<p>The invention is concerned with the construction and detection of sequences of symbols containing sub-sequences which satisfy a unique equation which is defined in one or more transmitters and at least one receiver. Symbols may be binary or non binary and the unique equation may be based on a logic function or a function using Galois field arithmetic. Multiple transmitters using distinct sequences may communicate or send remote commands to a receiver which only needs to employ a single detector. A feature of the invention is that by providing a counter which counts the number of times sub-sequences of a received sequence satisfy the unique equation and comparing the counter state with a threshold a reliable means of sequence detection is provided even in the presence of received symbol errors. It is shown in one embodiment that asynchronous detection may be used avoiding the need for clock recovery. Additionally the invention provides a flexible means of increasing the robustness of sequence detection.</p>
