Decoding LO-19 Telemetry…

January 20, 2008 | Amateur Radio | By: Mark VandeWettering

I heard that the telemetry signal from LO-19 was quite strong, and could be easily picked up with even the simplest equipment. It’s sent as 12wpm morse on 437.125 Mhz or so. I don’t really have any equipment that does Morse reception on that frequency, but I figured that I might hear it anyway.

The beacon as received from my FM HT.

As you can hear, it is audible (very clearly) as decreases in the background noise (precisely what you’d expect). The telemetry consists of “E LUSAT HI HI”, followed by a 2 digit version stamp, and then 8 three digit groups. I’m pretty rusty at Morse, but since I had it recorded, I could just read it directly off the spectrum display in Audacity. Here’s how I read it.

E LUSAT HI HI AO AVA ABV TDT ANV TBE ANA AVU AE6
              	 131 173 080 193 075 191 132 156

		0 = T = -	5 = E = .
		1 = A = .-	6 = 6 = -....
		2 = U = ..-	7 = B = -...
		3 = V = ...-	8 = D = -..
		    4 = ....-	9 = N = -.


-----------------------------------------------------------
Channel			Formula			Value
-----------------------------------------------------------
CH 1: +5 volts 		(639/x)			+4.88 volts
CH 2: +10 volts		(0.064*x)		+11.0 volts
CH 3: Cw xmtr. temp.	0.353*(134.7-x)		19.3 deg. C
CH 4: Output power TX	((10.9+x)^2)/40.1	1027 mw
CH 5: Box temp #4.	0.356*(136-x)		21.7 deg. C
CH 6: +10 v current	0.7*x			134 ma
CH 7: +Z voltage panel	0.15*x			19.8 volts
CH 8: +8.5 voltage	0.056*x			+8.74 volts
-----------------------------------------------------------

Pretty nifty.

Addendum: Robert, NH7WN (whom I’ve chatted with on the birds before, giving me the awesome BL11 gridsquare, which is Hawaii) sent me an awesome picture of a cute little QFH antenna and a screen dump of Sound Forge, which is how he read off the LUSAT telemetry. I did it precisely that way too, but I used Audacity. Here’s the waveform display, and if you know Morse, you will be able to read “E LUSAT HI HI” by interpreting the quieter regions as dots and dashes.


Dots and dashes…

Share Button
Be Sociable, Share!

Write a comment






five + = 6