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RE: Re: RE: Geo Opportunity
At least on 10 meters, we will more easily be able to
generate the kilowatt I think we are going to need.
10 dB here, 17 db there and pretty soon that adds up
to real noise (sorry Senator Dirksen).
Bob
N4HY
-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of John Stephensen
Sent: Thursday, July 31, 2003 02:55
To: Bob Bruninga; Keith N6ORS
Cc: amsat
Subject: Re: [amsat-bb] Re: RE: Geo Opportunity
There is background noise at GEO generated by the black hole(s) at the
center of our galaxy. At 28 MHz it is about 17 dB above thermal noise at 290
K. It increases by 6 dB/octave at lower frequencies and decreases by 6
dB/octave at higher frequencies, intercepting the 3 K thermal background
noise of the Big Bang at about 2000 MHz.
73,
John
KD6OZH
----- Original Message -----
From: "Bob Bruninga" <bruninga@usna.edu>
To: "Keith N6ORS" <k2@pe.net>
Cc: "amsat" <amsat-bb@AMSAT.Org>
Sent: Wednesday, July 30, 2003 22:19
Subject: Re: [amsat-bb] Re: RE: Geo Opportunity
> On Wed, 30 Jul 2003, Keith N6ORS wrote:
>
> > ok, this is for a Mode K transponder. 21.4 mhz uplink /29.4 mhz dnlink.
> > Using 5w on the uplink (portable qrp type nuts) , and 10w (single
> > signal) on the downlink.
>
> Yes, but if you use HF for the downlink, you have to throw in 18 dB of
> atmospheric noise to the link equation which washes out all advnatages of
> the better link budget. That is why we only planned to use 10m for uplink
> (where it has hardly any noise out at GEO)...
>
> I think...
>
> Bob
>
> > This would work nicely with a diplexer and a single tape whip with a 3/8
> > wave on 10m (1/4 on 15m).
> >
> > Keith (N6ORS)
> >
> >
> >
> > Uplink 15m
> > TX power 5W 37 dBm
> > TX Antenna Gain 3 dBi
> > Polarization loss -3 dB
> > Resulting EIRP 37 dBm
> > Path Loss at 10m -150 dBm
> > Receiver Antenna Gain 0 dBi
> > Received signal -113 dBm
> > Required for 10dB SNR
> > in 3 KHz bandwidth -119 dBm
> > ------------------------------
> > Margin +6 dB
> >
> > downlink 10m
> > TX power 10W 40 dBm
> > TX Antenna Gain 3 dBi
> > Polarization loss -3 dB
> > Resulting EIRP 40 dBm
> > Path Loss at 10m -153 dBm
> > Receiver Antenna Gain 0 dBi
> > Received signal -113 dBm
> > Required for 10dB SNR
> > in 3 KHz bandwidth -119 dBm
> > ------------------------------
> > Margin +6 dB
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
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> >
>
> de WB4APR@amsat.org, Bob
>
> PCsat WEB page http://www.ew.usna.edu/~bruninga/pcsat.html
> ISS-APRS FAQ: http://www.ew.usna.edu/~bruninga/iss-faq.html
> CUBESAT Designs http://www.ew.usna.edu/~bruninga/cubesat.html
> APRS LIVE pages http://www.ew.usna.edu/~bruninga/aprs.html
> APRS SATELLITES http://www.ew.usna.edu/~bruninga/astars.html
> MIM/Mic-E/Mic-Lite http://ssdl.stanford.edu/mims/
>
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
>
----
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