Re: Ok whats up with 107.7-107.9? WiFi interference? Dying power transformers?

"foo" <fotoobscura@xxxxxxxxx> hath wroth:

>I have had this problem off and on (and noticed it with others) for
>about two years now. It appears that everytime I get near a strong
>wireless signal there is this loud buzzing noise on the high FM radio
>frequencies.

One possibility of what you're hearing are the harmonics of the clock
oscillator that runs the access point, or the clock oscillators that
run the computah to which the wireless device is connected. You'll
have similar interference, although at different frequencies, with a
fax machine, digital clock, calculator, or any device that has a clock
oscillator.

Another possibility is entry directly into the audio circuitry. You
noted that it's from 107.7 to 107.9MHz, so this is probably NOT what
you're hearing, but does happen (to my cheapo hi-fi). The audio
amplifiers have very little RF bypassing and will respond to almost
any nearby RF signal. The SSID broadcast interval of the typical
802.11b/g access point is 10 times per second. I can hear that on my
cheapo hi-fi as a raspy buzz. Moving the access point away solved
that problem.

If you change the DTIM interval (or data beacon rate) on your access
point and the rate of the loud buzz changes, then you're picking up
the 2.4Ghz RF directly, or possibly one of the clock frequencies used
to generate the 2.4GHz, and not the clock oscillator as I previously
guessed. Note that todays 2.4GHz chipsets are all digital (no mixers
or local oscillators) which offer plenty of clock signals to radiate.

Wanna disclose what make and model of hardware is causing the problem
or is it every wireless device that you bring your radio near?

The RF that the lineman was referring to are harmonics of 60Hz. What
happens is that the AC power line waveform is normally fairly low
distortion and shows few harmonics. When the transformer core
saturates or a turn shorts, the waveform becomes distorted and starts
to show harmonics, which can easily extend into the RF region. Mostly,
you'll hear it on AM broacast band (1MHz) frequencies. However, I
don't think these will extend into the FM broacast band.

--
Jeff Liebermann jeffl@xxxxxxxxxxxxxxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

Relevant Pages

  • Re: help with physics ?
    ... of ONE master oscillator. ... A count of LINEAR accumulations from this oscillator ... is performed by a CLOCK. ... and the results are mapped onto one's MASTER TIME BASE. ...
    (sci.physics)
  • Re: Single command IR transmitter?
    ... This allows you to generate many different output frequencies no ... clock source so no need for external crystals or resonators. ... The circuit is tiny. ... Then all I did was have a timer routine, ...
    (sci.electronics.design)
  • Re: Potters Prediction -- that an oscillator will oscillate at a slightly higher frequency i
    ... Relativistic Effects on Satellite Clocks ... contained the first Cesium clock to be placed in orbit, ... synthesizer could be turned on bringing the clock to the coordinate rate ... that counts the cycles outputted from the SLAVE oscillator.) ...
    (sci.physics)
  • Re: Potters Prediction -- that an oscillator will oscillate at a slightly higher frequency i
    ... Relativistic Effects on Satellite Clocks ... contained the first Cesium clock to be placed in orbit, ... synthesizer could be turned on bringing the clock to the coordinate rate ... that counts the cycles outputted from the SLAVE oscillator.) ...
    (sci.physics)
  • Re: The Cost of Relativity
    ... | satellite in MEO/HEO orbit is an observed fact. ... | atoms in a cesium beam clock are in free-fall whether the clock is on ... A regular oscillator and a counter. ... gravity, then it follows that your oscillator should slow for me. ...
    (sci.physics.relativity)
Loading