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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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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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125 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
104 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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4k views

Why does WiFi have a shorter range than LTE?

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
86 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
65 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'...
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24 views

What is the difference between Antenna port and Physical Antenna in LTE?

I have just started working on the 5G NR physical layer and I have difficulty understanding the concept of Antenna Port at the downlink. In release 10 there supposedly 15-22 antenna ports for CSIRS (...
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2answers
61 views

RF range at 169 Mhz

I'm planning a sensor network for agriculture (that apparently doesn't exist yet in this form) and I'd like to understand the possibilities of the radio link. A good number of in-the-field soil ...
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2answers
90 views

Cheap Low Power Signal Transmission To Smartphone

For my university project I'm making a certain sensor which has to (one-way) communicate with a smartphone. The sensor needs to be as cheap/simple as possible (aiming at +- €0,50 in total) and only ...
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1answer
42 views

relay control with network and sms with main controller [closed]

I need this project for a melting plant. There must be two relays in the control (connected to the device), so if one of them is in trouble, another will work to disconnect. In the (current check) ...
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0answers
22 views

Wireless RPM Sensor

I want to build wireless RPM sensing circuits. Currently I am using PLL and multiplier for sensing the rpm... Now as circuit is to be wireless I am looking for some single chip that has in built ...
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2answers
83 views

What software use to hack wireless protocol ( logic analyze ) USBee

Q: What software do you use for logic analyze? Why: I try to hack(reverse engineering) my home wireless heating system control to make my own central control unit. Wireless: My heating system uses ...
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2answers
63 views

Keyboard wireless feedback from computer

This is a theoretical question. I want to ask, is the the modern keyboards communicate with PC such as wireless keyboards can 'get/read' some data from the PC? If not, what do I need to do for that? I ...
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1answer
66 views

Wireless communication [closed]

We are planning on making a wearable device for a group of ~40 people. What we would love to get some input on what kind of wireless technology is best fitted given the following requirements: The ...
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1answer
40 views

Can this ESP wifi board's firmware be rewritten?

I'm new to all this node mcu thing. I'm searching for relay shields because they're ready and well soldered, so I can put them into my light switches with no effort. I've found this pack which ...
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2answers
777 views

Question about sentence in application note: “incremented modulo-256”. Request explanation and clarification

Context: I am reading an application note for a UWB transceiver. In it they are describing the typical message frame format, in accordance with IEEE rules. There is some wording that is confusing me ...
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1answer
35 views

Nrf24l01 module works on breadboard but not on pcb

After using a breadboarded nrf24l01 for more than a year, I decided to shrink it and have it on a pcb using the wiring diagram exactly used in the breadboard. I am attaching the pictures of the first ...
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1answer
62 views

How is the signal Multiplied with the Carrier in AM

In wireless transmission, via Amplitude modulation, we multiply the message signal by a carrier wave to get the modulated signal $$x(t) = m(t) \times cos(\omega t)$$ Where \$m(t)\$ is the original ...
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1answer
48 views

Why no IEEE 802.11 version use 24 GHz ISM band?

IEEE 802.11 aka WiFi uses multiple ISM bands to transmit data,2.4,5 and 60 Ghz.The 24 GHz was never used in WiFi,why? Why did they jump from 5 to 60 and ignored 24? Why no wireless standard use this ...
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2answers
64 views

Understanding PLL performance: PFD output bandwidth

For an application I need to FM modulate a signal with a 10 MHz bandwidth. Due to constraints I have no control over, I have to do it in an analog way (so I can't just digitize the signal, IQ modulate,...
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1answer
113 views

How does cellphone idle time work?

Imagine a basic cell phone which operates in only 2G network and able to provide voice call & SMS service. Does this cell phone transmit any data to BTS in idle time (that is when the cell phone ...
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0answers
76 views

Can this push pull oscillator improved for experimental realization?

I am using the following push pull oscillator circuit is extracted from this Application Note for implementation of a wireless charging system. In simulations, it's efficiency is above above 85% when ...
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2answers
181 views

Are IOT wireless network protocol right for high throughput point to point communication?

I am trying to build a "professional" 2 way point to point radio system (like this) to control a RC 1/10 scale car (like this ) using UART, the challenge I am currently facing is finding the right ...
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1answer
42 views

Bluetooth headphones pair to some unknown device. Can't pair to my source [closed]

Apparently, there's some BlueTooth source in the building with a policy of "pair to everything". I am NOT able to find that and snap its neck off! For the headphones: I use the "restart" procedure, ...
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2answers
49 views

Antenna Design for Omnidirectional transmission

I have been working on a custom drone for quite some time now. One thing I have found an issue with is the remote control antenna orientation in relation to the drone. In some directions I will get ...
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1answer
69 views

Inside of 2.4 GHz Dipole Antenna

I bought the following dipole antenna: Now I want to add some extra simple reflector and directors next to this dipole to construct a Yagi-Uda antenna. For this aim, I need to know where is its ...
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46 views

What is the “minimum” transmit power for uplink cellular transmission

Can anyone help me in finding a good reference for minimum transmits power for uplink cellular transmission? is 0 dBm a good enough power for very low-power transmission in an indoor environment? ...
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2answers
60 views

Tiny Wireless Remote Kill Switch

I attached a tiny electric motor and battery to a small balsa wood glider. I'd like to add a tiny remote kill switch, with a range roughly around 20-40 meters. A switch that requires line-of-sight ...
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1answer
23 views

Connecting a Lithium battery directly to the GSM module

I have a GSM module (M66 from Quectel) and a single cell Lithium battery,Based on Datasheet module operated in the 3.3 ~ 4.6 V and as I know battery deliver 3.7 ~ 4.2 V based on it's sate of charge....
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1answer
54 views

What is the difference between SNR of a wideband system and the SNR for a narrowband system

I was reading Wireless Communications by Andrea Goldsmith in the book the author has stated that the Noise power for a wideband system with Bandwidth B is (B*N/2). Could someone help me understand why ...
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5answers
405 views

Is there a wireless protocol for 100m-1km range in rural property?

