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Questions tagged [wireless]

Using other than a wired connection to transfer signals or power. Includes optical and (ultra)sound, but most often refers to RF (radio-frequent). Distances can be as low as centimeters (e.g. RFID), there's no upper limit.

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What is the meaning of reciprocal communication range in the context of wireless communication?

Does it mean the carrier sense range is equals to the communication range, as this paper mentions the system has no hidden terminals due to reciprocal range ?
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1answer
28 views

What are the equations/values for Rayleigh Fading, path loss and log-normal shadowing?

I am to use the following equation as part of a model for a wireless communications network: I would like to know the specific parts of the eqautions: "k" - is this the Boltzmann constant? "v" - I ...
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3answers
237 views

Why can't the orthogonal PN codes help in the near-far effect?

The CDMA near far problem arises because handsets may be anywhere within the particular cell boundaries. Some handsets will be close to the base station, whereas others will be much further away. In a ...
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1answer
63 views

Wireless or wired solution for perimeter fence security?

We are currently working on a project where we would like to place around 350 vibration sensors on our university's perimeter fence for security. The field layout is almost 1km to 1km (square - 1km^2 -...
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36 views

Passive (or very low power sensor) sensor to wirelessly receive wake signal

Context. I am using an ESP32 and a small circuit to control an electronic lock on my one of my exterior doors. It is powered by batteries. It has a door magnet sensor to detect when the door is open ...
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1answer
31 views

Need help with understanding the pros and cons of geometric and stochastic based channel models. Which one s preferred under which conditions?

https://www.adv-radio-sci.net/9/165/2011/ars-9-165-2011.pdf https://ieeexplore.ieee.org/document/7794648 https://pdfs.semanticscholar.org/c301/8463116117ea64f69638e15aa78fe9e84093.pdf https://www....
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26 views

Air core design

what is the appropriate air core design for inductive power transfer that is suitable for 30khz? I used 200 turns and 7 inches diameter.
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5answers
2k views

Can wireless communciation be synchronous?

I understand that in synchronous communication, the sender and receiver need a common clock. Is it possible that wireless communication be synchronous? Can some common clocking element be there for ...
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26 views

APC220's not communicating

I am trying to establish a communication between my computer and an Arduino UNO using a pair of APC220 modules. First I struggled with the RF Magic software but finally got it to work and find the ...
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0answers
12 views

deriving an equation for wireless network capacity

I'm trying to derive an equation for wireless network capacity given topological constraints of the nodes and certain obstacles... but before I get that far, I want to understand the most simple case. ...
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1answer
137 views

Tesla coil troubleshooting help

I'm trying to make a Tesla coil with approximately 200 turns in the secondary coil using 28 gauge enameled copper wire. My primary coil has 3-6 turns with a thicker wire. I've made all the connections ...
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1answer
37 views

Vertical Farm Automation

I am building a system to automate a vertical farm (specifically watering, lighting, and drying) and am having trouble choosing between a wired or wireless system architecture. The farm is arranged ...
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35 views

Why does the receiver coil voltage of this WPT circuit decrease at varying rates as the distance between the transmitter and receiver coil changes

The circuit below is a circuit that wirelessly transfers power via inductive coupling. I used a digital oscilloscope and measured the output voltage of the receiver coil at varying distances between ...
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3answers
78 views

Why does the voltage induced in the receiver coil of this WPT circuit decrease when a load is added (in parallel)?

The following is a circuit that wirelessly transfers power via inductive coupling. The circuit is supposed to power a 12 V 0.15 A DC fan and a typical smartphone, which requires 5 V DC across it. The ...
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2answers
56 views

Is wireless technology only possible due to inductance?

