Message-ID: <A60F370210A146A78416BE869C6516BD@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <FFCC0848AFFE4FA396968D0635B46204@White> <8D2EABAF0379B74-9084-3D874@webmail-vd017.sysops.aol.com> <Pine.LNX.4.64.1511111644050.6519@plato.ucs.mun.ca>
Date: Wed, 11 Nov 2015 23:44:50 -0000
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Subject: Re: LF: VO1NA frequency
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Status: O

Hi Joe plaese be sending the cats bank account numbre and sort cod e so we 
may pay his inheritance  :-))

Alan
G3NYK

----- Original Message ----- 
From: <jcraig@mun.ca>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, November 11, 2015 11:35 PM
Subject: Re: LF: VO1NA frequency


Hi Markus (and thank-you to Chris, Urlich, Iban and Graham for
reports/relays)

Your critiques of my signals are very thorough and masterful.  I am
most grateful.  There is a concensus amongst you, Domenico and Stefan
that I've gone off frequency again, at times more than 1 mHz!
Hopefully this will be corrected soon. I'll post your nice plots
on the web if you don't mind.

In the mean time, I ran Paul's ebbaut.c on the MUN unix box and
an old Model B raspi. It compiled flawlessly.  I had to put in
arguments for -S and -r which I chose at random, my callsign and
pussycat's name and was rewarded with a long list of 0's and 1's.

So if I send a long carrier with a phase inversion every time a 1
is encountered, it will be a valid ebnaut transmission? What is
the duration of the elements and what arguments should I pass to
ebnaut.c?  Also, would a transformer + DPDT relay work?  A ring
mixer might not take kindly to a 12V squarewave.

Please excuse my naivety!  Also, XYL is wondering why you want the
other details of the cat.  She was my ground crew today while I was
atop the tower so I must be diplomatic!

MNI TNX
Joe VO1NA

On Wed, 11 Nov 2015, Markus Vester wrote:

