Neil Welcome to time-nuts. You say that your antenna is less then ideal. OK on time-nuts your going to find out details matter. So what does that mean? Typically the antenna needs to be high enough to have a clear view of the sky and it does matter. But there have been posts in the past about the Pi and I think there are internal issues with the Pi itself that may limit its use. Not an expert and maybe one day I will build a Pi NTP server. To many other things cooking. Regards Paul WB8TSL
On Mon, Jan 12, 2015 at 7:30 AM, Neil Green <nc...@hotmail.co.uk> wrote: > Hi all, > > This is my first post to the list. I have a Raspberry Pi B+ and a HAB > Supplies U-Blox Max-M8Q set in stationary mode connected to a Virgin Media > Superhub (broadband router) by a 0.5m cat7 ethernet cable. The GPS is > attached to the Pi's GPIO and has an external active antenna placed on an > inside window sill. The Pi is running Raspbian on a fast Class10 microSD > card and has a kernel (Linux raspberrypi 3.12.35 #1 PREEMPT Sun Jan 11 > 17:40:22 GMT 2015 armv6l GNU/Linux) rebuilt to disable tickless, enable PHY > timestamping and enable all appropriate PPS options, and has NTP > 4.2.8p1-beta5 compiled with: > > ./configure --enable-linuxcaps --enable-ATOM --enable-NMEA --disable-ipv6 > --disable-all-clocks --disable-parse-clocks --disable-debugging > > and with my ntp.conf file set up thus: > > ---------- > logfile /var/log/ntp.log > driftfile /var/lib/ntp/ntp.drift > statsdir /var/log/ntpstats/ > statistics loopstats peerstats clockstats protostats > filegen loopstats file loopstats type day enable > filegen peerstats file peerstats type day enable > filegen clockstats file clockstats type day enable > filegen protostats file protostats type day enable > leapfile /home/time/leap-seconds.3629404800 > > server ntp0.catn.com iburst > server ntp2c.mcc.ac.uk iburst > server ntp1.luns.net.uk iburst > server ntp1.uk.uu.net iburst > server ntp.colinbarrett.co.uk iburst > > server 127.127.20.0 mode 17 minpoll 4 maxpoll 4 prefer > fudge 127.127.20.0 flag1 0 flag2 0 flag3 0 flag4 0 time1 0.00000 time2 > 0.1137 > > server 127.127.22.0 minpoll 4 maxpoll 4 > fudge 127.127.22.0 refid PPS time1 0.000 flag2 0 flag3 1 > > restrict default limited kod nomodify notrap nopeer > > restrict 127.0.0.1 > ---------- > > After an hour or so, "ntpq -crv -pn; ntptime; ntpq -c clockvar" shows: > > associd=0 status=011d leap_none, sync_pps, 1 event, kern, > version="ntpd 4.2.8p1-beta5@1.3265-o Sun Jan 11 19:10:22 UTC 2015 (1)", > processor="armv6l", system="Linux/3.12.35", leap=00, stratum=1, > precision=-19, rootdelay=0.000, rootdisp=1.015, refid=PPS, > reftime=d85e39b2.e1489c74 Mon, Jan 12 2015 12:16:50.880, > clock=d85e39b4.0ea565be Mon, Jan 12 2015 12:16:52.057, peer=4258, tc=4, > mintc=3, offset=-0.000466, frequency=-17.209, sys_jitter=0.001907, > clk_jitter=0.001, clk_wander=0.000, tai=35, leapsec=201507010000, > expire=201512280000 > remote refid st t when poll reach delay offset > jitter > > ============================================================================== > *127.127.20.0 .GPS. 0 l 3 16 377 0.000 -1.066 > 2.801 > o127.127.22.0 .PPS. 0 l 2 16 377 0.000 0.000 > 0.002 > -87.124.126.49 195.66.241.3 2 u 34 64 377 29.758 8.186 > 0.977 > -130.88.200.6 130.88.200.4 3 u 14 64 377 17.783 1.952 > 0.580 > +217.114.59.3 158.43.192.66 2 u 7 64 377 15.947 4.033 > 0.814 > +158.43.128.66 193.67.79.202 2 u 15 64 377 10.319 1.873 > 0.553 > 81.174.247.243 .INIT. 16 u - 1024 0 0.000 0.000 > 0.000 > ntp_gettime() returns code 0 (OK) > time d85e39b4.49e7c8d4 Mon, Jan 12 2015 12:16:52.288, (.288693882), > maximum error 2000 us, estimated error 1 us, TAI offset 35 > ntp_adjtime() returns code 0 (OK) > modes 0x0 (), > offset 0.000 us, frequency -17.209 ppm, interval 256 s, > maximum error 2000 us, estimated error 1 us, > status 0x2107 (PLL,PPSFREQ,PPSTIME,PPSSIGNAL,NANO), > time constant 4, precision 0.001 us, tolerance 500 ppm, > pps frequency -17.207 ppm, stability 0.004 ppm, jitter 0.507 us, > intervals 73, jitter exceeded 45, stability exceeded 0, errors 0. > associd=0 status=0000 no events, clk_unspec, > device="PPS Clock Discipline", timecode=, poll=828, noreply=0, > badformat=0, baddata=0, stratum=16, refid=80.80.83.0, flags=4 > > I've tried using Banana Pi and Beaglebone Black SBCs and have also used > u-blox Max-7Q and Trimble Copernicus II GPS breakout boards with no > improvement (The Banana Pi is the best but is stuck on the Allwinner 3.4 > kernel, which I'm not thrilled about), leading me to believe the roadblock > to a more precise clock lies in my less than ideal antenna setup, but my > questions are: can I improve upon this and, if so, how? Have I made any > obvious errors? I'm relatively new to this and would appreciate any advice > I can get. > > Thanks, > Neil. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.