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Re: LF: EA in LF NOW !

To: "[email protected]" <[email protected]>
Subject: Re: LF: EA in LF NOW !
From: VIGILANT Luis Fernández <[email protected]>
Date: Sat, 16 Apr 2016 12:32:58 +0000
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References: <[email protected]cal>,<[email protected]>
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Thread-index: AQHRljiFIy44cOHBrE60yk/5d6NN2Z+Ki6mAgAHWW9L///KwAIAANCII
Thread-topic: LF: EA in LF NOW !
Hi Markus, LF

This morning I have interrumped transmissions to measure power and the inductance of coils
That causes the GPS recalibration process to work harder. First corrections are too low and two high
getting accurate on the third try, as DDS oscillator stabilizes. The problem with OP32 is that this
calibrations are just done after the transmission period is completed. So the overall process takes
about 100 minutes to complete

I'm not using the park feature. This is mainly to avoid birdies in other Rx when the U3 is not transmitting
as I understand it. Anyway, the GPS caibration process changes DDS frequency and should have
similar effects as the park feature

Have measured 0,7mH in the first coil + variometer at minimum, 1,23mH in the second and 4,73mH
in the third double layer coil. That makes the antenna to resonate just in 137.500Hz

Now I'm on air again, but first calibration may have pulled the frequency to .517 again

73 de Luis

De: [email protected] [[email protected]] en nombre de Markus Vester [[email protected]]
Enviado: sábado, 16 de abril de 2016 13:15
Para: [email protected]
Asunto: Re: LF: EA in LF NOW !

Hi Luis,
here are two hi-res screenshots (40 mHz span), showing your Opera carrier yesterday and today. Today's traces seemed generally weaker (propagation?), and there are visible frequency steps (presumably from the GPS recalibrations) which might have slightly affected opds's carrier detection. But pieces of carrier are still visible so coherence appears to be preserved.
Unfortunately I am not familiar with the U3 and it's features and settings. Klaus DJ6LB mentioned that there exists a "park" option to move the frequency away during key-up periods, which would most likely destroy phase coherence between symbols.
I am now detecting you on 137517.07 - have you moved 5 Hz up?
All the best,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: VIGILANT Luis Fernán dez <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 16 Apr 2016 12:12 pm
Betreff: Re: LF: EA in LF NOW !


M0DSZ decoded me in Opera Deep Search last night at 1596Km, so ODX so far

04:57    136 EA5DOM de M0DSZ Op32 Deep Search 1596 km -42 dB in NW Shropshire, IO82LS 1512.3 Hz
04:53    136 EA5DOM de EA5DOM Op32 0 km -10 dB F:1%_End in Albir 1510,3 Hz
04:23    136 EA5DOM de M0DSZ Op32 Deep Search 1596 km -43 dB in NW Shropshire, IO82LS 1512.3 Hz

Thank you for the report on the phase carrier Markus

I have been transmitting continous periods setting the "Frame Start" U3 menu to "00 00"
May be this is the reason for the phase coherent carrier. To test this, I changed the settings last night
So during last night I set 2 minutes pause between transmissions. This also allowed the U3 to make a GPS calibration
which did not happen before. Anyway, as there are no BS170 heating inside the box, frequency stability is quite good

From your correlation detections list looks like last night I didn't got so many. May be the phase is not coherent now ?

Finally, made an RMS measurement of U3 output over 50Ohm
Power is a few dBs over 100mW, but still QRP. The 100mW figure was at MF

73 de Luis

De: own[email protected] [[email protected]] en nombre de Markus Vester [[email protected]]
Enviado: viernes, 15 de abril de 2016 10:00
Para: [email protected]
Asunto: Re: LF: EA in LF NOW !

Plenty of good opds detections again here last night:
Moving the zoomed section of the spectrogram to your QRG shows a good and narrow (albeit slightly drifting) central carrier. This means that your version of the U3 is keying coherently with continuous carrier phase, helping opds to reach it's full sensitivity. According to earlier observations on MF, there also other Ultimate versions out there which apparently reset the DDS during the gaps, producing random-phase symbols with no continuous carrier.
Best 73,
Markus (DF6NM)

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