‰  NOW 20 WPM  ‰  TEXT IS FROM SEPTEMBER 2015 QST  PAGE 34 ‰

SERVICE OPERATION IN MIND FOR FSQ.  WE WANTED TO MAKE OPERATION AND KEEPING
IN TOUCH WITH FRIENDS EASY AND A PLEASURE THUS WE KNEW WE COULD ATTRACT
USERS WHO WOULD BE TRAINING AS EMERGENCY OPERATORS.  FSQ CODING AND
MODULATION  FSQ USES 33 FSK, WITH TONES ENCODED WITH IFK INCREMENTAL
FREQUENCY KEYING DIFFERENTIAL MFSK WITH AN OFFSET OF 1.  THIS SIGNALING
OFFERS IMPROVED PERFORMANCE UNDER NVIS PROPAGATION CONDITIONS BECAUSE THE
TONE ROTATION SIGNIFICANTLY REDUCES THE RISK OF ADJACENT SYMBOLS CAUSING
ISI INTER SYMBOL INTERFERENCE.  DATA IS DIFFERENTIALLY CODED, SO IFK HAS
SIGNIFICANTLY IMPROVED TOLERANCE OF DOPPLER SHIFT, FREQUENCY DRIFT, AND
POOR TUNING.  SYMBOL TABLE 32 TONE DIFFERENCES ARE AVAILABLE IN FSQ.  WE
ALLOCATED 29 TONE DIFFERENCES DIRECTLY TO THE MOST USED CHARACTERS LOWER
‰  END OF 20 WPM TEXT  ‰  QST DE W1AW  ƒ