Questions tagged [interference]

For questions about electromagnetic interference (EMI); see also the [emc] tag.

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84 views

If antennae work best at full, half or quarter wavelengths, why don't received signals at 1, 1/2 and 1/4 wavelengths interfere with each other?

How does a simple radio receiver-antenna differentiate between incoming wavelengths that are the same wavelength as the antenna, one-half and one-quarter? Or would I just hear static unless I have a ...
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33 views

Separating mains power from data lines

I'm an electronics hobbyist who's learning from wiring stuff together and searching the internet if something doesn't work. Hence my electronics knowledge is very patchy. I recently found out that ...
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1answer
20 views

Measure antenna S11 next to another source

I have a dipole antenna designed to work on ~800MHz and 2.44GHz frequency, and a miniVNA Tiny USB device that I can use to measure return loss of the antenna. I connect the antenna directly to the DUT ...
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1answer
35 views

Mesh Wire opening size for emi filter at frequency of 30Mhz

I want to use a mesh wire and I wanted to know how do I calculate an opening size of a mesh wire that can filter 30Mhz frequency. Your help is appreciated.
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26 views

ADVICES required PCB Design for domotic system using Odroid + STM32F103C + Different devices

I'm designing a PCB to connect all the devices I use for a domotic system together. I have a few general questions about it and I would like to hear some recommendations to improve it as I haven't ...
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1answer
41 views

How to eliminate electromagnetic interference when counting pulses using a micro controller?

I have written a pulse counter program for ESP32 micro-controller, the counter counts the pulses correctly when there is no EMI interference but as I turn on the small AC drill machine the counter ...
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1answer
29 views

Power interference when turning on speakers, causing monitor to go black

I have a small 2.1 external speaker system that I use with my laptop. I also have an external monitor that I use with the same laptop. Almost every time I turn on or off the speakers, the external ...
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2answers
66 views

How can picked up FM noise be demodulated?

I have a set of cheap computer speakers, which happens to use a TDA2822M. Its circuit is almost identical to the example circuit from TDA2822M's datasheet. It's USB powered and has no shielding. I ...
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0answers
39 views

Isolated step-down module for powering a Raspberry Pi from a speaker's 12V supply avoiding ground loop and interference

I have an older speaker with an iPod dock that I would like to extend with a Raspberry Pi as a streaming music player. At first, I tried powering the RPi from the dock connector with a Micro USB ...
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2answers
89 views

How exactly do inground electric dog fences work? I need help making a square perimeter with one side that dose not trigger the collar [closed]

I need help laying out an in ground electric dog fence in a square formation with one side of the square not triggering the collar. The issue it that the manufacture says that inorder to do that we ...
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1answer
50 views

Bluetooth and Wifi range onboard a boat

On my sailboat the range of wifi and Bluetooth appears to be very much shorter than in my home - I can't figure out why. ex1: At home I can stream video with Miracast from my basement to a room ...
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1answer
36 views

How do LTE radio networks deal with co-channel interference?

In 802.11 Wifi, I've read that a wifi adapter (like my laptop's wifi adapter/radio) will use Energy Detection to see if a channel is busy (if a certain energy threshold is detected on the channel, it ...
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1answer
39 views

Automatic mute radio on power-off [closed]

I have a small FM radio module I bought off eBay that runs off a few AA batteries, and have it essentially plugged right into a pair of PC speakers I have on all the time. To save battery power, I ...
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1answer
54 views

How many WiFi networks can operate concurrently?

Very hard information to find since Google always falls down in how many devices can be connected simultaneously to a single one network. Is there a limit to how many different WiFi networks can work ...
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1answer
115 views

WS2812b interference and bootup behavior

TL;DR: how can a slowly rising power supply voltage on an arduino crash the WS2812bs connected to it? How can I protect a signal wire even better from electrical interference? This my question in a ...
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3answers
177 views

What happens to parts of induction cooker magnetic field not covered with the pan?

An induction cooker works like this. There's a flat coil of wire under the cooker surface which is connected to a source of high frequency AC and it produces an oscillating magnetic field with field ...
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0answers
16 views

Downsides of Extending a USB Bluetooth Antenna?

