G8JNJ

I've now spent a bit more time playing with this application.

It's not the easiest thing to setup or initially use, but it does have some quite impressive features such as the ability to import various online databases and parse .xlsx files such as the 'Numbers and Oddities' and 'ITU monitoring' databases into a set of local databases that can be searched, sorted and indexed.

When driving a local radio or the Twente WEB SDR (or others of that type) it's very handy for click tuning, ID'ing or scheduling stations.

Definitely worth spending a bit of time with to get the hang of it, plus it incorporates some really good ideas and useful features.

Regards,

Martin - G8JNJ 

I think the loop is still unbalanced.

The split is to avoid a continuous 'screen' (Faraday screen to minimise E-Field pickup) around the loop. But if one end of the center conductor is connected to ground you may have a problem.

Check signal levels with the loop normal and 180 degrees as suggested previously.

A 1:1 transformer on the loop input may help improve balance. Try six bifilar turns through a BN73-202 core as a starting point. One winding as the (balanced) loop input (primary) the other as the output (secondary) unbalanced connected to the amplifier input, with one end of the winding connected to ground. This will also provide galvanic isolation.

You can also try a few more turns on the secondary as an experiment as this may improve reception on the LF bands.

If you made a balanced loop amplifier with a much lower value of input impedance (LZ1AQ or Wellbrook copy) you wouldn't need the loop outer screen to minimise E-Field pickup.

Regards,

Martin - G8JNJ

I recently found a broadcast database application that allows control of various receivers (including the Twente WEB SDR).

 http://www.df8ry.de/htmlen/csvub/features.htm

Although it's a bit of a pain to setup, it does have some 'interesting' features that may be of interest for KiWi admins and users.

Regards,

Martin - G8JNJ

The change has made a huge difference no sign of any audio 'stuttering' and a very fast and smooth scroll up and down in frequency at all zoom levels.

Thanks for that :-)

Regards,

Martin - G8JNJ

Quite a few 170Hz  / 100bd  FSK signals I've heard (but not decoded) turn out to be "Digital selective-calling system for use in the maritime mobile service" using a  ten-bit error-detecting code. 

All of the code structure is defined in https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.493-14-201509-I!!PDF-E.pdf

DSC calling frequencies

Regards,