> Now that I got it fully working - linux requires some patching of the
> nmea driver -, the offset is gone:
"gone" is a funny word. It's still there, but you can't see it
because the NMEA driver has switched to using the PPS to get the
fractional part of the second.
--
These are my opinions,
> >Well if I remember correctly someone said to me once that the
> >time-string returned by cheap gps device (like my garmin 18 lvc)
> >sometimes is a bit off while its PPS signal is fine.
>
> Yes, the pps is stated to be accurate to better than a microsecond. The
> interrupt time on your system w
Unruh wrote:
> Yes, 185 ms is about how long it takes to read the nmea string (about 70
> characters as 4800 baud is about 1/6 of a second) YOu can tell ntp to
> subtract off say 180ms but that would still leave you with a sizeable
> jitter.
you will retain
the jitter of the receiver sampling in
[EMAIL PROTECTED] (Folkert van Heusden) writes:
>> > day, but I think that was for long distances, bouncing off the
>> > ionosphere which changed height at night. I'd expect it to be
>> > pretty stable if you are close to the transmitter - ground wave.
>>
>> HBG is in Switzerland if I remember co
[EMAIL PROTECTED] (Folkert van Heusden) writes:
>> > Well if I remember correctly someone said to me once that the
>> > time-string returned by cheap gps device (like my garmin 18 lvc)
>> > sometimes is a bit off while its PPS signal is fine.
>> >
>> > Currently I'm syncing against NMEA/PPS and
> >Ok but the odd thing is: a friend of mine has the exact same garmin 18
> >lvc but not this big offset?
>
> Your PPS isn't working. That could be either hardware or software.
> What OS are you using? What version of ntpd?
> What is your friend using?
linux, 2.6.23 with the PPS patch
ntp-4.2.4
>Ok but the odd thing is: a friend of mine has the exact same garmin 18
>lvc but not this big offset?
Your PPS isn't working. That could be either hardware or software.
What OS are you using? What version of ntpd?
What is your friend using?
How about taking your unit over to his place and see
>To my pc I have connected a garmin 18lvc and a HBG radio clock receiver.
>Now what I would like to do is:
>- let the hbg receiver set the current time and when the HBG signal is
> not available (bad reception or the 59 seconds while it is receiving
> the broadcastmessage) use the PPS signal of t
In article <[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Hal Murray) writes:
>
>>Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:
>>
>> remote refid st t when poll reach delay offset jitter
>>===
Folkert van Heusden wrote:
>>> Well if I remember correctly someone said to me once that the
>>> time-string returned by cheap gps device (like my garmin 18 lvc)
>>> sometimes is a bit off while its PPS signal is fine.
>>>
>
>>> Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:
>Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:
>
> remote refid st t when poll reach delay offset jitter
>==
>xGPS_NMEA(0) .GPS.0 l7 16 3770.000 -
> > Well if I remember correctly someone said to me once that the
> > time-string returned by cheap gps device (like my garmin 18 lvc)
> > sometimes is a bit off while its PPS signal is fine.
> >
> > Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:
> >
> > remote
Folkert van Heusden wrote:
> Well if I remember correctly someone said to me once that the
> time-string returned by cheap gps device (like my garmin 18 lvc)
> sometimes is a bit off while its PPS signal is fine.
>
> Currently I'm syncing against NMEA/PPS and seeing quiet a big offset:
>
>
> > day, but I think that was for long distances, bouncing off the
> > ionosphere which changed height at night. I'd expect it to be
> > pretty stable if you are close to the transmitter - ground wave.
>
> HBG is in Switzerland if I remember correctly, and from your post, you are
> in Netherlands
Hal,
AS little bit of digging in th NIST monograph of 1965 shows the change
in carrier phase lag at 60 kHz varies abouit one cycle or 17
microseconds over the day and night. This is for a 2460 km path between
Boulder and Ottawa where the ray angle incidence is rather small.
Another reference s
> day, but I think that was for long distances, bouncing off the
> ionosphere which changed height at night. I'd expect it to be
> pretty stable if you are close to the transmitter - ground wave.
>
> --
> These are my opinions, not necessarily my employer's. I hate spam.
>
HBG is in Switzerland
>The radio receiver will be late by of the
> order of millisec, while the gps will be "on time" to microseconds.
> Of course you may not care, but someone who has two onboard time sources
> would care, I would think.
The radio propagation delay can be "fudged" out.
How sta
[EMAIL PROTECTED] (Folkert van Heusden) writes:
>Hi,
>To my pc I have connected a garmin 18lvc and a HBG radio clock receiver.
>Now what I would like to do is:
>- let the hbg receiver set the current time and when the HBG signal is
> not available (bad reception or the 59 seconds while it is rec
Hi,
To my pc I have connected a garmin 18lvc and a HBG radio clock receiver.
Now what I would like to do is:
- let the hbg receiver set the current time and when the HBG signal is
not available (bad reception or the 59 seconds while it is receiving
the broadcastmessage) use the PPS signal of t
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