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Questions tagged [telecommunication]

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

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0answers
16 views

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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0answers
18 views

connection of 2G cell towers and support for 2.5G and 2.75G

I have read here: https://en.wikipedia.org/wiki/2G#Past_2G_networks that 2G will be superseded. But doesn't it mean that 2.5G and 2.75G will also be superseded given that 2G is the base? I suppose ...
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1answer
44 views

Electronic symboles in datasheets

I found these symbols in a electronic datasheet.. Are these all logic gates? or another?
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0answers
25 views

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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0answers
16 views

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 ...
2
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0answers
37 views

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 ...
2
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0answers
23 views

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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1answer
47 views

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 ...
1
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1answer
55 views

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, ...
1
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1answer
24 views

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'...
2
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0answers
58 views

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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0answers
16 views

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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24 views

Communications Question: Resource block parameters?

I am modelling a network using MILP/AMPL; in this network there are a multitude of UEs and 16 basestations (BS) (4 macro cells, 12 small cells). Each BS has resource blocks (RB) consisting of 12 ...
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1answer
28 views

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 ...
1
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1answer
47 views

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 ...
2
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1answer
34 views

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 ...
1
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1answer
51 views

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....
1
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0answers
45 views

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 ...
-2
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1answer
119 views

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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0answers
31 views

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 ...
1
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1answer
39 views

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 ...
2
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0answers
44 views

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 ...
1
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2answers
82 views

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 ...
1
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0answers
55 views

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 ...
2
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2answers
3k views

Why downlink frequency is greater than uplink frequency in mobile communications?

Generally, downlink freq. > uplink freq. in mobile communications. I was able to gather some answers as to why is so. But my seniors (in my company) seem not to be satisfied with the below answers. ...
1
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1answer
36 views

Why only the spectrum range of radio waves can be reflected from atmospheric layers while higher ranges (Infrared-Visible Light-Ultraviolet) can't?

From communication prospective why can't higher frequency ranges be reflected from atmospheric layers and what is the effect of parameters (like temperature, pressure, etc) of the atmospheric layer on ...
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2answers
249 views

Why does India have more than 1 MCC (Mobile Country Code)? [closed]

I was checking the list of MCC (Mobile Country Codes) on Wikipedia and found that India has two MCC: 404 and 405. 404 contains only GSM/UMTS/LTE operator bands and 405 contains both GSM/UMTS/LTE and ...
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0answers
28 views

How does the demapping/demultiplexing of transport channels to logical channels work?

I am trying to model WCDMA MAC, but I cannot figure out how to demultiplex HS-DSCH unto DCCH, DTCH. Also, since I am using E-DCH/HS-DSCH transport channel scheme, how does the data of DCCH and DTCH ...
-1
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1answer
37 views

Sending SMS using car horn [closed]

If you've been watching Bones series, there is an episode in which Bones and Hodgins were trapped beneath the ground, and they managed to send an SMS by wiring the phone to the car honk. Is this ...
0
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1answer
89 views

How does 4G know the reception of a voice call?

I know that the 4G network is only for data and doesn't support voice calls. Most of phones switch to 2G/3G when receiving a voice call. But my problem is how does the phone gets to know about the ...
3
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0answers
93 views

How does a cable-laying ship retrieve a partly-laid cable?

I was reading an article in the press this week about a project to lay an undersea cable across the Tasman Sea. The ship had had to return to port for repairs and return to complete the job later. ...
2
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1answer
117 views

Why is WiFi increasing frequency?

WiFi at 60 GHz provides a theoretical data-rate of 7 Gbit/s. The trade-off is limited range and penetration. The main reason for this awesome data-rate is a 9 GHz bandwidth, from 66 GHz to 57 GHz. I ...
2
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1answer
246 views

A 40MHz oscillator in usb wifi adapter

I disassembled a usb wifi adapter. I was surprised to see a 40MHz oscillator, when wifi works at 2.4GHz. How the output of the oscillator is scaled to the required frequency?
5
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1answer
1k views

Why do bluetooth headsets get interference (choppy sound quality) outdoors?

