Date: Wed, 14 Dec 2016 10:06:33 -0330 (NST)
From: jcraig@mun.ca
To: rsgb_lf_group@blacksheep.org
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Subject: Re: ULF: Finally 100 mA on 2.97 kHz / 65 km ULF experiment / EbNaut
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Well done Stefan!  That is an impressive bit of work.  Hopefully VLF
experiments will resume here soon.

On Monday we went to the hill and launched the kite with a small aerial.
By coincidence, we heard a very strong CW on 20m from Italy!
Also worked Poldhu using a Marconi transceiever with LO injection from
a DDS controlled by a Rasip3.

73 and congrats.

Joe VO1NA

On Wed, 14 Dec 2016, DK7FC wrote:

> Hi ULF,
>
> My post-processing of the 4 day recording is still running, almost 50% of the 
> data is shown on the spectrograms now.
> I'm happy to confirm the successful decode of a *5 character EbNaut message 
> over 65 km on the 101 km band, with a BIG SNR*! It's the one which started on 
> 08.DEC, 7 UTC. First there was no decode until i found that i made a mistake, 
> the actual start of the transmission is 6:58:40 UTC, an offset of -1 symbol.
> Capture in attachment. I also attach the wav file, if someone wants to play 
> with it, the size is very small.
>
> 73, Stefan
>
>
> Am 12.12.2016 14:50, schrieb DK7FC:
>> Hi ULF,
>> 
>> More news from the latest experiment on the 101 km band with QRB ~ 65 km.
>> Yesterday i have been in *JN39VH41HL* 
>> <http://no.nonsense.ee/qth/map.html?qth=JN39VH41HL> again and took all the 
>> equipment of this ULF experiment home again.
>> Everything has still been there and in its right place, which was the first 
>> good message. Here's an image showing the coupling of the loop antenna, 2 
>> turns primary and about 200 turns secondary on a big ferrite core: 
>> https://dl.dropboxusercontent.com/u/19882028/ULF/20161211_123535.jpg
>> 
>> Even the audio recording process was still running but the USB stick was 
>> almost full. Now i have saved a 29.7 GB raw file containing the audio data 
>> for post processing. This recording is almost 4 days long. 2 SpecLab 
>> instances are now running to produce spectrograms in 424 uHz FFT bin width 
>> and 10 minute per pixel scroll rate, using a noise blanker and a 4 kHz wide 
>> filter centered on 2970 Hz.
>> 
>> The accus (5x 7 Ah lead gel) were discharged to 12.17V, 
>> https://dl.dropboxusercontent.com/u/19882028/ULF/20161211_123758.jpg, so it 
>> was the right choice to use these 5 accus.
>> 
>> The single turn vertical loop circumference is about 45m out of 1.5mm^2 cu 
>> wire and the captured area is about 70 m^2.
>> 
>> Now, while writing this mail, the first pixels are coming in. So far the 
>> result is looking very very good, the SNR seems to be arround 20 dB, much 
>> more than expected! See attachment. I will write a summary when all the 
>> spectrograms and eventual EbNaut decodes are available. But in the moment 
>> it looks most promising that i successfully crossed 65 km distance on the 
>> 101 km band, which was the goal. This is the path:* 
>> http://no.nonsense.ee/qth/map.html?qth=JN39VH41HL&from=jn49ik00wd
>> 
>> *73, Stefan/DK7FC*
>> *
>> 
>> Am 09.12.2016 15:43, schrieb DK7FC:
>>> After doing a lot of modifications here on the TX side, the effect still 
>>> exists. I can't get rid of the unstable phase shown on the VLF tree 
>>> grabber.
>>> 
>>> One thing to mention is that the phase seems to change slowly, no sudden 
>>> phase jumps. Thus the peak is 40 dB S/N in 47 uHz. So obviously there were 
>>> much less uncorrected phase glitches than expected in the first moment 
>>> when i saw the effect.
>>> 
>>> Just to be sure i downgraded to the last SpecLab version, the one i used 
>>> since the last month. But the effect still exists.
>>> 
>>> Next to note is the i never saw the effect in my last tests. I still have 
>>> captures showing a very clear trace on 2970 Hz during the 31 km 
>>> experiment. OK that was in September. The QRN levels may have been a bit 
>>> higher and the signal was 7 dB weaker. So maybe the effect was just hidden 
>>> in the noise?
>>> 
>>> Next i found that some SpecLab configurations seem to be corrupted by 
>>> forth and back installing old (V2.90b2) and new (V2.92b2) version. So i am 
>>> now using the old version and a config file that was never opened in the 
>>> new version. It all seems to work fine on the TX side but i can still see 
>>> the effect. BTW i even disabled the NB and checked if this makes a change. 
>>> But thill the same result.
>>> 
>>> The _TX schedule for the experiment_ is:
>>> *07.DEC*: TX 2970.000 Hz (antenna current between 105...110 mA all the 
>>> time) since 13:30 UTC. The recording has started about 15 UTC.
>>> 
>>> *08.DEC*: EbNaut 5ch, 80s, 8K19A @ 2970.000 Hz starting 7 UTC, ending 
>>> 18:22:40 UTC. Then, carrier at 2970.000 Hz. Some interruptions happened in 
>>> the late carrier.
>>> 
>>> *09.DEC*: 0 UTC starting DFCW-10800 (3h per element), 'dit' at 2969.9975 
>>> Hz, 'dah' at  2970.000 Hz. The message is 'FC'. Between F and C there is a 
>>> break of 7 hours. In this time, starting 15 UTC: EbNaut 2ch, 68s, 8K19A 
>>> @2970.000 Hz.
>>> 
>>> *10.DEC*: End of DFCW message 'FC' at 13 UTC. Then, EbNaut 5ch, 80s, 8K19A 
>>> @ 2970.000 Hz starting 13 UTC (repetition of the message of 08.DEC.)
>>> 
>>> *11.DEC: *End of EbNaut message at 0:22:40 UTC. Then, carrier on 2970.000 
>>> Hz until 20 UTC. The recording will stopp in the late morning, due to 
>>> space limitations of the 32 GB USB-stick.
>>> 
>>> From the local recording i tried to decode the 5ch EbNaut message. But it 
>>> didn't decode. I just got a '*****' message and a false decode. This is 
>>> strange. The dots are quite concentrated in the two horizontal lines which 
>>> indicates a stable phase. See attachment. Also the signal peak is strong 
>>> and narrow. But in the red field there is nothing to see... This EbNaut 
>>> message was transmitted with the new PSK config in SL. It is the reason 
>>> why i will repeat the message in the end of the experiment again, using 
>>> the old settings and version.
>>> 
>>> I should have done more pre-tests before starting the experiment. But now 
>>> it is running. Well, the main goal is to detect a clear trace of my signal 
>>> in a spectrogram running at 300 uHz or so. The signals do not look bad on 
>>> the local grabber, not at all, despite the strange (propagation?) effect. 
>>> I'm still optimistic...
>>> 
>>> 73, Stefan
>