r the help.
Michael Eder
-Original Message-
From: questions-bounces+meder=whoi@lists.ntp.org
[mailto:questions-bounces+meder=whoi@lists.ntp.org] On Behalf Of unruh
Sent: Friday, July 15, 2011 10:39 AM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] Single GPS/PPS time source
unruh wrote:
On 2011-07-15, David Lord wrote:
Michael Eder wrote:
Again we are talking effectively what happens. There is a good deal of
logic what to do if the NMEA and/or pps does not come in and if the system
clock is significantly different from either the NMEA or pps. A whole day
on the
On 2011-07-15, David Lord wrote:
> Michael Eder wrote:
>> Again we are talking effectively what happens. There is a good deal of
>> logic what to do if the NMEA and/or pps does not come in and if the system
>> clock is significantly different from either the NMEA or pps. A whole day
>> on the la
Michael Eder wrote:
Again we are talking effectively what happens. There is a good deal of
logic what to do if the NMEA and/or pps does not come in and if the system
clock is significantly different from either the NMEA or pps. A whole day
on the lab bench with a scope on both the pps and the N
On 2011-07-15, Michael Eder wrote:
> Again we are talking effectively what happens. There is a good deal of
> logic what to do if the NMEA and/or pps does not come in and if the system
> clock is significantly different from either the NMEA or pps. A whole day
> on the lab bench with a scope on
: questions-bounces+meder=whoi@lists.ntp.org
[mailto:questions-bounces+meder=whoi@lists.ntp.org] On Behalf Of unruh
Sent: Thursday, July 14, 2011 5:50 PM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] Single GPS/PPS time source gets marked as a
falseticker
On 2011-07-14, Michael Eder
On 2011-07-14, Michael Eder wrote:
> Not using gpsd, just writing the NMEA time and receive time into SHM (0)
> like gpsd does. The pps does the same to SHM (1). Effectively the pps code
sounds like a bad procedure. You want to make sure that the nmea
actually gets associated with the second ma
> ??? Exactly which of the problems he mentioned had anything to do with
> "setting up ntp server in the ocean"?
inability to use a timing GPS receiver and having to use a nav type unit.
This entire problem would go away if he could use one of the more
common timing receivers and a fixed antenna.
and
PPS.
-Original Message-
From: questions-bounces+meder=whoi@lists.ntp.org
[mailto:questions-bounces+meder=whoi@lists.ntp.org] On Behalf Of Rob
Sent: Thursday, July 14, 2011 4:13 AM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] Single GPS/PPS time source gets marked
On 7/14/2011 9:46 AM, Uwe Klein wrote:
> Rob wrote:
>> The native binary protocol usually has a SPECIFICATION
>> about the time field in the messages (like: it is the
>> current time at the moment the beginning of the message
>> is leaving the receiver). The NMEA protocol has a
>> "time of fix
On 2011-07-14, Chris Albertson wrote:
> On Thu, Jul 14, 2011 at 7:04 AM, unruh wrote:
>
>> Why? That native binary will also suffer from large latency (the serial link
>> is slow no matter what is being sent over it) and probably also fairly
>> large jitter. And it suffers from the huge downside
>$GPZDA ?
I tried it on one unit. It didn't help. If anybody has examples of
it working please let us know what type of GPS receiver you tested.
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Rob wrote:
The native binary protocol usually has a SPECIFICATION about the time
field in the messages (like: it is the current time at the moment the
beginning of the message is leaving the receiver). The NMEA protocol
has a "time of fix", and that tells you nothing about what time it is
now.
On Thu, Jul 14, 2011 at 7:04 AM, unruh wrote:
> Why? That native binary will also suffer from large latency (the serial link
> is slow no matter what is being sent over it) and probably also fairly
> large jitter. And it suffers from the huge downside of your having to
> learn a whole new languag
unruh wrote:
> On 2011-07-14, Rob wrote:
>> Michael Eder wrote:
>>> We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
>>> (just one sentence) is also reliable with about a 680 ms latency and 10 ms
>>> jitter.
>>
>> Again, are you using gpsd?
>>
>> If so, you may want to tr
On 2011-07-14, Rob wrote:
> Michael Eder wrote:
>> We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
>> (just one sentence) is also reliable with about a 680 ms latency and 10 ms
>> jitter.
>
> Again, are you using gpsd?
>
> If so, you may want to try removing the (huge) 68
Michael Eder wrote:
> We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
> (just one sentence) is also reliable with about a 680 ms latency and 10 ms
> jitter.
Again, are you using gpsd?
If so, you may want to try removing the (huge) 680ms offset inside gpsd
instead of in n
Michael Eder wrote:
We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
(just one sentence) is also reliable with about a 680 ms latency and 10 ms
jitter.
Here is the configuration file I am now using (any combination of tos
entries seems to make no difference). When I star
At 04:38 PM 7/13/2011, Michael Eder wrote...
