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Re: "DEAF" PACKET



Matt and Group,

This shows that if you run 5 or 50 watts, it will NOT make a difference if 
there are packet collisions.

So, 5 watts into a 18db gain antenna will put your 5 watts up there where it 
needs to be.
Not too many stations have the antenna to do that.
So, 50 watts to a 9db gain antenna will yield you that ERP to get above the 
nominal signals up into space.

Seeing it is not a contest to capture ISS, 5 watts to an antenna that is at 
unity will yield you fair to poor results if others are running more ERP.

Just a few thoughts....

73, Scott WA6LIE



>From: "Matt Squire" <MESquire@LindgrenRF.com>
>To: <sarex@AMSAT.Org>
>Subject: [sarex] "DEAF" PACKET
>Date: Wed, 7 Aug 2002 09:30:54 -0500
>
>LADS & LASSIES
>
>MY RECENT EXPERIENCE STIRRING UP THE ANTHILL FROM PIKE'S PEAK ON 28.400 
>146.52 AND 446.00 GAVE ME A SMALL PEEK AT THE  AMOUNT OF QRM AND HETERODYNE 
>THE SPACE STATION IS HEARING, REMEMBER THIS IS ONLY 14,100 FEET, A WEEKDAY 
>AT ABOUT 13:00-15:00 LOCAL TIME.
>PACKET IS MUCH PICKIER IN WHAT IT DECODES, SO IN ADDITION TO A 6dB CAPTURE 
>RATIO TO CLIMB OVER THE TOP OF OTHERS, MOST PACKET NEEDS AT LEAST A 12dB 
>SIGNAL TO NOISE RATIO (JUST GUESSING) FOR THE TONES TO BE CONSIDERED 
>UNCORRUPTED.
>THAT'S A TOTAL OF 18 dB.
>DO THE MATH FROM A 5W STATION +37dBm ON A VIRGIN PASS WITH NO ONE ON THE 
>UPLINK +18dB  = +55dBm OR AROUND 300 WATTS OR SO. TO "CLIMB OVER" THE QRM 
>AND BE DECODED.
>MOST PEOPLE ARE RUNNING 5-50 WATTS ON THE UPLINK, THIS IS ONLY 8dB FROM ONE 
>LEVEL TO THE OTHER.
>I'D GUESS FOR MOST OF A US OR HIGH-DENSITY HAM COUNTRY PASS IT DOESN'T GET 
>OVER THE HETERODYNE STAGE.
>YOU CAN SEE "FUZZED" OR CORRUPTED PACKETS BEING REPEATED OCCASIONALLY HERE 
>IN CHICAGO.
>
>ANY BELIEVERS?
>
>DE MATT
>MATTHEW E. SQUIRE  WB9YLP, T2
>SR. R&D TECHNICIAN
>LINDGREN RF ENCLOSURES
>400 HIGH GROVE BLVD.
>GLENDALE HEIGHTS, IL. 60139
>	USA
>TEL. 630.307.7200 X 1055  FAX 307-7571
>MESQUIRE@LINDGRENRF.COM
>
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