[ntp:questions] Re: TrueTime GPS-Receiver

David L. Mills mills at udel.edu
Wed Feb 4 00:35:41 UTC 2004


John,

As you might know, TrueTime was devoured by Symmetricom, although it
seems they will continue to market the NTS-200 at least. TrueTime used
to make (and maybe Symmetricom still does) a GPS receiver with serial
output (type 5). What you may have is the TrueTime TT560 GPS/IRIG PCI
card, which uses a different driver (type 41). I have not tested any of
these.

Dave

John DeDourek wrote:
> 
> I have been looking at this issue also.  This is what I think is
> correct.  I would appreciate a correction from anyone who can point
> to appropriate documentation that more clearly answers the question
> posed.
> 
> Unfortunately, I believe that the "drivers" in the ntp distribution
> are drivers that load into the application itself.  The TrueTime
> driver appears to presume that the true time "GPS" receiver is one
> with a serial line output.  The linux kernel already has drivers
> that operate the serial line and feed the bytes to the application
> so that the ntpd application driver merely needs to parse the
> byte string into an appropriate time stamp.
> 
> In the case of an ISA or PCI card, I presume that a Linux kernel
> driver is needed as well.  This would allow the "application
> level driver" in ntpd to "open" a special character device and
> obtain the timestamp as bytes (probably binary) read directly
> via the I/O bus, no through a serial port.
> 
> John DeDourek
> 
> "Richard B. Gilbert" wrote:
> >
> >    Part 1.1    Type: Plain Text (text/plain)
> >            Encoding: 7bit



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