Kiintorastit Solvalla

Another run on the Solvalla map with fixed controls. Last one was in April.

Problems on the second control (#50) where at first I didn't know exactly where on the dashed path I had come down from the hill, and then inside the control circle I looked for stones north up the hill when the control-stone was lower down in the forest.

2015-06-27_solvalla

NTP stratum-1 on Ubuntu 14.04LTS

Some (incomplete) notes on setting up a stratum-1 NTP server on Ubuntu 14.04LTS

To handle the upcoming leap-second we want a leapfile, from: http://www.ietf.org/timezones/data/leap-seconds.list

The path of the leapfile goes into /etc/ntp.conf
leapfile /etc/leap-seconds.list
But Ubuntu uses apparmor, so we must grant permission for the ntp service to read this file in /etc/apparmor.d/usr.sbin.ntpd by adding:
/etc/leap-seconds.list r,
To make apparmor parse and apply the new rules we do:
sudo apparmor_parser -r /etc/apparmor.d/usr.sbin.ntpd
when the ntp service starts it is useful to look at /var/log/syslog where ntp will complain if it doesn't have permission to read the leapfile or if it is badly formatted.

Now let's edit the default options for the ntp service in /etc/default/ntp by adding:
NTPD_OPTS='-gN'
(-N runs ntpd at highest priority, -g makes it more robust agaist large time offsets, see man ntpd)

To get time in NMEA-format and a pulse-per-second (PPS) from gpsd we add two shared-memory (type 28) refclock drivers to /etc/ntp.conf

# GPS Serial data reference
server 127.127.28.0 maxpoll 3
fudge 127.127.28.0 time1 -0.230 refid GPS

# GPS PPS reference
server 127.127.28.1 prefer maxpoll 2
fudge 127.127.28.1 refid PPS

(the time1 adjustment number needs to be calibrated somehow..).

Finally we let ntp distribute time to the outside world by adding this line to /etc/ntp.conf (this is usually at the end of the file).
restrict default noquery

Now let's set up gpsd. The service configuration file is /etc/default/gpsd, and as suggested in the file we edit it with the utility:
sudo dpkg-reconfigure gpsd
The options that worked for me are device /dev/ttyS0 and options -n (don't wait for clients to connect). After running the utility /etc/default/gpsd should look something like:

START_DEAMON="true"
GPSD_OPTIONS="-n"
DEVICES="/dev/ttyS0"
USBAUTO="false"
GPSD_SOCKET="/var/run/gpsd.sock"

You can verify that gpsd is working with cgps, xgps, or gpsmon.

This should result in Ubuntu automagically starting gpsd and ntpd in the correct order at bootup, and ntpq -p should show something along the lines of:
Screenshot - 06262015 - 10:18:31 AM

If you want to manually restart (or just start or stop) the services, required e.g. after any changes are made to /etc/ntp.conf, it is done with
sudo service ntp restart
sudo service gpsd restart

CONT vs RCON mode on the 53230A frequency counter

This is a follow-up to my earlier notes on the 53230A noise floor.

Naively I did the initial frequency-counting tests using READ?, which is wrong both because it produces data with dead-time and because the consensus for what is meant by Allan deviation assumes pi-counting.

Driven by marketing, no doubt, the 53230A employs internal averaging (something akin to lambda-counting) both with the simple READ? command and the continuous CONT mode mentioned in the manual. Amazingly you have to use the undocumented RCON mode to get pi-counting which will produce correct Allan deviations.

Here is a plot. The opportunity for making errors (with pi- vs. lamda-counting, and gap-free data) is less in time-interval mode, and I have indicated the 12 ps RMS noise floor (1.8e-11/tau in terms of Allan deviation) with a black dashed line. In RCON mode the noise floor has the same 1/tau dependence and I get about 3e-11/tau. If however you simply use the built-in settings of the counter with READ? or CONT you get a noise floor of about 2e-12/sqrt(tau) due to the internal averaging going on behind the scenes.

RCON_vs_CONT

For a paper that explains pi- and lambda-counting see Dawkins2007 (fulltext PDF on ReaserchGate). Enrico Rubiola also has notes on counters.

Datafiles and script for ADEV and figure: 2015-06-18_rcon_cont.zip

Louna-Jukola

Big mistake on #9, where I stopped at the wrong cliff/hill, and the control was just to the right, but I did a big loop left before realizing this.

Otherwise mostly OK going in terrain that was much easier to run in compared to 2014 in Kuopio.

Jukola2015_2os_1600px

Itärastit Paloheinä

Last itärastit event for this spring. See you again in August.

Probably also last orienteering practice before Louna-Jukola next weekend.

2015-06-06_itr_paloheina_qr

#2 found the correct ditch but passed close by the flag before turning around to find it. +2 min.

#9 ran too far along the road and passed close to #4 before turning towards the control.

#15 nothing much wrong but still a bad split. straighter through the green apparently is faster.

Länsirastit Kellonummi

Long boring runs along roads followed by slow climbing up and down stony steep hills.

2015-06-04_lr_kellonummi_qr

Itärastit Kauhala

Three good splits on 1, 2, and 7.
Bad mistake on 3 costing about +5 minutes. This was followed by a map badly needing updates on the 3-4 leg...

2015-05-30_itr_kauhala_qr

Firmaliiga Luukki

Ran past #1 to the bigger road. +90s at least.

Too carefully towards #5, also drifting too much east, and then across the road at the wrong place. +2min maybe.

#7-#8 was first steeply downhill, then over the road, and steeply uphill. Didn't hit the right spot on the uphill and this is the worst split by far.

Firmaliiga returns in August with three more events.

 

2015-05-25_fl_luukki_qr

Itärastit Ämmässuo

Three major mistakes: ran well past #1, a strange loop before #6, and through the wrong valley towards #11.

Four OK legs with top-20 placings and mostly <1 min lost.

2015-05-23_itr_ammassuo_qr

Firmaliiga Kattilajärvi

Firmaliiga today on the shorter course, just 4.0 km.

#1 a strange loop south before settling for the road as a good choice. Might have paid off to run at 90-degrees to the control-line in the beginning and use the road for the entire leg. Bad split.

#2 a little slowly to the swamp and steep cliff around 50% of the leg, then OK north on the narrow swamp via the big stone and entering the control circle via the small cliff. Good split.

#3 safe road-route until the lake, then a bit carefully crossing the wet bit and steeply up the hill to the control. Good split, could have been 30-60s faster with less hesitation at the lake and more speed up the hill.

#4 tried but failed to find the dashed path, drifted roughly in the correct direction but the 90-degree turn up the big hill next to the wrong lake is unforgivable. Mostly with help of other runners I find the right lake and the control. Much time lost, maybe +3 min. Should not let orienteering get out of control like this - must find clear land-marks during the leg before risking overshooting the control. Bad bad split.

#5-#6-F quite easy along the path. +40s on the short leg to the Finish is not great. More speed please.

10th overall is OK.

2015-05-19_fl_kattilajarvi_qr_splits2

© 2015 anderswallin.net

Theme by Anders NorenUp ↑