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Re: uo-36 tnc's



Hi All,

At 03:27 PM 8/3/2000 -0400, you wrote:
>Hi Jeff,
>
>The future of digital data can expect to see a few increases in speed now
>that we have broken the mould of the band width problem thanks to people like
>James Miller and Ulf Kumm. Before we was limited by the cost and radio's in
>circulation, now that we have the IFD Board which we can go all the way to
>153k with a simple filter change, or 76,800 baud as the IFD baud comes.

What will you do if we end up with satellites on 38k4, 76.8 and 153k6? Will
you switch between 3 IFD boards or just use the fillers for 153k6. Doing so
will require 6 db more gain in your ground antennas than you really need for
38k4.

Are the large Oscar antennas that much of an over kill for 38k4?

What are the smallest gain antenna needed for UO-36 at 38k4?

>Almost TNC's have the limiting factor of been a slow IF speed, less than 12
>MHz will not allow you to reach 38,400 or higher normally, so you need a
>better internal speed like 16 MHz or higher to be future proof for the next
>generation of speeds.

The other limitation is the connection speed between the TNC and the computer.
I have used a  PacComm  Spirit-2 to receive 38k4 from UO-36 but its top RS-232
speed is 57.6 kb.  The top speed of the Symek TNC3S is 115.3 kb.  I think 
that a satellite using the PacSat broadcast protocol with 153k6 downlink 
would overrun
the TNC to computer link.

You could use the option on the TNC3S to use the serial port not as a RS-232
port but as a link to a HDLC card in the PC. If you have such a card then it is
just as easy to attach the modem cards direct to it and skip the TNC.  In any
case I do not believe that WISP supports a HDLC card.

I am still ready to order a TNC3S to experiment just how fast we can go.

What would I like to see from Symek and others?

         1. A high speed modem whose speed  can be software select 
between           38k4,  76k8 and 153k6.

         2. A USB interface to the TNC3s with WISP supporting it.
                  or
            WISP support of a HDLC (with DMA) card in the PC.

         3. More amateur high speed birds in the sky.

What am I working on?

         I am looking at doing my own modem design with selectable speeds
         (19k2,38k4,57.6 and 153.6).

         I am writing my own software to support a HDLC card that will
         be a PacSat file server.

         Using the above software and a 153.6 modem to send JPEG files
         down on S-Band (2 watts) on a satellite to be launched next year.

         Looking at a follow on satellite that will drop all this high 
speed FSK
         stuff and change over to QPSK, FEC, and encoding schemes for a
         new generation of high speed amateur LEO satellites.

>Most of the recent UoSat satellites are already capable
>of 76,800 baud downlinks as they have DSP modems installed, it is just that
>we have never moved beyond 9600 baud until now. I am sure that Phase 3D is
>also very capable to speeds which the TNC3S will work too, I believe that
>they will be trying the latest 153k data rate.

Will P3D stick with FSK?  It believe it can support other modulation schemes.

>People like Chris Jackson, Ulf Kumm, Roy W0SL, Colin Hurst with graphics many
>others including me think we have ironed out most of the bugs that the Beta
>teams found. Now you just have to wet your feet and enjoy making the move to
>the next generation of satellites, you will not regret it, all of us found it
>hard to contain our selves when seeing those byte counters ripping on and off
>the screen. Watch the "T" counter at the bottom of MSPE in WiSP and see the
>numbers roll, it is like a dream come true. Watch the smaller 65kb image
>files come down, we now download many in a single pass, something that all of
>us on the 9600 baud satellites wished for and Chris Jackson and the UoS team
>gave us.

It was great watching 38k4 from JAWSAT before it was launched.

>We all look forward to seeing many more callsigns on UO-36 as this will
>signal to the makers (UoS) that we are also ready to make the move to 76,800
>baud and above.

I may get on more but I expect to be experimenting with 153k6 in the next few
months.

>Hope that gives you one person's view, and I look forward to seeing you
>working the satellite soon. (That is when I service my rotors (G5600B) too,
>seams it is time for us all to service them, Hi.)

I need to fix my rotors too but I thought you had to wait for winter to do 
those
projects. Also I have to replace the backup battery in my Trackbox it keeps 
moving my QTH around the world when I turn it off.

Thanks Chris, Jeff and others for pushing the digital speed.  I just wish 
we could
get WO-39 back up and running 38k4. Look for a new satellite with 153k6 next
year.

73, Randy N7SFI

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