G06K 7/10079

Methods or arrangements for sensing record carriers, {e.g. for reading patterns} by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation {sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions}