Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Cellphone and cordless phone

  1. Nov 1, 2004 #1
    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?
  2. jcsd
  3. Nov 1, 2004 #2
    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.
  4. Nov 2, 2004 #3
    what exactly is frequency hopping?
  5. Nov 3, 2004 #4
  6. Nov 3, 2004 #5


    User Avatar
    Science Advisor
    Homework Helper

    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?
  7. Nov 3, 2004 #6


    User Avatar
    Science Advisor
    Homework Helper

    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.
  8. Nov 5, 2004 #7
    hey i thought that the higher the frequency the shorter the wavelength, so why are you getting longer ranges still?
  9. Nov 10, 2004 #8
    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.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Cellphone and cordless phone
  1. Cellphone Worries (Replies: 1)