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 Frequency). Distances can be as low as centimeters (e.g. RFID); there's no upper limit.

Filter by
Sorted by
Tagged with
47 votes
4 answers
46k views

Why don't we use wireless electricity today?

I was reading about Nikola Tesla today (via the Oatmeal) and read about the Wardenclyffe Tower which (among other things) was intended to transmit electricity wirelessly. Forgive the naivety of the ...
n00b's user avatar
  • 581
41 votes
9 answers
11k views

Why is wired Ethernet losing its speed advantage over wireless?

This has been bugging me for a while now. I did a couple wireless transmission courses back in my university days and it's a known fact that wireless transmission is hard. Partly because it's a shared ...
Francois's user avatar
  • 577
36 votes
5 answers
10k views

Why 2.4 GHz Band?

Bluetooth, WiFi, Zigbee, Remote Controls, Alarms, Cordless Phones etc.. Why all of these protocols, devices, etc. use 2.4 GHz band instead of 3.14 GHz. What is so special about it?
cbr's user avatar
  • 463
36 votes
1 answer
35k views

What is XBee and how is it different from Zigbee?

It's easy to get an introductory explanation of Zigbee. Zigbee on Wikipedia Home networking with Zigbee Zigbee alliance But technical information on XBee seems harder to find. It's unclear to me ...
Craig McQueen's user avatar
34 votes
5 answers
22k views

How come radio signals don't interfere with each other all the time?

I'm a newbie on wireless technologies and I'm trying to understand how they work. One thing I don't understand is this: How come transmissions from different devices don't interfere with each other ...
Ram Rachum's user avatar
30 votes
2 answers
5k views

Why can't USB-C receivers be as small as their USB-A counterparts?

We're all familiar with the USB-A 2.4 GHz receivers from companies like Logitech that are absurdly small and barely protrude from the port. But when looking at available USB-C equivalents, they are ...
Adam's user avatar
  • 411
23 votes
1 answer
53k views

I need the most basic circuit diagram for wireless energy transfer please

I have been all over the net looking for the most basic circuit diagram or instructions to put together a small project on wireless energy transfer. If anyone knows of a good schematic that is super ...
Digital Brent's user avatar
20 votes
7 answers
104k views

Why do higher frequency waves have better penetration?

In free space, lower frequency signals seems to go farther because the signal is either diffracted by the ground or reflected by the upper atmospheric layers, making it actually go farther. In urban ...
pstan's user avatar
  • 921
19 votes
9 answers
14k views

Ideal WiFi to Serial (or SPI) bridge?

What are some recommendations on an ideal WiFi to Serial bridge? My ideal qualities would be: Simple connectivity, SPI or Serial Reasonable fast speed, at least 1mbit/sec ideally (though probably ...
davr's user avatar
  • 6,802
19 votes
4 answers
2k views

How can I measure the temperature wirelessly inside a piece of meat?

For a cooking experiment, I'd like to be able to measure the temperature inside a piece of meat while it's being cooked. Due to the mechanics of the cooking process, it's going to be difficult to use ...
Rocketmagnet's user avatar
  • 27.4k
17 votes
2 answers
84k views

Calculate distance from RSSI

I am working on an indoor positioning system where I need to: Compute distance based on RSSI (I understand this won't be 100% accurate) Then do trilateration to pinpoint the location of the wifi ...
zengr's user avatar
  • 273
16 votes
3 answers
5k 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 ...
ObsessionWithElectricity's user avatar
15 votes
5 answers
2k views

Why do we still use cable for a lot of forms of data transmission?

Like many people I'm often annoyed by ugly cable clutter, especially when it's long distance. In my opinion it would be ideal if cables could be eliminated altogether, so that you'd just have two ...
user avatar
15 votes
3 answers
2k views

What is the underlying mechanism behind Wi-Fi getting slower with greater distance?

It's common knowledge that the further you go from a Wi-Fi network point, the slower the network over Wi-Fi gets. But why would this be the case? Radio signals propagate at essentially the speed of ...
TheEnvironmentalist's user avatar
15 votes
6 answers
8k views

Wireless communication between more than two Microchip PIC microcontrollers

I would like to create wireless communication between Microchip PICs for my simple project. It's actually an one way communication but there is one server and more than one client (about 2-4, all ...
Felician's user avatar
  • 151
15 votes
1 answer
42k views

How can I tell if an RF transmitter is transmitting?

In my project, I use a use an RF transmitter and receiver. One of the RF components seemed to fail because the connection between my Arduinos no longer works. I cannot determine whether the RF ...
slippery's user avatar
  • 339
15 votes
2 answers
1k views

Why does the 802.11 wifi spec allow for 11 channels?