> Joe,
> Ā
> more of the same from last night, this time withĀ frequency and level 
> plots. Again we see some frequency variation of similar size as yesterday. 
> It is not clear how much of that is due to propagation,Ā I only think that 
> theĀ riseĀ near the end is due to DopplerĀ from theĀ descent of the 
> ionosphere at sunrise.Ā RussianĀ Loran lines on 137475 and 137482.5 seemed 
> to have less overnight variation (~ 0.1 mHz), but then of course the 
> intra-European path from Slonim is very different from yours.Ā
> Ā
> Regarding EbNaut carrier analysis:Ā for some reason (lack of coffee?), I 
> only saw Domenico's earlier mail after I hadĀ sent mine, so please excuse 
> me for basically having describedĀ the same procedure again.Ā Anyway it's 
> good that weĀ bothĀ arrived at the same conclusion:Ā If Joe started 
> sendingĀ EbNaut PSK with hisĀ oscillator asĀ it is now, we would very 
> likely be able to decode it here.Ā
> Ā
> Joe so all you need now is a diode ring-mixer for PSK modulation and 
> Paul's ebnaut-tx program.Ā SymbolĀ timingĀ willĀ be derived fromĀ the PC 
> clock,Ā so with NTPĀ available there's no need to involve GPS at all. If 
> Paul brought his LF receiver back to life, he could probably copy you 
> evenĀ if you reducedĀ TX power to 0.1 Deccas.
> Ā
> How many cats do you have? We want to knowĀ names, colours, sex and age 
> for all of them ;-)
> Ā
> All the best,
> Markus (DF6NM)
> Ā
> Ā
> PS. SpecLab question: Wolf is there a way to extract peak frequencies from 
> past spectrogram lines (semi-)automatically, without having to manuallyĀ 
> moveĀ and read the mouse cursor over each point, e.g. something like a 
> peak_f(f1,f2, time) interpreter function?
>
> Ā
> -----UrsprĆ¼ngliche Mitteilung-----
> Von: Markus Vester &lt;markusvester@aol.com&gt;
> An: rsgb_lf_group &lt;rsgb_lf_group@blacksheep.org&gt;
> Verschickt: Mi, 11 Nov 2015 1:24 am
> Betreff: LF: VO1NA frequency
> Ā       Hi Joe,
> Ā
> the attached plot shows the  frequencyĀ stability ofĀ yourĀ opds trace 
> received last  nightĀ http://df6nm.bplaced.net/LF/opds32_151110_0736.pngĀ 
> .  Each data point is the interpolated peak of a  single 438 uHz FFT (i.e. 
> 38 minute window). The average frequency seems to be  0.7 mHz belowĀ 
> nominal, and there are small temporal variationsĀ up  toĀ 0.5 mHz in 
> either direction.Ā Though some of thatĀ is  probablyĀ attributableĀ to 
> noise and propagation, I believe that there  is also a bit of inherent 
> instability inĀ the frequency  source.Ā Actually a few parts per billionĀ 
> is quite good for a free  runningĀ OCXO (assuming the "D" stands for 
> "double oven" and not "discipled"), and that the calibration was done over 
> a 10  MHzĀ HF link.
> Ā
> Is this good enough for EbNaut? During the  experiments with IZ7SLZ we 
> found that for full sensitivity the phase variation  over the EbNautĀ 
> sequence duration should not be much more than 90Ā°. Thus  for a half-hour 
> message the frequency should be ideally constant and known to  about 0.14 
> mHz. If there is more variationĀ weĀ oftenĀ can still  getĀ decodes, but 
> we will have to find the best frequency offset by trial  and error, which 
> can be cumbersome if the signal is weak.
> Ā
> I also fed opds data files from your Sat/Sun  transmissions to the EbNautĀ 
> decoder. The idea was to see ifĀ your Opera  transmissions would actually 
> produceĀ the all-asteriskĀ decode which is  expected for a non-PSK-keyed 
> straight carrier, and to observe the symbol phase  evolution over the 38 
> minute duration.Ā Starting midnight UT, one decode was attempted every 30 
> minutes,  using a setting for 464 raw symbols (4 characters)Ā and 5 
> seconds per  symbol. AĀ frequency offset of -0.6 mHz wasĀ selectedĀ to 
> obtain  flat phase during the first decodes, andĀ that offsetĀ wasĀ kept 
> for  all later attempts. Despite the Opera gaps  whichĀ degrade or drop 
> half of the available symbols,Ā 12 out of 13  decode attemptsĀ produced 
> the  correctĀ "****" message,Ā e.g. http://df6nm.bplaced.net/LF/r0317.png 
> . However at times the frequency drift was quite visibleĀ on theĀ phase 
> plot,Ā e.g. in http://df6nm.bplaced.net/LF/s0317.pngĀ (flat  phase around 
> 3:17) versus http://df6nm.bplaced.net/LF/s0347.pngĀ (upward  phase slope 
> around 3:47).Ā
> Ā
> Scaling down to VLF, deviations from the same  oscillator will be 16x 
> smaller (~30 uHz at 8.3 kHz). This will be probably good  enough even forĀ 
> narrow FFT bins, corresponding to several hours coherent  carrier 
> integration or slow EbNaut decodes.
> Ā
> All the best,
> Markus (DF6NM)
>
>
>  From: jcraig@mun.ca
> Sent: Saturday, November 07, 2015 3:45 PM
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: VO1NA opds-32
>
>
>
>
> LF Group,
>
> Again, thanks to SV8RV DF2JP PA7EY and DF6NM for  the reports.
>
> In my last post I reported the drift was constrained to  within 1 Hz.
> This should be 1 mHz.Ā Thanks Markus for your assurances  that this
> should be adequate for EbNaut which I hope to use to send send our
> cat's name on LF.Ā The little curls appear often on the QRSS traces  on
> your high res spectra.Ā Doppler variations were removed from the 10  MHz
> WWV signals with harmonic regression when the DOCXO was calibrated
> so  this effect is seen on LF but not as strongly.
>
> AfterĀ reading about  EbNaut on Paul Nicholson's pages it seems I have
> much catching up  ahead.Ā Fasinating stuff!
>
> Can the EbNaut phase inversions be done  without an absolute time
> reference?Ā I'm cheap and lazy so hoping GPS  will not be needed.
>
> The Opera will be doing an encore tonight and if the  wind stays low
> a tower climbing expedition is planned for the  afternoon.
>
> 73
> Joe VO1NA
>
>
> On Sat, 7 Nov 2015, Markus Vester  wrote:
>
> &gt; Hi Joe, LF,
> &gt;
> &gt; during the last couple of nights,  opds detected all of your 
> transmissions between about 22Ā and 7:30  UT.
> &gt;
> &gt; Attached is a zoomed 40 mHz section from my opds-32  spectrogram, 
> showing your central coherent carrier which contains half of the 
> transmitted average power. It seems to be about 0.5 mHz below 137477 Hz 
> (possibly due to a calibration error in my receiver). The 2.7 mHz spaced 
> sidelines during the early part (bottom) were caused by 6-minute-periodic 
> interruptions from my own MF WSPR transmissions. However the little curls 
> near  the carrier can presumably be attributed to Doppler-shifted 
> multipath  components. The carrier was still weakly visible for another 
> hour after the last  detection.
> &gt;
> &gt; Comparing the looks of the carrier to earlier IZ7SLZ  transmissions, 
> the stability of the signal and the path seems quite sufficient  for 
> half-hour EbNaut PSK transmissions. Unfortunately I missed the opportunity 
> to save the raw data and analyze phase evolution using the EbNaut decoder 
> itself  - will try that next time.
> &gt;
> &gt; All the best,
> &gt; Markus  (DF6NM)
> &gt;
> &gt;
> &gt;
> &gt;
> &gt; From: jcraig@mun.ca
> &gt; Sent: Saturday, November  07, 2015 12:03 AM
> &gt; To: rsgb_lf_group@blacksheep.org
> &gt;  Subject: Re: LF: last night opera opds detection in  km07ks
> &gt;
> &gt;
> &gt; LF Group,
> &gt;
> &gt;
> &gt; I am grateful  to Joe DF2JP for his captures QRSS and Opera
> &gt; Dionysious SV8RV for his OP  decodes to Domenico IZ7SLZ
> &gt; for his OPDS decodes, and thanks to DF6NM for  opds!
> &gt;
> &gt; I do not know if my DOCXO is stable enough for  EbNaut.
> &gt; It was set a couple of years ago and has not drifted more  than
> &gt; 1 Hz since then.Ā It seems the phase decoherence has  stopped
> &gt; haunting me.
> &gt;
> &gt; I am hoping to replace the halyard  for the other 100m wire soon.
> &gt;
> &gt; OP32 again tonight as send this  email.
> &gt;
> &gt; 73
> &gt; Joe
> &gt;
> &gt;
>
>
>