‰  NOW 25 WPM  ‰  TEXT IS FROM MAY 2015  QST  PAGE 41 ‰

SIGNAL TRAPPED ALONG EARTHS MAGNETIC FIELD LINES MIGHT EXPLAIN ECHO DELAY
TIMES LONGER THAN 138 MS.  PERHAPS THE EXPLANATION IS CORRECT, BUT I CANT
EXPLAIN A MECHANISM THAT GENERATES A SHORT DELAYED ECHO AT BOTH A
FUNDAMENTAL OFFSET FREQUENCY AND AT A HIGHER FREQUENCY APPROXIMATELY DOUBLE
THE LOWER FREQUENCY OFFSET.  FURTHERMORE, WHILE THE TIMING OF EACH HIGHER
FREQUENCY ECHO WHEN PRESENT COINCIDED WITH THE TIMING OF THE LOWER
FREQUENCY ECHO, I NEVER OBSERVED THE HIGHER FREQUENCY ECHO TO OCCUR ANY
MORE FREQUENTLY THAN ABOUT EVERY 2R5 SECONDS.  A SPECTROGRAM FIGURE 2 SHOWS
15 OF THE 60 RECORDED DITS THAT PRODUCED SHORT DELAYED ECHOES DURING MY 225
PM DATA COLLECTION.  THE SPECTROGRAM DISPLAYS THE SIGNAL FREQUENCY ALONG
THE Y AXIS ORDINATE AND INCREASING TIME ALONG THE X AXIS ABSCISSA.  THE
RELATIVE AMPLITUDE OF THE SIGNAL IS COLORED BLUE FOR LOW AMPLITUDE AND RED
FOR THE HIGHEST AMPLITUDE SIGNALS.  I RECORDED THE SIGNALS USING
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