GSM mobile phone audio design, RF immunity, and low noise dead bug point-to-point prototyping.

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By YTB

27 thoughts on “Eevblog #23 – gsm mobile phone audio design”
  1. Avataaar/Circle Created with python_avatars muhammad shahzaib says:

    Watching in 2021,?

  2. Avataaar/Circle Created with python_avatars Dadmezz says:

    Reminded me of an event at work in late 70s…radio wave antenna above lab and analog equipment chart pen recorders going haywire when company spoke with Liberia….what challenge it was to get it corrected….thanks for the nudge to remember.

  3. Avataaar/Circle Created with python_avatars Jeremy O says:

    awesome video and tips!

  4. Avataaar/Circle Created with python_avatars Becca Bayless says:

    CfC

  5. Avataaar/Circle Created with python_avatars David G says:

    It is not "peek-a";  it is "pike-a"  to pronounce greek "Pica" properly.

  6. Avataaar/Circle Created with python_avatars AJMansfield says:

    The audio on this video is out of sync.

  7. Avataaar/Circle Created with python_avatars Jack Evans says:

    Thanks for the info Dave. Great work !

  8. Avataaar/Circle Created with python_avatars Greg says:

    R\F … Shes a harsh Mistress … Drive around town with a VHF in the car and see how dirty the city is … ( not using the gutter side of my brain here ) … Dave knows what I mean ….

  9. Avataaar/Circle Created with python_avatars Greg says:

    Hey Dave. Love your vid blogs ….got a question ? In Canada here most electronic minded folks have the same likes and dislikes , my question is im a electronic fan foe many years and like my pals decided to dive into the hobbby of Ham Radio . So much fun with VHF/UHF and HF just scratches the surface; Dave have you also that intrest yourself ? My Call sign is VE9XMQ …. was just wondering …. Steve in Canada. …

  10. Avataaar/Circle Created with python_avatars dodaroxer says:

    awesome Video Blog, Dave. By the way, Don't get mad but you're like a kind of RadioShack's Pee wee Herman. XD

  11. Avataaar/Circle Created with python_avatars N0SSC says:

    Take back what you said about RF. RF is not horrible…it's magical!

  12. Avataaar/Circle Created with python_avatars Jodi C says:

    We have neighbours who go through spells of playing really loud music, mostly it is manageable, although the time I complained kicked up a stink, so Sarah suggested we should take a technical approach to solving the problem if it gets out of hand again, by injecting noise into the amplifier to screw up the audio if its loud at 3AM every weekend. (and sometimes in the week)

  13. Avataaar/Circle Created with python_avatars Aid Vllasaliu says:

    "youre screwed in all sorts of ways" hahaha

  14. Avataaar/Circle Created with python_avatars EEVblog says:

    @CoolDudeClem That doesn't help much, you can get pickup on the input and output and power leads.

  15. Avataaar/Circle Created with python_avatars CoolDudeClem says:

    What about putting the whole audio part in some kind of metal shield? That's what I did when one of my stereos kept picking that noise up.

  16. Avataaar/Circle Created with python_avatars CoolDudeClem says:

    So phones in other parts of the world make the same sounding interference? I may be sounding stupid here, but I'm absolutely serious here, I thought just cellphones in England did that, since I've never heard it until now on any videos outside of England.

  17. Avataaar/Circle Created with python_avatars Technoguy3 says:

    Don't other technologies do that as well (not just GSM)? I thought phones on Verizon's network did that too.

  18. Avataaar/Circle Created with python_avatars EEVblog says:

    @enliteneer The RF pulses are at 217Hz spacing.

  19. Avataaar/Circle Created with python_avatars enliteneer says:

    If RF can inject itself on the Output going to the headphones, how would a radiation immune IC prevent that? Wouldn't you still need the RF Traps (33pf | 10pf) at the output?

    Also, in the beginning, you mention 217Hz is the frequency to watch out for, but in the end, your traps are only for the 800/900/1800Mhz? Where did 217Hz factor in?

  20. Avataaar/Circle Created with python_avatars EEVblog says:

    @dingobabystealer No, it's an example of how some things are sometimes just better solved with an already optimised COTS solution. We could have dicked around for a few more weeks or months (if we had the time) and possibly came up with a discrete solution, but that didn't fit into our requirements.
    Many people learned a lot from this video, so that's good enough for me.

  21. Avataaar/Circle Created with python_avatars dingobabystealer says:

    I was really getting into troubleshooting the problem there, and then his solution turned out to be a commercial solution. I've got to say I was a bit disappointed. It feels like I've just been told, "Leave it to the real engineers." I didn't learn anything here that I couldn't have gotten from a Maxim ad.

    Also, word on the street is dead-bugging chips leaves the IC itself more vulnerable to RF interference. Just sayin'.

  22. Avataaar/Circle Created with python_avatars dingobabystealer says:

    I was really getting into troubleshooting the problem there, and then his solution turned out to be a commercial solution. I've got to say I was a bit disappointed. It feels like I've just been told, "Leave it to the real engineers." I didn't learn anything here that I couldn't have gotten from a Maxim ad.

  23. Avataaar/Circle Created with python_avatars EEVblog says:

    @irishdude79 Yep, a stanley knife or a small dremel tip.

  24. Avataaar/Circle Created with python_avatars Tasbo1982 says:

    Can you send me a high quality recording of rf interference please? thats not a joke, i would really like one. cheers

  25. Avataaar/Circle Created with python_avatars Afrotechmods says:

    You are a smart cat

  26. Avataaar/Circle Created with python_avatars RipRocK Bladez says:

    Hello Dave! Just wanted to let you know how much I enjoy watching your videos and really appreciate the educational value in them. Found your eevblog from hackaday.

    Keep up the great work and thanks!

  27. Avataaar/Circle Created with python_avatars EEVblog says:

    Yes, even the battery, so completely isolated and shielded. (mention of this did not make the final video cut)
    Made little difference, RF still gets in via the headphone leads.

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