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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2answers
70 views

Is interleaving used in MIMO?

Correct me if I'm wrong, this is my understanding of MIMO: Is this how MIMO is able to increase data rate?
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1answer
76 views

How does MIMO increase data rate?

I understand how using multiple antennas helps improve reliability as it combats multipath propagation through redundancy. But how does using multiple antennas increase data rate?
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22 views

Confusion about basic reference distance based path loss formula in wireless communication

In the following, I am confused about results I am getting by the reference distance based pathloss formula. My transmitter power is 1 mW (i.e. -30 dB). But the received power is much much higher than ...
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1answer
70 views

Antenna Radiation Patterns Explained

Been struggling to find information that I find to be obviously missing on how to interpret antenna radiation patterns. For example have a look in the datasheet for my chip antenna. I can understand ...
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7answers
2k 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 ...
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46 views

Modifying library for the WSSFM10 Sigfox module for compatibility with STM32L476RG

Arduino IDE version 1.8.13 installed. Selected options: Board: "Nucleo-64" Board part number: "Nucleo L476RG" U(S)ART support: "Enabled (generic 'Serial')" USB support (...
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0answers
24 views

Spatial receive diversity: a different view

It is well known that spatial diversity can combat multipath small scale fading in a SIMO system by offering the receiver multiple options of independent receptions using more than one antenna. The ...
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18 views

Having trouble setting up a data call via AT Commands and using the wifi chip as a hotspot

I have a WiFi chip embedded on an evaluation board which also has an application processor which runs A-grade Linux, in addition to a modem processor. I want to set it as a hotspot via hostapd which I ...
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16 views

Why use both packet detection and symbol time estimation in the receiver of WLAN(WIFI) in 802.11

n IEEE 802.11 Wlan, at the receiver side, we first use packets detection algorithm to detect the start of the packets, and then uses fine symbol timing estimation algorithm to find the start of the ...
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1answer
51 views

What connector is this? (Inside a wifi modem)

I was about to attach an antenna to my 4g modem and thus trying to identify which connector is there on my modem board and i found this connector (4 of them, 2 for 4g and 2 for wifi). I tried ...
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1answer
32 views

Wireless sensor network in practical for beginner

I am a master student, and I used to implement my protocol or scheme of WSN in the simulator(e.g., N3S or MATLAB). I am ...
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0answers
31 views

How to model MIMO channel matrix for numerical results

I am willing to include the channel matrix in my analytical model (which only includes pathloss and antenna gains). But from what I have seen, channel matrix can't be used to produce numerical results ...
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49 views

Does my Wireless Charging PCB need to have FCC, UL, CSA, certified marks?

I have a simple 5W output wireless charging device that uses a tx coil to transfer power to a phone, this is powered from a 1800mAh battery. Do I need any certifications for this?
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35 views

Open/close gate

This would seem like a problem that could be solved by buying it at a store, but it doesn’t seem to exist. I have a fenced backyard with two gates. When I let the dog out I’d like to be able to look ...
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1answer
30 views

Amplifying signal strength of a u.fl antenna

I have a mini pcie wlan card which uses a mini pcie to pcie x1 adapter card. The adapter card has 2 threaded male connectors which look exactly like conventional rg6 but smaller. Those lead directly ...
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1answer
61 views

Nearby jail's signal jammer affecting cellphone and devices using 2.4GHz band

I just rented an apartment that seemed perfect at the first sight. However, once I moved in, I noticed a lot of instability on my cellphone signal. I found that odd, so I did some research and ...
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1answer
85 views

What is the benefit of dual polarization in radio communication?

Why are some PtP antennas and radio units connected by two feed lines -- one for horizontal polarization and one for vertical polarization? I know the difference is in the orientation of the electric ...
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1answer
69 views

Viewing and capturing marine aquarium activities on television set and computer monitor larger screens

https://en.wikipedia.org/wiki/Marine_aquarium Is it possible to view and capture real time activities of a marine aquarium using wired, wireless, CCTV technology on television set or computer monitor ...
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1answer
29 views

About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundementals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
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2answers
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?
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11 views

LTE FDD and TDD bands

Can an LTE band whether TDD or FDD in a user end (the mobile phone) be used for only one direction, i.e. only to transmit or only to receive?
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12 views

Integration of PSD (Doppler Spectrum)

The expression for received signal PSD corresponding to a simple cosine wave (frequency fC) being transmitted is given as: \begin{equation} S_r(f) = \mathcal{F}[A_r(\tau)]=\begin{cases} \frac{...
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2answers
141 views

How exactly does a basic EMF sensor work?

Halloween is coming up, and inspired by the simplicity of this project, I'm asking for a more technical explanation (and / or resources to do that) - this seems to be either missing or too obvious to ...
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9answers
2k views

Why doesn't wireless transmission and reception require a common reference voltage

so I have been struggling with this for a while now. I have tried to search for the answer but haven't succeeded yet. Here is how it goes: If we take USART as an example for wired communication ...
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1answer
117 views

Is Lora maximum transmission 1 km in real?

