[aprssig] What is "TNC Channel Switching"?
AndrewEMT at hotmail.com
Fri Apr 11 09:54:58 CDT 2014
Actually, there would be a reason to prohibit if the Kamtronics units couldn't handle it; they couldn't _transmit_ such packets to RF.
But what software could attempt to send such packets in Command or Converse mode on a KPC? Nothing modern. KISS mode wouldn't have a problem.
Sent from my Verizon Wireless BlackBerry
From: Rick Green <rtg at aapsc.com>
Sender: aprssig-bounces at tapr.org
Date: Fri, 11 Apr 2014 10:44:37
To: TAPR APRS Mailing List<aprssig at tapr.org>
Reply-To: TAPR APRS Mailing List <aprssig at tapr.org>
Subject: Re: [aprssig] What is "TNC Channel Switching"?
On Fri, 11 Apr 2014, Stephen H. Smith wrote:
> The Kantronics "stream switch" characters were a way of accommodating
> multiple logical channels in the 7-bit ASCII world that predated KISS, by
> using two typeable characters that were not used much (at least in American
> English and if you weren't a Unix programmer!).
That doesn't answer the OP's real question. Is it necessary to treat
these characters as 'reserved', and prohibit their use within APRS
To answer this, I feel we need to know the answers to two other
Were the Kantronics dual-TNCs sensitive to these characters in received
data on the radio side? Would they cut off the current stream and switch
the received data to the other radio in mid-packet??
Did the Kantronics command language provide any way of 'escaping' these
characters so that they could be embedded within packets? It was
mentioned that in practice they were 'prefixed' to a command to indicate
which stream this command is to apply. Is it possible that the TNC was
ONLY sensitive to a stream switch character immediately after a ctrl-C as
it enters command mode, or immediately after a carriage return if already
in command mode?
If it can be shown that the Kantronics TNCs are only sensitive to these
characters on the serial side, and as a prefix to a command, then there
is no reason to prohibit their use within the protocol itself.
Rick Green, N8BJX
We, the People of the United States of America, reject the U.S. Supreme Court's
Citizens United ruling, and move to amend our Constitution to firmly establish
that money is not speech, and that human beings, not corporations, are persons
entitled to constitutional rights.
aprssig mailing list
aprssig at tapr.org
More information about the aprssig