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[aprssig] Chemical sensors

Brian Riley (maillist) n1bq_list at wulfden.org
Fri Oct 8 21:54:37 UTC 2004

 I second the motion .... We need to look at the spec to see how best we can
create an extensible telemetry set ... Do we modify the weather data format
or do we modify the telemetry format or do we create a new frame, it must be
open ended and provide for easy extension to new kinds of data.

The problem I see is one Bob has pounded on, one frame should not depend on
reception of a prior frame. So maybe data should be sent

: ssss ttdddd ttdddd ttdddd ttdddd ... cccc

 where ssss is a sequence number in hex, tt is hexadecimal data type, and
dddd is data in hex and ccc is CRC16 of the data and sequence, that gives us
255 data types, and 16 bit data. How big can we make it? If you have more
values to send, generate an additional frame. 255 not enough do three hex
digits or maybe base 91.

I was thinking we could add a 'data set identifier' and it would be a simple
single char indicating that the data type identifier is part of a 'standard
set' some specific set ... Or nonstandard set ... Then the APRS Clients
could see that and if it were a standard set it could decode it and if it
were not it would leave it alone.

 ... Just thinking put loud

On 10/7/04 11:18 PM, "Spider" <spider at rivcom.net> wrote:

> Not to change the subject...because it really fits.....There are discussions
> taking place about adding extra sensor data to a weather packet.


> I also have two  O2 sensors for entering into places that might not let a
> person breath too well!  So there are all sort of neat things people could
> explore using sensors and APRS.

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