I found the document about Trimble ACE3 module:
http://www.symres.com/files/ACE3.pdf
Here is the paragraph about WNRO:
====================================================
Effect of GPS Week Number Roll-over (WNRO)
The ACE III GPS module has been designed to handle WNRO, and there are
no problems
with either dates or first fix after WNRO through the year 2015.
[* Note – GPS Week Numbers system, as defined by the ICD200 GPS
Specification, occupy
a range from zero to 1023. The Week Number Roll Over (WNRO) occurs every
1024
weeks, or approximately every 19 years 8 months. August 1999 was the
first roll-over for
the GPS system since the beginning of GPS time on 06 January 1980.]
[ Caution – Trimble OEM GPS receivers have reported the true GPS Week
Number in TSIP
messages 0x41 and 0x8F-20 as a number between 0 and 1023. The ACE III
GPS outputs
the Extended GPS Week Number as the absolute number of weeks since the
beginning of
GPS time or 06 January 1980. If the true GPS Week Number is desired, the
system
developer should ignore the extra MSBs of the Extended GPS Week Number
and use only
the 10 LSBs]
====================================================
I tried to modify the "demo" code to obtain FW of my GPS module. But I
had no luck with it, since
"bcGPSMan" subroutine always return ERROR state in response to packet ID
0x1F.
Regards,
V.P.
On 2014-02-09 16:05, [email protected] wrote:
In a message dated 09/02/2014 15:31:47 GMT Standard Time,
[email protected] writes:
On 09/02/14 12:56, [email protected] wrote:
Oh well, full credit to Mr Trimble for getting it right, he does bake
exceedingly nice GPS modules and the Ace3 doesn't have a rollover
issue
and it
does report the date correctly.
Unfortunately, as far as I can tell anyway, the BC637PCI takes the
raw
GPS
time data from the Ace3 and performs its own calculation which is
where
the
problem seems to occur, certainly it's a 1024 week issue with the
date
from the BC637 being displayed as June 26 1994 in all versions of
the
associated demo software.
It is possible to set the date correctly but the next packet from the
GPS
module promptly overwrites it again.
I still don't recall seeing this before, although with two boards
behaving
in the same fashion I'm having doubts about that, but more to the
point
these boards indicate a firmware date of 2003 which implies they were
put
into the field like this, and that doesn't make much sense either.
Any ideas anyone?, and again has anyone else seen this and/or am I
missing
something glaringly obvious?
If the ACE3 gives correct date, but the BC637 FW does not, then it is
obvious that the FW does the unwrapping itself just like a problematic
GPS receiver would. Most probably would the ACE3 have issues if it
looses it's CMOS backup.
I haven't looked at those details, but you should be able to disable
the
date from being set by the GPS. Maybe play around there.
Might be that the FW needs an update, which naturally may not be in
existence. Can you read-out the EPROM?
Only proves to show that my comment that NTPD needs to do the 1024
week
correction for other GPS dependent drivers than the NMEA (NTP bug
2466)
is a correct assumption. See the posting I forwarded yesterday.
Cheers,
Magnus
Hi Magnus, and thanks for your comments.
I arrived at the same conclusion regarding the BC637 firmware and
that's
the issue I'd like to resolve, but I'm a bit cautious given that these
were
produced after 1999 as I can't understand why the firmware wouldn't
already
have been updated.
It is possible to set the board for other than GPS, (Timecode,
Freerunning,
or 1PPS) but I suspect I might then loose the conditioning, something
I'd
need to check. Either way, I'd like to have the correct GPS date too if
possible, but it's the conditioning that's of more interest so I'd do
without
the correct date if needs be.
I've identified two programmable devices, the version H manual with
schematics is very useful:-), the first being a OTP configuration PROM
for the
Spartan FPGA and the other a TMS29F010 flash mamory IC which I suspect
holds
the firmware. That is socketed but I don't think I have the necessary
32
pin quad adapter to be able to read it.
This was only intended to be a quick test, funny how "quick tests"
soon
become major projects:-), so these might have to go back into
hibernation
again shortly, for the time being at least.
Regards
Nigel
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--
WBW,
V.P.
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