I am an electornics hobbyist. A friend of mine, who is building an organics farm, wants to wirelessly automate some devices in his property, and asked for ideas. His problem is to "talk" to remote ...
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1answer
53 views

Replacing Antennas for Wireless Communication

I have been working with NRF modules for some time now. I have been using the 100m rang version as shown here. They are working great but I want to increase the range, so I have bought the PA + LNA ...
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1answer
46 views

Wireless radio reception power vs distance

I found a PDF online that says: The diagram shows that one unit of power is required to achieve a given data rate over one unit of distance. But to maintain the same data rate over x the distance, ...
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1answer
157 views

What is the difference between inductive coupling and resonant inductive coupling?

The resonant inductive coupling is better than inductive coupling, the difference between them, is that resonant inductive coupling use the "resonance" in their favor. But what is the difference in ...
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2answers
160 views

How does the diagram really work? [closed]

Good afternoon, I am a high school student and in my scientific fair project, I would like to do an experiment about wireless energy. I want to implement the resonant inductive coupling. According ...
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2answers
47 views

Small wireless high temperature sensor

I'm looking for a wireless, relatively small (think a quarter dollar size) temperature sensor capable of withstanding and measuring temperatures up to 600 °C (1100 °F). It is going to be located ...
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1answer
49 views

What is rapid signal attenuation?

Attenuation describes the weakening of the signal as it travels from the transmitter to the receiver. However, this textbook describes a concept called "rapid signal attenuation" as a way to allow ...
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2answers
49 views

CC1101 Transceiver pair not working when relatively close to each other

I have a pair of cheap CC1101 boards transmitting at 433MHz. (1): One oddity that first led me to believe that they weren't functional is the fact that they do not receive data when they are within ...
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2answers
46 views

Alimented coil close to a passive coil

If I build a coil A, of 10cm height with iron core and a 4cm diameter, and alimented it with a DC 15v,6amp source, it will produce a magnetic field. Let’s say A is set vertically. Will building ...
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2answers
86 views

What are the different antenna types used by various IEEE 802.11 standards?

I've been working on an assignment about the IEEE 802.11 standards and I've had some trouble with one aspect of a question. I need to explain the differences between various features of the different ...
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2answers
46 views

Determine current consumption of XBEE [closed]

How to determine the current consumption for a device like xbee? which draws 120mA current when transmitting only.Rest of the time it takes 1mA. In our application the xbee transmits 5 packets per ...
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3answers
130 views

Why is wireless power transfer done between two coils at their self-resonant frequency?

I was reading this paper about wireless power transfer via strongly coupled magnetic resonance: http://www.ijirem.org/DOC/1_Wireless%20Power%20Transfer%20via%20Strongly%20Coupled%20Magnetic7a7f01ee-...
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0answers
30 views

Low coupling capacitor of a SEPIC / ZETA / CUK for Wireless Power Transfer using coupling capacitance

I am studying a converter, which is a modified version of a Buck-boost, which is basically a SEPIC converter with very low coupling capacitance. The low capacitance comes with the need of wireless ...
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1answer
43 views

Emulating a Doppler Test under laboratory enviroments

Background I intend to test the Doppler effect of LoRa. To do so, I actually had to drive a vehicle at varying speeds ranging from 40-110 kmph at different places on the country while using a low ...
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2answers
55 views

Does multipath apply to sub-1kHz signals?

Based on my (currently naive) understanding of EM field propagation, it would seem that in the near field (e.g. <10m), low frequency (e.g. sub-1kHz) signals would be oscillating so slow such that ...
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2answers
34 views

what is the performance of an OFDM system in one-path channel (Flat response channel),with no multi path propagation?

i work on modelling a OFDM system in a indoor optical wireless channel (LOS channel), since my channel is LOS there is no multi -path propagation , so the delay spread of my channel is much smaller ...
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3answers
285 views

How is the phase of a local oscillator synchronized to the carrier for demodulation?

How are phases of a wireless TR/RX pair synchronized for coherent demodulation? I understand PLLs will match the frequency of the local oscillator to the carrier via maintaining a constant phase ...
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32 views

What resistors and capacity do I need for TSOP382 IR Sensors?

I already asked in the RasPi section because I'm using my IR sensor with one but they told me I could get more specific answers here. That's why I ask here again 😀 I'm interested in the correct way ...
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0answers
151 views

LTE UE REPORTED CQI - Defined by RS-SINR or by Transport Block Mapping?

First than anything, let me assure you I am fully aware that no one REALLY knows HOW UE manufacturers specifically implement the CQI reports sent on the UL, but there should certainly be a better ...