[Elecraft] Obscure RTTY bug?

[Kok Chen]

The odd thing is that the glitches in Iain's recording appear to occur  
a cycle or two before a frequency shift.  It almost appears to be due  
to an improperly windowed FIR filter, but it could be caused by  
anything else...

If you have an audio editing program, you can see the envelope  
glitches quite clearly in Iain's wav file.  There is one at 2.9235  
seconds into the recording, and another at 3.253 seconds into the  
recording, for example.  You can see the frequency shift about 2 or 3  
msec following those glitches.

73
Chen, W7AY