The general wisdom is that it is better to only ever use channels 1, 6, and 11 as they are the only three non-overlapping channels for 2.4ghz wifi (in the US), and two adjacent networks on the same ...
AndrewH's user avatar
  • 283
14 votes
5 answers
9k views

Is it possible to jam wireless home alarm systems?

Sorry if this is the wrong community for this question but in my mind, it's the best fit. Please close or move to a more appropriate community if it's off topic. The other day, several home alarm ...
Classified's user avatar
14 votes
2 answers
11k views

How electronic price tag works?

Today I was in Tesco in my city and I saw something quite interesting, that was electronic price tag: I don't know how it happend, but on a parking I found this price tag in my basket beneath some ...
SP5RFD's user avatar
  • 243
13 votes
5 answers
7k views

How did wireless telegraphy reach so far?

Even as far back as the early 1900s, telegrams transmitted wirelessly could reach hundreds of miles. For instance, the Titanic communicated with Canada, 400 miles away, with relatively low-powered ...
InterLinked's user avatar
13 votes
4 answers
10k views

How does wireless communication work?

This is a problem that's always baffled me a bit. How does high frequency (more than 100MHz anyway) wireless communication actually work? I understand that it has an antennae and for receiving it ...
Earlz's user avatar
  • 3,376
13 votes
8 answers
27k views

Wireless communication over long distances

Would like to communicate between an Arduino and a PC but over a distance of 2500+ feet outside in the open, wirelessly. What would be the best way of doing this? The communcation devices I have ...
littlebirdceo's user avatar
13 votes
3 answers
2k views

What's the purpose of such weird wiring inside this smart card?

Here's a scan of a stripped MIFARE Ultralight smart card That's some plastic film with (I assume aluminum) foil wiring acting as the antenna for both powering the chip and providing radio ...
sharptooth's user avatar
  • 12.4k
13 votes
4 answers
2k views

What are some alternative power sources for wireless sensors?

I'm looking to power several small, Wi-Fi enabled sensors, in a domestic home or office environment. As such I'm interested in keeping them powered as long as possible between charges. Obviously an ...
Jon Hadley's user avatar
13 votes
3 answers
63k views

Broadcast audio to multiple receivers via Bluetooth

I want to be able to connect multiple Bluetooth devices to a Bluetooth transmitter, and then stream audio from a portable MP3 player, via Bluetooth, to all of the connected Bluetooth receivers. Is ...
Johnny's user avatar
  • 151
12 votes
2 answers
39k views

Difference between Hirose U.FL and IPEX connectors

Both these connectors are used to connect antenna to Mini PCI cards. Wikipedia does not explain the difference between those naming issues: U.FL, IPEX, IPAX, IPX,[1] AMC, MHF and UMCC is a ...
Olivier's user avatar
  • 223
12 votes
6 answers
3k views

How to avoid interference in wireless communication?

I am working on wireless communication system. We are using around 10 pairs of transmitter and receivers. We are using atmega16 microcontroller for encoding and decoding by USART ports. Now we are ...
user934070's user avatar
12 votes
2 answers
7k views

Why is channel capacity a factor of bandwidth instead of frequency?

I'm trying to understand the concept of capacity for a wireless channel. Some help would be appreciated. For a AWGN channel capacity is calculated as: $$C=B \cdot log_2(1 + S/N)\text{ bits/sec}$$ ...
Drew's user avatar
  • 123
12 votes
2 answers
1k views

How does the plastic-tube inductor in this wireless transmitter work?

This single layer PCB (solder side shown here) is from an old fan remote: The inductor in the plastic tube is not connected physically to any components; however, the two loops of wire surrounding it ...
Diractance's user avatar
12 votes
7 answers
5k views

wireless temperature sensor [closed]

Are there any low-cost (<50$USD) wireless ambient temperature sensors available? I would like a simple to interface to the sensor i.e. IP over Wifi if at all possible.
jldupont's user avatar
  • 555
12 votes
4 answers
24k views

Wireless Home Automation 2.4GHz versus 433MHz [closed]

Project specifications - This is an **Arduino** project - This is supposed to be internationally applicable I am working on a home automation project which might go into smaller production. The ...
Roberto Anić Banić's user avatar
12 votes
6 answers
36k views

ultra low power mini wireless transmitter / receiver?

