# Questions tagged [wireless-communication]

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### Creating a Multi-SIM Cellular Connectivity Solution for Raspberry Pi Zero 2 W

I'm looking to set up my Raspberry Pi Zero 2 W so it can use various SIM cards from different telecom providers. While this might sound unusual, it's actually quite practical. In some areas, certain ...
8 views

### Two-Ray Ground-Reflection Model: Understanding the Difference in Phase Offsets at the Receiver

Currently, I'm trying to understand the Two-Ray Ground-Reflection Model. During my research, I came across the following simplification expressing the received power as follows (taken from Wikipedia): ...
32 views

### Can wireless charging become more energy efficient?

I've stumbled upon a few articles saying that wireless charging takes more energy to charge something compared to the cable. Like this one. Like in the test from the article, it takes 47.33 % more ...
17 views

### Wireless Power Transfer Modelling

I am trying to develop an analytical model for RF wireless power transfer from an external antenna to an implant antenna, embedded inside layers of lossy tissue. The external antenna will be ...
14 views

### FPV for drone setup recommendation

Looking for recommendations of hardware for setting up FPV with recording with off the shelf components. Requirements: Receive 1080p video feed on the receiver side, and at the same time record the ...
70 views

### Should we use Maximal ratio combining and an equalizer together?

I have confusion on MRC (Maximal Ratio Combining) method, which I would like to clarify. An example is where I have 1 transmit antenna and 4 receive antennas. The concept of MRC is to combine all the ...
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561 views

### Why do we always use 3.8 x 10^(-3) value as Forward Error Correction (FEC) threshold?

When we want to calculate the bit error rate (BER) for any communication system, why do we always select the 3.8 x 10-3 value as Forward Error Correction (FEC) threshold? Couldn't another value be ...
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31 views

### how would I identify when and who enter through a doorway, assuming they can have part of the technology on their person

I am working on setting up a system that senses when an object goes though a door. I've seen things using lasers or induction. I have a set of objects smaller than 1 square inch. I just want to know ...
61 views

### Real-world CQI-to-MCS and SNR-to-CQI tables?

How can I get real-world CQI-to-MCS and SNR-to-CQI tables? I am particularly looking for 5G-NR or LTE-A related tables. Can someone share any references? Edit: I had found one table for CQI-MCS ...
• 101
1 vote
63 views

### Do they sell some sort of non-"consumery" GPS trackers?

I have seen these expensive things that you can put in a moving box while moving, to keep track of your stuff in case the moving people drive away with their truck and steal it. I also see expensive ...
1 vote
20 views

### Transforming a Wireless Computer Mouse into a Wireless Switch [closed]

With no computer involved whatsoever, I want to be able to read oscillator outputs from my wireless mouse and switch an LED on a left click AND off on a right click. I have taken my mouse apart to try ...
18 views

### Building drone transceiver module with 2 recievers onboard to switch gates ON/OFF to turn motors On/Off

I'm looking for any resource that can help me build a radio (no infrared) controlled circuit with two receivers onboard a drone. The purpose of this circuit is for research and education. Whenever ...
66 views

### 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 ...
35 views

### Wireless communication modules transmitting through body

I wanted to be able to transmit data from a wireless module to an Arduino. It is possible that a human body could come between the wireless module and the Arduino or someone might cover up the module ...
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1 vote
140 views

### 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 ...
• 83
1 vote
12 views

### 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 ...
109 views

### Was our wireless home telephone in the 1990s encrypted or completely insecure? And how did it work so far from home?

In the mid-1990s, our family got a cheap (I assume, since we weren't rich) but at least brand new telephone which either had two wireless "units", or one (my memory is a bit foggy on this detail), but ...
569 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 ...
77 views

### Intuitive interpretation of the U-shaped Jakes Spectrum

I was wondering if there is an intuitive interpretation for the Jakes spectrum? If I look at it in the time domain, which is basically the Bessel function zeroth order, it gives me a reading, how long ...
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31 views

### Small wireless proximity device to alert me when my cat gets into my WiFi range

I have the following situation. My cat goes outside every day, the problem is I have no way of telling when he is back around the house unless I go outside myself. I need some small wireless device I ...
1 vote
32 views

