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LF: VLF CW transmision from Speleo amateurs in Spain

To: "[email protected]" <[email protected]>
Subject: LF: VLF CW transmision from Speleo amateurs in Spain
From: VIGILANT Luis Fernández <[email protected]>
Date: Thu, 8 Jun 2017 11:09:48 +0000
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Thread-topic: VLF CW transmision from Speleo amateurs in Spain

Hi VLF ….. a bit off topic but seems that this is the right place to talk about “almost DC” radio experiments, isn’t it ?  ;-)

 

Got news from Juan Leandro. Not a radio amateur (yet) but strong enthusiast and technician who has developed

a series of electronic aids to perform communications from speleo amateurs inside caves with the team outside

The system was initially designed to provide a signal reference to measure angles from surface and then use this data

to make 3D charts of the caves. But the last version, called SUMMER can also be used to transmit CW to the surface

It uses a magnetic antenna at 38.4KHz

 

The last operation took place last weekend june 4th inside a siphon which included diving. SUMMER was used to inform

surface team and keep them aware about the development of the activity. It was a distance of 70,5m trought rock package

The design of the SUMMER is tailored to speleo needs, not radio amateurs. The operator terminal is a ruggerized Android

phone running “Morse Player” and sending the keying to SUMMER via Bluetooth. All IP66 proved and very rugged  ;-)

 

At surface, a regenerative Rx and two decoders were used. One Android with App “Morse reader” and MultiPSK in a laptop

 

This links to the website of the group. Sorry, Spanish only but you can see a lot of pictures here

http://extopocien.es/galeria-de-fotos

 

There is also an audio of the CW signal here. OOO copy indeed J

https://drive.google.com/file/d/0B35G5k4xUp5VeFUwXzFaN1pkNkE/view

 

And a video showing the surface operation

https://drive.google.com/file/d/0B35G5k4xUp5Vck9LMEpEemRISnM/view

 

You will probably find interesting the description of the SUMMER transmitter, which is in few pdf docs at this links

https://dl.dropboxusercontent.com/u/7162072/Docs/Espeleo%20gonio/Summer%201%20descripcion.pdf

https://dl.dropboxusercontent.com/u/7162072/Docs/Espeleo%20gonio/Summer%201%20Tcontrol.pdf

https://dl.dropboxusercontent.com/u/7162072/Docs/Espeleo%20gonio/Summer%201esq.pdf

https://dl.dropboxusercontent.com/u/7162072/Docs/Espeleo%20gonio/Emisor%20summer1descRecA.pdf

 

A lot of room for improvement, but keep in mind that this guys are not looking for squeezing the last dB

but making a realiable and easy to operate system. They can not deal with very slow modes and all must be kept

reasonably simple, which most of the times means also, reliable. Cave explorers are not DX operators  ;-)

 

Comments and advices are thruly wellcome. Juan Leandro is one of the (many) readers of this reflector

 

73 de Luis

EA5DOM

 

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