Brilliant explanation Davis. Reminds me of the vehicle USB MP3 player (with the FM modulator), interesting how everyone around the device(in traffic) is forced to listen to the user's playlist, it gives all the interference 12V can give. On 5/15/09, Davis Waithaka <daviswaithaka@gmail.com> wrote:
BTW, when we say multiples of the fundamental frequency, we mean there will be harmonics, a.k.a noise from the kplc substation at 100 Hz, 150 Hz, 200 Hz, ........ 96300000 Hz (Eazy), .... 98400000 Hz (Capital), .... 10520000 Hz (Classic) etc all the way up to infinity.
But the amplitude of this noise reduces as the frequency increases. Remember, this noise is everywhere around us, especially in urban areas, but the amplitude (magnitude) is key in determining its significance
On Fri, 2009-05-15 at 10:14 +0300, Davis Waithaka wrote:
Every time we have a changing electric quantity (voltage or current), we get harmonics (sinusoidal frequencies) generated at multiples of the fundamental frequency (in our case this would be 50Hz). These multiples ideally go up infinitely.
As the frequency of the harmonic increases, its amplitude decreases. Therefore, at your house or office, where your fundamental frequency is at 240 volts, the harmonic at 98.4 MHz, or 105.2 MHz would have too little an amplitude to affect your radio.
Near a sub-station however, where the fundamental frequency is at 11 kV, 33 kV or 66 kV, the amplitude of the harmonics at the FM radio band, ie your Capital FMs, KISS FMs etc, would be significantly large. Your car radio will thus pick them up when tuned to 98.4 MHz and mix them with the clean signal from Capital. This harmonic will be delivered to your car speakers as noise.
On Thu, 2009-05-14 at 23:10 +0300, aki wrote:
if you saw the fields and attenuation caused on RF by metalic objects on a spectrum analyzer, its a freak show with waves sweeping across the low end spectrum. metalic objects can behave as low pass or high pass filters, depending on surface area, angle of approach and the usual deflection back. anything near or passing in these fields is bombarded with AC field varying but the power output will temporarily kill any comms device including shielded ones that. Point of impact on device is antenne or parabolic dish and the wavelength changes thus cancelling out itself. Its as good as not having an antenne or parabolic dish. ( remembering the old days ) :-)
_______________________________________________ Skunkworks mailing list Skunkworks@lists.my.co.ke http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks Other services @ http://my.co.ke Other lists ------------- Skunkworks announce: http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks-announce Science - http://lists.my.co.ke/cgi-bin/mailman/listinfo/science kazi - http://lists.my.co.ke/cgi-bin/mailman/admin/kazi/general -- Davis Waithaka Maina Business Development Manager Systems Kenya Solutions 4th Fl. KCB Building Enterprise Rd., Nairobi www.systemskenya.com +254 721 305 374
_______________________________________________ Skunkworks mailing list Skunkworks@lists.my.co.ke http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks Other services @ http://my.co.ke Other lists ------------- Skunkworks announce: http://lists.my.co.ke/cgi-bin/mailman/listinfo/skunkworks-announce Science - http://lists.my.co.ke/cgi-bin/mailman/listinfo/science kazi - http://lists.my.co.ke/cgi-bin/mailman/admin/kazi/general