I'm new to wireless communication and Lora. I'm using Lora Ra-02 and Arduino UNO and small 800 Mhz antenna. I'm using Arduino website library. How can I increase that range? What do I need to do to ...
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0answers
7 views

MIMO suitability for CP-OFDM and DFT-OFDM

Is CP-OFDM more suitable for MIMO than DFT-OFDM? In both schemes orthogonal subcarriers are modulated directly by symbols and by the DFT of these symbols respectively, so I was wondering if MIMO ...
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2answers
70 views

Mechanism of conversion of electrical energy to EM energy in LEDs

I've always been intrigued that electrical energy can just disappear out of a circuit 'into the aether' as RF. Of course thinking about it, some energy 'vanishes' as EM radiation even in a filament ...
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2answers
62 views

DIY Antenna with minimum components for proof of concept

I am going to try a simple transmitter-receiver(assuming receiver circuit is same) circuit using the following circuit: Now, I have got the BJT part and the LC oscillator part figured out. What I ...
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3answers
115 views

TV remote mystery

My TV remote has this hole. The hole exists for the propagation of the EM waves coming from inside the remote correct? I guess plastic would absorb those EM waves and we don't want that to happen. ...
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0answers
15 views

WCDMA , 8PSK signal, 3 G , user end sensitivity, required SNR

Does anyone know how the User End receiver sensitivity for a 3G WCDMA, 8 PSK signal is calculated? and what is the typical SNR required to detect the signal?
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2answers
84 views

Wireless Time Synchronization Project

I am part of a team project involving baseball where we would like to determine whether a runner stepped his foot on the base (first base, for example) before or after a fielder (the first baseman) ...
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0answers
13 views

WCDMA equalization and filter ripple

WCDMA uses the rake receiver for equalization, this necessitates that the multipaths need to resolvable, i.e. longer than the chip period if a SAW filter is used in a receiver, what are the chances ...
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0answers
22 views

How do I know more about the 3GPP release version info with decimal numbers?

Can someone help me understand the decimal numbers in the 3GPP release here after 12? This is an example. Intuitively I can tell they are incremental releases, later ones have higher numbers after ...
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2answers
67 views

Communication within 5-10 meters: RS-485 or Wireless?

As a follow-up for my previous question, can anyone please recommend for my application (communication between two floors of a building) as whether to use RS-485 or any wireless technique (I am ...
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4answers
214 views

How can we interpret the negative side of a double-sided frequency spectrum

We know that a frequency spectrum includes both positive and negative frequencies. However, how can we explain the negative frequency physically? For example, in a wireless communication system, ...
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0answers
21 views

Create a log file using Blynk server

I'm working on a project to turn on and off an LED using my phone (android OS). I use DOIT ESP32 devkit V1 board hich is connected to an LED and is controlled by Blynk app via Wifi. I want to ...
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0answers
30 views

GSM Interference - SIM800L

I did a GSM based alarm system using SIM800L modules.One is transmitter & the other one is receiver.When the transmitter button pressed it will make a call to receivers number & receiver ...
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1answer
80 views

What is the difference between capacity and throughput in context of wireless/cellular communication?

From what I understand: Throughput tells you how much data was actually transferred from a source at any given time Bandwidth tells you how much data could theoretically be transferred from a source ...
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1answer
61 views

Control DOIT ESP32 DevKit V1 using Blynk app

I'm a beginner and I'm working on a project to light an LED using DOIT ESP32 devkit v1. I want to turn on and off the LED using a phone app via wifi (using Blynk application). I'm using the following ...
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0answers
52 views

Feedback on 2.4GHz RF circuit design

Looking for some feedback on this RF feedline and antenna area. Starting from the MCU pins, we have: Murata RF connector with integrated switch (MM81302600) - for inserting the VNA and tuning the PI ...
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1answer
17 views

LTE, downlink multiple antenna channel estimation with and without Channel State Information (CSI)

In an LTE downlink with CSI at the transmitter, is the radio Tx in the base station and Rx at the user end hardware part of the channel estimation? example: Tx to Tx and Rx to Rx isolation between ...
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1answer
47 views

Circuit for selecting between PCB antenna and external

I'm just developing the second iteration of an 2.4Ghz sensor and receiver set. Because I can't afford the expensive development path of a big commercial project and because the environment these ...
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1answer
54 views

I'm completely new to electronics, can I make a wireless keyboard wired?

I lost the dongle to an old wireless keyboard, can I make it wired?
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0answers
27 views

Spatial receive diversity and antenna coupling

Spatial Receive Diversity works best if the receive antennas are not correlated, i.e. if each antenna sees a different wireless channel. MRC ensures that in case of 2 antennas for example , the 2 ...
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1answer
46 views

Wireless tagging for beginners

I will preface this question with a caveat: I'm a reasonably talented programmer, but an absolute novice in electronics. This will be my first project. My dad has a 1/19th scale model railway. I'd ...
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1answer
45 views

Can you have “directional” wireless power transmission (to power an LED)

I've tried to research this, but the only circuit examples I can find use an "oscillating field". I have a project where I would like to put two differently colored LEDs in an object, and ...
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1answer
30 views

MIMO relationship with OFDM and why are the two that much linked to each other?

Why is OFDM the most suitable waveform for MIMO. Does anyone know of a paper or text book that clearly answers this simple question? I looked into a book titled "MIMO-OFDM Wireless ...
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0answers
74 views

Analytically understanding wireless power transfer

https://youtu.be/M8aZoM9p43k This YouTube link shows a experiment I quickly made. Two resonant lc circuits that use magnetic fields to wirelessly light up a led. I manually found the best frequency ...
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2answers
44 views

OFDM , cyclic prefix

If OFDM did not have a cyclic prefix or zero padding would have equalization of the individual sub-carriers been possible in the frequency domain?
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22 views

Spatial multiplexing MIMO, antenna critical spacing, antenna isolation

How does antenna isolation affect single user spatial multiplexing MIMO performance? Text books talk about a critical antenna spacing in a rich scattering environment of 1/2 of the wavelength. Would ...

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