Abstract: A shutter plate for a self-locking cover for a telephone paystation coin receptacle includes a coupler for joining a shutter control arm to the shutter plate that deforms when a force having a predetermined magnitude is applied to the control arm. The deformation of the coupler provides an indicator that an attempt to move the shutter plate to expose an aperture in the self-locking cover has occurred. The coupler may be one or more holes in a portion of the shutter control arm that is external of the self-locking cover. The coupler may take the form of a weld that joins the shutter control arm and the shutter plate. Frangible material may also be used to fill openings in the control arm to provide a tamper indicator. The tamper indicator facilitates detection of tamper attempts by visual inspection.

Abstract: A method and apparatus for transmitting and receiving a direct sequence spread spectrum signal encoded using two or more chip sequences to encode an information signal. The encoded information signal is received using a bank of matched filters (501a-501l), a bank of threshold comparators (505a-505l), a non-frequency locked bit clock circuit (509, 509') and a bit detector (510). Frequency locking is avoided by performing correlation on both the I- and Q- baseband signals and by logically combining the correlation results to recover the bit clock. In one embodiment, the method and apparatus uses binary phase shift keying to modulate the direct sequence spread spectrum signal with a carrier. In another embodiment, quadrature phase shift keying is used.