Next success contact with Czech team from OK2KQQ 81km distance

In the summer months, we did not think the optical connection.
Holidays, sweltering heat do not give the possibility to experiment with optical contact.
In late summer, however, Rado organized next attempt with our friends from the Czech Republic.
Elected Radhost hill, which is accessible by car and it is 81km from Velka Javorina.
Weather did not appear initially very good. Two days before the experiment is much colder,
which significantly reduce the water vapor in the atmosphere.
Almost impossible a reality. On the day of the experiment was almost perfect weather.

Rado with Vlado went a little earlier, testing equipment for VHF contest.
On the evening when I arrived, we started to build equipment for the optical connection.
2x Spotlight, 2 x optical transmitter and 2m transciever for setup of directions.
We roughly estimated direction. After consultation with the OK to switch on the light side for their direction.
Estimation of direction was quite nearby. 15 degrees when looking for small light point,
is significant divergence. I was a bit disappointed because a friend from Czech republic
somehow not understand the need of navigation lights and so the mutual navigation slightly extended.
We had to start opposite. Czechs tried to tighten our navigation lights.
After a few minutes of navigation we are able to see laser from Radhost hill.
100mW from a distance of 81 kilometers, I accepts the full fine. Even when retracted screen
(about 15 mm aperture) signal was clearly legible. First connection was made with OM2ZZ equipment.
This was followed by pile-up :-) when we made a contact, everyone followed the link to my equipment.
Without problems. Just one problem was, that my laser is set at 50% power 10mW laser and AM modulation
sweep + / -50%. This caused the impression that the laser is faint and difficult eye locatable.
But definitely it would be useful to improve future income OK2KQQ hand, so that larger distances to have problems.

Lessons learned from this experiment is unambiguous:

1. Honestly elaborate direction before the arrival on site the series. Materials like this. (Rado OM2ZZ)
2. Sensitize the highest possible level. (I work for the Primacy of PMT, which should be about 1000 times
more sensitive)
3. Quality Compass is a necessity.
4. Seek at all costs to reduce divergence. This may be detrimental. Listen carefully and record (AUDIO OM1LD-OK2SS) notice signal fluctuations due to non-homogeneties environment.
This non-homogeneties is caused by different temperature layers mixed the air thus creating a path of dynamic change of the refractive index.
The refractive index varies in different parts of the light path while dynamically change over time.
5. Orientation on the ground a minimum by well-known objects and goniometer
6. Spot Light 50W halogen lamp 4degres divergence, or 20W Xenon 4deg divergence, or a powerful laser to artificially stretching degrees of divergence at 2-4.
7. Quality 2 meter radio with directional aerials.

I hope that this autumn will be more successful to experiment with laser communications, towards 100km.

Photoalbum
More from Rado OM2ZZ You can see here

V letnych mesiacoch sme nemysleli na opticke spojenie.
Dovolenky, teplo a sparno nedavaju vela moznost podniknut experimenty s optickym spojenim.
Koncom Leta vsak Rado zorganizoval s nasimi kamaratmi z Ceskej Republiky dalsi pokus.
Zvolili si kopec Radhost, ktory je pristupny autom a sucasne dost daleko na zaujimave spojenie.
Pocasie spociatku nevyzeralo moc dobre.
Dva dni pred experimentom sa vyrazne ochladilo, co vyrazne znizilo obsah vodnych par v atmosfere.
Skoro nemozne sa stalo skutocnostou. V den experimentu bolo takmer dokonale pocasie.

Rado s Vladom odisli trochu skor, testovali zariadenie pre VHF zavod.
Na vecer, ked som dorazil aj ja, sme zacali stavat zariadenie pre opticke spojenie.
2x bodove svetlo, 2 x opticke vysielace a 2m transciever pre navigaciu.
Odhadli sme smer nahrubo. Po dohovore s OK stranou zapiname svetla na ich smer.
Odhad smeru bol dost vedla. Ak hladate maly svetelny bod je 15 stupnov moc velka odchylka.
Trochu som bol sklamany, lebo kamarati z Ceska si nejako neuvedomili potrebu bodovych navigacnych svetiel
tak sa vzajomna lokalizacia trochu predlzila. Museli sme zacat opacne. OK2KQQ/p sa snazili dotiahnut na nase
navigacne svetla. Po niekolko minutovom navigovani sa to podarilo.
Laser z Radhoste bol velmi dobre viditelny. 100mW z 81km vzdialenosti som prijimal uplne v pohode.
Aj pri zatiahnutej clone (apertura asi 15mm) bol signal jasne citatelny.
Prve spojenie sa uskutocnilo cez OM2ZZ zariadenie.
Nasledoval pile-up. :-) Ked sme si spravili spojenia kazdy s kazdym, nasledovalo spojenie s mojim zariadenim.
Bez problemov. Jedine co vadilo je, ze moj laser je nastaveny na 50% vykonu 10mW laseru a AM modulacia
je rozmietana +/-50%. Toto sposobovalo dojem, ze laser je slaby a tazko okom lokalizovatelny.
Jednoznacne vsak by bolo vhodne do buducna zlepsit prijem na strane OK2KQQ, preto ze vacsie vzdialenosti budu problem.

Ponaucenie z tohoto experimentu je jednoznacne:

1. Poctivo vypracovat smerovanie este pred prichodom na lokalitu. Takto to pripravil Rado OM2ZZ.
2. Zvysit citlivost na maximalnu moznu uroven.
(pracujem na Primaci s PMT, ktory by mal byt asi 1000 nasobne citlivejsi PMT vyvoj)
3. Kvalitny kompas je nutnost.
4. Nesnazit sa za kazdu cenu znizovat divergenciu. Moze to byt na skodu.
Vypocujte si pozorne nahravku (AUDIO OM1LD-OK2SS)> Spozorujete kolisanie signalu sposobene nehomogenitou prostredia.
Tato nehomogenita je sposobena roznou teplotou miešajúcich sa vzduchovych vrstiev cim sa vytvara
trasa s dynamickou zmenou indexu lomu, ktory v roznych castiach drahy svetla sa rychlo meni.
5. Orientacia v terene minimalne podla znamych objektov a uhlomeru
6. Spot light 50W halogen lampa 4degres divergencia, alebo 20W Xenon 4deg divergencia,
alebo vykonny laser s umelo roztiahnutou divergenciou na 2-4 stupne.
7. Kvalitne 2m radio so smerovou antenou.

Dufam, ze tato jesen bude na experimenty s laserovou komunikaciou uspesna a priblizime sa k hranici 100km.

Fotoalbum
Viac od Rado OM2ZZ najdete tu

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