Quoth randy warner at 2008-04-04 02:41...

Too late - at least for the 'stuck' unit, although I haven't powered it
with anything connected to the battery pin.  Testing it after removing
the battery I still got nothing, although I discovered that the fuse on
the 12V side of the power supply had blown.  I've checked the board to
see if I had accidentally made any solder bridges when removing the
battery (I hadn't) and am now wondering if a) the thing drew too much
current because the battery wasn't present or b) the fuse blew because
it was old (the power supply and interface came with the VP which was
out of an old vehicle installation) and I had been doing a lot of
switching on and off.

What I'd be interested to know is whether the Oncores CAN be run without
the backup battery.  As Randy says, TTFF is not a concern for me so I'd
rather have a less complex system that can be restored to a known state
simply by removing power.

That explains it!  The battery on the VP is giving the same pathetic
voltage as the ones on the GTs, yet it always fires up in NMEA mode.

One question - are the mnemonic commands listed in the Oncore manual
along side the binary commands what I should be entering when in NMEA
mode?  Can't quite work that out.  I am also assuming that commands for
the VP are the same as for the the GT/UT for which I have a manual.

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

On Fri, Apr 4, 2008 at 11:54 PM, Matthew Smith matt@smiffytech.com wrote:

Yes, I have two oncores running without backup batteries.

CK

--
GDB has a 'break' feature; why doesn't it have 'fix' too?

Matthew,

Yes, the backup batteries are not needed at all. The only thing is that if
you remove a battery from a VP/GT/UT type receiver thinking that you can
provide battery power externally, you will be disappointed.....

The mnemonic commands will NOT work while in NMEA. Actually, the mnemonic
commands are really not useful at all unless you are using a Motorola
program such as the old DOS program or WinOncore12. Sending "pos8 1" to a
receiver through an emulator will NOT work. The Moto program converts this
mnemonic in "@@Ea01<CS><cr><lf>. I wrote a paper on this about 5 years ago
which is still on the Synergy Systems website:

http://www.synergy-gps.com/content/view/42/89/

Jason Rabel also hosts another doc I did on the VP commands. Motorola never
converted the old VP manual into a pdf, so I ended up scanning Chapter 6
from the manual into my computer and using character recognition software to
pull out the text. Back in the old days this was tedious.... You can find
this at:

http://www.rabel.org/archives/Motorola_Oncore/

The doc you want is:  VPCommands.pdf

While on Jason's site, keep in mind that most of the documents there are
quite outdated and are more historical in nature.

Luckily, since the NMEA commands are just ASCII text, you can use a terminal
emulator or VisualGPS to talk while in NMEA mode. In Visual GPS, use the
"GPS Settings" window. The Moto receivers do not require checksums for
incoming commands, so that keeps things even simpler.

The NMEA commands for any of the Motorola receivers that support NMEA are
the same ones in the GT/UT manual (the back of Chapter 6 I think).

For instance, requesting the GGA message at a one second interval is:

$PMOTG,GGA,0001<cr><lf>

This is basically the same string that you would use in Visual GPS, except
that you can have Visual GPS add the <cr><lf> for you.

Randy

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Matthew Smith
Sent: Friday, April 04, 2008 11:55 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Oncore batteries

Quoth randy warner at 2008-04-04 02:41...

the

Too late - at least for the 'stuck' unit, although I haven't powered it
with anything connected to the battery pin.  Testing it after removing
the battery I still got nothing, although I discovered that the fuse on
the 12V side of the power supply had blown.  I've checked the board to
see if I had accidentally made any solder bridges when removing the
battery (I hadn't) and am now wondering if a) the thing drew too much
current because the battery wasn't present or b) the fuse blew because
it was old (the power supply and interface came with the VP which was
out of an old vehicle installation) and I had been doing a lot of
switching on and off.

What I'd be interested to know is whether the Oncores CAN be run without
the backup battery.  As Randy says, TTFF is not a concern for me so I'd
rather have a less complex system that can be restored to a known state
simply by removing power.

information

That explains it!  The battery on the VP is giving the same pathetic
voltage as the ones on the GTs, yet it always fires up in NMEA mode.

One question - are the mnemonic commands listed in the Oncore manual
along side the binary commands what I should be entering when in NMEA
mode?  Can't quite work that out.  I am also assuming that commands for
the VP are the same as for the the GT/UT for which I have a manual.

Cheers

M

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy

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Hi Folks

Thanks for those - I put a few of those in my library and have also
downloaded winOncore12 - which also can't bring that one GT+ back to
life, even with the battery removed.  It now has 'dead' written on it in
red marker pen.  If anyone within a reasonable cost postal distance
wants it to try to revive it or whatever, let me know.

The other GT+ has enough battery to retain its settings for a minute or
so - but reverts to default state afterwards so I won't worry about
removing the battery.  (I was only planning to remove them to prevent
the devices from getting into an indeterminate state.)

Interesting idea from Morris about putting that Schottky diode between
pin 1 and the positive point of the internal battery.  I'll consider
this if I ever decided that I need battery backup.

Now that I've got the one GT+ and the VP talking to me, I've examined
the GPRMC records per Hal's suggestion about looking for A/V records.
Interestingly enough, the VP puts out nothing but V records and the GT+
puts out nothing but A records.  It was the VP that I had talking to
gpsd, so maybe that would explain why things weren't working properly.
I'll do some longer testing tomorrow and see if the VP can give me any A's.

Thanks again to all for the help.

Time I was gone - very nearly beer o'clock.  (Not precise timekeeping,
but important.)

Cheers

M

0700 UTC
137'44.5225,-33'59.0904
Can see PRNs: 02,04,05,09,10,12,24,29,30,31

--
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
LinkedIn: http://www.linkedin.com/in/smiffy