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."