if I use binary, quaternary, 8-ary or 16-ary signalling scheme? For example let's say I have a ...
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3 answers
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Rotary Phones vs Pushbutton -- why did we ever have rotary?

I remember when we first got pushbutton phones -- I would say user experience is literally ten times better -- if you used a rotary phone extensively as part of your job, you would rapidly develop a ...
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How can a screen be projected on a transparent glass?

I am building something similar to Google Glasses although not exactly that. I am trying to find a way to project my 0.96inch OLED on a glass, but it can't block the front view. What I tried to do is ...
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Is it possible to assign several MSISDNs to a single IMSI in a GSM network?

Recently I've read a book on GSM standards and it stated that it was possible to assign an imsi with several MSISDNs. I made some googling and found out that there is a technology called SIMM — single ...
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2 answers
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Demodulation of AM signals in radio broadcast systems

I have a question regarding the demodulation of AM signals in radio systems (like car radio). I know that in order to send the audio signal from the broadcasting station to users we need first to AM ...
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2 votes
1 answer
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Does anybody know what this symbol is?

The last couple of weeks, I've been noticing this (wifi like) symbol next to some of my contacts in my Android phone. The symbol I am interested about is in the red circle that has the outline of the ...
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Double Stub Matching Impedance

I'm trying to understand the double stub matching impedance using Smith Chart. Here is the diagram for the double stub impedance: The impedance on the right has to appear purely resistive. So ...
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Calculate the temperature stability of wavelength demultiplexer

Hi ive been given this question: A wavelength demultiplexer (DMUX) used in a DWDM communication system has a channel spacing of 100 GHz. The operating pass band of each channel is 50 GHz. The ...
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Choosing a Project

Sorry if there’s any spelling mistake... I don't know if this is the proper place to ask, but I guess if it isn't, I'll get notified. Anyway, if it isn't, I apologize. I’m a telecommunications ...
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How to make a wireless modem using a normal Wi-Fi router and a 4g usb modem

I have a normal TP link (Model: TL-WR841N) router and an USB 4g modem. But the WIFI router does not have any USB port. I want to connect the USB modem with the router, want to share internet ...
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Ethernet extender kit claims to send data through power cables - Is this correct?

I own an ethernet extender kit which has two devices connected to mains. Its data sheet claims that the device "your homes electrical wiring to extend your broadband network anywhere in the house&...
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When recording VHS tapes from analogue TV back in the day, was the "Teletext" data also recorded?

Ever since I was a kid in the 1990s, I've been wondering about this. I have never been able to verify/test it in a conclusive manner. It may be almost forgotten now, but in those days, each TV channel ...
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Mesh Wifi Router Network for a Small Village

I was wondering if its possible to create mesh network of WiFi for relatively large area? I am talking about the size of small village (~20km2). The idea is to use centralized connectivity with enough ...
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Why radio communication was limited to military use and did not become popular with general public like cell phones have become today? [closed]

Why did no private company or government try to bring radio communications to general public like we have cell phone today? What were the hurdles and challenges?
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How were the tones for DTMF chosen?

In my limited engineering knowledge, and limited research skills, I couldn't find a complete answer for the reasoning behind the chosen tones for DTMF. I did find a hint that said something about ...
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Monitoring Connectivity on ZigBee

I am trying to figure out some ways in which a ZigBee network can be monitored. As is the case in any network, here we have a central coordinator and several slaves joined, however, there seems to be ...
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2 votes
3 answers
192 views

Bandwidth vs Capacity

Two questions on wireless transmission, packed into one. First: I am confused about the meaning of the term 'Bandwidth' in a wireless transmission environment. The two most common definitions I could ...
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1 answer
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How progressive scan televisions works in depth?

I'm trying to understand in depth the behavior of progressive scan TV monitors (LCD/LED - Digital Television). From what we already know, the tv's screen scans the image row by row (as rolling shutter ...
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With the "plain old telephone system", would two neighbors be able to call each other privately?

Suppose that Joe and Sue are neighbors out on the country. The year is 1950. But it could also be 1975. Or even 1999. Even though they live next to each other, and can see each other through the ...
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1 answer
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How is it possible that an *undertaker* invented the automatic telephone exchange? And as early as in 1888?

Strowger, an undertaker, was motivated to invent an automatic telephone exchange after having difficulties with the local telephone operators, one of whom was the wife of a competitor. He was said ...
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3 answers
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Would not a telephone call (from the late 1950s) auto-disconnect if one of the parties "closes the handle"?

In the Alfred Hitchcock Presents episode "Togeather", S03E15, at 17:17, you see a drunk man leaving a telephone without putting it on its handle, with the person he was talking to begging him to "...
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how to implement an encoder in matlab

How can I encode a quantized vector in matlab ? This is a part of a problem where I am asked to implement a communication block using matlab.
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1 answer
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Fourier serie signal approximation

I have to approximate the red function with Fourier harmonics. I am calculating complex Ck the following way. I am not sure what to put for period - T (6 or 2pi or what?). What integral limits to ...
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LTE to 3G IRAT Handrover: What happens afterward

Let's say that there has been a handover from LTE to 3G of a particular UE. Once the handover is complete, the MME is no longer required to maintain the sessions/bearers that has been established for ...
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Electronic symboles in datasheets

I found these symbols in a electronic datasheet.. Are these all logic gates? or another?
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Is it better ASTRA 19.2°E or 28°, in central continental europe?