This is more of a general physics question to help me understand how to choose sports headsets in the future, however it is too specific to a certain use case (bluetooth headset) to belong in the ...
0
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2answers
93 views

How can I make a GPS traceable microchip? [closed]

I am looking for making a chip or a microchip, which can be traced with the help of the satellites. Means it is merely a chip and when I tune my satellite to a particular frequency I would get to know ...
8
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1answer
3k views

What is the difference between Bluetooth Low Energy and Bluetooth BR/EDR in Park mode?

It is known that Bluetooth Low Energy transmits data only during short time intervals called Connection Events. Connection events occur regullary with predefined period. The rest of the time Bluetooth ...
2
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0answers
51 views

Effect of bad weather on P2P Communication or Broadcasting?

I stop receiving TV signals whenever their is cloud cover outside. On the other hand I have never had any such problems with my internet connection or GPS system. I cannot understand why and how often ...
2
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3answers
194 views

Why not only GSM (3G/4G/..)? Why do we need Bluetooth, Wifi,etc…?

It is quite frustrating to have multiple adapter for connecting to desktop. For example, if I want to connect my phone to desktop I need Bluetooth/wifi; why can't I just just use the Mobile's main ...
3
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0answers
128 views

How is modulated the Primary Synchronization Signal in LTE?

PSS is based on 62 values from a Zadoff-Chu sequence. Three different sequences can be used by an LTE Cell, to represent the Physical Cell ID within the Cell ID group. The formula is the following, $...
1
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1answer
60 views

Will the water in a gold fish bowl signficantly abosorb Bluetooth or WiFi if transciever is at bottom of bowl?

Using WiFi or bluetooth frequencies 5.8GHz and 2.4-2.485GHz respectively, I want to place a hermetically sealed circuit at the bottom of a gold fish bowl, and want to know if the water will ...
3
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0answers
42 views

What is PSS waveform formula?

I want to know how is exactly modulated a LTE subcarrier. Since I'm working on Synchronization Signals (P-SS, S-SS) the subcarriers I'm talking about are centered around DC. I have coded the ...
2
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1answer
105 views

Why is Li-Fi faster than regular wifi?

I was wondering, basicly every radio-transsmission works with electromagnetic waves which travels at the same speed whether I modulate the information with a low frequency or high frequency such as ...
3
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0answers
107 views

FM transmission exercise

I'm encountering some troubles while trying to solve this exercise. Let us consider a radio link between a geostationary satellite and a ground station. We send a binary signal (represented by two ...
6
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0answers
513 views

How does LTE eNodeB set the Base Station output power?

I'm interested into the power radiated out of an eNodeB (LTE/4G) radio base station: which parameters does this power depend on, if they are constant or relying on the environment... All of this in ...
4
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0answers
154 views

LTE channel characterization from Time Domain waveform

I am currently interested into the diverse Downlink LTE channels broadcasted over air after some (QPSK, 16QAM...) modulation. More precisely their waveform. I would like to know if, with a good ...
2
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1answer
40 views

What is the thinnest possible depth of any given material required to display an image? [closed]

I am interested in creating a screen to display moving images (similar to moving desktop background), however I am looking for the thinnest possible material available i can use as the screen to ...
2
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1answer
172 views

Hilbert transform LTI

I'm studying the Hilbert transform and its properties. I found out that Hilbert transform can be considered as a linear time-invariant system. How can I show this? I guess this should be trivial as ...
0
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1answer
470 views

How far can my FM transmitter signal reach?

I have a working FM transmitter on a raspberry pi2. I'm running my FM raido at 103.3MHz, and the antenna that I connected to the GPIO4 is a 70cm copper wire. More data:(checked with a multimeter ...
0
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1answer
92 views

how to calculate the time for retransmission in slotted Aloha

I need to configure my code to make retransmission in slotted Aloha in case of collision, how to choose the timer ?
2
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1answer
82 views

How does a carrier signal work from a receiver's perspective?

for example : Sender: A cellular signal tower(Base Station(BS)) sends data(voice, GPRS, VOIP) to the cellphone. The sender will obviously have the carrier frequency and more power(voltage+current) to ...