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Fw: atv?




----- Original Message ----- 
From: "Miles" <wf1f@comcast.net>
To: <kc5rbq@amsat.org>
Sent: Saturday, September 06, 2003 8:23 AM
Subject: atv?


> Hi Tracy,
>
> not sure if i found your address?
> If you can please post to amsat, i am not part of that list at this
> time.
>
>
> The reason we skipped ATV is because of the Expense and Link Budget
> issues.
>
> Real ATV uses 6 mc of Radio bandwidth.
> The 440 band only has 3 mc allocated by the united nations for satellite
> usage.
> That means that to transmit legeally from Space we would need to go to
> 1.2 or 2.4 gc.
> Those bands cost a lot more.
> The coax loss is greater, need special pre amps, etc.
>
> Then there is the power issue, called Link Budget.
> When you compare a 1 watt voice radio to a real 1 watt ATV signal, you
> will
> find the 1 watt voice signal travels a lot farther than the ATV signal.
> The ATV transmitter will need about 200 watts to have a similar range
> (these number are approximate).
>
> Instead of ATV we are looking into a more efficient mode i call DATV.
> Digital ATV.
> DATV will use a video format called H.323.
> It requires 128kbit digital modems and uses less than 500k of radio
> bandwidth.
> The tranmistter power levels needed will be lower than ATV and there are
> other
> benefits too.
> We are still working out the details and we will need a lot more help on
> this project.
> I think it will be cheaper than ATV from space and more band friendly.
>
> take care
> Miles WF1F
>
>
>
>
>
> Subject: Re: [amsat-bb] MSNBC Story
>     From: "D. Tracy Lane" <kc5rbq@xxxxxxxxxxxxx>
>     Date: Sat, 6 Sep 2003 08:00:45 -0700
>
>
>
>
> SSTV via ARISS is great!  But why don't we just go straight to ATV
> instead?
> Why the leap backwards in technology?
>
>                                                  Tracy  KC5RBQ/7  (out
> of
> lurk mode)
>
>
> > Date: Fri, 5 Sep 2003 20:19:21 -0500
> > From: Jeff Davis <jeff@ke9v.com>
> > Subject: [amsat-bb] MSNBC Story
> >
> > Sorry if this has already been covered, but I was just visiting the main
> > MSNBC news Web site and saw this prominent link about the "ham radio cam
> > on the ISS".
> >
> > http://www.msnbc.com/news/962313.asp?0cv=CB20
> >
> > 73,
> > - -- 
> > Jeff
>

----
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