diff --git a/submission_thesis/CH5_Examples/copy.tex b/submission_thesis/CH5_Examples/copy.tex
index 364c54e..caa380c 100644
--- a/submission_thesis/CH5_Examples/copy.tex
+++ b/submission_thesis/CH5_Examples/copy.tex
@@ -909,6 +909,10 @@ Were this failure to have safety implications, this FMMD analysis will have reve
 this undetectable condition; this would likely prompt re-design of this 
 circuit. A typical way to solve an undetectable fault such as this is 
 to periodically switch in test signals in place of the input signal.
+%
+Alternatively, two amplifiers could be used with different gains, from the 
+same outputs, and the results scaled and then compared (perhaps in software)
+to detect any failure.
 %\footnote{A typical way to solve an un-observability such as this is 
 %to periodically switch in test signals in place of the input signal.}.