Message-ID: <477E178F.4000907@freenet.de>
Date: Fri, 04 Jan 2008 12:25:03 +0100
From: =?ISO-8859-1?Q?Wolfgang_B=FCscher?= <dl4yhf@freenet.de>
User-Agent: Thunderbird 2.0.0.9 (Windows/20071031)
MIME-Version: 1.0
To: rsgb_lf_group@blacksheep.org
References: <BEA259931570B948B5DF6825FA3F2D640BE74473@EXUKMB49.eur.nsroot.net> <003801c84e2a$8dd1f7c0$0100a8c0@W1KW> <019601c84e51$9ef47ec0$6401a8c0@p4> <001501c84e64$f67e0810$0d00000a@AGB>
In-Reply-To: <001501c84e64$f67e0810$0d00000a@AGB>
Subject: Re: LF: Re: GM4ISM 500KHz Grabber
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Hello Mark,

I guess the problem with the Javascrip refresh method is this:

The javascript begins to update the screen, regardless of the transfer 
speed. Even if the previous update isn't finished, it begins a new 
update. If, for example, the transfer of the image requires 25 seconds, 
but the Javascript tries to update it every 2 seconds, there will be 
endless activity but no new screen because the embedded image is only 
update when it's complete (this reduces flicker, and is the main 
difference between the javascript page, and the simple java-less page 
which updates itself through an html meta tag) .

What Graham could try is to enter a larger value in the "Refresh 
Interval" box at the bottom of the screen (on Mark's "index" page with 
the 500 kHz spectrogram). For example, set the update interval to 30 
seconds (the default was 2 seconds, which was my mistake, because 2 
second refresh only works through a local network).

As long as you permanently see the message "transferrig data from 
82.something" on the bottom of your browser (but never the "Ready"), you 
know that your browser requests the image too often. With 30 second 
refresh, I get a stable periodic refresh from Mark's MF viewer.

If we have a Javascript expert here: Any idea how a Javascript (embedded 
in an HTML document) can detect if all embedded graphics have been 
updated ? In that case, the "refresh" interval could be restarted after 
the previous refresh is finished.


Best regards,
  Wolfgang "Wolf" DL4YHF .

Graham schrieb:
> Mark,
>  
> Just had a look, but only seeing a small strip at the top of the 
> screen, which is flickering ,  only way to  view full page, is to  
> click on the 'slow' link ..
>  
> Graham ..
>
>     ----- Original Message -----
>     *From:* Mark <mailto:markhughes1@blueyonder.co.uk>
>     *To:* rsgb_lf_group@blacksheep.org
>     <mailto:rsgb_lf_group@blacksheep.org>
>     *Sent:* Thursday, January 03, 2008 9:43 PM
>     *Subject:* LF: GM4ISM 500KHz Grabber
>
>     Gents,
>     Thanks to Wolfgang DL4YHF, the grabber at my QTH is now running a
>     new beta version of Spectrum lab, that should stop the problem of
>     multiple users getting partial images.
>     After an initial rush of activity, the number of users has calmed
>     down, rather as expected.
>     Feel free to jump on board and try to break it again!
>     The system is connected to my main antenna but this is at minimum
>     height and not correctly matched. Still it works pretty well and
>     many signals were visible last night.
>     I have also got the magnetic antenna working, (placed temporarily
>     on the shed roof) and it will be re-mounted when the weather
>     permits, it seems slightly better than the reduced height main
>     antenna.
>      
>     I dont have the fantastically low noise floor that John GM4SLV
>     offers, but I hope to leave the grabber running for the duration
>     of the UK experiment or longer, if it is considerd useful. It is
>     far enough away from other grabbers to perhaps be of some use for
>     the experiment. It is also a testing ground for possible similar
>     systems at SHF giving 'inverse' beacons for propagation indication.
>      
>     any comments or problems encounterd, please let me know!
>     Regards
>     Mark GM4ISM
>     www.dc2light.co.uk <http://www.dc2light.co.uk>
>     follow the MF / LF link, at the bottom of the page is the grabber
>     link.
>
>     ------------------------------------------------------------------------
>     No virus found in this incoming message.
>     Checked by AVG Free Edition.
>     Version: 7.5.516 / Virus Database: 269.17.13/1207 - Release Date:
>     1/2/2008 11:29
>