‰  NOW 35 WPM  ‰  TEXT IS FROM DECEMBER 2008 QST  PAGES 33, 35 AND 74  ‰

A MODULAR RECEIVER FOR EXPLORING THE LF/VLF BANDS PART 1, LAST MONTH,
PRESENTED THE FRONT END PIECES OF A HIGH PERFORMANCE LF/VLF RECEIVER.  THEY
ALSO COULD BE USED TO MAKE A STAND ALONE CONVERTER TO USE WITH YOUR 80
METER AMATEUR RECEIVER OR TRANSCEIVER.  LAST MONTHS ARTICLE ALSO PROVIDED A
SIDEBAR WHATS DOWN THERE?  TO PROVIDE A BRIEF OVERVIEW OF THE INTERESTING
LISTENING TO BE FOUND IN THAT REGION OF THE SPECTRUM.  THIS MONTH WE WILL
COMPLETE THE PROJECT BY MAKING OUR OWN LF/ VLF SOFTWARE DEFINED RADIO SDR
RECEIVER.  A BRIEF LOOK AT THE DESIGN THE THREE MODULES MAKING UP THE
RECEIVER ARE SHOWN IN FIGURE 6 AND IN BLOCK DIAGRAM FORM IN FIGURE 7.
DETAILS OF THE CONVERTER AND ANTENNA POSSIBILITIES APPEAR IN PART 1.
FOLLOWING THE CONVERTER IN FIGURE 7 IS THE I Q DETECTOR.  THIS IS THE REAL
HEART OF THE RECEIVER AND ITS NAME STEMS FROM THE FACT THAT ITS FUNCTION IS
TO EXTRACT BOTH AN IN PHASE I COMPONENT OF THE SIGNAL AS WELL AS A 90 OUT
OF PHASE Q, OR QUADRATURE, COMPONENT.  THIS IS THE APPROACH FOLLOWED IN
MOST MODERN RADIO DESIGNS.  THE REASON I Q DETECTION IS SUCH A FAVORED
TECHNIQUE AMONG RECEIVER DESIGN ENGINEERS IS THAT ONCE YOU HAVE BOTH THE I
‰  FROM PAGE 74  ‰
ID W0EA 621 2 3 2,416 IA The FPL Group K8ESQ K8QBR 533 2 5 2,406 MI Barrie
ARC VE3GCB VE3ORC 475 2 36 2,380 ON Hamilton ARC VE3DC VE3DF 940 2 40 2,380
ON CTARC WD5IYF KE5OMZ 628 2 12 2,372 OK Wyandot Area Ham Operators
‰  END OF 35 WPM TEXT  ‰  QST DE W1AW  ƒ