RE: FreeBSD Garmin 18x LVC receiver

Hello Gary

Thank you for the answer. I didn’t knew that the prescision is a constant. While googling I saw other outputs with a precision of -3 and the like. So I tought it has something to do with “how accurate the position is”

Many of the tools that are mentioned on the gpsd howtos are not available on freebsd. So I only had the telnet output at hands.

Since I had the impression that the receiver is not “precise” I debug ntpd further😊

> Did you read the time howtos?
I mostly read howtos on gpsd, ntpd and installing the receiver and a huge chapter on PPS scaling (all from the gpsd website) is there any other how to I should have a look at? I’m currently re-reading the gpsd-time-service-howto

My ntp.conf is

# $FreeBSD: releng/12.1/usr.sbin/ntp/ntpd/ntp.conf 337649 2018-08-11 17:42:42Z brd $

# default access restrictions (ignore everything)

restrict default ignore

restrict -6 default ignore

# allow unrestricted access from localhost

restrict 127.0.0.1

restrict -6 ::1

# NTP servers geographically close to you.

server metasntp11.admin.ch iburst maxpoll 9 # S1-NTP1

server metasntp13.admin.ch iburst maxpoll 9 # S1-NTP1

server ntps1-0.eecsit.tu-berlin.de iburst maxpoll 9 # S1-NTP1

server time0.swissix.ch iburst maxpoll 9 # S1-NTP1

# for these servers we need permission from the operator to use them

server tick.as34288.net iburst maxpoll 9 # S1-NTP1; permission granted by christian.wittenhorst@ksz.ch 20190301

server ntp.freestone.net iburst maxpoll 9 # S1-NTP1; permission granted by cramer@freestone.net 20190301

# peers

peer s1-ntp2.glattnet.ch

# allow remote servers

restrict metasntp11.admin.ch nomodify notrap noquery nopeer

restrict metasntp13.admin.ch nomodify notrap noquery nopeer

restrict tick.as34288.net nomodify notrap noquery nopeer

restrict ntp.freestone.net nomodify notrap noquery nopeer

restrict time0.swissix.ch nomodify notrap noquery nopeer

# who will gets timeservices from us

restrict 10.3.5.0 mask 255.255.255.0 nomodify notrap noquery nopeer # B2B Router Cisco

restrict 10.20.0.0 mask 255.255.0.0 nomodify notrap noquery nopeer # FTTH

restrict 10.21.0.0 mask 255.255.0.0 nomodify notrap noquery nopeer # CPE

restrict 192.168.3.0 mask 255.255.255.0 nomodify notrap noquery nopeer # Systemnet

restrict 192.168.6.0 mask 255.255.255.0 nomodify notrap noquery nopeer # Signaling

restrict 10.75.2.0 mask 255.255.255.0 nomodify notrap noquery nopeer # Xchange

restrict 80.242.192.0 mask 255.255.240.0 nomodify notrap noquery nopeer #

restrict 94.247.216.0 mask 255.255.248.0 nomodify notrap noquery nopeer #

restrict 145.14.208.0 mask 255.255.240.0 nomodify notrap noquery nopeer #

restrict 185.82.204.0 mask 255.255.252.0 nomodify notrap noquery nopeer #

restrict 31.25.120.0 mask 255.255.248.0 nomodify notrap noquery nopeer #

restrict 2A00:A680:: mask ffff:ffff:: nomodify notrap noquery nopeer

#server 127.127.1.0

#fudge 127.127.1.0 stratum 10

#server 127.127.20.0 minpoll 4 maxpoll 4

#fudge 127.127.20.0 time1 0.1 refid GPS

#server 127.127.20.0 minpoll 4 maxpoll 4

#fudge 127.127.20.0 refid PPS

#server 127.127.20.0 minpoll 4 maxpoll 4

#fudge 127.127.20.0 tim1 0.000 refid PPS

# The GPS receiver on COM1 at 4800 baud

# mode 1 = use $GPRMC statements

# time1 = trimming offset

# flag3 = enable Kernel PPS discipline

server 127.127.20.0 mode 1 prefer

fudge 127.127.20.0 time1 0.000 refid PPS

statistics loopstats

statsdir /var/log/ntp/

filegen peerstats file peers type day link enable

filegen loopstats file loops type day link enable

# MRU (Most Recently Used)

mru maxdepth 1200

mru mindepth 60

mru maxage 600

# See http://support.ntp.org/bin/view/Support/ConfiguringNTP#Section_6.14.

# for documentation regarding leapfile. Updates to the file can be obtained

# from ftp://time.nist.gov/pub/ or ftp://tycho.usno.navy.mil/pub/ntp/.

# Use either leapfile in /etc/ntp or periodically updated leapfile in /var/db.

#leapfile "/etc/ntp/leap-seconds"

leapfile "/var/db/ntpd.leap-seconds.list"

I was playing with the fudge lines, that’s why a few of them are commented out… tried different things

I’m currently in Home-Office and can’t put Hands on the GPS receiver. I’ll update you when I be onsite and can give you more details about ntpshmon. Unfortunately the receiver is disconnected

Tia

Philippe

From: gpsd-users <gpsd-users-bounces+pmaechler-ml=glattnet.ch@nongnu.org> On Behalf Of Gary E. Miller
Sent: Friday, October 16, 2020 7:29 PM
To: gpsd-users@nongnu.org
Subject: Re: FreeBSD Garmin 18x LVC receiver - precision -20

Yo Philippe!

On Fri, 16 Oct 2020 12:11:51 +0200
"Philippe Maechler" <pmaechler-ml@glattnet.ch> wrote:

> I'm running my own ntp server and will now install a gps receiver to
> let my server be more accurate

Cool.

> gpsd:INFO: KPPS:/dev/cuau0 kernel PPS will be used

KPPS installed. Good.

> gpsd:INFO: PPS:/dev/cuau0 Assert hooks called clock:
> 1602842711.000178108 real: 1602842711.000000000: accepted

KPPS working. Good.

> My interpretation is, that the receiver is connected to 9 satellites
> but still does not get an accurate time ("precision":-20)

You realize that "precision" is a constant? All PPS time is "-20".
It tells you nothing. You want to look at the ntpd jitter. Or better
yet, install and run ntpviz.

> All in all my ntp server does not get time data from PPS (?). ntpq
> tells me, that its not reachable. But I'll get to this when I'm sure
> that gpsd is working

You did not share important info:

What does ntpshmmon tell you?

What is your ntp.conf

> Any help or insight are appreciated

Did you read the time howtos?

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem@rellim.com Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin

From:	Philippe Maechler
Subject:	RE: FreeBSD Garmin 18x LVC receiver - precision -20
Date:	Mon, 19 Oct 2020 14:57:27 +0200

RE: FreeBSD Garmin 18x LVC receiver - precision -20