[A-DX] Shortwave transmission faults (5850 kHz WRMI)

Roger
Montag, 09. August 2021, 21:49 Uhr

http://homepages.ihug.com.au/~daz2002/tech/SWF/index.html


*** Update Aug 5th, 2021 ***
A series of low frequency sinewave ramps were added to the RNEI program 
to measure the system LF distortion characteristics.

Observed distortions were:

     LF clipping (a certain amount of this is probably from normal 
Optimod behaviour)
     Some asymmetric LF distortion (probably modulator/PA nonlinearity)
     Severe peak breakup above -6dBFS (system overload or instability)
     Random glitches on peaks (possibly due to #3)

This proves that there is something in the 5850 modulation signal path 
that is overloading or unstable.

Some possible causes may be:

     Excessive playout system level or EQ boosting
     Modulator distortion/instability or perhaps loss of negative feedback


http://homepages.ihug.com.au/~daz2002/tech/SWF/ramps.png


https://www.qnx.com/developers/docs/7.0.0/#com.qnx.doc.neutrino.audio/topic/audio_ramp.html


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aber auch bei der 7780 kHz gibt es Probleme:

Shortwave Radiogram (via Twitter)
@...
·
20 Std.
Jeff at WRMI tells me: "We’ve been having some problems with that 
transmitter.  Something burned up, and I’m told it will be off tonight 
and hopefully back on tomorrow."



roger