[time-nuts] Datum/Exactime 9390-6000

Ziggy ziggy9 at pumpkinbrook.com
Tue Jun 12 16:26:34 UTC 2012


The GPS unit is a module, which seems to be a a Trimble SVeeSix-CM3, or 
variant of some kind. It's marked 26889-81 on a sticker and 25040-  -D 
silk screened on the board.

Just as an interesting observation: This GPS module has two MCX 
connectors, one on the top of the board for the antenna and one on the 
bottom which mates with the system board. Directly adjacent to this is a 
16.368 (or thereabouts) TCXO can. It works with a standard antenna, so 
it looks like this is setup to work with both downconverting and 
standard antennas.

I had to go to the Internet Archive to find the old Trimble page 
(http://www.trimble.com/y2kwnro/index2.htm) on Y2k/WNRO status. While 
this specific module wasn't listed, it didn't look encouraging. I do 
have a Trimble ACE III receiver which I am going to try using tonight. 
It is supposed to report the absolute GPS week since 06 January 1980 as 
an integer value and not truncated to 10 bits. Trimble says: "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." Not 
sure what happens after 2015...

Note that due to the 16.368MHz TCXO can being right next to the GPS 
module, I had to modify the ACE III by changing the connector type to 
match the existing connector and move it to the other side of the board. 
I'll report back with the results. Maybe I'll get lucky for once.

Paul



On 06/12/2012 03:52 AM, Azelio Boriani wrote:
> Is the GPS unit built-in (TBolt-like) or is it a separate module? Maybe
> there is a firmware update for the GPS unit itself to fix the rollover
> problem.
>
> On Tue, Jun 12, 2012 at 5:26 AM, Ziggy<ziggy9 at pumpkinbrook.com>  wrote:
>
>> I've recently acquired one of these, primarily to use as an alternative to
>> (and for comparison with) my Thunderbolt. This was a DC model that was
>> inoperative when I received it and at $225 (price from the OEM) to replace
>> the failed DC-DC converter, I installed an AC supply. So far, so good. The
>> unit powers up, tracks, locks the OCXO and things look generally good. I'm
>> giving it some burn in time before I try to characterize it. However, I
>> have a couple of issues. I did search the archives, and have contacted
>> Symmetricom (who politely told me this unit was obsoleted 2 generations of
>> product ago :)
>>
>> The menus and serial command responses do not match any version of the
>> manual that I can find, although the Datum 9390 manual on Didier's site is
>> pretty close on the commands. Does anyone have a manual that covers this
>> model/firmware?
>>
>> This unit suffers from a GPS epoch rollover problem. This makes the date
>> produced incorrect, and there is no way to override it, or offset it in my
>> firmware (DT813MP) other than running it in 'freewheel' or undisciplined
>> mode. It's my understanding that there may have been a firmware update to
>> address this, so if you have a firmware image, or a unit with later
>> firmware it would really be great to get a PROM copy/image.
>>
>> And perhaps a silly question: Is the LCD supposed to be illuminated?
>> Because mine isn't. I haven't taken the front panel apart yet to check out
>> the display - I've been more concerned with getting the unit operational.
>>
>> In the end, it's pretty usable the way it is, but the date being off irks
>> me. I'd like to fix that if I can, and docs that match the hard/firmware
>> would be nice. Any help would be greatly appreciated.
>>
>> Best regards,
>> Paul - K9MR
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