SOHLA

How to measure the spin rate of SOHLA-1

SOHLA-1 FSS measurement data graph


http://www.sssrc.aero.osakafu-u.ac.jp/HP_M/html/TSA.html



How to measure the spin rate of SOHLA-1 (16Jun2009)

Because SOHLA-1 is the spin satellite, FSS(*) is in the sunlight and enters
in the eclipse and repeats them itself periodically. You can calculate the
spin rate by measuring the time before being the sunlight again after being
the sunlight now.  (*)Osaka Prefecture(Furitsu) University Sun Sensor

You run a KISS file which you received from the satellite by the software
'SOHLA-1 Telemetry Decoder'. You need to find the brightest data on the
yellow indicator in the middle of the stairs of Decoder and you need to
records the counter value (t1) at the time. You push the button of the lower
right of Decoder and push forward the data and record a counter value (t2)
when the indicator became the most brightest again. This t2 - t1 [sec] is
the spin time. In the example below, the spin time is 26 - 16 = 10 [sec].





You can calculate the spin rate, so the number of the revolutions per a
minute, by 60 / ( t2 - t1 ) [rpm]. Because the spin rate does not suddenly
change in a short time, this value is the calculation result of the spin
rate. In the example above, the spin rate is 60 / (26 - 16) = 6.0 [rpm].

The aim of the standard of the brightness of the yellow indicator is
difficult so that the solar angle to prove right changes by a day. And
I think that this calculation method becomes one aim.

Because the sampling of the data is a thing every one second, the precision
is not so good. But It seems that it is enough values for an aim. It is
necessary to warn you because the data which the sun shines are missing and
measure time for two laps by mistake if there are many blanks of the data.
You should examine it at a place with a few omissions of data.

Supplement:
By the normal use such as the FSS normal mode use, the counter increase by
one every 1 second. But it is an exception at the time of the measurement
by the high mode, then the counter increase by one every 0.2 second.

About this article above that I wrote, I had the many advice from SSSRC,
Small Spacecraft Systems Research Center in Osaka Prefecture University.
I thank them and DK3WN, Mike Rupprecht very much.


SOHLA-1 telemetry analysis
http://www.ne.jp/asahi/hamradio/je9pel/sohlanal.htm

SOHLA-1 Telemetry Decoder Ver1.04
http://www.dk3wn.info/files/sohla.zip