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70 cm QRM (was Re:2.4GHz QRM)



We are not using 70 cm on P3E or Eagle as a downlink.  It is an uplink.  
There is insufficient power in these devices even if we assume them to 
be ubiquitous to raise the noise temperature at the spacecraft to  the 
point of being detrimental to the several hundred watt EIRP ground 
station transmitting on 70cm.   For Mode J satellites this could be an 
issue if one of these RFIC's was in your driveway or garage and active.

I doubt they are a problem (yet).

Bob


Tony Langdon (ATC) wrote:
>> I'm a little concerned about the message here - are you saying that 
>> RFICs in 434 MHz will encroach on our allocation in 435-437?  These 
>> are minuscule power devices (since, for example, sitting on the 
>> freeway I don't want to get warnings about the tire pressure of 
>> another Volvo 1/2 mile away.) So before I get all bent out of shape 
>> by this can you provide some credible data or (ugh) statistics that 
>> it will have any real impact in the next 20 years?
>>     
>
> I suspect these will cause you guys few issues.  Over here, 434 MHz devices
> are a real problem, but it's not the door bells, garage door openers or the
> vehicle remotes that are causing the problems, but it's the hiher powered
> high duty cycle devices (they're allowed up to 25 mW EIRP) that cause all of
> the problems, cordless headphones and industrial crane controllers being the
> worst offenders.  All made worse by the fact that this part of the spectrum
> overlaps most of our repeater inputs. :-(
> ----
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>   


-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
"An expert is a man who has made all the mistakes which can be
made in a very narrow field."  Niels Bohr
----
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