Can Changing the Frequency of a Cellphone Affect a 900MHz Cordless Phone?

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SUMMARY

Changing the frequency of a cellphone to 900 MHz can potentially cause interference with 900 MHz cordless phones, particularly older models lacking frequency hopping technology. Most modern cellphones operate on 800 MHz and 1800 MHz bands, making direct interference less likely. Digital cordless phones may produce static rather than clear interference. The discussion highlights that GSM technology scrambles signals, which could prevent any significant disruption when using a cellphone near an older cordless phone.

PREREQUISITES
  • Understanding of GSM technology and its signal scrambling capabilities
  • Knowledge of frequency hopping and its application in cordless phones
  • Familiarity with the differences between 2.4 GHz and 5.8 GHz frequencies
  • Basic principles of radio frequency and wavelength relationships
NEXT STEPS
  • Research the principles of frequency hopping in digital cordless phones
  • Explore GSM technology and its impact on signal transmission
  • Investigate the differences in performance between 2.4 GHz and 5.8 GHz cordless phones
  • Learn about FCC regulations regarding power outputs for different frequency bands
USEFUL FOR

Telecommunications engineers, audio engineers, and anyone interested in understanding the interaction between cellphones and cordless phone technology.

exequor
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I know that i can change the frequency of a cellphone since afterall most these days are tri-band or quad-band capable. so i was wondering if i changed the frequency to 900mhz what sort of interference i could cause to a 900mhz cordless phone?
 
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in the early days of cordless phones, before frequency hopping was implemented it wasn't all that strange to hear faint echoes of another call when you were talking on your own cordless.

if you were able to get a cell phone to run at 900 MHz (if I'm not mistaken, most of those dual and tri-band phones run at 800/1800 or something like that), then I expect you'd probably get a similar effect.

a lot of cordless phones are digital now, so you might also just get a lot of static.
 
what exactly is frequency hopping?
 
What are the real differences between 2.4 GHz and 5.8 GHz? I've read everything from that 5.8 GHz give you better range, sound quality, and security, to that there's no difference at all, and it is just that the competition in the 2.4 GHz market became so much that they had to open up a new market just so they could charge more.

Specifically, what is meant by 2.4 GHz? What is actually going at that frequency? And how does that effect anything?
 
I'm not so sure that most 900 MHz phones would have frequency hopping. They seem to put those kind of features mostly in the 2.4 or 5.8 GHz phones. The 900 MHz frequency is the most commonly used frequency outside of North America for cell phones, so if you went there (say to Europe) and talked near an old cordless phone then... wait, I still think nothing would happen. I believe GSM technology does something to scramble your signal, and decodes incoming signals before you hear them, and an old 900 MHz phone would not be encoding and decoding its signals, so, like I said, I would guess that still, nothing would happen.
 
hey i thought that the higher the frequency the shorter the wavelength, so why are you getting longer ranges still?
 
Don’t quote me on this but I don't think it is because of electrical qualities but more about the FCC laws concerning different power outputs on specific frequencies. The license may be different at that freq. allowing them to make a more powerful device. It also could just be a gimmick.
 

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