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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Where can I buy mini cameras with the zoom in feature? [closed]

I'm looking for a mini camera (smaller than the palm and lightweight) which supports zooming in within the app. As I'm a beginner to electronics, I'm unsure about what terms to search. I've searched ...
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Wirelessly measuring voltage between two points? [closed]

I would like to measure a voltage between two points, wirelessly, but am stuck on the need to have physical contact between two points to be able to get a voltage reading... So I would like to be able ...
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Revisiting multipaths in wireless communications [closed]

Someone once asked a question about multipath: How can it be statistically beneficial in a one to one antenna wireless link when all text books talk about the problem of flat fading and its impact on ...
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2x2 MIMO communications, SNR, and data throughput vs link robustness trade off

With information about data throughput in a 2x2 MIMO environment and without knowing the channel state information is there a way one can reliably estimate the receive SNR based on the throughput in ...
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Is there any shortcut to wireless charging, preferably Qi compatible or NFC?

Qi charging is awesome, can push a lot of power from the sender to the receiver, enough to quite rapidly charge a mobile phone. I do however find the circuits to be very advanced and involve a lot of ...
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Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its bluetooth signal?

Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its Bluetooth signal for both transmitting and receiving data? Can I solder this type of 2.4G antenna to boost the ...
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Why don't you see UWB location systems running at lower frequencies?

Just something I was curious about. I was recently working with an indoor UWB tracking module and the frequency ranges are 3-6GHz. But there isn't anything at say 433MHz or lower which would better ...
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Unintentional Beamforming

Suppose I have two cross polarized transmit antennas sending the same signal in a rather line-of-sight dominated environment to a receive antenna, is there any chance of creating unintentional ...
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Multipath destructive and constructive fading and the law of conservation of energy

Multipath in a Rayleigh fading environment causes fading, this fading could be destructive or constructive at a certain point or location in the far field, how does that align with the law of ...
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How to determine the radiation pattern of a receiver antenna

I am designing a receiver antenna for a wireless power transfer application. The transmitter is a 2m x 2m horn antenna array that transmits a power signal at a frequency of 35 GHz from 100 meters away ...
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Could the electromagnetic field (EMF) from a power station disrupt wireless signals?

I know that power stations can generate an electromagnetic field, but is that field strong enough to disrupt nearby wireless signals, such as Wi-Fi, Bluetooth, cell service, etc? I'm sure that, in ...
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3 votes
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Why does the quality factor include 2*pi?

The quality factor is defined as the ratio of stored energy and dissipated energy (see below). The formula includes \$2\pi\$ as a constant coefficient. Why do we need \$2\pi\$ to calculate the stored ...
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Coding and SNR gain

How does coding reduce the amount of SNR required to detect data for a certain modulation and at a certain bit error rate and does that imply that coding reduces noise power?
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Unreliable wireless comunication between 2 arduino boards

I am facing a strange and very frustrating issue while realizing a basic radio comunication between 2 arduino boards, one Arduino Nano and one Arduino Uno. For such a purpose, I am using the NRF24L01 ...
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1 vote
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Antenna mutual coupling and estimation of angle of arrival

If I have two RX (receive) antennas at a distance of lambda/2 from each other there is a formula which relates the phase difference to the angle of arrival. The formula is however assuming no mutual ...
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2 answers
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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 ...
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Wireless charging IC

I am building this wireless IC circuit and I don't understand the term HOST, TRI-STATE an BI-STATE. What do they mean?
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Max range between Bluetooth 5 LE device and a smartphones

What is the maximum range achievable between a Bluetooth 5 LE device and a smartphone? This would be assuming ideal outdoor condition with no obstacles etc. The amount of data to be transferred is ...
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3 votes
1 answer
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Is there sufficient 'ambient hum' to obtain a 60/120 Hz reference wirelessly?

In a typical urban (USA etc) setting, we seem to be awash in 'powerline hum'. Has it been done, or could it be practical, to recover this to get a wireless reference for a battery-powered system, like ...
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How to send a large amount of data via LoRa

I'm trying to implement a LoRa communication between two devices (master and slave). I studied two modules that seem to be interesting RFM96WE and SX1276. From the ...
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1 vote
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How should I understand this interpretation?

Studying spatial diversity in telecommunication engineering (Fundamentals of Wireless Communication, D. Tse and P. Viswannath), I read this paragraph. $${\text {In}}\,{\|}{\textbf h}{\|}^{2}{\text {...
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When running a wireless charging circuit, my power supply whines and the transistor gets super hot even though everything works, is anything wrong?

I created a wireless LED power circuit to drive adafruit wireless LEDs.The circuit works great, LEDs are fully lit but my desktop power supply lets out an awful whine whenever its running (it normally ...
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Confusion about MIMO (spatial multiplexing) in Rayleigh fading

A Rayleigh fading channel is supposed to be constituting a rich scattering environment thus suitable for spatial multiplexing, yet Rayleigh fading BER performance is very bad when compared to an AWGN ...
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Wireless real-time control of RGB led strip using PWM and RF

I would like to send three 8-bit PWM values (generated using an ESP32 and the ledc library) wirelessly in real-time. From what I've come across, RF seems like a good option, however I would prefer not ...
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1 vote
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Interference effects on a wireless signal

I am trying to get my head around the effects of interference on a wireless signal and its signal strength. I do not have an engineering background, but I do have a background in wireless sensor ...
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1 vote
2 answers
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Best way to secure MMCX jack-to-jack adaptors?

