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Questions tagged [telecommunication]

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

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0answers
20 views

Why are Erlang B and Erlang C formulas different? [closed]

Erlang B determines the probability that a call is blocked and is defined as: $$Pr[blocking]= {{A^C \over C!} \over {\sum_{k = 0}^{C} {A^k \over k!}}}$$ while Erlang C determines the probability ...
-2
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1answer
47 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 ...
0
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0answers
9 views

During the GSM call flow when is the audio channel established?

I will like to know concretely when and how is the audio channel established to asses if it is possible that an eavesdropper can hear audio while the phone is ringing.
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0answers
13 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
35 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 ...
0
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0answers
20 views

Cosine Sum Identity vs In phase and Quadrature

I've come across a problem with my understanding of phasors it seems. I keep getting two different answers for $\cos(A+B)$. The first method just uses a trig identity and the second with a phasor ...
1
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2answers
52 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 ...
0
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0answers
10 views

Can dispersed in time radio signal be “assembled” together, to make it stronger and more efficient?

When the signal is transmitted, then aside of signal that gets directly to the receiver antenna, it propagates through many different stuff around. It scatters and depending on frequency it can be ...
1
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0answers
53 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 ...
0
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1answer
1k 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
35 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 ...
0
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2answers
118 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
19 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
36 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
72 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 ...
4
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0answers
82 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. ...
3
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1answer
108 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
159 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
606 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
81 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 ...
9
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1answer
2k 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
48 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
184 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
112 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, $...
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1answer
56 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
40 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
97 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
104 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 ...
7
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0answers
390 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
133 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
37 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
149 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
394 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
52 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 ?
0
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0answers
80 views

What is the carried load in pure aloha throughput equation

I made an enhancement on aloha protocol and I succeeded to decrease the total number of collided frames among the simulation time. Now, I need to calculate throughput to see if the number of ...
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 ...
3
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1answer
730 views

signal-to-interference-plus-noise ratio (SINR) and others calculation

I am considering some empirical signal propagation models (like Hata, Ericsson models) to calculate 4 parameters: Path loss Received Signal Strength (RSS) signal-to-interference-plus-noise ratio ...
0
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1answer
27 views

Could a one sensor node in a cluster sense a data more the others?

I want to know if the sensor nodes in any cluster in a wireless sensor network may detect events in a different ratio i.e.some nodes could detect events more others in the same cluster, so is power ...
6
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0answers
370 views

BER peroformance of MPSK and MQAM in Rayleigh fading channel

I have a question regarding bit error rate (BER) performance over the Rayleigh channel. I observed BER performance over the AWGN channel using Simulink in MATLAB. I used to change the "SNR" parameter ...
1
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0answers
883 views

seeking help for decoding a call log / PCHR trace files (Call logs)of Huawei V900 R015 machine(.log files) [closed]

I have PCHR trace files of the above mentioned server . But unfortunately I couldn’t find an appropriate decoding software to read those files. I tried manual through a c program but it didn’t work ...
2
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1answer
988 views

What kind of signal is the signum function? A power signal or an energy signal?

I'm studying "signals and systems". We can indentify two kinds of signals: power signal and energy signal. The definitions are: Energy of a time-continous signal $$ E_x = \int_{-\infty}^{+\infty}{|x(...
3
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0answers
47 views

Viability of creating a wireless LAN bridge between mobiles and PCs using a portable router?

I am creating a network to share files between a mobile device and multiple PCs directly through a LAN. The purpose of which is to use smart phones to capture files from remote devices which are ...
1
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1answer
128 views

How to join between two PBX telephones wirelessly?

I have two PBX telephones. Each one has a line cables to the houses, but there is no connection between these two pbx telephones, neither wire nor wireless. How can I join between them wirelessly? ...
3
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0answers
47 views

Wifi modulation and standard interoperability

I've been reading this summary(info.tek.com) of Wifi standards from Tektronix, which seems to do a pretty decent job of explaining things, but has left me with a couple of questions: For access ...
12
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4answers
641 views

Is interference between aircraft an issue for fly-by-wireless technology?

I was reading up on fly-by-wire development, and I saw a short section about fly-by-wireless technology. It seems like a great idea, with the potential to lower costs, weight and complexity. I can see ...
8
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3answers
402 views

Protecting device from microwaves in microwave oven.. but allowing Bluetooth?

I am building a device that needs to be inside of a microwave oven but somehow needs to communicate with another device outside of the microwave. How can I reflect microwaves so they don't come into ...
2
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2answers
243 views

Control RF wave direction or path

I have a rf module transmitting from an antenna. As you see in Figure 1, I have a radio mast that sends waves in all directions. I don't want this. My plan for controlling wave direction is Figure 2. ...
2
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1answer
1k views

What are the pros and cons of between Zigbee and Z-Wave communication protocols used in IoT device space?

Recently, both Zigbee and Z-wave tend to be the most commonly used protocol to communicate between Internet of Things (IoT) devices. Most of these IoT devices tend to have a combination of mechanical ...
5
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1answer
114 views

Why does the LTE Specification define SC-FDMA as the modulation scheme for the reverse link?

The LTE specification specifies SC-FDMA as the encoding scheme for the reverse link (mobile to base station) when the forward link uses OFDMA. What is the reason for the difference?