From: apogosso@tpg.com.au   
      
   "Don Pearce"  wrote in message   
   news:4e22c684.16025155@news.eternal-september.org...   
   > On Sun, 17 Jul 2011 04:14:48 -0700 (PDT), Patrick Turner   
   >  wrote:   
   >   
   > Have you tried a synchronous detector? Generate a well-limited square   
   > wave at the IF frequency and use it to switch a full wave diode   
   > bridge. This will recover - with perfect linearity - any AM signal,   
   > even one modulated well beyond 100% (provided it has been carried out   
   > properly).   
      
   Alex:   
   I have with success. In fact I fit a synchronous PLL based detector module   
   into old radios. It allows to detune the radio so that a carrier sits on the   
   slope of the IF responce curve, suppressed and working only as a pilot tone,   
   so to speak. Demodulation is performed by CMOS switches. Virtually only one   
   sideband is used. This sideband now almost completely falls into a 6...7kHz   
   IF bandwidth. The sound is amazing -- like on FM, and even better because   
   there is no this "screeching" sometimes caused by multipath propagation. By   
   detuning the radio one way or another you can choose a sideband less jammed   
   by interference.   
      
   On crowded SW it is still better not to detune the radio, but uave the   
   carrier in the middle. It gives more loud reception of weaker stations.   
   Resilience to fading is great. SW becomes listenable. For fun I listen to   
   "Radio Russia" in Russian and also to Chinese propaganda intended for Russia   
   (also in Russian).   
      
   Unfortunately for the tubefanatics on this list, this synchro module CAN NOT   
   BE BUILT using TUBES. It uses ICs: TLE2704, 74HC74, 74HC4046, MCP602, LM339,   
   LM78M05 and several p-JFETs in auto PLL lock band control.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)