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

Re: ATV from Space? Power needed



Here are some rough numbers for ATV from Space verses
CD-ATV
These values are only approximate from calcuaitons
from the 

Jan A. King   Version: 1.0  link calcualtor

For CD-ATV
On the 70cm band you will need a 15dbi gain antnna.

For VSB-ATV
On the 70cm band you will need a 30dbi gain antnna.




CDATV

Parameter:	Value:	Units:
Spacecraft:		
Spacecraft Transmitter Power Output:	10.0	watts
Spacecraft Antenna Gain:	3.0	dBiC
Spacecraft EIRP:	11.6	dBW


Ground Station:		
Ground Station Antenna Gain:	15	dBiC
System Desired Data Rate:	128000	bps
System Link Margin:	3.2	dB



VSB ATV
Parameter:	Value:	Units:
Spacecraft:		
Spacecraft Transmitter Power Output:	10.0	watts
Spacecraft Transmission Line Losses:	-1.4	dB
Spacecraft Antenna Gain:	3.0	dBiC
Spacecraft EIRP:	11.6	dBW


Ground Station:		
Ground Station Antenna Gain:	30	dBiC
System Desired Data Rate:	6000000	bps
System Link Margin:	1.5	dB
		


--- Cathryn Mataga <cathrynm@junglevision.com> wrote:

> Dave Hartzell wrote:
> 
> > Why not start out with a simpler FSTV downlink of
> real-time video of 
> > the Earth?
> >
> > It might get boring after a while, but it would be
> a good opportunity 
> > to learn about link characteristics, etc for FSTV
> in space...
> >
> > Cloud cover and geography could be viewed, and
> maybe ham information 
> > could be broadcast in-band via Closed Caption! ;-)
> 
> 
> I think this graph would apply...
> 
> http://www.hamtv.com/giffiles/DXgraph1.jpg
> 
> I checked ISS and it was about 350km up. When it's
> at horizon it's going 
> to be
> pretty far away. According to this, at 300 miles
> with 100 watts signal, 
> looks like
> around 28DB of gain? That's a lot of power and
> antenna for 70cm. That 
> 436CP42
> has 16.8db -- and that's pretty big already. Maybe
> with like 4 of these 
> suckers, and 200 watts
> on the transmit and some gain on the transmit
> antenna side it could 
> work? That
> is a lot of stuff though.
> 
> (I always make some horrible mistake when I work
> this stuff out, but I 
> think this
> is right.)
> 
> Imo, would be cool to have camera on the ISS and see
> astronauts walking 
> around or chatting
> or something. I don't see how the numbers add up for
> 70cm though.
> ----
> 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
----
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



AMSAT Top AMSAT Home