Date: Sat, 5 Jan 2008 10:45:22 +0000
From: John Pumford-Green GM4SLV <gm4slv@sighthound.demon.co.uk>
To: rsgb_lf_group@blacksheep.org
Message-ID: <20080105104522.6bb3468b@lurcher.twatt.local>
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Organization: The Gammy Bird
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Subject: Re: LF: 500 grabbers
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On Fri, 4 Jan 2008 19:10:55 -0000
"mal" <g3kevmal@talktalk.net> wrote:

> Hi all
> The majority of the grabbers are running too slow for normal CW,
> which is the predominant mode on 500 khz.

My grabber isn't meant to be used to read CW, that's what your ears and
brain are for!

The grabber is meant as a remote signal reporting tool. Admittedly it
allows reading of QRSS3 CW visually, but that's more by accident than
design. 

To use it to check your own signal all you need to do is key down, or
send CW etc.... on a known frequency at a known time, (perhaps a series
of long dashes?) and then check the grabber via the web. 

I admit that it makes identifying unknown "real" CW difficult, but you
can't have everything! Most signals (especially CW beacons) are
identifiable once you know the usual QRG and have heard the signal
yourself to know what it sounds like - eg Finbar's callsign and long
dash are easily ID'd visually once you know what they sound like.


Imagine the speed it would have to scroll to show real CW and the number
of web updates needed to keep it reasonably up to date for the remote
viewer! 

At present mine fills a screen in about 4 minutes with a 300ms scroll
speed, and uploads each screenful every 5 minutes.

This allows you (watching via the web) to see a reasonably continuous
picture of activity with reasonable refresh rate. 

To scroll fast enough to read CW by eye would require much faster
scrolling speed and to ensure nothing is missed by the viewer
watching online the picture would need uploading to the web that
much more often. 

I figured my setup balanced utility with bandwidth. 

I also archive each and every picture locally so it's possible to
provide historical data for any day/time. If the screen was scrolling
fast enough to read CW by eye I couldn't do this - too much data to
store! Guess how much data I have stored already - 5 minute updates
running continuously 24/7 since July......!!

> Speclab  grabbers do not give the time, which I find useful on the
> others.

Mine does. There's a box at the bottom of the picture showing date/time
etc of the capture and vertical marks for each minute (with the time
marked at the foot of each minute). The time is accurate too - the PC
is locked to NTP time.


I hope my grabber is of use to people. One of the stated aims in my NoV
application was to provide a remote station to be of assistance to
other NoV holders - and while I have been unable to get on the air to
have QSOs recently at least I've been able to make a contribution to
the experiment! 

I figure I can at least make my station useful for something when I
can't operate it myself.

Regards,

John