### How I can controller the reach of WIFI antenna?

I would like to know, which antenna 802.11 model, it your reach can be controlled. In a some researches, I'm discovered a tool called "iwconfig", native on some Operation systems Unix Like. It is ...
• 111
76 views

### How can a Wi-Fi access point be visible from one device but not from another?

We have a strange issue while trying to configure small router for bridging between available access point and ethernet network. While this AP is perfectly visible from desktops and mobile devices, it ...
33 views

### What does this bandpass signal equation indicates?

This is the equation for bandpass signal from transmitter. What are the values for different parameters present in this equation. For example, what should be the value of P, Sl(t), Fc etc. Also what ...
1 vote
330 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 ...
1 vote
222 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 ...
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41 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 ...
1 vote
31 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 ...
167 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 \$...
36 views

### what is the best way to communicate among multiple raspberry pi boards?

so i was planning to make a project were a system of computers( in my case raspberry pi's) need to communicate to do a certain job. And i am having a trouble choosing a way of communications. so i ...
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1 vote
22 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 ...
• 111
1 vote
38 views

### What's the best way to get an ultrasonic sensor that can vary its operating frequency

Long story short I'm looking to build an ultrasonic sensor that can also be used to communicate with a seperate sensor. (So it must be able to send out a pitch around ~42kHz, but also alter the pitch ...
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252 views

### Can wider range (i.e. 600-700 MHz) antenna replace lower range (650-700 MHz) antenna?

I had an appliance (wireless audio receiver), which has operational range 662-698 mhz (and had same ranged antenna exactly from factory), like this: However, that antenna was broken accidentally and ...
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1 vote
68 views

### Most practical way to wirelessly transmit a single bit of information? [closed]

If I have a single Boolean value that I wish to transmit wirelessly over a relatively short distance (assume <2m) then what of the many possible options would be the most practical. To define what ...
• 488
240 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....
• 111
89 views

### What criteria to focus on when selecting a BLE module?

I am trying to select a BLE module for low power application. I have looked into different BLE modules from different chip manufacturers. For example: ISM78G1D Bluetooth Low Energy SIP from Inventek ...
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1 vote
18 views

### Orthogonal Channels in a RAKE receiver?

Can I use the delay of different paths of a RAKE receiver for orthogonal channels. The idea is that if I have a square law detector for a packet of bits there will be no channel interference because ...
66 views

### dB/s/Hz in spectrum efficiency

Here is link of research paper in which spectrum efficiency is given in terms of dB/s/Hz. How can we define it? https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-016-0792-0
1k views

### Making my microcontroller transmit audio to any bluetooth headphones/speakers

I am creating a microcontroller on a custom PCB design for an MP3 player. I would like to consider integrating bluetooth into it. When I say integrating bluetooth into it, I specifically mean ...
113 views

### Can you detect the operation of a wireless radio (or other wavelength) receiver?

I am Comp-sci student doing a software engineering paper about designing a program, planning the software like you were actually planning a real-life software project, short of writing actual pseudo-...
1 vote
42 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 ...
703 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 ...
95 views

### How to decode radio thermometer / hygrometer bytes to floats?

I'm playing around with a radio receiver on 433MHz and I am receiving signals from a temperature / humidity sensor. I already figured out what bytes represent humidity, but I'm stuck with the ...
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1 vote
314 views

### What are alternative to installing LTE / Cell Tower to address capacity issue?

One of the cellular vendors wants to install a 180 foot monopole antenna in our neighborhood. They claim that there is significant growth in LTE consumers. So in order to better serve the customers ...
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415 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?
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3k 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 ...
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178 views

### Why GPS receivers are more sensitive than GSM or WiFi receivers?

GPS receivers are able to operate at signal level of -150 dbm or less, but mobile phones need far more than -115 dbm level signal. Why GPS receivers are so much more sensitive than GSM or WiFi ...
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136 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 ...
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1 vote
472 views

### How are three satellites sufficient to find a unique point in GPS? What happens in case of an overlap?

Consider: Is it because the 2nd and 3rd satellites' centres are collinear? Can a satellite overlap happen? If so then how is it avoided? If not avoided then what happen to the signal that is sent ...
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