I found an interesting video about how to extend the range on a USB Bluetooth antenna by resoldering a new antenna in its place: (https://www.youtube.com/watch?v=cwKWOdOHiWY). I'm planning on using a ...
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0answers
42 views

Prevent Reception from an Extended Distance (Beyond Design)

I have a magnetic field that is being induced onto a power line by a transmitter, which is following the length of the power line to the receiver. The receiver communicates via a loosely coupled coil ...
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5answers
336 views

Waves on raspberrypi camera feed, Ground loops? electrical interference?

I run a video recorder in a vehicle built on Jetson Nano (Very Similar to raspberry pi). It runs on 5V . The vehicle has a 24V power supply. I power the video recorder with an automotive-grade 24V to ...
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2answers
109 views

Fixing power supply interference issue (?)

I am working on a project that involves controlling WS2812B led strips using a Teensy 4.0 microcontroller. I got everything working during the testing phase, but now, after transitioning from ...
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0answers
74 views

How to prevent common ground circuits messing with each other

I made an Arduino based 18650 battery tester that has 4 identical circuits that charge and drain. Testing one battery at a time gives one set of results which I deem to be correct but testing more ...
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2answers
443 views

What's this noise?

As in other years at precisely this time I'm experiencing an effect somewhat like GSM frame-rate audio breakthrough in my auditory systems - completely different frequencies but equally wideband. I've ...
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0answers
83 views

Radio static caused by windscreen wipers

I was driving past a radio station transmitter of the radio station I was listening to. I turned on my windscreen wipers, which caused a noticeable static to be emitted through the speakers for the ...
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0answers
67 views

Experimenting with a Walkie Talkie

This is one weird bizarre thing which I noticed while I was in the electronics lab. I had this Power Supply and a walkie talkie similar to this I have not ventured in RF side yet. The power supply ...
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1answer
37 views

How to conclude the nature of interference for such scenarios?

This is abit a hypothetical question. Imagine a signal chain where a AC-DC power supply is powering a transducer and the transducer output is coupled to a data acquisition input by a BNC cable. Or I ...
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34 views

Touchscreen keeps failing to communicate with raspberry pi, except when I touch the INT pin

I bought a display with a i2c touchscreen from Aliexpress and hooked it up to my Raspberry Pi 3b+. The screen part works fine, however, the touchscreen part is flaky. When I just boot the pi, the ...
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3answers
411 views

2.4GHz WiFi module causing interference on 433MHz RF receiver module

I have a prototype board which has two RF modules on it, a 2.4GHz Wifi module (ESP-01) and a low cost 433.92MHz RF receiver module (Wenshing RWS-371F-6). My 433MHz transmitter (a remote control) sends ...
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0answers
24 views

Can these SPICE models be used to compare single ended versus 4-20mA current signals?

I want to compare the environmental or common mode interference effect to current vs voltage signals by using two different transducer types current and voltage respectively. Below I compare two ...
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1answer
43 views

PCB with 5 Pluggable RF modules and 1 LTE puggable module - will it cause issues for reception at different antennas?

I am designing a prototype PCB which shall have 5 pluggable RF modules and one 4G LTE module as shown in the image The Base board size shall be 240 x 140 mm, RF board size is 40 x 50 mm and LTE board ...
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2answers
9k views

Does Bluetooth interfere with WiFi?

I've read that WiFi b/g/n is using 2.3995 to 2.4845 GHz. Bluetooth is in between: 2.4000 to 2.4835 GHz. So what will happen when I put a Bluetooth sending device next to a WiFi sending device? Will ...
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0answers
27 views

Voltage variation and electrical fields Maxwell Equations

I actually know without knowing the reason or the mathematical expression of the physical phenomenon, that if we apply accross a capacitor a voltage which varies in function of the time, it produces ...
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0answers
41 views

Hall effect current sensor and proximity to EMI

I am preparing to layout a PCB. I have an ACS723, that I want to use to sense the current going through a relay. In addition to the relay I have a Meanwell IRM-12-20 to supply ac to dc voltage to the ...
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1answer
103 views

DC brush motor EMI

What kind of frequency does a DC brush motor generate? There are a few explanations online as to what causes EMI in DC brush motors (commutator sparking for example) and how to reduce it, but no ...
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0answers
41 views

How far does a PCB antenna need to be from a capacitive sensing touch button?