I asked a friend how capacitative coupling works in glass-mount antennas. He said it's like when installing a sound system; where you want to keep the power & audio cables separated, to avoid ...
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2answers
59 views

Is it possible to induce negative/positive charge wirelessly

Sorry if this question doesnt belong here. I have no clue of what I'm about to ask. I want to know, if possible, how to induce negative/positive charge on objects inside recipients? What I want to ...
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1answer
34 views

Trying to read the data from an ASK RF transmitter

I'm trying to duplicate the operation of a simple RF remote control (for some remote power outlets). In the remote control there is an unmarked 8-pin microcontroller. I've worked out which pins are ...
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2answers
131 views

Why aren't tethered balloons used instead of Cellphone towers? [closed]

If we use tethered balloons with wireless gateways fitted on them (let's say for Cellular or LPWAN communication), they can provide much more coverage. Why aren't they used then? While there are many ...
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0answers
17 views

What is the purpose of Gamma distribution in Nakagami-m fading wireless channel?

A gamma distribution is a general type of statistical distribution that is related to the beta distribution and arises naturally in processes for which the waiting times between Poisson distributed ...
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1answer
34 views

Antenna polarization and antenna directivity are the same?

I'm working on an RFID project, and looking for information about the antennas that I have to use, I have the following doubt: Antenna polarization and antenna directiivity are the same? Thanks!
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1answer
54 views

how rubber keypad works [closed]

Press on the keyboard, how does he connect the circuit of this key? Two thin films, coated with conductive rubber circuit, with a thin film in the middle, with holes, used to isolate two thin films ...
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1answer
34 views

Wireless LAN standard

I'm taking a module on wireless design and we were told that the IEEE 802.11b standard has a band of 2.4 to 2.4835 GHz and that it is divided into 13 channels. Now, my question is, does that mean that ...
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1answer
57 views

Creating a wireless transmitter/receiver for off-the-shelf siren

Since I oddly enough haven't been able to find a suitable off-the-shelf product that's reasonable priced (less than 50-60 EUR/USD) and somewhat good looking with Google, I'm about to try a small ...
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2answers
34 views

Optimizing magnetic field force of a coil

For a personal project, I've done a redesign of Samy Kamkar's MagSpoof project. Basically, it is possible to use an electromagnet, h-bridge, and microcontroller to trick a magnetic card reader into ...
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1answer
46 views

Radio activated on/off switch

TL;DR: I want to know if there is anything, That on which when a radio frequency falls, and it turns on an LED. Basically an on off switch but controlled when radio waves hit it. What I hope to ...
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2answers
52 views

Should the antenna be 'better' for the transmitter or receiver?

I intend for this to be a general/conceptual question that could apply to any wireless communication setup, however I will use a specific example to make things easier. For my example, I'll be ...
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0answers
76 views

Long distance internet connections

My friends and I are PC enthusiasts and we are making a NAS, unfortunately we live in a suburb of Melbourne, Australia and internet here is garbage (lower than 8 megabits most of the time) so this is ...
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2answers
154 views

Name of an electronic component

Can anybody kindly tell me what this electronic component in the picture is called? I've seen this component in: Mobile phone circuit WiMax modem circuit GSM Module circuit I tried but was unable ...
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1answer
25 views

SAW Filter input power restriction

I have front end module (915MHz freq band) in circuit Which is having 30dBm output power. Between This FEM and antenna I have to insert filtering circuit. I came across few SAW filters from Murata, ...
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2answers
65 views

Can you turn two inductively coupled conductors into a transformer?

So I'm working on a school project, and to be honest. Don't know a lot about electromagnetism. I want to make a wireless charging station that could be plugged into the outlet. Of course I don't want ...
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1answer
38 views

Wifi/BT on Realtek 8723 - Is FCC, CE certification needed for Wifi if we disable Wifi and use only Bluetooth?

I'm planning on importing a generic mini pc that comes with an onboard Realtek 8723 for Wifi and Bluetooth. We will need to get it FCC, CE, IC certified before we sell it in North America/EU. Getting ...
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1answer
31 views

Setting Up Long Distance Unidirectional Wifi Antenna

A neighbor has graciously offered us temporary access to their wireless for basic internet access, but we are about 100 meters apart. I have a wireless NIC, but I wanted suggestions as to the setup. ...
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1answer
165 views

why do resonant inductive coupling circuit operate at high frequencies?

