SYMBOL DISPLAY SYSTEM

摘要

This invention discloses a symbol-display subscriber unit for use with a broadcast system, the broadcast system including a headend and a network operative to transmit a composite signal from the headend to a multiplicity of subscriber units, the composite signal including an encoded broadcast signal encoded in accordance with a plurality of control words (CWs) and a plurality of encryption control messages (ECMs), each of the plurality of ECMs being associated respectively with one of the plurality of CWs and including CW generating information, the multiplicity of subscriber units including at least one said symbol-display subscriber unit, said symbol-display subscriber unit including: a receiver receiving the composite signal from the network, security apparatus in operative engagement with the receiver, the security apparatus receiving each of the plurality of ECMs from the receiver and generating the associated CW from the CW generating information comprised within each said ECM, and a decoder for decoding the encoded broadcast signal for display on a display device, the decoder receiving the encoded broadcast signal from the receiver and receiving the CW from the security apparatus, wherein the security apparatus supplies symbol display information to the decoder, and the decoder provides a symbol to the display device for display thereon, the symbol being based, at least in part, on the symbol display information. A method for producing a symbol is also disclosed.