System and method for interrogating electronic labels

A method of interrogating a plurality of electronic labels using an interrogation device, the method including:

• (a) the interrogation device generating an interrogation fields the interrogation field having an interrogation signal, the interrogation signal containing information in the form of a plurality of symbols, each symbol having at least one time interval between consecutive dips in amplitude of the interrogation signal, each time interval having a value from a finite set of values, the values ranging from a minimum to a maximum value, adjacent values having a higher to lower value ratio which exceeds a predetermined amount;
• (b) one or more of the electronic labels located within the interrogation field detecting and decoding the interrogation signal to obtain a power signal and a data signal, the data signal including the symbols;
• (d) the electronic labels using the power signal to interpret the recovered symbols;
• and
• (e) in response to interpreting the symbols the electronic labels responding to the interrogation signal.