[aprssig] Is the APRS Spec for APRS Data Type Identifier just randomly ignored? Should it be?
steve at dimse.com
Thu Aug 18 08:11:05 CDT 2005
On Aug 18, 2005, at 12:48 AM, James Washer wrote:
> I guess I'm just arguing for a STRICT interpretation of the spec. I
> believe that if findu would display "ILLEGAL PACKET", possibly with
> some text explaining what rule was broken, for any searches where
> the packets were not in strict adherence, folks might start fixing
> their configs. Most folks are probably mis-configuring out of
> ignorance, and when they look on findu and find their station they
> figure everything is good.
The error.cgi page is meant for a specific reason, as a page for
people to go to look when their data isn't appearing on findU. For
data parsed and displayed, findU's type checking is rather strict, a
result of the use of regex in the parser. Going from there to an
explanation of why a packet is bad is much more work, and not worth
my effort. As to the specific telemetry issue, these packets are not
that commonly used, and I've never seen someone sending telemetry
that was mis-formatted, so again the return does not justify the effort.
If someone's position packet is wrong, they will not appear on findU.
If someone sends some other sort of non-APRS packet, like a BEACON
packet, that is simply ignored by findU. This is as I think it should
be, I'm not going to make their position disappear because there is a
non-APRS packet in the system. As I said, there are legitimate
reasons why a beacon packet could appear on the APRS-IS.
> btw, I guess I should add that I believe that a packet "claiming"
> to be a Telemetry packet that does not meet the requirements of a
> telemetry packet is a BAD Telemetry packet, much as a packet that
> claims to be a posit without the N/S fields is a bad posit.
Except it isn't a telemetry packet, it is a beacon packet that
happens to start with the letter T. There is a very specific reason
that letters and numbers are not used as type-id's, because they can
be confused with beacon packets common in elsewhere in packet. T is
an exception, because it was created outside of APRS by a TNC
manufacturer. It would be nice if the spec said telemetry was T#,
there is precedent for multi character TIDs, for example ! vs !!.
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