XPost: rec.radio.amateur.equipment, uk.radio.amateur   
   From: et472@ncf.ca   
      
   On Mon, 26 Jan 2015, FranK Turner-Smith G3VKI wrote:   
      
   > "gareth"  wrote in message   
   > news:ma2gv9$2ac$1@dont-email.me...   
   >> "G3XBM via rec.radio.amateur.moderated Admin"   
   >>  wrote in message   
   >> news:047d7b5d612a205e9c050d737a33@google.com...   
   >>> Although not impossible, it is quite difficult to demodulate a DSB signal   
   >>> on a simple direct-conversion receiver. DSB rigs are ideal as simple   
   >>> transceivers to communicate with SSB rigs.   
   >>   
   >> The reason being that to resolve DSB, the injected carrier must have a   
   >> very close phase relationship with the original carrier, and at a certain   
   >> phase relationship (don't remember but probably 90 degrees) there's   
   >> no output at all!   
   >>   
   > Why not just filter out one sideband and resolve it as SSB?   
      
   That is generally the point of using DSBsc.  Since SSB receivers are now   
   common, using a DSB transmitter means a simpler transmitter compared to an   
   SSB transmitter, but no pesky carrier to waste power at the transmitter.   
   The only "cost" is double the bandwidth used.  It was certainly done in   
   the earlier days of SSB, and I gather from articles many people didn't   
   notice the extra sideband.   
      
   But if you are building a DSB station, you then can't have a simple direct   
   conversion receiver if you hope to talk to similar stations.  You'd need   
   an SSB receiver, either a superhet with an SSB filter, or a phasing method   
   receiver. Once you have that, the simplicity is gone, and you also might   
   as well apply such methods to the transmitter to get full SSB.   
      
   DSB works because most of the other stations will be SSB, so a simple   
   transmitter and receiver works.   
      
       Michael   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)