signal to noise ratio on polymerase chain reaction?

noise refers to the amplification of non-specific DNA fragments.  whenever you do PCR, you get your product (if you're lucky) plus a low amount of non-specific background.  this usually results when your primers anneal to regions where they're not supposed to.

thus, the signal (the specific product you want) has to be greater than the noise (the background).  if you have a low signal to noise ratio, usually that means you're not getting enough amplification of your product.  

when people optimize, they usually change the annealing temperature first.  the best thing is to raise it a degree or two.  if that doesn't work you can lower it a degree or two also.