[amsat-bb] Re: TNC Reccomendation

[Nate Duehr]

On Nov 12, 2007, at 5:07 PM, John Henderson wrote:

> I would like to get into the digital sats and would like some ideas  
> on TNC
> to consider. I looked at the MFJ web site but it appears they have
> discontinued many of their models. Also looking KAM but have no idea  
> which
> one to pick. Appears major deltas are baud rates 1200 vs 9600.
>
> Thanks for any ideas or things to consider.


The first question you need to ask is "Why a hardware TNC?"   This  
will lead to some eye-opening research for you.

Is there a specific application or mode you're wanting to work that is  
available on any of the existing satellites on-orbit that requires a  
feature or mode only available in a (relatively expensive) hardware  
TNC that can't be done with a soundcard interface and software?  (Big  
breath... wow that was a long sentence!)

That's probably the first "homework assignment" to start with... and  
there may be no "correct" answer, but you should be aware that  
hardware TNC's have largely been supplanted by software and sound card  
to rig interfaces in many instances.  However, that may not be true in  
what you want to accomplish.

It's easier to engineer the system to do what is desired than to  
recommend gear that will "do everything", really.  Which birds and  
modes are you most interested in?  Other things might be pointed out,  
like some birds may be very difficult to access without tracking  
antenna systems, etc... if you share what you'd like to try.

Some forms of satellite digital communications don't require "much" at  
all to do, others require quite a station to pull off successfully and  
consistently.

Bob will point you to his web pages on APRS via satellite as one of  
the simplest and effective ways to do digital comms on satellite, and  
rightly so -- while others have interests that go far deeper into high  
speed and other modulation types/schemes... how far down the rabbit  
hole do you want to go?

;-)

--
Nate Duehr, WY0X
nate at natetech.com