Still snow on the ground for maybe 30% of the route. Quite wet and soft.
Mostly ok but just inside the #32 control circle we somehow lost faith and did a loop in the wrong direction.
55k ringroad ride
Around +2..+3 C with a cold shower towards the end.
Keysight 53230A noise floor test
We got a new 53230A counter to the lab, so I decided to run some basic tests on it.
I collected time interval data using a 1-PPS source (H-maser through a SRS DG645), and wired this with a T-connector from CH1 to CH2 with a ~1 m (10 ns delay) cable. This should show the noise floor for time interval measurements as well as CH1/CH2 timing skew when measured the other way around (i.e. from CH2 to CH1). The 10 MHz external reference (at the back) was connected to a H-maser.
The results show standard deviations of 12 ps (CH1->CH2) and 11 ps (CH2->CH1) respecively, with a channel skew of 112 ps. Compare to the single-shot spec of sqrt(2)*20 ps = 28 ps and Agilent/Keysight's marketing video on youtube.
I also collected 10 MHz frequency counter readings on CH1 (source: H-maser) with gate times of 0.1 s, 1.0 s, and 10.0 s. I collected the data with a simple program that just calls the "READ?" function repeatedly, which does result in some dead-time between measurements.
Here are the results in terms of Allan deviation. I used allantools.
The time interval noise floor looks like white phase noise with an Allan deviation of 1.8e-11/tau. This is consistent with the 12 ps RMS value found above. It is left as an exercise for the reader to show that ADEV(1s) = sqrt(3)*RMS-time-interval-noise (correct??).
The frequency counting noise floor depends on the gate time, and I get 5e-12/sqrt(tau), 2e-12/sqrt(tau), and 6e-13/sqrt(tau) for gate times of 0.1 s, 1.0 s, and 10.0 s, respectively. This looks like white frequency noise. Enrico Rubiola has notes on frequency counters that may explain the numbers.
Korttelirastit Tapiola
Last Sunday of the winter-orienteering series. 3km sprint-course + 3km ordinary course. OK steady pace, 58:16.
Solar Eclipse behind clouds
A bad phone-camera picture of today's partial solar eclipse which was hidden behind clouds. Taken through the eyepiece of an 80mm/f=600mm ED telescope.
See also eclipse pictures from 2008 when the weather was sunny.
Aurora Borealis over Helsinki
It's quite rare to see aurora borealis in Helsinki, I've mostly only seen them around 400 km or more north.
Fairly weak and variable. I was only able to point my camera south and up, not north where the auroras normally are brightest - because of buildings and light-pollution in that direction.
As usual only green is visible to the naked eye, while the camera also picks up reds and maybe blues.
Canon 500D with 17-40/F4L lens at 17mm/F4 on tripd. iso400, 8-10 s exposure with cable-release.
See also: Kilpisjärvi auroras from 2012, and Oravais auroras from 2011.
Korttelirastit Koivukylä
Short sprint-o course on 1:4000 map today. +4 C and grey.
Korttelirastit Otaniemi
6 km course, about +2C and cloudy. Most snow has melted - no need for spiked shoes. 7.99km route at 5:51/km pace. Placing around 18th out of 107 runners. About 2 min of error in total.
- Just after #2 there is no way through directly towards #3, but I still run that way and check that the fence is really there. +30s.
- Out of #8 there is a steep hill to climb on the direct route - but I choose the easy way around instead. +30s.
- Running down the hill from #9 towards #10 I plan to round the building to the right - it looks better - but then follow others the left route around the building. Again probably +30s.
- At #13 it's hard to say from the map if there is a passage between the buildings, and the left more direct route would work. The long way around (right of the building) and back is slow and probably at least +30s again here.
Korttelirastit Heureka
Start -> #1: along the rail-road in front of Heureka, then along the street might have been better. My route is more scenic along the river.
#5->#6 route choice between left or right side of the rail-road for the long straight bit. Close to the control I slow down at the right smaller road/path towards #6 but then I fail to make the turn there.
#8->#9 and #9->#10 on both of these legs the left route choice seems better in hindsight. Especially my S-shaped route to #10 does not look good.
6km course, 9km route in 48min48s or 5:22/km. 11th out of 86 runners. Around +2 C, windy, and snow/rain at the start.
Korttelirastit, Hakaniemi-Kruunuhaka
Sprint-O on familiar streets today. The 5 km course was composed of two sprint-courses, 2.4 km in Hakaniemi and 2.6 km in Kruununhaka. I didn't use a compass today 😉
The Polar V800 GPS did not work great on the Hakaniemi map and I had to correct the GPS-trace a lot to get this result. Mostly OK going, but out of #12 I took the wrong path down from the control-hill, assumed I had hit the right street leading towards #13, and ended up close to the forbidden area (Hämeentie). Green arrows show the correct path, probably up to 2 min lost here.
On the second course I didn't make any major mistakes. #3 was hard to say if it was reachable only below from the sloping hill, or also from the top along the much easier terrace with a fence. I took the slower path from below and then climbed the fence after finding the control. The way out from #8 towards #9 seems awkward and slow, but maybe there is no route directly south out of #8?
Total time 47min 22s for both courses. 12th place out of ca 63 runners.
