44 votes
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Does Bluetooth interfere with WiFi?

Yes, WiFi and Bluetooth can disturb each other. But both are equipped to handle that. A standard that is not capable to handle disturbance and/or interference will simply be unusable under many ...
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39 votes
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Is it possible to jam wireless home alarm systems?

A "denial-of-service" wireless attack is very easy. It will disrupt radio communication between sensor and panel. Hopefully, the panel is smart enough to detect that one (or more) of its sensors has ...
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26 votes
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Why are many IR receivers in metal cages?

[ added 2_D resistor_grid methodology for exploring shielding topologies ] You want that IR receiver to respond to photons, not to external electric fields. Yet the photodiode is a fine target for ...
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22 votes

Does Bluetooth interfere with WiFi?

Wifi uses a listen before transmit system. If the channel is busy, it holds off transmitting. Eventually it gets through. Each channel is fixed. If it tries to use a channel that is busy, from ...
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  • 71.2k
21 votes

Is it possible to jam wireless home alarm systems?

First of all, to clear some things up: All digital signals are built up by analog signals. As already mentioned in the comments, all wireless communications can be jammed, encrypted or no. And last ...
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  • 3,777
16 votes
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Why do cell phones sometimes interfere with amplifiers

The usual problem with interference from GSM cell phones is caused by rectification of the strong RF signal at the semiconductor junctions at the input of the amplifier. GSM uses Time Domain ...
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13 votes
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50MHz SPI PCB routing, use vias or resistors?

SPI bus at 50MHz can easily run a couple of inches thru a few vias without hitch. Wavelength of 50MHz is 6 metres but realistically because fast edges are used you need to think ten times faster. Even ...
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  • 389k
11 votes

Radio static due to neighbor's shredder

Take a look on the bottom or back of your radio. You should see something about FCC rules Part 15: (Source) In particular: This device must accept any interference received, including interference ...
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9 votes
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What are some quick, cheap hacks for determining the source of EMI in my house?

A yagi antenna and a cheap SDR might be good to play around with. Make sure the antenna and SDR work in the frequency range of interest (so if you want to look for wifi signals, then the antenna and ...
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8 votes

50MHz SPI PCB routing, use vias or resistors?

From the comment "Could you please explain how your loop was created? Through an answer with some pictures? It would be helpful to know." Erm. It's embarrassingly boneheaded actually. I don't have ...
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  • 2,568
8 votes
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Wireless Home Automation 2.4GHz versus 433MHz

Putting this in an answer just because it's easier to type here. I did a similar automation project at home like you describe, so I'll share how I felt when the project was finished. I did custom ...
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8 votes

Does a twisted pair cable radiate more EM radiation than non-twisted pair?

Yes, it is vice-versa, through the principle of reciprocity. Any "antenna" is just as (in)effective at transmitting as it is at receiving, so the advantages of twisting the conductors together apply ...
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  • 165k
8 votes
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Long wires causing Raspberry Pi to die?

The wire has inductance and, the longer the wire is the more inductance it has. An inductance likes to maintain the current flowing through itself so, when your switch opens, the small stored energy ...
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  • 389k
8 votes

Radio static due to neighbor's shredder

The dipole antenna connected to the Bose Wave Radio might have a pretty good null off the ends. Since your neighbor is in the apartment above you, it's worth a try using that null to reduce the ...
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  • 3,195
7 votes
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2.4GHz Wi-Fi interference between devices in close proximity, even though they're using completely non-overlapping channels?

It depends on the internal architecture of the receivers in each box - these are designed to match a specification and down to a price. A radio receiver has two functions - selectivity, and ...
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7 votes

Dealing with signal noise over 50 foot communication link

Single-ended signalling is the source of your troubles. Differential signalling will drastically improve crosstalk and noise. RS-422 would be an appropriate choice. I2C is not ideal, as its ...
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  • 8,484
7 votes
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Why is an HDMI signal causing interference with Over-The-Air digital television?

ATSC is an all digital feed. As such math, can be used to compensate for weak and / or corrupted signals. This can be done to such an extent that the recovered data may be indistinguishable from the ...
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  • 3,100
6 votes
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How to shield for electromagnetic interference (DIY level)?

I'm not entirely surprised that you've got pickup. You've got wires hanging all over the place. I'd suggest two things to do: 1) Twist your phototransistor wires (blue and yellow) together to form a ...
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6 votes

Will the data throughput decrease if the transmitter and receiver are in motion?

I don't know why everyone else is focusing on the carrier frequency. The data throughput is a question about the modulating frequency (i.e., baud rate). The Doppler effect applies to modulation, as ...
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6 votes
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433 MHz RF noise problems

Are you using such type of modules? If yes, then don't expect them to work without proper software noise filtering algorithms. This module will give out data at Rx output even if there is no other ...
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6 votes
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Transformer vs capacitive vs both coupling to speaker

Option E: None of the above. None of those have anything to do with your problem. The problem you describe is caused by RF (radio frequency signals) getting in to the amplifier circuit. The ...
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5 votes
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FCC part 15 "must accept interference from other sources": what does this mean?

"Interference" in this context applies to one, radiated RF signal affecting the reception of another radiated RF signal. The interference is not produced within the interfering transmit ...
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5 votes

Using PC audio to listen to electrical noise on power line?

NEVER make a straight connection between mains power and any other device unless you 100% know what you're doing. Since you have to ask, I assume you lack the knowledge to work with mains voltage ...
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5 votes
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Oscillating Amplifier

Those amplifiers have 30dB+ gain each. You need a longer, skinnier board, to keep the output tracks further away from the input tracks. I presume the board is solid ground plane on the reverse? If ...
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  • 144k
5 votes

Unusual interference

It's an experiment someone tried a long time ago to teach animals to fly and it got a little out of hand. NORAD has been tracking the repercussions of this experiment for the past 60 years and as far ...
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5 votes

Will this PCB trace GSM antenna be affected by EMI?

Apart from EMI issues, I have a hard time believing that this will work at all. Is there a reference design available for something similar? From what I would guess (I'm not an antenna specialist at ...
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  • 7,747
5 votes

Is it possible to jam wireless home alarm systems?

Yes, it is possible to jam wireless alarm systems, probably even with low-cost, low-tech DIY devices (google "broadband jamming DIY"). There are a couple of articles online which report successful ...
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