Non-decode on strong signal - MKII ..... FIXED.....

5 posts / 0 new
Last post
VK2XV
VK2XV's picture
Offline
Last seen: 4 years 9 months ago
Joined: 2008/12/15 - 19:48
Non-decode on strong signal - MKII ..... FIXED.....
AttachmentSize
Image icon WSPR_VK4YEH.jpg2.02 KB
Image icon Argo_VK4YEH.jpg8.77 KB

********* THIS PROBLEM HAS BEEN TRACED TO WSPR NEEDING A SOUNDCARD SAMPLE RATE OF 48000SPS.**********
When soundcard switched to 48000sps (was 44100sps) the 'non-decode of strong signals' behaviour disappeared. Apparently the soundcard XP OS default driver does a better job of downsampling from 48000sps to the 12000sps WSPR sample rate as they are harmonically related.

Further to mention of non-decode of strong signals I offer an explanation. See attached pictures of a strong station (VK4YEH).

Tim's (VK4YEH) signal is strong at times here and is a clean, stable signal as viewed on WSPR. See WSPR_VK4YEH.jpg attachment.

When viewed in higher resolution (see Argo_VK4YEH.jpg attachment) it continues to be shown as a clean, stable signal (not a banana signal). The difference is that at times we can see the signal QSBs out completely. Maybe this defeats WSPR...???

I read somewhere that high angle signals are more subject to phase shifts and cancellations than lower angle signals - something to do with high angle signals being reflected from a smaller area than low angle signals - apparently resulting in more frequent complete cancellations in the high angle signal - whereas the low angle signal has more refraction points and so complete cancellation is less likely. Not my theory - but I did read it somewhere recently.

Maybe this explains the disconnect between strong signals over short paths received via the ionosphere and the success rate of decoding...

Just a thought...