Abstract: A method and apparatus for determining network access delays in a communications network is disclosed. The communications network has a plurality of stations interconnected in a communications network. An access delay interval determining means determines a network access delay for each of the plurality of stations. That is, a time interval between a station predetermined sequence of symbols received from each of the stations and a local predetermined sequence of symbols is determined based upon a point of predetermined correlation between the station predetermined sequence of symbols and the local predetermined sequence of symbols. The time interval is used in determining the network access delay for each of the stations. The stations transmit data packets at times based upon their corresponding network access delay.

Abstract: A subscriber terminal includes a digital conditional access module receiving a transport bitstream comprising a plurality of multiplexed conditional access and product packets. Selected ones of the conditional access packets are addressed to respective terminals and include an encrypted new decryption key code, an encrypted authorization bit map and an authorization list range delete code. The conditional access packets are decrypted by the conditional access modules of respective addressed terminals, the decrypted new decryption key code being stored for subsequent use by the conditional access module, the decrypted authorization bit map being used to refresh the authorization bit map memory of the module and the decrypted delete code being used to delete a specified range of authorization codes from the authorization list memory of the module.