At 11:50 20 November 2012, pcool wrote:
Of course, what else could it be held inside that few characters?
Time of course, Flarm Id, lat-lon, altitude, speed, direction.
The whole story is about sorting out the flarm id from a long list of
collected logs, to understand when was the lost glider before it
disappeared.

The flarm protocol did not change, to my knowledge, after the latest
compulsory update.

Actually all that is needed is ID, time, position (lat/long), and altitude
everything else can be calculated from that data using consecutive fixes,
exactly what a logger does and who has not seen maggot racing?. Breaking
code where the contents of the encoded message are unknown can be a long
process however where you know exactly what the message should be cracking
the code is very very easy.
It all depends on how badly you want to do it and whether using FLARM for
SAR purposes is the best way to go when there are other better suited
devices on the market.
Having said that an instrument that takes on the functionality of FLARM and
SPOT, with the security and reliabilty that such critical devices should
have, would be a major contribution to safety but where is anyone going to
recoup the developement costs? Not from glider pilots that is for sure, the
market is just too small.
So what we have is glider specific instruments, produced with minimal
development costs and almost no certified quality control or an instrument
produced for the GA with official certification, and all the expense that
entails, and never the twain shall meet.




"Roel Baardman" wrote in message
...

I think this is unlikely, as the format of the data in these records is
quite likely the packet format on the air.
It appears to have changed a little from the specification from 2008 (what

was post here at least), but not a whole lot.

I would not be surprised if these records are just packet dumps. This is
consistent with the story of later on finding out what you can do with
them.
Also, I wouldn't want to release their specification if I were to send
them

on air aswell. Encryption over the air was in 2008 not very complicated
(and
the processor used has little room for
complex encryption), so revealing this format (and thus the packet format
on
the air) again opens up the market for protocol-compatible devices. You
could just brute-force the encryption using a
regular PC.

Disclaimer: this is all guessing from what I could read from the data. I
haven't actually decoded these records. And I'm not sure I would want to,
if
it means Flarm will have to change formats
again.