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Re: Local Noise on 2.4 GHZ



The interferance you describe most certainly originates
from a 2.4 GHz cordless phone. The phone could be several
blocks away and the non directionality is due to multi path
reflections.  If you switch your receiver to FM and tune to one 
of the noise peaks you will in most cases be able to make out
much of  the conversation.
These phone auto select an unused channel and the lowest 
of the 20 or so channels falls on the AO-40 downlink
.   
I dont think there is much of a practical solution. Amateurs
have just lost out to the market place because we  were
not using the frequencies. 

Clare VE3NPC

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Subject: [amsat-bb] Local Noise on 2.4 GHZ


>Most of the time the AO-40 S downlink is wiped out by
>some kind of noise on the entire 2.4 GHZ  band here. 
>
>I can't seem to locate the direction with the dish. It peaks
>nearly at many different directions and occurs every
>few KHZ across the band, with a VERY strong
>signal at 2402.505. It may actually peak at another 
>freq. outside of the ham band.
>
>There are times when the noise
>stops suddenly for a few minutes or more. It has a 
>buzz like a sawtooth wave at about 120 HZ much like
>power line noise. 
>
>I have tried attenuating the signal to see if the receiver or
>downconverter/pre amp is being overloaded. The noise still
>can't be pinpointed in either plane.
>The peaks are 20db over S9 and the valleys are about S9
>when hunting it with the dish while listening to 2402.505
>with no attenuation.
>
>My dish is 60' from the house and up 30' above ground, so 
>it should be out of the near field of any noise from the computer.
>If it were coming from the computer, I should be able to point
>the dish toward the house to peak the noise. It doesn't appear
>to be coming from the house.
>
>This may be something simple that I've overlooked, but it
>is a problem when trying to work AO-40, causing lost QSO's
>whenever the noise starts up.
>
>I live in Dallas, TX and there are a LOT of RF sources here.
>
>Can anyone tell me what this noise could be or how to pinpoint
>it?
>
>Ken
>
>----
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>






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