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Re: LF: Grabbers - how do you do it?

To: [email protected]
Subject: Re: LF: Grabbers - how do you do it?
From: John GM4SLV <[email protected]>
Date: Mon, 15 Nov 2010 00:07:49 +0000
In-reply-to: <[email protected]>
Organization: The Gammy Bird
References: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]

There are several ways to do this, as you'd imagine!

Three that spring to mind

1) The old fashioned geek-way: Spec Lab saves a screenshot every X
minutes and you have a script that automates an upload of this image
via FTP to your "ISP provided" Webspace. 

I've run this style before, for a long time, and though it's cumbersome
to set up, it works well, assuming your ISP is reliable with it's
FTP upload servers and its webspace.  You have to get to grips with the
scripting (in Linux it's "shell scripts" and in Windows it's "batch
files") though. You also need some software like "pycron" that is able
to run the script at a frequency of your choosing.

2) Use the in-built HTTP server in Spec Lab. This requires you to open
a hole in your router's firewall for a specific port and configure a
"port forward" between the router and the PC you're running Spec Lab
on. If you have a dynamic IP address from your ISP then for people to
find you easily you also need a service like DynDNS to automatically map
your variable IP address to a fixed URL. 

I have a fixed IP address so it's never been necessary for me to do

I've used this method (the HTTP server in Spec Lab) and it's all well
and good - if you don't mind that every person who views your grabber
is using more of your upstream bandwidth.

My newer, and preferred method:

3) Install "Dropbox" - a free online file
archiving/sharing/syncronising system. Then make Spec Lab save its
regular screenshots in the "public" Dropbox folder. This is a special
folder in Dropbox that can be accessed from the internet by anyone who
knows the URL of the specific file. All you need to do is make sure
Spec Lab puts the screengrab in a folder on your PC and it's
automatically copied between any of your other PCs that have Dropbox
installed, and is copied to secure storage on the internet, with no
effort on your part.

This works very well and is really simple to set up.

Here's a grabber shot from when I used this method recently.

The bandwidth used by each viewer isn't to your PC, it's to Dropbox's
online servers.

Drop me a private email if you want help to set it up.



On Sun, 14 Nov 2010 22:32:01 +0000
Roger Lapthorn <[email protected]> wrote:

> *Apologies if this sounds a pathetically stupid question to ask the
> experts here, but I believe it is better to confess ignorance and ask
> anyway:
> *Assuming one has a decent VLF receiver/E-field probe antenna and a
> package (like Spectrum Lab or Spectran) that captures screengrabs
> periodically, what is then needed to make these visible to others? I
> am not an IT expert so I'm looking for a really simple way of doing
> this. I have Virgin Media webspace (unused) and ideally it would be
> good to be able to upload the jpg image(s) to this. I've also heard
> about people using their PC as a web server, but honestly I've no
> idea what this is or how I would go about it.
> So, can someone offer me an "*idiot's guide to setting up a grabber*"
> please?  This must be quite straightforward as people must do this
> for home security cameras. Again, please don't baffle me with jargon
> that I won't understand: simple, easy, and "noddy guide" style please.
> If I could set up a VLF grabber at the home QTH it could be pretty
> useful for people in SE England doing VLF experiments, including me.
> 73s
> Roger G3XBM

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