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[aprssig] Re: More thoughts on Connected Packet - telpac_node

Ray McKnight shortsheep at worldnet.att.net
Thu Dec 30 00:30:43 UTC 2004


Jim, looking at Telpac more closely, in relation to
The traditional method of connecting to Winlink via
HF PACTOR, I concede that certainly this method does
Have some promising capabilities.  But I think many folks
Don't understand the differences.

Most stations connect to Winlink via HF over PACTOR-III.
It is possible to achieve a 3.6kb data rate via this method.
Yes, over HF, it can be THREE TIMES faster than 1200 baud
Packet!  This is due to the advanced compression and signal
Processing built in to the PTC modems.

I believe the intent on adding Telpac was mainly for
Hams who don't have a license to operate on HF.  Telpac gives
Them the ability to get into the system using existing, inexpensive
2 meter packet gear.  This method also opens the door for
other innovative things like WiFi and other wireless implementations
at the LOCAL LEVEL, or "last mile" as they refer to it.  But
we shouldn't overlook the fact that Telpac will be very slow
delivering that "last mile" when the data has to pass through
the 1200 baud packet pipe to the end user.  Because they are
using only TNC's there is no benefit from the advanced compression,
at least that's what I see here.  But if a WiFi link can be
established directly to a Telpac node, then you have something
to brag about, and it should be very fast!

There is also a trade-off by the use of Airmail as the mail
Client (or ANY client for that matter other than ASCII), as
They all add some overhead for processing.  This increases the
Amount of data needed to send and receive messages, but probably
The convenience of a nice user interface outweighs that downside.

But WiFi isn't Amateur Radio.
And no license would be required,
Except maybe a trained op to set it all up.

Of course, the biggest drawback of Telpac is that it's
Basically all done line-of-sight, local to the node, and
Thus offers no benefit outside the local area.  Having
Only 479 nodes worldwide, being that modes nodes are located
Near metropolitan areas, there's a good chance many won't be
Of benefit during a disaster.  But they don't require too much
Effort to set up when needed, as long as an Internet connection
Can be found.

-----Original Message-----
From: aprssig-bounces at lists.tapr.org [mailto:aprssig-bounces at lists.tapr.org]
On Behalf Of Spider
Sent: Wednesday, December 29, 2004 16:04
To: TAPR APRS Mailing List
Subject: Re: [aprssig] Re: More thoughts on Connected Packet - telpac_node


----- Original Message ----- 
From: "Bill Vodall" <wa7nwp at jnos.org>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Wednesday, December 29, 2004 11:49 AM
Subject: [aprssig] Re: More thoughts on Connected Packet - telpac_node


> "However, Airmail may be used for VHF/UHF Packet under limited 
> circumstances.  Airmail  is required for a radio user to
> connect to Winlink 2000 over HF radio.  Once connected to a compatible 
> station, message transfer is completely
> automatic.

The information on anything WinLink is poor.  This is a perfect example.



> Looks like it's finally time to check out Airmail since it's a smaller 
> application then Paclink
> and isn't suffering from .NET.
>
> Thanks...
> Bill

Yep...It works great on vhf packet.  There are some head scratching tricks 
to learning the difference between "post" and "send" but other than that, 
it's all automatic and works great!  You have to learn that you 'post' a 
message (like a que) and then you send it.  You can post a bunch of messages

and then send them all at once!  And everything is sent compressed and 
typical compression is 10 to 40%, depending on the message.....and that is a

step in the right direction.
If you need help email me off sig or call me.

Jim, WA6OFT




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