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

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.

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

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

Firmaliiga Pirttimäki

2015-05-12_fl_pirttimaki_qr

#1 probably 30s lost due to indecision and slight uncertainty because everyone else around me had another course and ran in other directions...

#2 OKish but not a great split

#3 went for the wrong stone when inside the control circle. At least +30s again.

#4 could have chose a straighter route in the beginning. #5 and #6 quite OK.

#7 zigzag along paths. Then #8-#9-#10-#11-F fairly OK again.