[amsat-bb] Re: Decoding SAFIR-1 from TRACE ON

[Masahiro Arai <m-arai@xxxxxxxxxxxxx>]

SAFIR-M is transmitting only even numbers due to bit0=0 problem now.
This means SAFIR-M may transmit incorrect data. Non hex code character
should change. If you find '@'(=40hex) in the telemetory, you must
change '@' to 'A'(=41hex).

The correct telemetry on Andy, G0SFJ's trace file at 1859utc 31/12/02
is 000000A0008D8A244B00. Another odd numbers may be in the telemetry.
The accident error is +1.

  trace data (hex)   30 30 30 30 30 30 40 30 30 30 38 44 38 40 32 34 34 42 30 30
  ascii              0  0  0  0  0  0  @  0  0  0  8  D  8  @  2  4  4  B  0  0

  correct data (hex) 30 30 30 30 30 30 41 30 30 30 38 44 38 41 32 34 34 42 30 30
                                       ^^                   ^^
  corecct ascii      0  0  0  0  0  0  A  0  0  0  8  D  8  A  2  4  4  B  0  0
                                       ^                    ^

Here is the table ascii/hex data.
     ascii   hex data
       0       30       may 31(=1)
       1       31   *
       2       32       may 33(=3)
       3       33   *
       4       34       may 35(=5)
       5       35   *
       6       36       may 37(=7)
       7       37   *
       8       38       may 39(=9)
       9       39   *
       A       41   *
       B       42       may 43(=C)
       C       43   *
       D       44       may 45(=E)
       E       45   *
       F       46
       @       41       change 40(=A)
    *: not seen in telemetry (trace file)


I don't know why non hex characters (v,*) are in 1829utc 30/12/02
telemtry, 0000008v008*88244b00.


73

JN1GKZ Masa
   jn1gkz@jamsat.or.jp     http://www.ne.jp/asahi/m-arai/gkz/




>i thought that those of you who can only receive frames using TRACE ON
>might like to see how I have managed to decode the telemetry packet from
>the raw hex received:
>
>
>How to decode data frames from safir-1
>
>
>1. Look for the hex sequence starting 
>
>81 82 98 82 62
>
>These correspond in decimal to the ascii codes for DATA1
>
>2. Locate the last 21 hex items. Discard the last one and take the
>immediate preceding 20. ( at the moment) these start with 30 six times ie
>30 30 30 30 30 30
>
>3. using Win calculator, enter one by oneall the 20 hex codes  into the
>calculator and check the decimal box: this returns 20 decimal ascii codes.
>Enter each one into Word by pressing left-ALT then the ascii using Numeric
>keypad then release ALT.
>
>4. Copy the exact stream including punctuation (20 items) into the Safir-1
>decode program.
>
>This method has produced the following:
>
>Heard at 1829utc 30/12/02:
>
>
>SAFIR-M Telemetrie (DP0AIS)
>
>Raw Data:          0000008v008*88244b00
>Temperature Board: 4.0ーC
>Temperature PA:    4.0ーC
>
>Voltage [Accu]:    13.6 Volt
>Voltage [5.5V]:    5.48 Volt
>Voltage [3.3V]:    3.31 Volt
>
>Biterror:          00 Errors
>
>
>Heard at 1859utc 31/12/02:
>
>SAFIR-M Telemetrie (DP0AIS)
>
>Raw Data:          000000 0008d8 244b00
>Temperature Board: 0.0ーC
>Temperature PA:    70.5ーC
>
>Voltage [Accu]:    00.8 Volt
>Voltage [5.5V]:    5.48 Volt
>Voltage [3.3V]:    3.31 Volt
>
>Biterror:          00 Errors
>
>
>73 de andy G0SFJ
>----
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