With sufficiently brief phase steps, those discrete sidebands will fall outside the loading coil bandwidth and be well attenuated. But, does that bring back the audible clicks from the PA and coil? I
Nice work. The 22:00 message Eb/N0 is 13.8dB calculated from the symbol error rate, but when the decode is used to reverse the modulation so as to reconstruct a steady carrier, its S/N corresponds to
Bad weather prevents me putting the LF rx back out but tomorrow (19th) looks like it might give a long enough pause in the rain. I'm very keen to make some measurements of your LF carrier! -- Paul Ni
Nice chart. I'm glad to see that you're getting some decodes down below zero Eb/N0, that's more like a proper test! Are you running with list size 200? There's about another dB of coding again availa
My rx is back on from 19th 15:06 UT, recording 135kHz to 138kHz. I couldn't decode the 15:00 message, losing the first 6 minutes was too much. It is quite possible to decode with a third of the messa
. I just tried 17:17:20,+2m in 8.33 mHz and got a nice sharp line on frequency. S/N 17.3 dB in 120 seconds, signal calculator says you should be Eb/N0 = 7.08 dB with that. But no decode of the 17:00
Finally a decode! From the 18:00 message found rank 0: JS PARIS. IZ7SLZ ps [ 10 90 90 90 90] re-encode 340/1040 ber 3.27e-01 Es/N0=-9.9 Eb/N0=0.4 effrate=1/10.83 This with zero time and frequency off
I'm looking at the 30 minute carrier and there's obviously a problem http://abelian.org/vlf/tmp/151119c.gif The main peak is off frequency and it's jumping around a lot. Could be a problem with my ti
Definitely a timing problem at my end. http://abelian.org/vlf/tmp/151119d.gif shows the time offset reported by my timing program (vttime from vlfrx-tools), during Domenico's 18:00 message. It's havi
I see what you mean, the carrier looks quite ragged on there too. I guess I'm used to the nice sharp lines we get a VLF. These super high frequencies are a bit different! But I certainly have a probl
The 20:30 message from IZ7SLZ: found rank 0: GE PAUL TNX RPRT ps [ 1 180 180 180 180] re-encode 296/1040 ber 2.85e-01 Es/N0=-7.9 Eb/N0=2.4 effrate=1/10.83 In this case, the initial reference phase wa
Sorry I was unable to decode this one. Tried list 100k with time offsets -0.1 to +0.9 in 0.02 second steps. My receiving system is not very good. You guys are doing much better because you have prope
Contemplating building a receiver for LF. I probably have all the parts. First I have to clear the decks http://abelian.org/vlf/tmp/151119b.jpg to make a few square cm of bench area. So many half fin
I force the stuff down just for the useful boxes. Such is the effort one must make for this hobby. Spot the Trio 9R59D which I've had since I was a boy, still going and is used for listening to CW o
I'll look out for your signal Joe, although that's a complicated pattern to look for unless we know just when you start your sequence. But if someone gets a strong enough signal it should be a clear
I just looked again at 137.777 and am getting a strong signal with clear phase reversals: In 10 second measurements UT phase 2015-11-21_21:32:10 122.0 2015-11-21_21:32:20 40.1 2015-11-21_21:32:30 85.
I can't do a long average because of the complicated pattern, but a 40 second sample shows 15dB in 0.025 Hz. That means you can use 1 second symbols 8K19A 13 characters. message length 896 seconds =
