A C wrote:
On 8/23/2011 21:50, Mischanko, Edward T wrote:
-----Original Message-----
From: questions-
[email protected]
[mailto:questions-
[email protected]] On
Behalf Of A C
Sent: Tuesday, August 23, 2011 8:25 PM
To: [email protected]
Subject: Re: [ntp:questions] Fwd: Re: NetBSD GPS/PPS using
4.2.6p3
On 8/23/2011 15:27, unruh wrote:
On 2011-08-23, Uwe Klein<[email protected]> wrote:
unruh wrote:
But from his test, his system is labelling both edges.
so he has bounces on the line?
either that or rise/falltime is so low and noise so high
that receiver hysteris is not sufficient to supress multiple
HL/LH changes?
No, his test shows that the line changes and then 100ms later
it changes
back and 900ms later it changes again (ie once per second it
rises and
falls.) Ie, it is behaving exactly as it should if it were
detecting a
pulse 100ms long.It is detecting both the rising and falling
edge.
I just checked and the pulse is almost exactly 100 ms low going
and 900
ms high (within about 1 ms) so it's 90% duty cycle high most of
the time
with a swing low. The signal itself is clean down to microvolt
levels.
The total voltage swing is about 12 volts (which would stand
to reason
since I'm feeding the TTL level PPS output of the GPS board
through one
channel of a MAX232 level shifter).
Therefore the machine is receiving a nice, clean PPS signal on
DCD (DCD
pin was also verified yet again and is correct by hardware
specifications).
[Mischanko, Edward T]
Seems like your PPS pulse is inverted? You may want to add
Flag2 1 to your fudge line.
server 127.127.22.1
fudge 127.127.22.1 flag2 0 flag3 1 refid PPS
I did try that before but I'll try it again and see what happens.
However, a low going voltage should be an assert under RS232. So this
signal is swinging to low voltage during the pulse.
If you've had pps working then you probably have flag2 correct
as it's unlikely all your other ntp sources are 100ms out.
"PPS Clock Discipline" from html directory of ntpd-4.2.6p3
has 'flag2 1' = falling (clear) edge as default
and 'flag2 0' = rising (assert) edge
David
_______________________________________________
questions mailing list
[email protected]
http://lists.ntp.org/listinfo/questions
