[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: RE: Geo Opportunity

On Wed, 30 Jul 2003, Russ Renaud wrote:

> Assuming a 2 metre downlink, a 1 dBW ERP (LP) from the
> satellite and a 1.8 wavelength long CP yagi in a quiet
> location with a good preamp:
> satellite ERP 1dBW
> path loss -168dB
> polarization loss -3dB
> transponder loading -10dB
> station antenna gain 13.7 (dBic)
> antenna/system temperature 500 degrees k
> receiver bandwidth 2.7 kHz
> 10log 1.38E-23 * 500 * 2700 = -167 dB noise power

Isnt 500K a pretty poor system?  The YAGI is pointing up at cold sky.  SO
it does not see the 300K earth even.  WIth a good LNA, cant we do much
better?  Then what is the SNR?


> I come up with a 1dB s/n ratio.  I guesstimated the
> system noise temperature using the VE7BQH antenna
> table at:
> http://web.wt.net/~w5un/144gt1.doc
> and then I doubled the Ta.

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