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,

I think that the problem is almost certainly loop imbalance. 

You can check this by rotating the loop to peak a known station. Note the signal level then rotate the loop 180 degrees and note the signal level of the peak in that direction. 

If the loop is properly balanced the signal levels should be the same. If it isn't the peaks will be different as the imbalance means that it is now configured as an Aperiodic loop. 

Which are often used for phased receive arrays like this commercial version.

Three other signals I've decoded (so far)

Regards,

Martin - G8JNJ

Take a look at this thread.

It's probably Super Darn. I normally see it around 12MHz but your screen grabs look very similar.

Regards,

Martin - G8JNJ

The LMS "denoiser" and "autonotch" filters work quite well and are a very welcome addition, so thanks for that.

However I can't open any of the three test sites on my iPad running Chrome. The URL resolves OK but I just get a blank white screen.

The purpose of the 'Slow Dev' button isn't obvious - I think it needs to be called something else

I'd prefer the 'Slow Dev' waterfall to be white rather than a 'strange' green colour, so that it is a higher contrast display that can be more easily be seen outdoors.

Should the 'rainbow' spectrum amplitude display bar also be in black and white when the 'Slow Dev' option is enabled.

The mute button needs to be either on the main pane or the audio panel needs to open by default rather than the waterfall when the browser session opens.

Why is it WFO rather than WF - what does the 'O' stand for ?

Should the spectrum display button now be on the WFO pane ?

If the spectrum display button is moved could a second mute button be added in it's place ?

Should the green arrow URL button be aligned under the up and down arrow buttons ?

I'd still prefer the S-Meter scale to be at the top of the control pane

I still think that the new dBm reading needs to be differentiated from the rest of the S meter scale

Could the waterfall contrast schemes be better named ? I think they correspond to:-

Regards,

Martin - G8JNJ

I'd also like to add the KiWi ID to the time and date, so that it makes it easier to use the data at some later date if a centralised database is ever established.

Covered in these previous threads.