IGC File Name Decoding Made Easy

X-no-archive: yes
In article s, Martin
Gregorie writes
On Tue, 06 Sep 2005 13:41:53 +0100, Tim Newport-Peace wrote:

As I recall, IGC adopted a file naming system which was used on the
early Cambridge Recorders, which pre-date the specification. But any
flight that is 10 years old or more is history.

The 8-digit filename came about when DOS and Windows where limited to
8-digits. The specification now allows for Long Filenames (see
Specification Appendix 1 Paragraph 2.5.2) but no-one seems to use them.

There's one unexplained item in the GNSS file specification: some loggers,
e.g. the EW model D, have a serial number of the form Dnnnn which does not
convert into the three alphanumeric characters in any obvious way. There's
not a hint in the file specification as to how this feat might be
performed.

The serial number is specified as three alphanumeric characters in both
short and long form file names.

Dnnnn is not the serial number. The serial number is held in the
Firmware and is used in the IGC filename (but not the *.EWT filename.

On some older recorders the serial number is expressed to Base-10. This
has to be converted to Base-36 for use in IGC filenames.

Tim Newport-Peace

"Indecision is the Key to Flexibility."

On Wed, 07 Sep 2005 14:53:10 +0100, Tim Newport-Peace wrote:

X-no-archive: yes
In article s, Martin
Gregorie writes
.....
There's one unexplained item in the GNSS file specification: some
loggers, e.g. the EW model D, have a serial number of the form Dnnnn
which does not convert into the three alphanumeric characters in any
obvious way. There's not a hint in the file specification as to how this
feat might be performed.

The serial number is specified as three alphanumeric characters in both
short and long form file names.

Dnnnn is not the serial number. The serial number is held in the Firmware
and is used in the IGC filename (but not the *.EWT filename.

I've just looked again at the GNSS FR Specification. Section 2.5.3 allows
for a 5 digit internal serial number to be converted to the 3 character
external group but:

- the 5 digit serial number must appear in the A record
- it doesn't say how the conversion is to be done
- the s/n on the case must match the XXX form in the file name
- existing loggers in 1995 could "grandfather" their existing rules
but new loggers must obey section 2.5.3 exactly

Let's see how this fits my EW model D:

The A line from a trace: AEWAD0430 99429850
The serial number on the case: D0430
The serial number in a filename: 79Y

On some older recorders the serial number is expressed to Base-10. This
has to be converted to Base-36 for use in IGC filenames.

79Y in base 36 is 9430 - so base 36 is certainly possible if EW
number their model D loggers from 9000 in the firmware.

So, either exact implementation this part of the GNSS spec would appear to
be optional or the EW model D is an older design than I thought it was,
i.e. pre 1997. In that case, just how old are the EW models A, B and C ???

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

X-no-archive: yes
In article s, Martin
Gregorie writes
On Wed, 07 Sep 2005 14:53:10 +0100, Tim Newport-Peace wrote:

X-no-archive: yes
In article s, Martin
Gregorie writes
....
There's one unexplained item in the GNSS file specification: some
loggers, e.g. the EW model D, have a serial number of the form Dnnnn
which does not convert into the three alphanumeric characters in any
obvious way. There's not a hint in the file specification as to how this
feat might be performed.

The serial number is specified as three alphanumeric characters in both
short and long form file names.

Dnnnn is not the serial number. The serial number is held in the Firmware
and is used in the IGC filename (but not the *.EWT filename.

I've just looked again at the GNSS FR Specification. Section 2.5.3 allows
for a 5 digit internal serial number to be converted to the 3 character
external group but:

- the 5 digit serial number must appear in the A record
- it doesn't say how the conversion is to be done
- the s/n on the case must match the XXX form in the file name
- existing loggers in 1995 could "grandfather" their existing rules
but new loggers must obey section 2.5.3 exactly

Let's see how this fits my EW model D:

The A line from a trace: AEWAD0430 99429850
The serial number on the case: D0430
The serial number in a filename: 79Y

On some older recorders the serial number is expressed to Base-10. This
has to be converted to Base-36 for use in IGC filenames.

79Y in base 36 is 9430 - so base 36 is certainly possible if EW
number their model D loggers from 9000 in the firmware.

So, either exact implementation this part of the GNSS spec would appear to
be optional or the EW model D is an older design than I thought it was,
i.e. pre 1997. In that case, just how old are the EW models A, B and C ???

All present EW models have grandfather's rights.

Tim Newport-Peace

"Indecision is the Key to Flexibility."

At 16:42 07 September 2005, Martin Gregorie wrote:
On Wed, 07 Sep 2005 14:53:10 +0100, Tim Newport-Peace
wrote:

X-no-archive: yes
In article , Martin
Gregorie writes
.....
There's one unexplained item in the GNSS file specification:
some
loggers, e.g. the EW model D, have a serial number
of the form Dnnnn
which does not convert into the three alphanumeric
characters in any
obvious way. There's not a hint in the file specification
as to how this
feat might be performed.

The serial number is specified as three alphanumeric
characters in both
short and long form file names.

Dnnnn is not the serial number. The serial number
is held in the Firmware
and is used in the IGC filename (but not the *.EWT
filename.


(snip)

On some older recorders the serial number is expressed
to Base-10. This
has to be converted to Base-36 for use in IGC filenames.

79Y in base 36 is 9430 - so base 36 is certainly possible
if EW
number their model D loggers from 9000 in the firmware.

So, either exact implementation this part of the GNSS
spec would appear to
be optional or the EW model D is an older design than
I thought it was,
i.e. pre 1997. In that case, just how old are the EW
models A, B and C ???

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |



EWA Serial numbers convert directly to base36
EWB add 2000 to the serial number and convert to base36
EWD add 9000 to the serial number and convert to base36

Cambridge, Garrecht (Volkslogger), Zander all use the
external serial.

Filser,LX,Colibri,PrintTechnik convert external serial
directly to base36

Please see my other post for the continuation of this thread. Please
don't add to this thread.

"FAI/IGC/CAI File Name Decoding - Automated"

I've got a head of steam up on getting this right.

Enjoy, John
email: johnatderosaweb.com