‰  NOW 25 WPM  ‰  TEXT IS FROM JANUARY 2014 QST  PAGE 65‰

MOVING RAIN CELL.  STATION A TRANSMITS, AND STATION BS RECEIVING ANTENNA IS
ROTATED WHILE WATCHING THE DISPLAY.  STATION BS OPERATOR IS LOOKING FOR A
SCATTERED SIGNAL.  ONCE A BIT OF SIGNAL IS FOUND, STATION B TRANSMITS AND
STATION A PEAKS HIS ANTENNA.  THEY KEEP REPEATING THIS PROCEDURE UNTIL THE
SIGNAL IS STRONG ENOUGH FOR A CONTACT.  IT IS EVEN POSSIBLE TO MAKE
CONTACTS WHEN SIGNALS ARE TOO WEAK TO HEAR, BY USING VERY SLOW CW AND
READING THE CW IN THE PASSBAND DISPLAY.  IN FIGURE 2, I CAN READ RR
CLEARLY, WHILE THE SIGNAL IS ONLY A FEW DB ABOVE THE NOISE.  SIGNALS TOO
WEAK TO HEAR IT IS POSSIBLE TO SHOW A SIGNAL TOO WEAK TO HEAR BY USING VERY
NARROW BANDWIDTHS WHERE THE FILTERING IS DONE IN THE SDR COMPUTER SOFTWARE.
NOISE POWER IS PROPORTIONAL TO BANDWIDTH A WIDE FILTER PASSES MORE NOISE,
WHILE A CW SIGNAL HAS A NARROW BANDWIDTH.  IF WE REDUCE THE FILTER
BANDWIDTH, WE REDUCE THE NOISE, IMPROVING THE SIGNAL TO NOISE RATIO.  WHEN
‰  END OF 25 WPM TEXT  ‰  QST DE W1AW  ƒ