I'm trying to tune my satellite receiver, particularly to receive the signals of the Astra satellites, which are ASTRA 19.2E and ASTRA 2 at 28º East. Looking at the picture the signal from ASTRA 28 ...
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Spectral Efficiency of FDD, TDD, and FD

I would like to show at high level that, in principle, the spectral efficiency (SE) of frequency division duplex (FDD) equals the SE of time division duplex (TDD) and both of them are half the SE of ...
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Non Orthogonal Multiple Acess and Channel Quality Indicator

As we know in a 4G network, the LTE give us a correlation about the SNR of user and the data rate of the user. This correlation is usually a table called Channel Quality Indicator (CQI) which is found ...
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Mobile Frequency and Carrier Frequency not Matching

I am using a Google Nexus 6 Mobile in India with Airtel as Network Provider. Recently Airtel has upgraded their Network to 2300 Mhz 4G. Whereas Google Nexus 6 Operates on Band 3 (1800Mhz) LTE. When ...
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2 votes
1 answer
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What is the purpose of colour code for telephone wires?

I'm trying to understand how telephone wires work. I've stumbled upon this kind of identification method with colours. I can't manage to understand the reasons why is used and if it's still common to ...
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1 vote
1 answer
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Material to absorb very low frequency radio

Is there any material that will absorb very low frequency radio light? I know that stealth aircraft use radar absorbant materials in their design that absorb radio light best at certain frequencies, ...
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1 vote
1 answer
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why can't remove the Image frequency using a band-pass filter?

why can't remove the Image frequency using a band-pass filter? I've been asked to search for the reason why we can't use BPF (band-pass filter) in order to remove the effects of the Image frequency? I'...
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2 votes
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Negative transmit power in dBm

I am calculating the transmit power for $K$ single antenna IoT devices in an Indoor scenario. The receiver has 64 antennas. I am trying to minimize the transmit sum-power, i.e., $\sum_k p_k$, where $...
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1 vote
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Modeling of a Wireless Channel with known BER

I have to model through software a wireless (my choice: 3g,4g, 802.11...) channel with given Bit Error Rate. I'm searching some distributions, I'm reading tons of papers but I can't find how to ...
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ADSL near end crosstalk (NEXT)

During a lecture my teacher told me that the UPSTREAM in ADSL is very much affected from near end crosstalk due to DOWNSTREAM, while DOWNSTREAM is not affected by this phenomena. This lead to the ...
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1 vote
1 answer
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What is tonal masking?

I have checked the definition of tonal masking on Wikipedia and google but I saw the definition of sound masking and auditory masking. Auditory masking Sound masking But I want to know what ...
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2 votes
1 answer
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Propagation loss in USRP antenna

Problem I have two USRP antennas close to each other. I know that signal strength on the receiving end has to be at least -80 dBm. Both antennas have 2 dBi of gain. I want to compute what ...
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Tethered Balloons vs Towers for Wireless Communication

If we use tethered balloons (aerostats) with wireless gateways fitted on them (let's say for Cellular or LPWAN communication), they can provide much more coverage owing to the height they can reach (e....
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What are the strengths and limitations of the antenna design of the Montjuïc Communications Tower?

The Montjuïc antenna is an interesting design for an antenna. I presume the design is principally an antenna, but perhaps it is not? If the ring + mast is an antenna, how does the ring work to ...
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-2 votes
1 answer
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Why is Morse code used in satellite communication compared to ASCII encoding

My knowledge about methods of transmission of data is limited, but I believe that communication between transmitters and receivers often uses Morse code to send information. If say, a satellite ...
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How EnB will inform to UE about incoming call in RRC connected state in LTE?

Generally if UE is in RRC Idle state, ENB will inform to ...
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1 vote
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A radar that is not an OTH detection distance

Let's say that we have a radar that is not an OTH on a boat, and it is placed 30 meters above the ground. Is there a way for it to detect an offshore platform 152 kilometers away from it, since the ...
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How can the Microsoft and the Facebook Fibers reach 160 Tbps between Virginia and Bilbao?

According to this article, Microsoft and Facebook have completed a 160 terabits cross-Atlantic cable. Based on my calculations, this doesn't seem probable, so what did I miss in my calculation? The ...
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1 vote
2 answers
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How do I get data from my Hardware to server or so? [closed]

Brief I am actually of 17 not even in college but I have dream for making my project/dream/aspiration/or So to come true so I am thinking of making a device that performs a function say like ...
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Can a casio fx series do this operation?

"Calculators stackexchange" doesn't exist, so I guessed this would be the right place to ask. Can a calculator solve $-0.2 \cdot e^{-0.06-4.2i}$? Or any $e$ to a complex for that matter. I've been ...
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