Re: [amsat-bb] Re: Why preference for mode J?

[Bob Bruninga <bruninga@xxxxxxxxxxxxx>]

On Sat, 29 Jul 2000, Jim Walls wrote:

>     A couple comments about the preference for mode J.  .......
>     What is the issue with the typically equipped FM station that  would
> be any different between mode V-U (or J) and U-V (or B).  

About 9 dB to an omni receive antenna.  This is why it is so much easier
to receive a satelltie mobile or at home with an omni antenna if the weak
downlink is on 2 meters.  There is a 9 dB advantage.  This is why we are
advocating a 2m downlink for our mobile statellite APRS system.

> receiving 435 MHz here in the Los Angeles is much easier than 2M due to
> the much lower noise floor.  

Conversly, of course, if you are going to track the satelite in AZ and EL
anyway, then it is easier to have a gain antenna on UHF then on 2
meters...  So it all depends on the mission...

> remember that in some parts of the world, mode U-V is not available due to 435 MHz
> not being authorized for amateurs.  Charlie - VR2XMT in Hong Kong has commented
> about that before.
> 
> 73
> -----------------------
> Jim Walls - K6CCC
> k6ccc@amsat.org
> http://home.earthlink.net/~k6ccc/
> 626-302-8515    FAX  626-302-9999
> AMSAT member 32537 / WSWSS member 395
> 
> 
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APRSdos REPLY/COMMENT:

Reply mail addr:   wb4apr@amsat.org   
US mail address:   115 old Farm Ct, Glen Burnie, MD 21060
See DAYTON97 HISTORY:    http://web.usna.navy.mil/~bruninga/dayton.html
See Maryland APRS LIVE:  http://web.usna.navy.mil/~bruninga/aprs.html
See GPS on ANY radio:    http://www.tapr.org/tapr/html/mic-e.html

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