Replacements of thick film pads with smaller, thinner, metal contacts or straps are used to eliminate many of the stress-related failure modes associated with the larger contact pads. The rear plate is perpendicular to the bottom plate for securing an expansion card thereon. A descrambler, an entitlement control message decoder and means for storing entitlements are associated to the receiver. This alarm system is unique because it utilizes the existing wiring in the area you are trying to secure. The echo canceler comprises such a block length computer and such a block length controller, wherefore the echo attenuation amount can ultimately be made to be equal to or greater than the desired echo attenuation amount.