Signal monitor system

An intended reference level crossing detector means, adapted to receive a data signal formed as a sequence of data samples, having a crossing detector output, said reference level crossing detector means comprising:

• an incoming signal amplitude range classifier for determining whether said data samples are within certain amplitude ranges and having first and second classifier outputs, said incoming signal amplitude range classifier being capable of providing (i) as a first classifier output signal an indication for each said data sample, at said first classifier output, whether that said data sample has a value that is within a first selected range, and providing (ii) as a second classifier output signal an indication for each said data sample, at said second classifier output, whether that said data sample has a value that is within a second selected range;
• a high range storage means having a high range storage means input and a high range storage means output, said high range storage means being capable of providing as a high range storage means output signal an indication, at said high range storage means output, whether a said data sample, preceding that said data sample corresponding to a current value of said first classifier output signal, had a value that was within said first selected range, said high range storage means input being connected to said first classifier output;
• a low range storage means having a low range storage means input and a low range storage means outut, said low range storage means being capable of providing as a low range storage means output signal an indication, at said low range storage means output, whether a said data sample, preceding that said data sample corresponding to a current value of said second classifier output signal, had a value that was within said second selected range, said low range storage means input being connected to said second classifier output;
• a falling pattern AND logic gate means having first and second falling pattern AND logic gate means inputs and a falling pattern AND logic gate means output, said first falling pattern AND logic gate means input being connected to said second classifier output and said second falling pattern AND logic gate means input being connected to said high range storage means output;
• a rising pattern AND logic gate means having first and second rising pattern AND logic gate means inputs and a rising pattern AND logic gate means output, said first rising pattern AND logic gate means input being connected to said first classifier output and said second rising pattern AND logic gate means output being connected to said low range storage means output;
• and
• a combining OR logic gate means having first and second combining OR logic gate means inputs and a combining OR logic gate means output, said first combining OR logic gate means input being connected to said falling pattern AND logic gate means output and said second combining OR logic gate means input being connected to said rising pattern AND logic gate means output.