James Hartley wrote:
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> On 4/11/07, Marc Balmer <mbalmer@openbsd.org> wrote:
>>
>> When you use cu or tip directly on the serial line, do you see any NMEA
>> 0183 sentences?
> 
> 
> Thanks to both you Marc & Otto.  Your comments have helped with a number of
> questions.  I'm currently questioning the power supplied to the Garmin 
> which

The Garmin GPS18 LVC needs 5V power supply.  I used a free USB port to 
"steal" it.

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> I will get to tomorrow.  For now, I've gone back to my T43 laptop where I
> have a USB Delorme GPS LT-20.  I can now see the sensor as well as NMEA
> sentences through cu there.
> 
> Three questions.
> 
> I'm still not seeing anything appear in /var/log/daemon.  How soon should
> log messages appear?
> 
>  From the archives, I remember a statement made that without a pulse per
> second (PPS) signal, a GPS unit would only be able to minimally coordinate
> the time through ntpd.  This statement was also made in reference to a USB
> unit.  Are PPS signals inherent to all GPS units but are lost through an 
> USB
> interface?  Is there something within the NMEA sentence traffic which 
> should
> tell me that I have a PPS signal?

Not all GPS receivers have a PPS signal.  If you use -current, the time 
information is quite precise, even w/o PPS (you will be off by 100-200 
ms).  And no, you will not see in NMEA traffic if there is a PPS signal.

And one last thing:  You need to program you GPS unit to actually issue 
the PPS signal.

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> 
> Thanks again for your clarifications.
> 

You're welcome, but make sure you read the documentation of your Garmin 
unit.