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

ATV from Space?, Try CD-ATV



>From WF1F

Hi All,
This part one of many on TV in space.
ATV, has been one of my pet projects for years,
however, I never found a way to make it affordable. Or
overcome some of the technical and legal issues.

But lets get more people and do it.

ATV  basics:

Frequency issues:
ATV uses a lot of radio spectrum (Space), about 6 mc
for a VSB signal, which is similar to normal TV
format.  The 440 / 70cm band for satellites is only 3
mc wide.  So we need to form a team to start
petitioning the ITU for More room and More Uplink and
down link satellite bands.

In the USA we can use full fast speed TV on 440, 900,
1.2 gig and 2.4 gig (on Earth).  In space  we smaller
band segments for satellite, 440 = 3 mc, 1.2 gig =10
mc,  2.4 gig, not sure, but it has killer 110k Doppler
for LEO satellites.  So if we do go into space we will
need to deal with the band-width issues and Doppler

Range:
Assume you have a WalkiTalki that is running 1 watt FM
Voice into a Zero Gain antenna on the 440 band.  If
you wanted to send a VSB ATV signal the same distance,
with the same Zero Gain antenna you would need
approximately 200 watts.
The short range is caused by the Large size of the
radio channel, over 6 mc for VSB format, and even more
for FM-ATV.  To compensate for the large channel you
need a Big antenna and or a big transmitter.  That¡¦s
why TV stations run 30,000 to 50,000 watts.

In order to legally run VSB or FM ATV full speed/frame
TV in space our choices are 1.2 gig uplink and down
link on 2.4 GHz.  And a big antenna and lots of power.
 And don¡¦t forget Cables losses on 2.4 gig, you start
counting inches to save on coax loss.

There is another solution that is more appealing and
it is called CD-ATV, Compressed Digital Amateur Radio
TeleVision.  The Big benefit of CD-ATV, is it uses
much much less bandwidth than VSB or FM TV signals. 
CD-ATV at 128 kbit data rates, uses less than 150 kHz,
 that¡¦s over 30 times less bandwidth than VSB TV. 
And when you run a smaller signal, you get better
range!

In 2004 Icom loaned me some Beta hardware for their
D-Star ID-1 project.  This radio runs on 1.2 gig and
will send digital data at a 128 kbit clock rate. With
these early Beta-radios, I was able to set up a low
speed audio video link using NetMeeting video
conferencing software.  The proof of concept phases
prove to me that it could be done and that there was a
more affordable way to put ATV on Earth and in Space. 
I submitted a proposal to ARISS as a possible ISS
project.  Two big issues popped up and one was that
there are going to me more European Satellites using
the 1.2 gig band.  This will prevent hams from getting
Down-link access from Ham satellites on the 1.2 gig
band.  The second problem was, Icom was only making a
1.2 gig version of the 128 kbit radio.  So the only
option is to wait for Icom to make a 70cm version of
this radio, so I can resubmit the proposal again.



CDATV on ISS
Compressed Digital Amateur Radio TV
Analog Video
Ü Analog FM Video requires 20 MHz 
Ü Analog FM can only be Down-Linked on 13 cm and
higher bands (2400 MHz). 
Ü Analog FM can be Up-linked on 23 cm... and higher
bands (1290 MHz). 
Ü Analog FM provides good quality Video and Audio. 

CDATV
Ü CDATV Requires < 150 kHz RF band width (128 KBPS). 
Ü CDATV Down linked on 70. 
Ü FCC allows 1260-1270 for satellite uplink.
Ü CDATV will send a lower quality image at  QCIF
rates of 5-15 Frames per second.
Digital transceiver ID-1


Ground Station Requirements
CDATV
Ü Antenna-U/D: 23 cm  12 dbic $200
Ü Amp and Preamp: optional 
Ü Rotor System and Tower: $1000 
Ü Radio: $1500 
Ü Transverter: None 
Ü Video Converter H.323: $200 
Ü Approximate cost: less than $3000 
Ü Doppler TX/RX: 40 kHz

 
Ease of use CDATV
Ü To receive CDATV on 23 cm, you need to compensate
for a Doppler frequency shift to 40 kHz. 
Ü 
Goal and Objective
Ü Install and easy to use CDATV system on ISS. 
Ü Design the system for easy access to experience
Amateur Radio Stations. 
Ü Video will be in a Half-Duplex mono band mode.
Ü Provide live WEB Video

Available Options
Ü The CDATV project is not for beginners, however
Video can be saved on Web pages for easy access to
Schools. 
Ü  ISS will need other Amateur Radio Projects
specifically designed for Beginners (2-Meter Mono-Band
packet, etc.)
Ü Data modem supports 128-kbit which can be used for
other projects.

Ü 


So lets  get some heads together and put ATV in space

Miles WF1F
Just $16.99/mo. or less. 
dsl.yahoo.com 
----
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