I'm looking for suggestions for a wireless transmitter & receiver combination. I'm basically just trying to bridge several buttons over a wireless signal(s) (i.e. send a 1 bit signal) in as small ...
None's user avatar
  • 1
11 votes
5 answers
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 ...
h_r_kr_shn_n's user avatar
10 votes
5 answers
855 views

Fault modeling for embedded systems

I have a wireless sensor circuit with a microcontroller and a 2.4 GHz transceiver module, some integrated sensors with I²C interface, a UART port and the necessary discrete components. This board is ...
clabacchio's user avatar
  • 13.5k
10 votes
3 answers
28k views

BLE Scan interval and window

With Bluetooth Low Energy, you specify a scan window (how long to scan) and interval (how long to wait between scans). Would there be any difference between scanning for 10 ms every 100 ms, or ...
Maestro's user avatar
  • 981
9 votes
2 answers
2k views

What is the meaning of dBi?

When we say, for example, an antenna has spec of 22 dBi; Does it mean that its power is 22 dB stronger for any point at fixed direction than if it were to emit spherically?
Noob_Guy's user avatar
  • 433
9 votes
7 answers
3k views

Why can a square wave (or digital signal) be transmitted directly through wired cable but not wireless?

Like ethernet cable, optical fiber. We have a square wave signal, do we just send that squre-wave signal directly down along the cable? If we do send it directly, why we can not send the square-wave ...
Yuan Xiao's user avatar
9 votes
3 answers
663 views

What is a sensible approach to connecting devices to your computer via wireless technology?

I remember with fondness the X-10 days, when you could connect your computer to every wall plate in your house, using power-line carrier to transmit signals to addressable receivers (with varying ...
Robert Harvey's user avatar
9 votes
2 answers
13k views

Can I remove a GSM module from an old cell phone?

I found this project that uses a GSM module (scroll down to see Picture 5). It seems the module has to be bought separately. I have old GSM cell phones lying around in the house. Shouldn't these ...
sauparna's user avatar
  • 175
9 votes
2 answers
3k views

Autonomously-powered (battery-less) wireless pushbutton

What would be a feasible approach/circuit-design to make a self-powered wireless pushbutton, assuming it is even realistic? This is what I mean by each of the three terms: Self-powered: Power ...
boardbite's user avatar
  • 4,912
9 votes
6 answers
15k views

Best choice for low-power, short-range wireless communication

I'm working on a project which relies on wireless communication, and I'm looking for the best alternative. These are the design requirements: Is easy to interface with Arduino Works over a small ...
Giulio Muscarello's user avatar
9 votes
2 answers
2k views

Upgrade ARM over the air

We will create an ARM board with a GSM modem on-board. We want to be able to upgrade the ARM firmware over the air. Is there any good, reliable, open source solution for that? If not, is there a paid ...
hotips's user avatar
  • 401
9 votes
3 answers
18k views

Long Range RF communication

After playing with Arduino and different kind of sensors for my garden, now I'm starting a new project for my free time. I want to work with RF communications because I need a long range device for ...
Yolco's user avatar
  • 367
9 votes
3 answers
1k views

Rather complicated sensor network

I was working on a project recently and it was the first one which was involved enough to make the sensor networking complicated. In the end, I think the communication was the bottleneck in terms of ...
NickHalden's user avatar
  • 4,177
9 votes
1 answer
6k views

Why is 433 MHz still used?

The new RF frequencies are 868 MHz for Europe and 915 MHz for the US. I heard 433 MHz is barely regulated, read: it's chaos. Then why are 433 MHz RF modules still used? Are they cheaper to produce?
Johan.A's user avatar
  • 1,816
9 votes
4 answers
2k views

What is a good communicaton device among teensy and arduino besides "XBees"

I have been using XBees to communicate my teensies so far. However, as you know, XBees are really expensive and when I want multiple devices to communicate with each other, I have to pay for several ...
Matthew Kim's user avatar
9 votes
2 answers
3k views

How to build a cheap device to determine where Wi-Fi interference is coming from?

In this post, the ServerFault guys use a fancy tool to map out the WiFi spectrum under normal conditions, with a microwave running, and with a baby monitor on. The baby monitor and microwave cause a ...
BlueRaja - Danny Pflughoeft's user avatar
8 votes
4 answers
3k views

Do cell-phone base station antennas emit the same power as cell phones?

Do cell-phone base station antennas emit the same power of waves as from a cell phone? I would assume so because both waves need to travel the same distance, right?
JobHunter69's user avatar
8 votes
9 answers
4k views

What are the ways I can make my circuit communicate with a computer?

I am a novice at electronics hacking. I would like to know how I can make a circuit communicate with a PC. Take for example, a simple circuit, with one LED and a switch. The switch on the circuit ...
sauparna's user avatar
  • 175
8 votes
4 answers
3k views

Why do most FPV 5.8 GHz video transmitters use PAL or NTSC?

I am not much into the details of video transmission in general. However, I wonder since most displays and electronics are digital, why have suppliers for FPV equipment chosen an analog transmission ...
user avatar

1
2 3 4 5
24