From my basic understanding, capacitive touch works by having a small voltage applied to a touch plane on a PCB, resulting in a uniform electrostatic field. When a conductor (human finger) touches the ...
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1answer
96 views

Can two Radar motion sensor, running next to each other, result a false detection?

I have two CDM324 Radar motion sensors. I want to run the two sensors close to each other. The transmitted frequency is roughly 24 GHz and I am afraid that a small shift in one sensor transmitted ...
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3answers
193 views

I2C noise from 433MHz transmitter

I have built a little thermostat based on BMP280 temperature sensor over I2C, ESP8266 Lolin v3 and STX882 433Mhz transmitter. I have not added additional pull-up resistors or decoupling capacitors. ...
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1answer
53 views

Calculating Capacitance / Rolloff Frequency for Across the Line RFI Supression

I’m in the process of restoring my first All American Five (AA5) tube radio – in this case, a GE Model 115 from the late 1940s. As I’m getting ready to order replacement capacitors for it, one of ...
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1answer
72 views

ADC signal close to D+/D- signals layout suggestion

My circuit is laid out in way so that the analog front end is on a different pcb than the MCU board. The two PCBs are connected with a vertical connector of which 4 pins are used to transfer two low ...
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2answers
83 views

What's the suitable wire size for 9VDC @25 Amps line?

I am trying to put together the requirements for a cable and I was wondering what would be the most suitable wire size to load the DUT with 25Amps @ 9VDC. I will have few other high current lines ...
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1answer
114 views

When are 1:1 baluns worth it?

I am trying to build an antenna to connect to the GOES-16 satellite (downlink at 1690,1MHz, linear polarization) with my SDR. My plans are using a 1m offset parabolic dish with a BiQuad feed, ...
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1answer
145 views

Can an isoSPI interface work without isolation?

Ive got a LTC6820 that I will be communicating with a LTC6811 and they both use isoSPI but all the example diagrams show the connections going through a transformers and twisted wire like this: But ...
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0answers
51 views

How to measure noise on an antenna in system

I am working on an antenna based RF receiver (AM/FM radio) that appears to be picking up interference from other parts of the circuit. I want to view the noise spectrum, but the receiver chip doesn't ...
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1answer
70 views

Where to place RF shield

I'd like to put a pump drive circuit similar to the one shown below on the same PCB that has two I2C devices, a GPS module, seven analog signals, an ESP32 MCU transmitting WiFi via a trace antenna, ...
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1answer
529 views

Brushless motor back and high current and IC

I'm trying to replace the brain of my neato vacuum which is broken. I've already repair a cleaning MOP but with this one I have a problem with the brushless motor which is throwing some party fun in ...
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1answer
96 views

Radar and Standing Waves

I have a doubt about the working principle of a simple Radar. Consider a stationary object, which does not move with respect to our transmitter. We send an electromagnetic wave to it, and it will ...
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1answer
173 views

SPI interfering with ADC sample

I'm attempting to record 8-bit/8kbps audio to an SD card using the samd21g18a microcontroller. I'm having an issue where the ADC sample value drops whenever the SD card is being written to. This ...
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2answers
44 views

Adjacent Signal Selectivity: Section 6.1 of ETSI EN 303 372-2 (RED testing). Bad procedure/standard?

I'm doing pre-certification testing to ETSI EN 303 372-2 V1.1.1 (2016-04), specifically the Adjacent Signal Selectivity test in Section 6.1. I am a Systems engineer with lots of experience designing ...
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1answer
42 views

Unexpected audio signal interference with camera recording

When watching this video I noticed that low audio frequency creates a visual ripple effect. I'd like to know how this is possible. I guess this can't be due to software smoothing of whole-camera ...
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1answer
107 views

Thin CAT6 cable - RFI problems?

I have got a short length (1m) of standard fat CAT5 shielded cable that runs inside a piece of equipment before the signal exits via a bulkhead connector to a PC. It's the old kind that is a real pain ...
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2answers
102 views

MAX 485 performance

I wanted to test the performance of MAX485 drivers. I set up one driver and one receiver 2-3 meters apart. A 100 Hz square wave was being sent down the line. Roughly in the middle of the cable I put a ...

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