‰  NOW 35 WPM  ‰  TEXT IS FROM JULY 2012 QST  PAGE 38‰

SDR UPGRADE FOR ANALOG HF RADIOS BRING THE BENEFITS OF DIGITAL PROCESSING
TO YOUR VETERAN HF TRANSCEIVER.  ALEX SCHWARZ, VE7DXW  MOST MODERN
COMMERCIAL HF TRANSCEIVERS USE DIGITAL SIGNAL PROCESSING DSP TO ENHANCE
PERFORMANCE.  DSP, PARTICULARLY IF THE PROCESSING IS AT INTERMEDIATE
FREQUENCIES, OFFERS SUPER SHARP FILTERING AT AS MANY BANDWIDTHS AS DESIRED,
WITHOUT THE NEED FOR ADDITIONAL CRYSTAL FILTERS.  IN ADDITION, DSP CAN
PROVIDE FAR MORE EFFECTIVE NOISE REJECTION THAN OTHER TECHNIQUES AND CAN
PERFORM MANY OF THE MODULATION AND DEMODULATION TASKS PREVIOUSLY PERFORMED
BY ANALOG CIRCUITRY.  THOSE WITH OLDER TRANSCEIVERS STILL HAVE EQUIPMENT
THAT MAY BE MORE THAN ADEQUATE IN TERMS OF RF PROCESSING.  THIS SDR IF AND
AUDIO UPGRADE ALLOWS THE OLDER, BUT EFFECTIVE, RF STAGES OF EARLIER
TRANSCEIVERS TO BE COUPLED TO A DSP BACK END TO PROVIDE AN OPTIMUM MIX OF
TECHNOLOGY, WHILE PRESERVING THE LOOK, FEEL AND INVESTMENT OF EARLIER
RADIOS.  THIS PROJECT WILL RESULT IN AN ADAPTER THAT CAN PLUG INTO A
CRYSTAL FILTER SOCKET, DIGITIZE THE IF SIGNAL AND DEMODULATE IT USING
SOFTWARE AND THEN PLAY THE AUDIO THROUGH THE COMPUTER SPEAKERS OR CONNECTED
HEADPHONES.  PROJECT OBJECTIVES THIS GROUP EFFORT FIRST ESTABLISHED A SET
OF OBJECTIVES FOR THIS PROJECT.  THE OBJECTIVES INCLUDED TO CREATE A
SOFTWARE AND HARDWARE INTERFACE THAT IS USABLE FOR DIFFERENT MODELS OF
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