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Re: Decoding SAFIR-1 from TRACE ON



Message text written by "Woodware LLC"
>
Help me with how you figured this out. According to what I remember about
ASCII/HEX and DECIMAL and verified by
http://www.fosh.com.au/Fosh/Support/hextoascii.htm

D = 44 hex or 68 decimal
A = 41 hex or 65 decmial
T = 54 hex or 54 decimal
A = 41 hex or 65 decimal
1 = 31 hex or 49 decimal

73's

Don Woodward
KD4APP
AMSAT 33535
kd4app@amsat.org
http://kd4app.webhop.org

<
Don

Sorry for any confusion. I typed this just over the New Year midnight and
gremlins crept in, sorry!

 i forgot to say that sometimes the decimal needs to be divided by 2 (I
don't know why)

The correct opening sequence is:

D = 88 hex to dec /2
A =82 hex  to dec/2
T = a8 hex  to dec /2
A = 82 hex   to dec/2
1 = 62 hex   to dec/2

Convert these hex to decimal, divide by 2 and enter as ascii.

I just put in a sequence to identify it not to decode it. For me the key
hex is the sixth, 62, in a sequence of that length.

You can also identify MH, INFO, DP0AIS etc in the early sequences this way,
but it is laborious. have a look at my early postings.

You might also be interested in these thoughts  which i have sent onto my
friend Rob G8ATE:

COPY:

>From the AATIS website it is clear that there are many other functions
onboard:

a) a digital voice module, up to 60 seconds repeated every 2 minutes,
commanded from the Ground station

b) In orbit programming of the conrtol PIC

c)A Cosmic ray test using a flash eeprom - I think this must be loaded with
zeros and continually scanned, the idea being to find a change due to a
proton hit.

d) telemetry - see below

e) data beacon including cosmic ray tests
f) M Heard of all uplinks heard

g) it's planned to change the data beacon on 145825 to and from 1200 and
9600.


Data thoughts

looking at my and G8ATE's  decodes I think the data format of the 20 hex
numbers (loaded into the program) is:


0
012345

For the cosmic ray experiment?

0
67
Temperature Board degrees C

0
89
Temperature Board decimal degrees C

1
01
Temperature PA

1
23
Accu Volts

1
45
Volts [5,5v]

1
67
Volts{3.3}

1
89
Bit Error


However i think the telemetry may be useless as they report on their
website that  the PIC controller has the least significant bit stuck on 0 -
this they say applies to the "external memory" which gives false reading on
MH (Ithink it is giving  a false reading on the beacon as well).

Between my two beacons (approx 1 day)

NO CHANGE

0                          1
012345      89   456789

CHANGE TO NIL

0
67


UNBELEIVABLE CHANGE
1
0123


So it doesn't look good for the beacon!

Any thoughts??

END

Don,
Sorry about any errors, please treat this as work in progress, as I have no
connection with AATIS! But what I am saying is that if you take TRACE ON
and decode the hex, dividing by 2 if necessay, there seem to be good
results. I'd be very interested in your results.



andy g0sfj
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