Questions tagged [interference]

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

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7
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2answers
521 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 ...
0
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0answers
211 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 ...
0
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0answers
69 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 ...
1
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1answer
38 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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0answers
40 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
1k 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 ...
0
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1answer
48 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 ...
33
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2answers
20k 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 ...
0
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0answers
69 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 ...
1
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1answer
192 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
58 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 ...
0
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1answer
128 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 ...
0
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3answers
250 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. ...
0
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1answer
66 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 ...
2
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1answer
79 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 ...
2
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2answers
106 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 ...
3
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1answer
160 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, ...
0
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1answer
206 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 ...
0
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0answers
67 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 ...
1
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1answer
78 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, ...
0
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1answer
675 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 ...
3
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1answer
165 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 ...
1
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1answer
224 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 ...
1
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2answers
48 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 ...
0
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1answer
48 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 ...
0
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1answer
147 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 ...
1
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2answers
109 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 ...
2
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3answers
116 views

If a PEC surface completely reflects an EM wave, why doesn't an ungrounded shield work?

I was thinking about shielding and its effectiveness. An ungrounded shield doesn't work well for either inductive or capacitive coupling. However, if you think about plane wave theory, a PEC surface ...
0
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1answer
122 views

Can wax really improve the performance of a FM transmitter?

Why would the use of wax improve the performance of a FM transmitter? Consider this from the video How to build a FM radio transmitter, at 4 min 14 secs: "Theoretically this helps decrease onboard ...
1
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1answer
87 views

Individual Three Phase Potential Transformers vs Three Potential Transformers in one case

If I had to select between Individual Three Phase Potential Transformers vs Three Potential Transformers in one case for a 600V system (which doesn't require many inches of spacing between phases to ...
1
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1answer
65 views

Interference from well pump pressure switch and microcontroller

I am using the Parallax Propeller to start and stop timers for an auto racing timing system. Out of 250 cars there were timing issues with about 10 or so. It was very random and hard to diagnose. I ...
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2answers
105 views

Is this quote about interference from wireless charging coils accurate?

This blog post suggests that apple dropped their promised AirPower wireless charging mat because it didn't pass EMI standards, specifically due to the (unconfirmed) idea that they were using a large ...
1
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0answers
45 views

Using a switching DC-DC converter in high dynamic range current/voltage sensing

I'm thinking of making a power meter circuit which will have a high-side current-sensing amp (LTC6102), a resistive voltage divider for sensing the voltage, a dual op-amp (OPA2365) as a buffer for the ...
2
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0answers
122 views

Weird SWD debug port behaviour

Today I have started to encounter strange problems with SWD debugging. The debug only works if I keep my finger on the SWD pins. To be more interesting I have the same problem with the boards I was ...
1
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4answers
76 views

How is electromagnetic interference possible when measuring voltage difference?

This question is primarily concerned with audio but it's probably applicable to other areas as well. As far as I understand, EMI is caused by electromagnetic waves adding power to wires as they ...
0
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1answer
65 views

Wireless phone chargers in a lab environment? [closed]

We are talking about devices that are designed to pump out quite a bit of power in the MHz. Admittedly the chips have comms protocols so they don't spew all the time, and the resonant circuits are ...
1
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2answers
157 views

Shield grounding location for an STP cable in a balanced system

If a balanced source or driver is coupled to a differential balanced receiver via a balanced STP cable as shown in the hand drawn illustration below: in such case I have read that grounding the ...
0
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0answers
420 views

Grounding the components of a DIY cnc machine

I'm in the process of building a DIY cnc machine. It already runs, but I noticed it has some interference problems (steppers act weird on occasions, the full graphic smart controller LCD has trouble ...
1
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1answer
86 views

Heaphone amplifier PSU noise

I built myself a headphone amplifier using the LM49600 and a PGA2310 for volume control. This part of the circuit is fairly standard and I don't think it's the problem. I wanted it to be powered by a ...
0
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1answer
56 views

Standards for conducted EMI testing

I have some doubts to interpret the CISPR standards, one of them is in relation to the test environment for EMI conducted (150kHz up to 30MHz). The minimum size indicated for the vertical or ...
0
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0answers
192 views

How to reduce spike in Power Supply and GND (SCR + Ignition Coil)

My circuit: Signal coupled in power supply (3.3V) of STM32F103 during spark: Is there any benefit to using this diode (circled in red) or not (without this diode the snubber circuit will start ...
0
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1answer
99 views

How to conclude the necessity for unbalanced to balanced signal conversion for this scenario?

This is a bit specific system related question about simultaneous data-acquisition for several transducers. Therefore hope you don’t mind for the long intro and the question. It would be too implicit ...
0
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1answer
464 views

What could be causing this interference and how to eliminate it?

(update: Please also see the major edit at the end) A sensitive electronic equipment Device 1 below is basically composed of a power line EMI filter at the mains entry, an SMPS power supply which ...
1
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1answer
62 views

Question related to the interference seen at the spectrum analyzer's receiver

I am preparing for the RF course exam. I have an old question on hand that I am trying to solve. Please review my attempt. Question: A simple spectrum analyzer with superheterodyne receiver ...
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0answers
85 views

Electro magnetic interference with Arduino Uno and a portable radio

I'm surprised when I'm working with Arduino Uno, by just sitting beside a portable radio, like when I was powered on both Arduino & Radio and when they are close to each other I got some noise ...
1
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2answers
184 views

How to connect a switch to a microcontroller in an extremly noisy environment

I'm currently working on redesigning the control circuit of a CNC machine (more specific: an Isel milling cutter). Only the digital part will be of interest, I'll keep the old power electronics (motor ...
0
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1answer
57 views

Why are inductively coupled RFID systems put in certain frequency bands when there are no EM waves used?

LF - 125 kHz HF - 13.56 MHz Those frequencies refer to the magnetic field that is used to induce a voltage in the transponder. Can the magnetic fields actually interfere with EM waves in the ...
4
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2answers
1k views

Long wires causing Raspberry Pi to die?

I've been working on a simple project involving a Raspberry pi and some switches. I would never thought I would have any problem for something as simple as a switch, but here I am. The 2 wires from ...
0
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2answers
83 views

Influence of copper thickness on interference between PCB tracks

Explanation : I have designed a PCB for motor control. On this PCB there is a power part and a logic part. The power part is composed of MOSFETs, MOSFET drivers, hall sensor for current feedback and ...
3
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1answer
118 views

GSM Interference with Meanwell Switch mode PSU

I am having trouble with interference from a GSM modem and my switch mode PSU. I do not know much about interference and how the radiation patterns works for GSM. Below is an image of the circuit ...