Abstract: A method and apparatus for signal acquisition in an OFDM receiver relies on a preamble training sequence to synchronize the receiver in time (e.g. determining the start of a frame) and in frequency (carrier frequency offset compensation). The preamble training sequence has a periodic structure and the method and apparatus perform a cross-correlation technique using a matched filter to achieve time synchronization and/or frequency synchronization and/or channel estimation, the latter being especially useful in multi-antenna receivers for diversity combining purposes. Many advantages derive from performing at least two and preferably all three operations jointly, in terms of latency, hardware complexity, and length of training sequence required to achieve satisfactory convergence on all counts. The periodicity of the training sequence is exploited to reduce considerably the main filter complexity and optionally dynamically adjust carrier offset compensation throughout the filtering process.

Abstract: A method and apparatus for signal acquisition in an OFDM receiver relies on a preamble training sequence to synchronize the receiver in time (e.g. determining the start of a frame) and in frequency (carrier frequency offset compensation). The preamble training sequence has a periodic structure and the method and apparatus perform a cross-correlation technique using a matched filter to achieve time synchronization and/or frequency synchronization and/or channel estimation, the latter being especially useful in multi-antenna receivers for diversity combining purposes. Many advantages derive from performing at least two and preferably all three operations jointly, in terms of latency, hardware complexity, and length of training sequence required to achieve satisfactory convergence on all counts.

Abstract: An array receiver which reduces complexity and cost by exploiting multiuser information in signals received from a plurality of transmitting users preprocesses (40) samples of antenna signals (x1, x2 . . . , xN) from the antenna elements (22/1, . . . , 22/N) to form basis signals (yO, . . . , yM) together having fewer space-time dimensions than the space-time dimensions of the combined antenna signals. The receiver processes and combines the basis signals to produce sets of estimated received signals (z0, . . . , zM), each for a corresponding one of the users. Each of the basis signals comprises a different combination of the antenna signals. The receiver combines the basis signals to provide a user-specific output signal, and periodically updates parameters of the filters (40/0, . . . , 40/M) used for deriving each particular basis signal such that each user-specific output signal will exhibit a desired optimized concentration of energy of that user's received signal as received by the array antenna.

Abstract: A picture frame turn button has a base plate with at least one fastener for attaching the base plate securely to a picture frame back. Pivotably mounted to the base plate is a latch plate with an arm and a tongue portion opposite of each other. The latch plate may be pivoted about base plate between an engaged state, where the picture frame back is locked closed, and a disengaged state, where the picture frame back may be removed to replace a picture sandwiched between the picture frame and picture frame back.

Abstract: An array antenna system comprising an array of antenna elements and a receiver which uses a subset of the signals from the antenna elements, the selection of the subset of signals which should be used for a particular user is made on the basis of measurements of potential performance of the receiver with each subset of signals, combined, rather than of each individual signal.

Abstract: The improved pinless hinge assembly (24) includes a first hinge plate (28) having a curled edge (28a) defining a center roll having a longitudinal axis (P) with an aperture (42) in the first hinge plate (28). A second hinge plate (30) having a free edge (30a) curled about the center roll. A locking lug (40) extends from the free edge (30a) of the second hinge (30) and is routed first through the first aperture (42) in the first hinge plate (28) and then through the second aperture (44) in the second hinge plate (30). The locking lug (40) is engaged in a seat (46) in the second hinge plate (30) to maintain the free edge (30a) of the second hinge plate (30) curled about the center roll when the first hinge plate (28) rotates relative to the second hinge plate (30) about the longitudinal axis (P). A pair of locking lugs (40) may be also be used.

Abstract: The self-locking hinge (24) includes a first plate (28) hingedly connected to a second plate (30). Fasteners (24) are provided on the plates to secure them to a member, such as a easel strut hinge (24) of picture frame back (20). A locking structure is connected to the first plate (28) and the second plate (30) for maintaining the second plate (30) in the substantially open position relative to the first plate (28). The locking hinge (24) includes a protrusion (36) on the first plate (28) that removably engages with a free edge (34) of the second plate (30). The hinge (24) also includes a structure for maintaining the second plate (30) in rotating arrangement with the first plate (28) when the plates (28, 30) are hingedly secured to one another in a rolled pinless fashion. Locking lugs (40) are used to maintained the second plate (30) rolled about the first plate (28).

Abstract: An array antenna system comprising an array of antenna elements and a receiver which uses a subset of the signals from the antenna elements, the selection of the subset of signals which should be used for a particular user is made on the basis of measurements of potential performance of the receiver with each subset of signals, combined, rather than of each individual signal.

Abstract: A snap latch device has a handle with a pair of cam members extending from a lower end. The device also has a flexible snap which protrudes from the handle. The front end of the snap has a barbed lip. The device is designed to interlock a shuttle assembly to a stationary chassis. The device is pivotally mounted to the shuttle which carries a board with connectors. The device is movable between an engaged position and a retracted position. In the engaged position, the cam members engage an end wall on the chassis and the snap inserts through and engages a hole in the shuttle. The mechanical interlock between the cam members and the end wall rigidly secures the shuttle in the chassis. The device is moved to the retracted position by pulling back on the snap to dislodge the barbed lip. This release allows the device to rotate so that the cam members disengage the end wall. After the snap and cam members are clear of the hole and end wall, respectively, the shuttle may be completely removed from the chassis.