Just as the title says. Whenever I read a research paper on wireless power transfer via resonant inductive coupling the authors just mention frequencies that range in the kHz and Mhz range, but none ...
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1answer
36 views

What is the basic concept (philosophy) behind the modelling of Nakagami-m fading wireless channel

I understand that that NAKAGAMI-m probability density functions that describes the random behavior of signal in a wireless channel. But I am very confused about one thing, by what concept did these ...
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89 views

difference between ISO 14443 vs ISO 18092 and collision detection

I have been studying about contactless payment specifications and protocols and I have few questions about them. Are ISO-14443 and ISO-18092 called NFC and RFID in general terms, or are they a ...
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1answer
42 views

Wireless power through air [duplicate]

I know this might be far fetched. In normal everyday life, we have huge amounts of data traveling through the air in the form of electromagnetic radiation. But what if instead of transmitter data ...
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1answer
38 views

Locating mobiles/UE by base stations in a cellular system [closed]

After understanding a bit about how actual cellular systems function, I realized that identifying the mobile/UE location is key in assigning the UE to correct base station and thus to guarantee a ...
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1answer
89 views

Transmitter and Receiver antennas in mobile phones

I understand that in old cellular systems where FDD were employed, we used to have same antenna at the mobile phone (User equipment) for transmission and reception.Moreover, a duplexer was used to ...
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1answer
216 views

Analog beamforming vs digital beamforming

I am reading some research articles on wireless communication where they talk about beamforming techniques and their differences in Multiple antenna Tx-Rx systems (MIMO). It says analog beamforming ...
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0answers
13 views

What will be Directional antenna gain formula, encompassing all lobes?

In the attached figure, one can find the antenna gain formula. But the authors have simplified it for the main lobe only. Can someone please let me know the exact form of the following simplified ...
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20 views

About Directional Antenna, Transmit Gain, and Rician fading

In my research, I assumed a directional antenna for the indoor environment. I took the approach of considering Rician fading channel b/w Transmitter \$T_x\$ and Receiver \$R_x\$. My received power is ...
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1answer
27 views

Finding success probability for wireless channels

This seems a very dummy question, but I cannot figure out how the following equation has been solved by authors: $$P_{secure} = \text{Pr}\{\epsilon cP_sd_{su_i}^{-n}|h_{su_i}|^2> cP_sd_{se_i}^{-n}|...
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1answer
48 views

LoRa modulation and chirp process clarification

I am new to LoRa and I would like to get some confusion on chirp-based modulation process clarified. I was reading the very good thread Understanding the relationship between LoRa chips, chirps, ...
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1answer
58 views

Are watts consumed in wireless electricity? [closed]

If I put a transistor on a coil of wire connected to a 120v AC circuit, and made it so my toaster was now wirelessly powered, if I turned the toaster on would it consume watts that are able to be ...
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1answer
71 views

Alternative wireless technology for passive RFID tags

I am working on a project where I have 3 boxes and a RFID reader (mfrc522) attached at the bottom of each box. I keep my wallet/keys/etc in these boxes and a LCD screen displays what is in each box ...
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3answers
154 views

Methods for confirming on both sides that a signal was received in one direction

Say there are two devices (A & B) that talk to each other (full duplex). For the sake of this example, let's say the medium is RF (wireless). If device A sends a message to device B, what ...
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1answer
114 views

Fast, cheap, wireless data transmission with Raspberry Pi [closed]

I need some advice on a project. I want to wirelessly transmit packets of data from a Raspberry Pi to several microcontrollers (Arduino or other). The frequency must be at least 15 packets/s per ...
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3answers
4k views

Why does WiFi have a shorter range than LTE? [closed]

It seems confusing that my phone receives -87 dbm LTE signal and shows a full 4 bars with the speeds of UPLOAD: 20Mbps DOWNLOAD:13.6Mbps But my WiFi is showing 1 bar at -89 dbm and I get ...
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1answer
170 views

Can’t get simple LoRa receiver to work

I’m in the process of attempting to create a very simple, small, LoRa sensor based on an sx1276 module and an ATmega328P. My ATmega328p is communicating with the sx1276 module happily, but I can’t ...
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1answer
66 views

How can I measure my smartphone transmitted power? [closed]

I was wondering if I can measure my phone's transmitted power with an SDR by tunning in the transmission bandwidth but then, I'm not sure how to know whether this power is coming out of my phone or it'...