I'm currently using an MMCX jack-to-jack adaptor to connect a wire from a transceiver to another wire from an antenna. Through this adaptor, the wires click into it. However, I would like to better ...
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What is Channel Vector?

When I read research paper, there is a word named "Channel Vector". I think it is too abstract, so it is hard to understand for me. What does it mean? For example: Consider the downlink ...
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Bluetooth pairing in wireless keyboard

I am trying to create a wireless USB keyboard. Currently, I have all the USB output information coming from a microcontroller and into an EFR32BG1 bluetooth chip and I have a BT851 USB transceiver to ...
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1 vote
1 answer
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Proof of Shannon capacity theorem

I was looking for a formal proof of the Shannon capacity theorem, which states the condition which is the maximum data rate possible between two wireless channels. I could not find the proof. Does it ...
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How would I make a wireless pressure switch for turning on and off a flash light?

I want to make a wireless pressure switch for a flash light mounted on an airsoft gun I have figured out that I would have to use an RF transmitter/receiver like this one: https://www.amazon.com/3-7-...
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1 vote
1 answer
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Estimating Received Signal Strength of a DTV transmitter

Goal: Estimate the received signal level in dBm (where 0 dBm corresponds to 0.224 volts) on a spectrum analyzer for a given TV transmitter. Scenario: I have many details on the transmitter, including ...
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1 answer
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Are there any noise cancellation algorithm used in wireless communication? if so in which layer?

I understand that there are 7 layers in the OSI model. I would like to know is there any noise cancellation algorithm used in wireless communication? If so in which layer is it used? I am looking for ...
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Question regarding bandwidth of digitally modulated signals

Assume that there are two carrier frequencies, 20 GHz (RF) and 200 THz (Optical). Both of these carrier waves are modulated by a digital signal using QPSK scheme. Consider the frequency spectrum (or ...
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Is it POSSIBLE for a wireless device to use the cellular frequencies without approval from the FCC

My question is purely hypothetical and does NOT apply to any real life scenarios. Is it possible for a wireless device to use the cellular quad band successfully without FCC approval or knowledge.
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5 answers
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How is our voice tone transmitted and received without the change of our own voice?

For example lets take mobile communication, transmitting and receiving what we speak is fine, but how does it retains different flavors of our unique voice (that is if someone who we knows speaks over ...
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1 vote
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How to wirelessly stream from sensor such as Adafruit LIS3DH

I'm extremely new to electronics and with some help, I was able to identify an accelerometer (Adafruit LIS3DH) that matched my needs, but I have no clue how to stream data from it to my computer or ...
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6 votes
1 answer
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2.4GHz sender cause 433MHz receiver jammed, vice versa

I have a 433MHz receiver placed near a 2.4GHz sender, and they have about a 20cm gap. When 2.4G is actively sending, the 433M receiver can't hear anything from the 433M sender (433M receiver been ...
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1 vote
1 answer
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Multipath and antenna radiation pattern

Multipath causes fading in wireless communication systems. Depending on the RMS delay spread vs the symbol period this fading can be frequency selective or flat The question is does multipath in any ...
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1 answer
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What is the difference between Antenna gain and Channel gain? [closed]

I have a fairly simple question that I've written in the title but just writing this body to meet stack's 'quality standards' What is the difference between Antenna gain and Channel gain?
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1 vote
2 answers
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Indoor SISO wireless Rician channel performance

In wireless communications and when you have a SISO system, multipath is considered to be an impairment according to theory. Suppose now that we have an indoor SISO Rician channel (a strong line of ...
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How does a wireless USB mouse or keyboard work?

Wireless mouse or keyboard works on the principle of radio frequency (RF) technology. The transmitter of a wireless device is located inside the device itself and it sends the electromagnetic signals ...
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1 answer
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Why does it take so long to join a wifi network? [closed]

Accessing a text-only website, including TLS handshake, averages under half a second from first GET request to completely loaded, using my none-too-fast wifi. Yet ...
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1 vote
1 answer
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Friis Free Space Equation for Received Power

According to Friis Equation the received power is directly proportional to the square of the wavelength or inversely proportional to square of the frequency. But is this not misleading. There is ...
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-2 votes
1 answer
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Impact of Bandwidth Increase on Shannon Capacity

What is the impact of doubling of bandwidth on Shannon Capacity, assuming noise power spectral density and signal power remain the same?
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3 votes
5 answers
1k views

Handling simultaneous messages in wireless communication

I have a generic question regarding wireless communication and what techniques can be used to detect if two transmitters send the message at the exact same time. Since this is generic question and ...
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2 votes
1 answer
126 views

How are simultaneous transmissions decoded at the receiver?

I am finding it hard to understand how does a receiver differentiate between the interference and the signal intended for the corresponding receiver. For example in a case where two user pairs are ...
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244 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 ...
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Manchester and NRZ coding schemes

How does NRZ recover the clock? For example, Manchester coding is a self-time scheme, but we still need to have DLL or PLL for the recovery, it can be done without those CDR circuits? and back to NRZ, ...
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Ground loop between two devices powered by the same power supply

I'm working on a project with a Raspberry Pi and a Bluetooth receiver which are sharing the same ground and the same power supply. The wireless receiver gets the signal (audio content) and sends it ...
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Related to multiple tags

I am trying to find out the following points related to multiple tags. Whether multiple tags can have same information in them or they will always have different information. Real life example of ...
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