We have looked at our GPS on a scope, the PPS it is dead on and the
NMEA
(just one sentence) is also reliable with about a 680 ms latency and
10 ms
jitter
ce000:~/current# ./ntpstatus | tee ntplog.txt
remote refid st t when po
Michael Eder wrote:
We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
(just one sentence) is also reliable with about a 680 ms latency and 10 ms
jitter.
680ms with an estimated error of the order of 10ms (I can't remember the
default minimum distance). 0 not in 680 +/- 2
We have looked at our GPS on a scope, the PPS it is dead on and the NMEA
(just one sentence) is also reliable with about a 680 ms latency and 10 ms
jitter.
Here is the configuration file I am now using (any combination of tos
entries seems to make no difference). When I start NTP is locks on to t
On 2011-07-12, Michael Eder wrote:
[snip: reformatted for 80 column displays]
remote refid st t when poll reach delay offset jitter
xSHM(0) .NMEA. 0 l 13 16 377 0.000 43.755 66.491
*SHM(1) .PPS.
On 2011-07-12, unruh wrote:
> On 2011-07-12, Michael Eder wrote:
>
>> We are using a Garmin GPS 16x. I should clarify these are platforms
>> in the
>
> 18x I presume.
https://buy.garmin.com/shop/shop.do?pID=13194
>> middle of the ocean so the sole time source is the GPS and PPS.
>
> Are they r
On 2011-07-12, Michael Eder wrote:
> We are using a Garmin GPS 16x. I should clarify these are platforms in the
18x I presume.
> middle of the ocean so the sole time source is the GPS and PPS.
Are they really waterproof enough to leave them out in the salty ocean?
> We have measured the time
On Tue, Jul 12, 2011 at 12:29 PM, unruh wrote:
> On 2011-07-12, Chris Albertson wrote:
>> The simplest explanation is that everything is working as expected but
>> your GPS receiver is just not very good. What you might try is
>> turning off all the NMEA sentences you are not using. I don't kn
Michael Eder wrote:
> We are using a Garmin GPS 16x. I should clarify these are platforms in the
> middle of the ocean so the sole time source is the GPS and PPS.
> We have measured the time delta between the GPS and the PPS and the GPS
> while delayed to process the NMEA string has a relatively
On Tue, Jul 12, 2011 at 12:06 PM, Michael Eder wrote:
> We are using a Garmin GPS 16x. I should clarify these are platforms in the
> middle of the ocean so the sole time source is the GPS and PPS.
Ok, then your requirements are modest. Typically when you see someone
using GPS he is setting up s
On 2011-07-12, Chris Albertson wrote:
> The simplest explanation is that everything is working as expected but
> your GPS receiver is just not very good. What you might try is
> turning off all the NMEA sentences you are not using. I don't know
> if the SHM driver degrades the accuracy or not b
reliable.
-Original Message-
From: questions-bounces+meder=whoi@lists.ntp.org
[mailto:questions-bounces+meder=whoi@lists.ntp.org] On Behalf Of Rob
Sent: Tuesday, July 12, 2011 1:25 PM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] Single GPS/PPS time source gets marked as a
Michael Eder wrote:
> Hi Folks,
>
> For our buoy deployments we have GPS and a highly accurate oscillator
> conditioned by the GPS PPS. Unfortunately when we let this run for longer
> periods we see both the GPS and PPS being marked as false tickers. There is
> a lot of information on the web ab
At 01:24 PM 7/12/2011, Chris Albertson wrote...
On Tue, Jul 12, 2011 at 10:16 AM, Mike S
wrote:
> At 08:01 AM 7/12/2011, Michael Eder wrote...
> Try adding "tos mindist 0.015" to your ntp.conf. This widens the
The above is technically correct but if you find that Internet pool
servers are ser
On Tue, Jul 12, 2011 at 10:16 AM, Mike S wrote:
> At 08:01 AM 7/12/2011, Michael Eder wrote...
> Try adding "tos mindist 0.015" to your ntp.conf. This widens the correctness
> interval used by the clock selection algorithm. Basically, it accommodates
> the jitter in the serial NMEA stream. 0.01 i
At 08:01 AM 7/12/2011, Michael Eder wrote...
For our buoy deployments we have GPS and a highly accurate oscillator
conditioned by the GPS PPS. Unfortunately when we let this run for
longer
periods we see both the GPS and PPS being marked as false tickers
I did try setting minclock and mins
The simplest explanation is that everything is working as expected but
your GPS receiver is just not very good. What you might try is
turning off all the NMEA sentences you are not using. I don't know
if the SHM driver degrades the accuracy or not but you might try
removing it. (See what others
Below is the NTP.conf file.
The system runs great but the status does not seem to like our sources.
remote refid st t when poll reach delay offset
jitter
==
xSHM(0) .NMEA. 0 l
Hi Folks,
For our buoy deployments we have GPS and a highly accurate oscillator
conditioned by the GPS PPS. Unfortunately when we let this run for longer
periods we see both the GPS and PPS being marked as false tickers. There is
a lot of information on the web about this, but I have not found a
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