[ntp:questions] Re: Configuring dual refclock/PPS sources

John R. Ackermann N8UR jra at febo.com
Thu Jan 15 19:51:05 UTC 2004

--On Thursday, January 15, 2004 6:33 PM +0000 Hal Murray 
<hmurray at suespammers.org> wrote:

>> I'm running ntpd version 4.1.1rc3 (from the FreeBSD 4.9 ports kit) so I
>> needed to use the "pps..." line to get the kernel discipline going.
>> Also,  without the "ttl 1" option, the hpgps driver never kicked in; I
>> have no  idea why.
> I think the "ttl 1" stuff is just a hack to set the serial port
> to 7 bit, odd parity.
> You can find the details in your source code.  I don't think that fix
> has made it into the official source pool yet.

I grepped for ttl|TTL in the ntpd directory and didn't find any (obvious) 
references to using it as a parity hack, and didn't find any references at 
all in refclock_hpgps.c.  But it did the trick, so who knows.  By the way, 
to make the Z3801A work, I modified refclock_hpgps.c to change the baudrate 
to 19200, and modified ntp_refclock.c to change to odd parity and 7 bits. 
As a suggestion, some method to override the serial port parameters short 
of source code hacking would be nice.



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