Re: [amsat-bb] Re: Discovery Project: Which Mission Next?

[Chris Maness <amsat@xxxxxxxxxxxxxxx>]

Have you guys tried VNC (Virtual Network Computing) it is freeware  from
AT&T.  They have versions for the UNIX flavors as well as Win32bit.  I
think the data is more compressed than net meeting.

                                   73's de KQ6UP

On 5 Sep 2000, Tony Langdon wrote:

> 
> Hello Howard!
> 
> 05 Sep 00 08:00, you wrote to All:
> 
>  HL> I wonder if there's any way of extracting the compressed digital
>  HL> output from, say, NetMeeting, and modulating that? A few years ago I
>  HL> fiddled with programming Video for Windows (which is the Windows API
>  HL> that NetMeeting uses), but I remember that it's quite a closed system,
>  HL> and that getting hold of the inputs or outputs of the Video Codecs
>  HL> directly wasn't possible (or at least I couldn't work out how to do
>  HL> it).
> 
> Probably not at the data level, without a heap of hack^H^H^H^Hcoding. :-)
> 
>  HL> Is there a reason why we can't use old 28.8 modem technology somehow?
>  HL> These use a low bandwidth (3kHz?) analog system, so there'd be no need
>  HL> to fiddle the TX/RX IF bandwidths. I guess one fundamental difficulty
>  HL> might be that phone lines are less noisy than the sorts of weak signal
>  HL> RF we're talking about. My modem knowledge isn't very good, although
>  HL> I'm sure some on the reflector would be able to explain.
> 
> Other problems include training, which takes several seconds for modems (listen
> next time you dial up).
> 
>  HL> I have tried NetMeeting in the past over a cellular 9600 link and it
>  HL> does work (slowly), including choppy audio and rather chunky video.
>  HL> Maybe even using a 9600 radio modem we could get something to work, if
>  HL> I could hook NetMeeting or something similar to the modem.
> 
> I'd want to see something a bit faster than 9600, I think.
> 
>  HL> I might try this directly in the following way. The SV2AGW Windows IP
>  HL> packet driver at 9600 could be the glue between NetMeeting and the
>  HL> radio. I have a feeling that being half duplex things might not be
>  HL> very good. I also don't think that IP or any packet style system would
>  HL> be the optimum medium for our requirements. The amount of lost
>  HL> bandwidth as stations switch from transmit to receive is quite high. A
>  HL> point to point connection at full duplex would improve things. Not to
>  HL> good for a satellite, though, with single uplink and downlink
>  HL> frequencies. Maybe you'd want to limit the information to one picture
>  HL> and a tiny bit of audio.
> 
> Extracting data at the IP level would be relatively simple.  However, running
> TCP/IP between random stations across the bird might be tricky, unless you
> define a large range of IPs (maybe experiment with 10.x.x.x) as a large
> subnet...  Still, fun to play with. :)
> 
> Tony, VK3JED
> 
> .. We might be nerds, but at least we're off the streets.
> --
> |Fidonet:  Tony Langdon 3:633/284.18
> |Internet: tlang@freeway.apana.org.au
> |
> | Standard disclaimer: The views of this user are strictly his own.
> 
> 
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